Metallurgical Processes
|
|
- Emil Arnold
- 6 years ago
- Views:
Transcription
1 Metallurgical Processes Chapter Thirty One: Welding Processes Dr. Eng. Yazan Al-Zain Department of Industrial Engineering 1
2 Introduction Welding processes divide into two major categories: Fusion Welding: coalescence is accomplished by melting the two parts to be joined, in some cases adding filler metal to the joint. Solid-State Welding: heat and/or pressure are used to achieve coalescence, but no melting of the base metals occurs and no filler metal is added. Fusion welding is the most important category. It includes: Arc Welding. Resistance Welding. Oxyfuel Gas Welding. Other Fusion Welding Processes. 2
3 Arc Welding Arc Welding (AW): a fusion-welding process in which coalescence of the metals is achieved by the heat of an electric arc between an electrode and the work. Electric arc: discharge of electric current across a gap in a circuit. Sustained by the presence of a thermally ionized column of gas (called a plasma) through which current flows. To initiate the arc, the electrode is brought into contact with the work and then quickly separated from it by a short distance. The electric energy from the arc formed produces temperatures of 5500 ºC or higher. A pool of molten metal, consisting of base and filler metal (if one is used) is formed near the tip of the electrode, and solidifies as the electrode is moved along the joint. 3
4 Arc Welding Arc Welding (AW). Fig The basic configuration and electrical circuit of an arc welding process. 4
5 Arc Welding General Technology of AW Some technical issues related to AW processes should be addressed. These include: Electrodes, Arc Shielding and Power Source in Arc Welding. Electrodes: classified as consumable or nonconsumable. Consumable Electrodes: provide the source of the filler metal in AW. Available in two principal forms: rods (also called sticks, 225 to 450 mm in length and 9.5 mm or less in diameter) and wire. The problem in weld rods is that they must be changed periodically, reducing arc time of the welder. This problem is avoided using consumable weld wire as it can be continuously fed. In both forms, the electrode is consumed by the arc during the welding process and added to the weld joint as filler metal. 5
6 Arc Welding General Technology of AW Electrodes: classified as consumable or nonconsumable. Nonconsumable Electrodes: made of tungsten (or carbon, rarely), which resists melting by the arc. Despite its name, a nonconsumable electrode is gradually depleted during the welding process (vaporization is the principal mechanism). Filler metal used in the operation must be supplied by means of a separate wire that is fed into the weld pool. 6
7 Arc Welding General Technology of AW Arc Shielding: the process of shielding the arc from the surrounding area to prevent chemical reactions, between the metals being joined and gases such as nitrogen, oxygen and hydrogen, that are accelerated at high temperatures. Done by covering the electrode tip, arc, and molten weld pool with a blanket of gas and/or flux that inhibit exposure of the metal to air. Shielding gases: argon and helium, both of which are inert. Flux: a substance used to prevent the formation of oxides and other unwanted contaminants, or to dissolve them and facilitate removal. During welding, the flux melts and becomes a liquid slag, covering the operation and protecting the molten weld metal. The slag hardens upon cooling and must be removed later. Flux additional functions: stabilize the arc, and reduce spattering. 7
8 Arc Welding General Technology of AW Power Source in AW: both direct current (DC) and alternating current (AC) are used in AW. DC machines are more popular. In all AW processes, power to drive the operation is the product of the current I passing through the arc and the voltage E across it. The power is converted into heat, but not all of the heat is transferred to the surface of the work, due to losses that reduce the amount of usable heat (conduction, radiation, etc). Heat transfer efficiency is greater for AW processes that use consumable electrodes because most of the heat consumed in melting the electrode is subsequently transferred to the work as molten metal. The process with the lowest heat transfer efficiency is gas tungsten AW, which uses a nonconsumable electrode. 8
9 Power Source in AW: the resulting power balance in AW can be expressed as: R H w Arc Welding General Technology of AW f1 f2ie U m A where R HW = power, J/s (W), E = voltage, V; I = current, A. w v Example
10 AW Processes Consumable Electrodes (1) Shielded Metal Arc Welding (SMAW): uses a consumable electrode consisting of a filler metal rod coated with chemicals that provide flux and shielding. The filler metal used has a composition usually being very close to that of the base metal. The coating consists of powdered cellulose (i.e., cotton and wood powders) mixed with oxides, carbonates, and other ingredients, held together by a silicate binder. The heat of the welding process melts the coating to provide a protective atmosphere and slag for the welding operation. During operation the bare metal end of the welding stick (opposite the welding tip) is clamped in an electrode holder that is connected to the power source. 10
11 AW Processes Consumable Electrodes (1) Shielded Metal Arc Welding (SMAW): uses a consumable electrode consisting of a filler metal rod coated with chemicals that provide flux and shielding. Currents typically used in SMAW range between 30 and 300 A at voltages from 15 to 45 V. Common applications: construction, pipelines, etc. The equipment is portable, low cost and produce high power density, making SMAW the most widely used of the AW processes. Base metals include iron alloys, and certain nonferrous alloys. It is not used or seldom used for aluminum and its alloys, copper alloys, and titanium. 11
12 AW Processes Consumable Electrodes (1) Shielded Metal Arc Welding (SMAW). Fig Shielded metal arc welding (SMAW). 12
13 AW Processes Consumable Electrodes (2) Gas Metal Arc Welding (GMAW): the electrode is a consumable bare metal wire, and shielding is accomplished by flooding the arc with gas. The wire (0.8 to 6.5 mm in D) is fed directly from spool. Shielding gases include argon and helium (for welding Al and stainless steel), and active gases such as carbon dioxide (for welding low and medium carbon steels). As the electrode is bare metal, no slag forms and thus cleaning and grinding of slag is not needed. Metal Inert Gas (MIG) Welding: applied to the welding of aluminum using inert gas (argon) for arc shielding. CO 2 Welding: gas used is CO 2 instead of the expensive argon, specially for steels. Advantages: no slag, no interruptions during welding (wire is used instead of stick), high deposition rates, etc. 13
14 AW Processes Consumable Electrodes (2) Gas Metal Arc Welding (GMAW). Fig Gas metal arc welding (GMAW). 14
15 AW Processes Consumable Electrodes (3) Flux-Cored Arc Welding (FCAW): the electrode is a continuous consumable flexible tubing (wire), contains flux and other ingredients (deoxidizers and alloying elements) in its core. Two versions of FCAW: Self-Shielded: arc shielding was provided by a flux core (thus the name selfshielded). Ingredients generate shielding gases for protecting the arc. Gas-Shielded: developed primarily for welding steels, obtains arc shielding from externally supplied gases, similar to gas metal arc welding. 15
16 AW Processes Consumable Electrodes (3) Flux-Cored Arc Welding (FCAW). Fig Flux-cored arc welding. The presence or absence of externally supplied shielding gas distinguishes the two types: (1) self-shielded, in which the core provides the ingredients for shielding; and(2) gas-shielded, in which external shielding gases are supplied. 16
17 AW Processes Consumable Electrodes (4) Electrogas Welding (EGW): uses a continuous consumable electrode and molding shoes to contain the molten metal. Applied to vertical butt welding (it can also be used for fillet and groove welds in a vertical orientation). Either a flux-cored electrode wire is employed, no external gases are supplied, and the process can be considered a special application of selfshielded FCAW. Or, a bare electrode wire is used with shielding gases from an external source, it is considered a special case of GMAW. The molding shoes are water cooled to prevent their being added to the weld pool. Together with the edges of the parts being welded, the shoes form a container, almost like a mold cavity, into which the molten metal from the electrode and base parts is gradually added. Applications: steels in the construction of large storage tanks and in shipbuilding. Stock thicknesses from 12 to 75 mm are within the capacity of EGW. 17
