K-TIG vs EB. Keyhole TIG and Electron Beam Welding Compared

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2 What is? Keyhole GTAW explained Overview A high energy density variant of GTAW, (Keyhole TIG) is a high speed, single pass, full penetration welding technology that welds up to 100 times faster than TIG welding in materials up to 5/8in (16mm) in thickness, and typically operates at twice the speed of plasma welding. works across a wide range of applications, and is particularly well suited to lower conductivity materials such as stainless steels, nickel alloys, titanium alloys and most corrosion resistant and exotic materials. It easily handles longitudinal and circumferential welds on pipe, plate, spooling, vessel, tank and other materials in a single pass: Titanium at 3mm to 16mm (1/8 to 5/8 inch) Stainless steel at 3mm to 13mm (1/8 to 1/2 inch) Carbon steel at 3mm to 9mm (1/8 to 11/32 inch) welding is a new productivity benchmark. The speed, penetration, quality and overall savings generated by the process are extraordinary. Attila Szabo, Principal Joining Engineer, GE s extremely fast welding times result in dramatic reductions in labor costs, welding cycle times, rework and repair costs, gas and power usage. s single pass, full penetration welds significantly reduce or eliminate grinding and reworking. The process dramatically reduces or eliminates the need for wire, eliminates edge bevelling, and requires only a square butt joint, but can also weld into all standard GTAW preparations. No root gap is required. The Process Keyhole TIG is not a Plasma welding process. It is a much simpler, high productivity GTAW variant developed by the Australian Government s Commonwealth Scientific & Industrial Research Organisation (CSIRO), in conjunction with the Cooperative Research Centre for Welded Structures before being acquired and commercialised by. The System The 1000 System has been precision engineered to deliver the Keyhole GTAW process in a robust, intelligent and user friendly form. The 1000 System is manufactured in Adelaide, South Australia, is being used by many of the world s most productive fabricators and has been exported to 18 countries. PAGE 2 OF 7

3 EQUIPMENT COST Circa $100K USD Circa $1.2 Million USD PENETRATION Up to 16mm Up to 60mm SPEED Up to 1000mm/min Up to 2500mm/min WELD QUALITY Very high due to benefits from keyhole mode Very high due to benefits from keyhole mode JOINT PREPARATION cost, simple square butt design cost, simple square butt design FIT-UP TOLERANCE Tolerant to joint imperfections Requires very precise fit-up WELDING CYCLE TIMES Very fast, high speed and deep penetration Very fast, high speed and deep penetration COMPLEXITY Extremely simple Highly complex, numerous critical parameters WELD APPEARANCE Very smooth and good contour; no dressing or grinding required on either crown or root Very smooth crown and good contour; root side has good shape but very rough with lots of spatter. Typically, dressing or grinding required on root KEYHOLE STABILITY High inherent stability, selfcorrecting keyhole Highly stable keyhole KEYHOLE CLOSE-OUT Very simple, just slope down, no voids Very simple, just slope down, occasional voids due to "spiking" at root of partial penetration during tail-out PROCESS CONSISTENCY Very consistent keyhole, no process drift Very consistent keyhole, no process drift MAINTENANCE COSTS Moderate, DP oil and seals need replacement SKILL OF OPERATOR High PAGE 3 OF 7

4 EQUIPMENT COST PENETRATION SPEED WELD QUALITY PAGE 4 OF 7 Circa $100K USD Circa $1.2 Million USD A remarkably low cost, complete welding system with all the benefits of high energy density welding without the high equipment cost; just connect to any mechanized motion system. A high end process with very high equipment cost. Vacuum chamber size has a large influence on overall equipment cost; power level has a smaller influence. Up to 16mm Up to 60mm comfortably performs single pass welds in 16mm thick titanium, 13mm austenitic stainless steels, Hastelloys, Inconels and a wide range of nickel and cobalt alloys, and 9mm in conductive materials such as ferritic steels & carbon steels. Depending on the power level (e.g., 15 kw or 30 kw), thicknesses up to 60mm or beyond can be penetrated with a single pass. Up to 1000mm/min Up to 2500mm/min Typical speeds are: 3mm material at up to 1000mm/min 4mm material at up to 750mm/min 6mm material at up to 600mm/min 8mm material at up to 500mm/min 12mm material at up to 350mm/min 14mm material at up to 250mm/min 16mm material at up to 200mm/min Typical speeds are: 3mm material at up to 2500mm/min 4mm material at up to 2000mm/min 6mm material at up to 1500mm/min 8mm material at up to 1200mm/min 12mm material at up to 1000mm/min 14mm material at up to 1000mm/min 16mm material at up to 1000mm/min Very high Very high One of the benefits of keyhole GTAW welding is the exit path available for any vaporized impurities to leave the weld through the back of the keyhole. This prevents the evolved gases from becoming trapped as porosity in the solidifying weld. The resultant weld typically has clean X-ray results. One of the benefits of keyhole EB welding is the exit path available for any vaporized impurities to leave the weld through the back of the keyhole. This prevents the evolved gases from becoming trapped as porosity in the solidifying weld. The resultant weld typically has clean X-ray results.