18 AW Processes Consumable Electrodes (4) Electrogas Welding (EGW). Fig Electrogas welding using flux-cored electrode wire: (a) front view with molding shoe removed for clarity, and (b) side view showing molding shoes on both sides. 18
19 AW Processes Nonconsumable Electrodes (1) Gas Tungsten Arc Welding (GTAW): uses a nonconsumable tungsten electrode and an inert gas for arc shielding. The term TIG welding (tungsten inert gas welding) is often applied to this process When a filler metal is used (sometimes not used), it is added to the weld pool from a separate rod or wire. Tungsten is a good electrode material (melting point = 3410 ºC). Shielding gases include argon, helium, or a mixture. Applicable to all metals in a wide range of thicknesses. Also used for joining dissimilar metals. Mostly used for Al and steels. Advantages include: high-quality welds, and little or no post weld cleaning because no flux is used. 19
20 AW Processes Nonconsumable Electrodes (1) Gas Tungsten Arc Welding (GTAW). Fig Gas tungsten arc welding (GTAW). 20
21 AW Processes Nonconsumable Electrodes (2) Plasma Arc Welding (PAW): a special form of GTAW in which a narrow plasma arc is directed at the weld area. A tungsten electrode is contained in a specially designed nozzle that focuses a high-velocity stream of inert gas into the region of the arc to form a high velocity, intensely hot plasma arc stream. Temperatures in plasma arc welding reach 17,000 ºC. Applications: automobile subassemblies, metal cabinets, door and window frames, and home appliances. Advantages include: good arc stability, better penetration control than most other AW processes, high travel speeds, and excellent weld quality. Limitations: equipment s high cost and larger torch size. 21
22 AW Processes Nonconsumable Electrodes (2) Plasma Arc Welding (PAW). Fig Plasma arc welding (PAW). 22
23 Resistance Welding Resistance Welding (RW): a group of fusion-welding processes that uses a combination of heat and pressure to accomplish coalescence, the heat being generated by electrical resistance to current flow at the junction to be welded. The components in RW include workparts to be welded (usually sheet metal parts), two opposing electrodes, a mean of applying pressure to squeeze the parts between the electrodes, and an AC power supply from which a controlled current can be applied. The operation results in a fused zone between the two parts, called a weld nugget in spot welding. Uses no shielding gases, flux, or filler metal; and the electrodes that conduct electrical power to the process are nonconsumable. Classified as fusion welding because the applied heat almost always causes melting of the faying surfaces. 23
24 Resistance Welding Fig Resistance welding (RW), showing the components in spot welding, the predominant process in the RW group. 24
25 Resistance Welding Power Sources in RW The heat energy supplied to the welding operation depends on current flow, resistance of the circuit, and length of time the current is applied: H I 2 Rt where H = heat generated, J; I = current, A; R = electrical resistance, Ω; and t = time, s. I used in resistance welding operations is very high (5000 to 20,000 A, typically, for short periods (0.1 to 0.4 s)), and low E is relatively (below 10 V). The current in RW is very high because the resistance is very low ( 1x10-4 Ω). Resistance in the welding circuit is the sum of (1) resistance of the electrodes, (2) resistances of the workparts, (3) contact resistances between electrodes and workparts, and (4) contact resistance of the faying surfaces (should be largest). Thus, heat is generated in all of these regions of electrical resistance. 25
26 Resistance Welding Power Sources in RW Example
27 Resistance Welding Power Sources in RW Resistance of the electrodes is minimized by using metals with very low resistance values, such as copper. Workpart resistance is a functions of the resistance values of the base metals and the part thicknesses. Contact resistances between the electrodes and the parts are determined by the contact areas and the condition of the surfaces. Resistance at the faying surfaces depends on surface finish, cleanliness, contact area, and pressure. 27
28 Resistance Welding Power Sources in RW Success in resistance welding depends on pressure as well as heat. The principal functions of pressure in RW are to: Force contact between the electrodes and the workparts and between the two work surfaces prior to applying current. Press the faying surfaces together to accomplish coalescence when the proper welding temperature has been reached. 28
29 Advantages of RW: No filler metal is required. High production rates Can be mechanized. Resistance Welding Power Sources in RW Operator skill level is lower than that required for arc welding Good repeatability and reliability. Drawbacks of RW: Equipment cost is high. Limited to lap joints for most RW processes. 29
30 Resistance-Welding Processes Resistance welding can be classified into three major types; Spot, Seam and Projection Welding. Resistance Spot Welding: By far the predominant process in this group. Widely used in mass production of automobiles, appliances, metal furniture, and other products made of sheet metal. If one considers that a typical car body has approximately 10,000 individual spot welds, and that the annual production of automobiles throughout the world is measured in tens of millions of units, the economic importance of resistance spot welding can be appreciated. 30
31 Resistance-Welding Processes Resistance Spot Welding: a RW process in which fusion of the faying surfaces of a lap joint is achieved at one location by opposing electrodes. Used to join sheet-metal parts of thickness 3 mm or less, using a series of spot welds. Size and shape of the weld spot is determined by the electrode tip (usually round). The resulting weld nugget is typically 5 to 10 mm in diameter, with a HAZ extending slightly beyond the nugget into the base metals. If the weld is made properly, its strength will be comparable to that of the surrounding metal. 31
32 Resistance-Welding Processes Fig (a) Steps in a spotwelding cycle, and (b) plot of squeezing force and current during cycle. The sequence is: (1) parts inserted between open electrodes, (2) electrodes close and force is applied, (3) weld time current is switched on, (4) current is turned off but force is maintained or increased, and (5) electrodes are opened, and the welded assembly is removed. 32
33 Resistance-Welding Processes Materials used for RSW electrodes consist of two main groups: Copper-based alloys. Refractory metal compositions; e.g. copper and tungsten combinations: noted for superior wear resistance. The tooling in spot welding gradually wears out as it is used. Whenever practical, the electrodes are designed with internal passageways for water cooling. 33
34 Resistance-Welding Processes Various machines and methods are available to perform spot-welding operations. These include: Rocker-Arm Spot Welders: have a stationary lower electrode and a movable upper electrode that can be raised and lowered for loading and unloading the work. The upper electrode is mounted on a rocker arm whose movement is controlled by a foot pedal operated by the worker. Portable Spot-Welding Guns: for large, heavy work it is difficult to move and position the part into stationary machines. Portable welders are the solution. 34
35 Rocker-Arm Spot Welder. Resistance-Welding Processes Fig Rocker-arm spot-welding machine. 35
36 Resistance-Welding Processes Resistance Seam Welding (RSEW): the stick-shaped electrodes in spot welding are replaced by rotating wheels. Fig Resistance seam welding (RSWE). 36
37 Resistance-Welding Processes Resistance Seam Welding (RSEW): seams have different types. Fig Different types of seams produced by electrode wheels: (a) conventional resistance seam welding, in which overlapping spots are produced; (b) roll spot welding; and (c) continuous resistance seam. 37
38 Oxyfuel Gas Welding Oxyfuel Gas Welding (OFW): the term used to describe the group of FW operations that burn various fuels mixed with oxygen to perform welding. The OFW processes employ several types of gases, which is the primary distinction among the members of this group. Oxyfuel gas is also commonly used in cutting torches to cut and separate metal plates and other parts. The most important OFW process is oxyacetylene welding. 38
39 Oxyfuel Gas Welding Oxyacetylene Welding Oxyacetylene Welding (OAW): a fusion-welding process performed by a high-temperature flame from combustion of acetylene and oxygen. The flame is directed by a welding torch. A filler metal is sometimes added, and pressure is occasionally applied in OAW between the contacting part surfaces. Composition of the filler (often coated with a flux) must be similar to that of the base metals. Flux helps to clean the surfaces and prevent oxidation. Acetylene (C 2 H 2 ) is the most popular fuel among the OFW group because it is capable of higher temperatures than any of the others up to 3480 ºC. 39
40 Oxyacetylene Welding (OAW) Oxyfuel Gas Welding Oxyacetylene Welding The flame in OAW is produced by the chemical reaction of acetylene and oxygen in two stages. The first stage is defined by the reaction: C 2 H 2 + O 2 2CO + H 2 + heat (Both products are combustible). The second-stage of the reaction: 2CO + H O 2 2CO 2 + H 2 O + heat The first-stage reaction is seen as the inner cone of the flame (bright white where maximum temperature is reached), while the second-stage reaction is exhibited by the outer envelope (nearly colorless). During welding, the outer envelope spreads out and covers the work surfaces being joined, thus shielding them from the surrounding atmosphere. 40
41 Oxyacetylene Welding (OAW) Oxyfuel Gas Welding Oxyacetylene Welding Fig A typical oxyacetylene welding operation (OAW). Fig The neutral flame (acetylene and oxygen 1 : 1) from an oxyacetylene torch, indicating temperatures achieved. 41
42 Oxyfuel Gas Welding Oxyacetylene Welding Oxyacetylene Welding (OAW): Example
43 Solid-State Welding Coalescence of the part surfaces is achieved by (1) pressure alone, or (2) heat and pressure. In some processes, time is also a factor. If both heat and pressure are used, the amount of heat by itself is not sufficient to cause melting of the work surfaces. In some cases, the combination of heat and pressure, or the particular manner in which pressure alone is applied, generates sufficient energy to cause localized melting of the faying surfaces. Filler metal is not added in solid-state welding. 43
44 Solid-State Welding General Considerations A metallurgical bond is created with little or no melting of the base metals. To metallurgically bond two metals, they must be brought into intimate contact so that their atomic forces attract each other. In order for atomic bonding to succeed, chemical films, gases, oil, etc. must be removed. Since no or limited melting, there is no HAZ. Also, some of these processes are quite applicable to bonding dissimilar metals, without concerns about relative thermal expansions, conductivities, and other problems that usually arise when dissimilar metals are melted and then solidified during joining. 44
45 Solid-State Welding Solid-State Welding Processes Solid-state welding processes include the following: Forge Welding. Cold Welding. Roll Welding. Hot Pressure Welding. Diffusion Welding. Explosion Welding. Friction Welding. 45
46 Solid-State Welding Solid-State Welding Processes Forge Welding: is a welding process in which the components to be joined are heated to hot working temperatures and then forged together by hammer or other means. Considerable skill was required by the craftsmen who practiced it in order to achieve a good weld by present-day standards. The process may be of historic interest; however, it is of minor commercial importance today except for in some cases. 46
47 Solid-State Welding Solid-State Welding Processes Cold Welding (CW): done by applying high pressure between clean contacting surfaces at room temperature. Surfaces must be very clean for CW to work, and cleaning is (done by degreasing) immediately before joining. One of the metals to be welded, must be very ductile. Metals such as soft aluminum and copper can be readily cold welded. The applied compression forces result in cold working of the metal parts, reducing thickness by as much as 50%; but they also cause localized plastic deformation at the contacting surfaces, resulting in coalescence. Applications of CW include making electrical connections. 47
48 Solid-State Welding Solid-State Welding Processes Roll Welding (ROW): a variation of either forge welding or cold welding. It is a solid-state welding process in which pressure sufficient to cause coalescence is applied by means of rolls, either with or without external application of heat. If no external heat is supplied, the process is called cold-roll welding; if heat is supplied, the term hot-roll welding is used. Application; e.g. cladding stainless steel to mild low alloy steel for corrosion resistance Fig Roll Welding (ROW.) 48
49 Solid-State Welding Solid-State Welding Processes Diffusion Welding (DFW): welding process that results from the application of heat and pressure, usually in a controlled atmosphere, with sufficient time allowed for diffusion and coalescence to occur. Temperature is equal to or less than 0.5 T m. Involves migration of atoms across the interface between contacting surfaces, with the plastic deformation being as low as possible. The time for diffusion to occur could be as long as 1 hr. Applications: joining of high-strength and refractory metals in the aerospace and nuclear industry. 49
50 Solid-State Welding Solid-State Welding Processes Explosion Welding (EXW): a solid-state welding process in which rapid coalescence of two metallic surfaces is caused by the energy of a detonated explosive. Commonly used to bond two dissimilar metals, in particular to clad one metal on top of a base metal over large areas. No filler metal is used, and no external heat is applied. Also, no diffusion occurs during the process (the time is too short). Applications include production of corrosion-resistant sheet and plate stock for making processing equipment in the chemical and petroleum industries. 50
51 Solid-State Welding Solid-State Welding Processes Fig Explosive welding (EXW): (1) setup in the parallel configuration, and (2) during detonation of the explosive charge. 1. When detonation is initiated, the explosive charge propagates from one end of the flyer plate to the other. 2. Explosion occurs in a progressive fashion, very rapid though (8500 m/s). 3. The resulting high-pressure zone forces the flyer plate to collide with the backer metal at high velocity. 4. The high-speed collision causes the surfaces at the point of contact to become fluid, providing intimate contact and leading to metallurgical bonding after solidification. 5. The result is a very strong bond over a large are (Mechanical Interlocking). 51
52 Solid-State Welding Solid-State Welding Processes Friction Welding (FRW): a solid-state welding process in which coalescence is achieved by frictional heat combined with pressure. Friction is induced by mechanical rubbing between the two surfaces. The parts are then driven toward each other with sufficient force to form a metallurgical bond. When properly carried out, no melting occurs at the faying surfaces. No filler metal, flux, or shielding gases are normally used. It is a mass production process that is applied in the welding of various shafts and tubular parts in industries such as automotive, aircraft, farm equipment, petroleum, and natural gas. 52
53 Solid-State Welding Solid-State Welding Processes Friction Welding (FRW). Fig Friction welding (FRW): (1) rotating part, no contact; (2) parts brought into contact to generate friction heat; (3) rotation stopped and axial pressure applied; and (4) weld created. 53