5 JOINT PREPARATION FIT-UP TOLERANCE WELDING CYCLE TIMES COMPLEXITY WELD APPEARANCE MAINTENANCE COSTS PAGE 5 OF 7 Low cost, simple square butt design Low cost, simple square butt design A simple square butt joint design is required, no groove to fill (unless > mm thick). A simple square butt joint design is required, no groove to fill. Very high tolerance for a keyhole process tolerance to joint gaps The process can maintain a stable keyhole even with joint gaps in excess of 0.5mm, although tight fit is better. The process can manage up to 20% high-low mismatch. The typical max joint gap permitted for EBW is 10% of thickness, not to exceed 0.1 mm. The process can manage up to 20% mismatch. Very fast Very fast The high energy density GTAW keyhole permits single pass penetration of thick joints at a very high travel speed, resulting in minimal weld passes accomplished in very short times. The high energy density EB keyhole permits single pass penetration of thick joints at a very high travel speed, resulting in minimal weld passes accomplished in amazingly short times. Extremely simple Highly complex, numerous critical parameters is very simple to operate. The arc structure and keyhole develop spontaneously and are maintained automatically by the controller throughout the weld. weld parameters are basic and simple to adjust. EB is widely regarded as a complex, beam welding process. There are more parameters to fine tune than for arc welding, and the set-up and fit-up of joints is very critical. Very smooth with good contour Very smooth crown, very rough root bead With proper gas shielding of the face and root sides of the weld, the process inherently produces a very smooth and uniform weld appearance that requires no further grinding or dressing. EB welding is done in a vacuum, so there is no gas shielding required, and the weld metal is free of any oxidation. The weld crown (when using a cosmetic pass) is normally very smooth and uniform, but the root bead is quite rough with a lot of spatter. Dressing or grinding of the root bead is commonly done. Moderate welding systems incur very low maintenance costs due to their simplicity. systems have few consumable components, are robust and extremely reliable. EB welding systems require regular and expensive maintenance, including replacement of diffusion pump oil, seals, and filaments.

6 High inherent stability, self-correcting keyhole KEYHOLE STABILITY keyholes have extremely high stability, due to the high travel speeds and surface tension in the weld pool. As a result, there is no requirement to seek a balance between arc force (plasma column) and surface tension - the nature of the keyhole surface is such that it naturally and dynamically self-corrects for fluctuations in the arc forces. Very simple, just slope down, no voids KEYHOLE CLOSE-OUT PROCESS CONSISTENCY SKILL OF OPERATOR PAGE 6 OF 7 The keyhole is produced from a high energy density arc and patented torch design, without any plasma gas or complex constricted arc required. As a result, at the overlap and slope out of a circumferential weld, the process is extremely simple to slope down to close out the keyhole and end the weld. High inherent stability EB is such a high energy density process that creating and maintaining a stable keyhole is readily achieved. Very simple, just slope down, occasional voids The EB process is capable of a smooth and orderly slope-out of the weld, including closing the keyhole and gradually reducing the penetration until the weld is terminated. The high energy density can occasionally lead to "spiking" defects (voids) during the slope-out. Very consistent keyhole, no process drift Very consistent keyhole, no process drift The high energy density arc from produces a smooth and consistent keyhole through the joint, with very little variation for the duration of the weld. The process is simple enough, and the electrode is large enough, that erosion (and process drift) are negligible. The high energy density electron beam produces a smooth and consistent keyhole through the joint, with very little variation for the duration of the weld. High requires minimal training due to the simplicity of the process and the sophistication of the controller. An unskilled operator is sufficient. EBW requires extensive operator training due to its complexity and sensitivity to the many critical variables involved.

7 THE FASTEST WAY TO WELD