54 Weld Quality The purpose of any welding process is to join two or more components into a single structure. The physical integrity of the structure thus formed depends on the quality of the weld. The Arc Welding (AW) process is the one for which the quality issue is the most critical and complex. 54
55 Weld Quality Residual Stresses and Distortion The sudden temperature changes in localized regions of the work during fusion welding result in thermal expansion and contraction that cause residual stresses in the weldment. These stresses can cause distortion and warping of the welded assembly. The situation in welding is complicated because: Heating is very localized. Melting of the base metals occurs in these local regions. Location of heating and melting is in motion. 55
56 Weld Quality Residual Stresses and Distortion Fig (a) Butt welding two plates; (b) shrinkage across the width of the welded assembly; (c) transverse and longitudinal residual stress pattern; and (d) likely warping in the welded assembly. 56
57 Weld Quality Residual Stresses and Distortion As welding proceeds, a molten pool is formed from the base metal that quickly solidifies behind the moving arc. The portions of the work immediately adjacent to the weld bead become extremely hot and expand, while portions removed from the weld remain relatively cool. The weld pool quickly solidifies, and as it and the surrounding metal cool and contract, shrinkage occurs across the width of the weldment. The weld seam is left in residual tension, and reactionary compressive stresses are set up in regions of the parts away from the weld. Residual stresses and shrinkage also occur along the length of the weld bead. 57
58 Weld Quality Residual Stresses and Distortion Since the outer regions of the base parts have remained relatively cool and dimensionally unchanged, while the weld bead has solidified from very high temperatures and then contracted, residual tensile stresses remain longitudinally in the weld bead. The net result of these residual stresses, transversely and longitudinally, is likely to cause warping in the welded assembly. 58
59 Weld Quality Residual Stresses and Distortion To minimize distortion in a weldment: Welding Fixtures: physically restrain movement of parts during welding. Heat Sinks: rapidly remove heat from sections of welded parts. Tack Welding at multiple points along the joint: can create a rigid structure prior to continuous seam welding. Welding Conditions (speed, amount of filler) selected to reduce warping. Preheating base parts: to reduce level of thermal stresses experienced by parts. Stress Relief heat treatment can be performed on the welded assembly. Proper Design of the weldment itself can reduce the degree of warping. 59
60 Weld Quality Welding Defects Defects other than residual stresses and distortion can appear in welding: Cracks: fracture-type interruptions either in the weld itself or in the base metal adjacent to the weld. Most serious welding defect because it constitutes a discontinuity in the metal that significantly reduces weld strength. Caused by embrittlement or low ductility of the weld and/or base metal combined with high restraint during contraction. Generally, this defect must be repaired. 60
61 Weld Quality Welding Defects Cracks. Fig Various forms of welding cracks. 61
62 Weld Quality Welding Defects Cavities: include various porosity and shrinkage voids. Porosity: consists of small voids in the weld metal formed by gases entrapped during solidification. Porosity usually results from inclusion of atmospheric gases, sulfur in the weld metal, or contaminants on the surfaces. Shrinkage Voids: cavities formed by shrinkage during solidification. Both of these cavity-type defects are similar to defects found in casting. 62
63 Weld Quality Welding Defects Solid Inclusions: nonmetallic solid materials trapped inside the weld metal. The most common form is slag inclusions generated during AW processes that use flux. Instead of floating to the top of the weld pool, globules of slag become encased during solidification of the metal. Another inclusion form is metallic oxides that form during the welding of metals such as aluminum, which normally has a surface coating of Al 2 O 3. 63
64 Weld Quality Welding Defects Incomplete Fusion: a weld bead in which fusion has not occurred throughout the entire cross section of the joint. Lack of Penetration: a related defect, which means that fusion has not penetrated deeply enough into the root of the joint. Imperfect Shape or Unacceptable Contour: weld should have a certain desired profile for maximum strength for a single V- groove weld. This profile maximizes the strength of the welded joint and avoids incomplete fusion and lack of penetration. 64
65 Weld Quality Welding Defects Fig Several forms of incomplete fusion. 65
66 Weld Quality Welding Defects Fig (a) Desired weld profile for single V-groove weld joint. Same joint but with several weld defects: (b) undercut, in which a portion of the base metal part is melted away; (c) underfill, a depression in the weld below the level of the adjacent base metal surface; and (d) overlap, in which the weld metal spills beyond the joint onto the surface of the base part but no fusion occurs. 66
67 Weld Quality Inspection and Testing Methods Visual Inspection: most widely used inspection method. An inspector visually examines the weldment for: Conformance to dimensional specifications on the part drawing. Warping. Cracks, Cavities, Incomplete Fusion, and other visible defects. Limitation: only surface defects are detectable; internal defects cannot be discovered by visual methods. 67
68 Weld Quality Inspection and Testing Methods Nondestructive Testing (NDT): various methods that do not damage the specimen being inspected. Dye-Penetrant Test: liquid sprayed on the weldment. It penetrates into the crack, if present, and a red color appears. (Note: defects should be open to the surface). Fluorescent-Penetrant Test: similar to dye-penetrant, but highly visible when exposed to ultraviolet light. Ultrasonic Testing: involves the use of high-frequency sound waves (>20 khz) directed through the specimen. Discontinuities (e.g., cracks, inclusions, porosity) are detected by losses in sound transmission. Radiographic Testing: uses X-rays or gamma radiation to detect internal defects. It provides a photographic film record of any defects. 68
69 Weld Quality Inspection and Testing Methods Destructive Testing: methods in which the weld is destroyed either during the test or to prepare the test specimen. They include mechanical and metallurgical tests. Mechanical Tests: similar in purpose to conventional testing methods such as tensile tests and shear tests. The difference is that the test specimen is a weld joint. Metallurgical Tests: involve the preparation of metallurgical specimens of the weldment to examine such features as metallic structure, defects, extent and condition of HAZ, presence of other elements, etc. 69
70 Weld Quality Inspection and Testing Methods - Mechanical Tests. Fig Mechanical tests used in welding: (a) tension shear test of arc weldment, (b) fillet break test, (c) tension shear test of spot weld, (d) peel test for spot weld. 70
71 Weldability Weldability: the capacity of a metal or combination of metals to be welded into a suitably designed structure, and for the resulting weld joint(s) to possess the required metallurgical properties to perform satisfactorily in the intended service. Good weldability is characterized by: The ease with which the welding process is accomplished. Absence of weld defects, and acceptable strength. Ductility, and toughness in the welded joint. 71
72 Weldability Factors affecting weldability: Welding Process: some metals or metal combinations that can be readily welded by one process are difficult to weld by others; e.g. stainless steel can be readily welded by most AW processes, but is considered a difficult metal for oxyfuel welding. Base Metal Properties: such as melting point, thermal conductivity, and coefficient of thermal expansion. Too low melting point: means that such metals melt too easily for good welding; e.g. aluminum. Too high thermal conductivities: such metals tend to transfer heat away from the weld zone, which can make them hard to weld (e.g., copper). 72
73 Weldability Factors affecting weldability: Filler Metal: must be compatible with the base metal(s). Surface Conditions: adversely affect the operation; e.g. moisture can result in porosity in the fusion zone. Oxides and other solid films on the metal surfaces can prevent adequate contact and fusion from occurring. 73
74 Design Considerations in Welding In welding, certain guidelines should be followed: Design for Welding: the most basic guideline is that the product should be designed from the start as a welded assembly, and not as a casting or forging or other formed shape. Minimum Parts: welded assemblies should consist of the fewest number of parts possible. For example, it is usually more cost efficient to perform simple bending operations on a part than to weld an assembly from flat plates and sheets. 74
75 Design Considerations in Welding The following design guidelines apply to AW: Good fit-up of parts to be welded is important to maintain dimensional control and minimize distortion. Machining is sometimes required to achieve satisfactory fit-up. Accessibility: the assembly must provide access room to allow the welding gun to reach the welding area. Whenever possible, design of the assembly should allow flat welding to be performed, since this is the fastest and most convenient welding position. (See figure next slide). 75
76 Design Considerations in Welding Fig Welding positions (defined here for groove welds): (a) flat, (b) horizontal, (c) vertical, and (d) overhead. 76
77 Design Considerations in Welding The following design guidelines apply to RSW: Low-carbon sheet steel up to 3.2 mm is the ideal metal for resistance spot welding. The spot-welded assembly must provide access for the electrodes to reach the welding area. Sufficient overlap of the sheet-metal parts is required for the electrode tip to make proper contact in spot welding; e.g. for low-carbon sheet steel, the overlap distance should range from about six times stock thickness for thick sheets of 3.2 mm to about 20 times thickness for thin sheets, such as 0.5 mm. 77
Manufacturing Process II. Welding Processes-1
Manufacturing Process II Welding Processes-1 1. Introduction: The term joining is generally used for welding, brazing, soldering, and adhesive bonding, which form a permanent joint between the parts a
More informationWELDING Topic and Contents Hours Marks
Topic and Contents Hours Marks 3.1 Introduction 04 Marks Classification and selection of welding process. Working principle of Gas welding and types of flames. 3.2 Arc welding process 08 Marks Metal arc,
More informationProduction Engineering II. Chapter Three. Welding & Bonding Technology. AAiT
Production Engineering II Chapter Three Welding & Bonding Technology AAiT Introduction to welding Joiningis generally used for welding, brazing, soldering, and adhesive bonding which form a permanent joint
More informationWELDING TECHNOLOGY AND WELDING INSPECTION
WELDING TECHNOLOGY AND WELDING INSPECTION PRESENTED BY: GOPAL KUMAR CHOUDHARY SVL ENGINEERING SERVICES CHENNAI CONTENTS: DEFINATION TYPES OF WELDING ELECTRODE GEOMETRY EQUIPMENT QUALITY PROCESS SAFETY
More informationIntroduction to Welding Technology
Introduction to Welding Technology Welding is a fabrication process used to join materials, usually metals or thermoplastics, together. During welding, the pieces to be joined (the workpieces) are melted
More informationMaterials & Processes in Manufacturing
2003 Bill Young Materials & Processes in Manufacturing ME 151 Chapter 37 Arc Processes Chapter 38 Resistance Welding Chapter 39 Brazing and Soldering 1 Introduction Arc welding processes produce fusion
More informationKasetsart University. INDT0204: Welding. Types of Welding
Types of Welding Fusion Welding (Chap. 27) Oxyfuel Gas Welding Arc-Welding Processes Consumable-Electrode Nonconsumable-Electrode Others Electron-Beam Welding Laser-Beam Welding Solid State Welding (Chap.
More informationManufacturing Process II. Welding Processes-2
Manufacturing Process II Welding Processes-2 6.2 Oxy-Fuel Gas Welding 6.2.1 Introduction Oxyfuel gas welding (OFW) is the term used to describe the group of FW operations that burn various fuels mixed
More informationStructure of Metals 1
1 Structure of Metals Metals Basic Structure (Review) Property High stiffness, better toughness, good electrical conductivity, good thermal conductivity Why metals have these nice properties - structures
More informationManufacturing Process-I Prof. Dr. D.K. Dwivedi Department of Mechanical and Industrial Engineering Indian Institute of Technology, Roorkee
Manufacturing Process-I Prof. Dr. D.K. Dwivedi Department of Mechanical and Industrial Engineering Indian Institute of Technology, Roorkee Module - 03 Lecture - 02 Welding Process Classification Welcome
More informationME E5 - Welding Metallurgy
ME 328.3 E5 - Welding Metallurgy Purpose: To become more familiar with the welding process and its effects on the material To look at the changes in microstructure and the hardness in the Heat Affected
More informationCopyright 1999 Society of Manufacturing Engineers FUNDAMENTAL MANUFACTURING PROCESSES Welding NARRATION (VO):
Copyright 1999 Society of Manufacturing Engineers --- 1 --- FUNDAMENTAL MANUFACTURING PROCESSES Welding SCENE 1. CG: Fusion Welding Processes white text centered on black SCENE 2. tape 528, 14:18:33-14:18:52
More informationNAME 345 Welding Technology Lecture 09 SAW, ESW & Resistance Welding
NAME 345 Welding Technology Lecture 09 Md. Habibur Rahman Lecturer Department of Naval Architecture & Marine Engineering Bangladesh University of Engineering & Technology Dhaka-1000, Bangladesh Submerged
More informationRoll Bonding or Roll Welding
1 2 3 4 Roll Bonding or Roll Welding The pressure required for welding is applied through a pair of rolls Can be performed hot (Hot Roll Bonding) Surface preparation is important for interfacial bonding
More informationChapter 32 Resistance Welding and Solid State Welding. Materials Processing. Classification of Processes. MET Manufacturing Processes
MET 33800 Manufacturing Processes Chapter 32 Resistance Welding and Solid State Welding Before you begin: Turn on the sound on your computer. There is audio to accompany this presentation. Materials Processing
More informationWelding Processes. Consumable Electrode. Non-Consumable Electrode. High Energy Beam. Fusion Welding Processes. SMAW Shielded Metal Arc Welding
Fusion Consumable Electrode SMAW Shielded Metal Arc Welding GMAW Gas Metal Arc Welding SAW Submerged Arc Welding Non-Consumable Electrode GTAW Gas Tungsten Arc Welding PAW Plasma Arc Welding High Energy
More information4 Shielded Metal Arc Welding*
4 Shielded Metal Arc Welding* * Abbreviated MMA (Manual metal arc welding). American designation: shielded metal arc welding (SMAW). Shielded metal arc welding (SMAW) is an AW process that uses a consumable
More informationA Practical Design Guide for Welded Connections Part 1 Basic Concepts and Weld Symbols
A Practical Design Guide for Welded Connections Part 1 Basic Concepts and Weld Symbols by James Doane, PhD, PE Course Overview This course is divided into 2 parts. Though it provides some basic concepts
More informationCHAPTER 3: TYPES OF WELDING PROCESS, WELD DEFECTS AND RADIOGRAPHIC IMAGES. Welding is the process of coalescing more than one material part at
41 CHAPTER 3: TYPES OF WELDING PROCESS, WELD DEFECTS AND RADIOGRAPHIC IMAGES 3.0. INTRODUCTION Welding is the process of coalescing more than one material part at their surface of contact by the suitable
More informationChapter Outline. Joining Processes. Welding Processes. Oxyacetylene Welding. Fusion Welding Processes. Page 1. Welded Joints
Joining Processes Chapter Outline R. Jerz 1 4/16/2006 R. Jerz 2 4/16/2006 Welding Processes Welded Joints Gas, electricity, or other heat source? Is electrode consumed? Is a filler material used? Is flux
More informationJoining Processes R. Jerz
Joining Processes R. Jerz 1 4/16/2006 Chapter Outline R. Jerz 2 4/16/2006 Welding Processes Gas, electricity, or other heat source? Is electrode consumed? Is a filler material used? Is flux used? Anything
More informationCommon Oxy Fuel Industry Terms
Common Oxy Fuel Industry Terms A ACETYLENE Gas composed of two parts of carbon and two parts of hydrogen When burned in the atmosphere of oxygen, it produces one of the highest flame temperatures obtainable.
More informationHail University College of Engineering Department of Mechanical Engineering. Joining Processes and Equipment. Fusion-Welding.
Hail University College of Engineering Department of Mechanical Engineering Joining Processes and Equipment Fusion-Welding Ch 30 Joining is an all-inclusive term covering processes such as welding, brazing,
More information3/26/2015. Processes of Arc Welding. Kate Gilland
3/26/2015 Processes of Arc Welding Kate Gilland Processes of Arc Welding Introduction Welding is a powerful technological advance. It allows for things to be conjoined that may have not been thought to
More informationChapter 1. Introduction Delmar, Cengage Learning
Chapter 1 Introduction Objectives After completing this chapter, you will be able to: Discuss the role welding plays in the manufacture of modern products today Explain the primary steps used in welding
More informationFundamentals of Joining
Fundamentals of Joining Chapter 30 30.1 Introduction to Consolidation Processes Consolidation Processes consist of Welding Brazing Soldering Fasteners Adhesives Shrink Fits Slots and Tabs Each Process
More informationModule 4 Design for Assembly
Module 4 Design for Assembly Lecture 2 Design for Welding-I Instructional Objective By the end of this lecture, the student will learn: (a) how a weld joint should be designed to improve the joint performance,
More informationEML 2322L -- MAE Design and Manufacturing Laboratory. Welding
EML 2322L -- MAE Design and Manufacturing Laboratory Welding Intro to Welding A weld is made when separate pieces of material to be joined combine and form one piece when heated to a temperature high enough
More information71T1 - Gas Shielded Flux Cored Welding Wire Provides excellent performance in all position welding. Weld Metal - Chemistry
Flux Cored Wire 71T1 - Gas Shielded Flux Cored Welding Wire Provides excellent performance in all position welding Description: Provides a stable arc, low spatter, easy to remove slag, and neat weld metal.
More informationIntroduction. Online course on Analysis and Modelling of Welding. G. Phanikumar Dept. of MME, IIT Madras
Introduction Online course on Analysis and Modelling of Welding G. Phanikumar Dept. of MME, IIT Madras Classification of Manufacturing Processes Manufacturing Processes Ingot Casting Shape Casting Power
More informationNAME 345 Welding Technology Lecture 07 Shielded Metal Arc Welding (SMAW)
NAME 345 Welding Technology Lecture 07 Shielded Metal Arc Welding (SMAW) Md. Habibur Rahman Lecturer Department of Naval Architecture & Marine Engineering Bangladesh University of Engineering & Technology
More informationCLASSIFIATION OF WELDING PROCESSES
Exp03: Welding Welding Welding is an art of joining metals by heating and then pressing together. Welding is a method of joining metals in which heat and/or pressure are applied to the area of contact
More informationLecture 23. Chapter 30 Fusion Welding Processes. Introduction. Two pieces are joined together by the application of heat
Lecture 23 Chapter 30 Fusion Welding Processes Introduction Fusion welding Two pieces are joined together by the application of heat Melting and fusing the interface Filler metal Extra metal added (melted)
More informationNAME 345 Welding Technology Lecture 03 (Welding Joint Design)
NAME 345 Welding Technology Lecture 03 (Welding Joint Design) Md. Habibur Rahman Lecturer Department of Naval Architecture & Marine Engineering Bangladesh University of Engineering & Technology Dhaka-1000,
More informationKCWONG. Shielded Metal Arc Welding (SMAW) Gas Metal Arc Welding (GMAW/MIG) Flux-cored Arc Welding (FCAW) Gas Tungsten Arc Welding (GTAW/TIG) KCWONG
1 Shielded Metal Arc Welding (SMAW) Gas Metal Arc Welding (GMAW/MIG) Flux-cored Arc Welding (FCAW) Gas Tungsten Arc Welding (GTAW/TIG) 2 Working Principle Equipment Filler metals Advantages Limitation
More informationWeld Imperfections and Preventive Measures
FOURTH EDITION Weld Imperfections and Preventive Measures Published by FOURTH EDITION Weld Imperfections and Preventive Measures Kita-Shinagawa, Shinagawa-Ku, Tokyo, 141-8688 Japan Published by KOBE STEEL,
More informationpdfmachine trial version
EFFECT OF WELDING TECHNIQUES (GTAW & SMAW) ON THE MICROSTRUCTURE & MECHANICAL PROPERTIES OF MILD STEEL SA 516 Gr. 70 By Dr. Muhammad Taqi Zahid Butt, S. Ahmed, S. Rasool, U. Ali and S. U. Rehman* ABSTRACT
More informationTHERMAL SPRAY COATINGS
THERMAL SPRAY COATINGS THERMAL SPRAY is a group of processes in which metals, alloys, ceramics, plastics and composite materials in the form of powder, wire, or rod are fed to a torch or gun with which
More informationWelding Inspection Defects/Repairs Course Reference WIS 5
Copy from Welding Inspection Defects/Repairs Course Reference WIS 5 Weld Defects Defects which may be detected by visual inspection can be grouped under five headings Cracks Surface irregularities Contour
More informationSolid-State Welding Processes
Solid-State Welding Processes Text Reference: Manufacturing Engineering and Technology, Kalpakjian & Schmid, 6/e, 2010 Chapter 31 Solid-State State Welding Processes Joining takes place without fusion
More informationWelding Engineering Prof. Dr. D. K. Dwivedi Department of Mechanical and Industrial Engineering Indian Institute of Technology, Roorkee
Welding Engineering Prof. Dr. D. K. Dwivedi Department of Mechanical and Industrial Engineering Indian Institute of Technology, Roorkee Module - 4 Arc Welding Processes Lecture - 1 SMAW- 1 So, dear students,
More informationTack Welder Level 3 Question Bank
Tack Welder Level 3 Question Bank I Fill in the blanks 1. Principle of GAS cutting is 2. Argon cylinder colour is 3. rays will emit from welding arc. 4. Tongs are used to hold 5. Full form of GMAW 6. Diameter
More informationWelding. What is Welding?
Welding Welding What is Welding? Welding is a joining process in which metals are heated, melted and mixed to produce a joint with properties similar to those of the materials being joined. Parent Metal
More informationSolid-State Welding Processes. Solid State Bonding 12/2/2009. Cold Welding
Solid-State Welding Processes Solid-State Welding Processes Text Reference: Manufacturing Engineering and Technology, Kalpakjian & Schmid, 6/e, 2010 Chapter 31 Joining takes place without fusion at the
More informationWelding Engineering Dr. D. K. Dwivedi Department of Mechanical & Industrial Engineering Indian Institute of Technology, Roorkee
Welding Engineering Dr. D. K. Dwivedi Department of Mechanical & Industrial Engineering Indian Institute of Technology, Roorkee Module - 1 Introduction Lecture - 2 Classification of Welding Processes -
More informationVALLIAMMAI ENGINEERING COLLEGE SRM Nagar, Kattankulathur
VALLIAMMAI ENGINEERING COLLEGE SRM Nagar, Kattankulathur 603 203 DEPARTMENT OF MECHANICAL ENGINEERING QUESTION BANK VII SEMESTER ME 6008-WELDING TECHNOLOGY Regulation 2013 Academic Year 2017 18 Prepared
More informationManufacturing Process - I Dr. D. K. Dwivedi Department of Mechanical and Industrial Engineering Indian Institute of Technology, Roorkee
Manufacturing Process - I Dr. D. K. Dwivedi Department of Mechanical and Industrial Engineering Indian Institute of Technology, Roorkee Module - 3 Lecture - 14 Reaction in Weld Region & Welding Defects
More informationLecture 29 DESIGN OF WELDED JOINTS VII
Lecture 29 DESIGN OF WELDED JOINTS VII This chapter presents the influence of various welding related parameters on fatigue behavior of weld joints. Attempts have been made to explain how (residual stress,
More informationUpon completion of this module
Welding 1.4 Upon completion of this module 1. Cite the advantages of welding over other joining methods 2. Name & identify the various welding and cutting processes currently used in industry 3. Recognize
More informationTechnical Data & Welding Guidelines for Ferralium 255SD50 Super Duplex Stainless Steel
Technical Data & Welding Guidelines for Ferralium 255SD50 Super Duplex Stainless Steel Technical Data & Welding Guidelines FERRALIUM Alloy 255 Ferralium 255SD50 Super Duplex Stainless Steel General FERRALIUM
More informationDesign for welding: Design recommendations
Design for welding: Design recommendations Arc welding can be used to weld almost any kind of assembly, including even complex structures. Arc weldments use a wide variety of ferrous and non ferrous metals.
More informationWELDING TECHNOLOGY TYPES UNIT I GAS WELDING DEFINITION
WELDING TECHNOLOGY UNIT I GAS WELDING 10 hrs. Welding techniques and terminology -Gas welding -Process variations -Equipment - Generation of acetylene -Types of gases -Flame characteristics -Flash back
More informationChapter 12. Flux Cored Arc Welding Equipment, Setup, and Operation Delmar, Cengage Learning
Chapter 12 Flux Cored Arc Welding Equipment, Setup, and Operation Objectives Explain the FCA welding process Describe what equipment is needed for FCA welding List the advantages of FCA welding, and explain
More informationGAS METAL ARC WELDING (GMAW)
GAS METAL ARC WELDING (GMAW) INTRODUCTION Gas Metal Arc Welding (GMAW) is also called Metal Inert Gas (MIG) arc welding. It uses consumable metallic electrode. There are other gas shielded arc welding
More informationAN OVERVIEW ON SHIELDED METAL ARC WELDING (SMAW) OF STAINLESS STEEL (SS)
Suggested Spec. for SMAW-SS - 1 - AN OVERVIEW ON SHIELDED METAL ARC WELDING (SMAW) OF STAINLESS STEEL (SS) Scope This document provides information on welding and related operations of stainless steel
More informationCasting, Forming & Welding
Casting, Forming & Welding (ME31007) Jinu Paul Dept. of Mechanical Engineering CFW- Welding marks distribution CFW Total Marks = 100 Casting =33, Forming = 33, Welding =33 End semester exam 50 % Mid semester
More informationStructural Steel Welding
PDH Course S150 Structural Steel Welding Semih Genculu, P.E. 2011 PDH Online PDH Center 5272 Meadow Estates Drive Fairfax, VA 22030-6658 Phone & Fax: 703-988-0088 www.pdhonline.org www.pdhcenter.com An
More informationAgenda. Hitsaustekniikka Kon Gas Metal Arc Welding Conventional control (solid wire) - Fundaments
Department of Engineering Design and Production Master Degree in Mechanical Engineering Hitsaustekniikka Kon-67.4200 Gas Metal Arc Welding Conventional control (solid wire) - Fundaments Materials Joining
More informationWELDING CONSIDERATIONS WITH HOT-DIP GALVANIZED STEEL. John du Plessis
WELDING CONSIDERATIONS WITH HOT-DIP GALVANIZED STEEL John du Plessis ABSTRACT Galvanizing has been in use for hundreds of years. Zinc forms a protective barrier between the steel and the environment. Welding
More informationThe principle Of Tungsten Inert Gas (TIG) Welding Process
The principle Of Tungsten Inert Gas (TIG) Welding Process This chapter presents the principle of tungsten inert gas (TIG) welding process besides important components of TIG welding system and their role.
More informationWelding Defects, Causes and Prevention
Welding Defects, and In welding the important objective is to obtain sound, defect free weld joint. But it is not always possible to get defect free joint. There will always be some kind of defects in
More informationFundamentals of Design for Welding. Kelly Bramble 32.1
Fundamentals of Design for Welding Kelly Bramble 32.1 Fundamentals of Design for Welding Copyright, Engineers Edge, LLC www.engineersedge.com All rights reserved. No part of this training program may be
More informationManufacturing Process - I Dr. D. K. Dwivedi Department of Mechanical and Industrial Engineering Indian Institute of Technology, Roorkee
Manufacturing Process - I Dr. D. K. Dwivedi Department of Mechanical and Industrial Engineering Indian Institute of Technology, Roorkee Module - 3 Lecture - 8 Submerged Arc Welding Welcome students. This
More informationManufacturing Process - I Prof. Dr. D.K. Dwivedi Department of Mechanical & Industrial Engineering Indian Institute of Technology, Roorkee
Manufacturing Process - I Prof. Dr. D.K. Dwivedi Department of Mechanical & Industrial Engineering Indian Institute of Technology, Roorkee Module - 3 Lecture - 11 Tungsten Inert Gas Welding Part 1 Welcome
More information!!!! WARNING!!!! WELDING FUMES AND GASES CAN BE DANGEROUS TO YOUR HEALTH.
CAREFULLY!!!! WARNING!!!! CAREFULLY WELDING FUMES AND GASES CAN BE DANGEROUS TO YOUR HEALTH. BEFORE USING THIS PRODUCT THE WELDER (END-USER) MUST READ AND UNDERSTAND THE COMPLETE PRODUCT WARNING LABEL
More informationGMAW Unit Topics. During this overview, we will discuss the following topics:
GMAW (MIG Welding) GMAW Unit Topics During this overview, we will discuss the following topics: Safety GMAW Basics Equipment Set-Up Welding Variables Process Advantages and Limitations AWS Connection National
More informationResistance Welding Principle
Resistance Welding Principle In resistance welding heat is generated by the electrical resistance of the work pieces and the interface between them. Pressure is supplied externally and is varied throughout
More informationG009: Remove weld metal from plain carbon steel, using weld washing techniques.
Welding 1 st Quarter DUTY A: Practicing Occupational Orientation A001: Follow safe practices. A002: Prepare time or job cards, reports, or records. A003: Perform housekeeping duties. A004: Follow oral
More informationChapter 31. Solid-State Welding Processes
Chapter 31 Solid-State Welding Processes Roll Bonding Figure 31.1 Schematic illustration of the roll bonding or cladding process. Ultrasonic Welding Figure 31.2 (a) Components of an ultrasonic welding
More informationSub-surface inspection of welds No. 6.03
Sub-surface inspection of welds Scope This Guidance Note applies to all welds in structural steelwork for bridges. It covers the sub-surface inspection of welds using ultrasonic inspection testing and
More informationPREVIEW COPY. Welding Principles. Table of Contents. Fundamentals of Welding...3. Oxyfuel Welding Equipment...35
Welding Principles Table of Contents Lesson One Lesson Two Lesson Three Fundamentals of Welding...3 Welding Safety...19 Oxyfuel Welding Equipment...35 Lesson Four Arc Welding Equipment...53 Lesson Five
More informationTechnical Data Sheet 321 Electrode Hi-Performance E-Z Arc Alloy
321 Electrode Hi-Performance E-Z Arc Alloy A quality electrode formulated to clean contaminants and produce good base metal penetration. Once welded, it lifts the contaminants into an easy-forming slag
More informationGMAW (MIG) / FCAW / MCAW
Welding Processes GMAW () / FCAW / MCAW Gas Metal Arc Welding (GMAW), Flux Cored Arc Welding (FCAW) and Metal Cored Arc Welding (MCAW) Gas Metal Arc Welding (GMAW) GMA commonly referred to as Metal Inert
More informationDissimilar Metals DISSIMILAR METALS. Weld Tech News VOL 1. NO. 14
Dissimilar Metals Weld Tech News VOL 1. NO. 14 WELD TECH NEWS is a newsletter for welders working primarily in maintenance and repair. Each issue contains useful information on materials (cast irons, steels,
More informationWelding Job Knowledge
Titanium and titanium alloys Weldability of materials Job Titanium and its alloys are chosen because of the following properties: high strength to weight ratio; corrosion resistance; mechanical properties
More informationb) provide evidence of his qualifications and practical experience in welding.
NEPALESE CIVIL AIRWORTHINESS REQUIREMENTS SECTION D APPROVAL PROCEDURES CHAPTER D.6 ISSUE 1 NOVEMBER 1994 1. GENERAL WELDERS 1.1 This chapter is applicable to persons who weld parts which are essential
More informationANSI/AWS D R An American National Standard. Recommended Practices for Root Pass Welding of Pipe Without Backing
ANSI/AWS D10.11-87R An American National Standard Recommended Practices for Root Pass Welding of Pipe Without Backing Key WordS Root pass welding, pipe, gas purging, consumable inserts, gas tungsten arc,
More informationInternational Journal of Advance Engineering and Research Development
Scientific Journal of Impact Factor (SJIF): 5.71 International Journal of Advance Engineering and Research Development Volume 5, Issue 03, March -2018 e-issn (O): 2348-4470 p-issn (P): 2348-6406 Study
More information3 TIG welding. 3.1 A description of the method. 3.2 Equipment
3 TIG welding 3.1 A description of the method TIG welding (also called Gas Tungsten Arc Welding, GTAW) involves striking an arc between a non-consumable tungsten electrode and the workpiece. The weld pool
More information49 CFR Part 192. Not applicable to welding during manufacture of pipe and components
49 CFR Part 192 Not applicable to welding during manufacture of pipe and components --- and other strange nomenclature A joining process that produces a coalescence of metals (or non-metals) by heating
More informationCIMC: Introduction to Agricultural Power and Technology
CIMC: Introduction to Agricultural Power and Technology Unit 3- Shielded Metal Arc Welding 1. Shielded Metal Arc Welding also goes by other names. Which of the following is another term for this type of
More informationModule - 4 Advanced Welding Processes Lecture - 1 Submerged Arc Welding (SAW)
Advanced Manufacturing Processes Prof. Dr. Apurbba Kumar Sharma Department of Mechanical and Industrial Engineering Indian Institute of Technology, Roorkee Module - 4 Advanced Welding Processes Lecture
More informationResidual Stresses and Distortion in Weldments
Residual Stresses and Distortion in Weldments By: Aziz Shafiei Residual Stresses 1 Causes of Residual Stresses Residual stresses in metal structures occur for many reasons during various manufacturing
More informationfamily of stainless steels can be divided into five (5) categories:
Welcome to the fifth issue of Tech Talk. This newsletter covers a range of topics on various welding products, applications, metallurgy, techniques, and economics. Previous issues are archived at www.unibraze.com.
More informationArc Welding. ROOP LAL Unit-6 (Arc Welding) Mechanical Engineering Department. Soft Copy Available at:
Arc Welding 1. Arc Welding: The welding in which the electric arc is produced to give heat for the purpose of joining two surfaces is called electric arc welding. In this the heat of fusion is generated
More informationExtended stickout guides are used to maintain a consistent CTWD (see Contact Tip to Work Distance section for more details).
WELDING TECHNIQUES Extended Stickout Welding (Cont d) Extended stickout welding is best suited to large diameter, high deposition Innershield electrodes, such as 3/32 in. (2.4 mm) and 0.120 in. (3.0 mm)
More information9. Welding Defects 109
9. Welding Defects 9. Welding Defects 109 Figures 9.1 to 9.4 give a rough survey about the classification of welding defects to DIN 8524. This standard does not classify existing welding defects according
More informationProcess Review Checklist
Process Review Checklist DISCLAIMER. Due to time constraints, the student process review exercise is only a few minutes long. A through, complete process review checklist is not expected as a result but
More informationElectric Arc Welding
Electric Arc Welding Electricity is passed through an electrode which jumps between the electrode and the work piece. This causes an arc which produces great heat melting the electrode and the work piece
More information4/19/2018. The heat generated for welding comes from an arc
Foundations of Agriculture The heat generated for welding comes from an arc Develops when electricity jumps across an air gap between the end of an electrode and the base metal. A. Alternating Current
More informationGrade 11 Term 1. Welding Simulation Project
Grade 11 Term 1 Welding Simulation Project Unit/Topic: STSENGS873 Welding Simulation STS Performance Criteria: 1.1,1.4-1.6, 2.1-2.4 AQF Unit & PC: N/A to selected TAFE units (AWS positions,1g,2g,2f) Name:
More informationMETROPOLITAN. O & M Procedure No: E UTILITIES DISTRICT I. GENERAL
Page: 1 of 10 I. GENERAL * Before any welder may weld on the Metropolitan Utilities District gas distribution and transmission system piping and facilities, the welder shall be qualified to perform the
More informationNAME 345 Welding Technology Lecture 12 Welding Defects & Discontinuities
NAME 345 Welding Technology Lecture 12 Welding Defects & Discontinuities Md. Habibur Rahman Lecturer Department of Naval Architecture & Marine Engineering Bangladesh University of Engineering & Technology
More informationGetting Started with Welding
Getting Started with Welding With the biochar crew at Living Web Farms Introduction Who we are What we re going to talk about: Basic concepts of working with metals, predominantly steel How to protect
More informationTable of Contents Page No.
Table of Contents Page No. Personnel... iii Foreword...v List of Tables...xii List of Figures... xiii 1. General Requirements...1 1.1 Scope...1 1.2 Approval...1 1.3 Definitions...1 1.4 Welding Symbols...1
More informationWELDING,FABRICATION AND REPAIRS
WELDING,FABRICATION AND REPAIRS FABRICATION Flat profiles and formed sections can be fabricated into larger items or finished structures using conventional welding procedures. Liners may be fixed to existing
More information