AN EXPERIMENTAL INVESTIGATION ON A36 CARBON STEEL IN SUBMERGED ARC WELDED JOINTS

Transcription

1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 4, April 2018, pp , Article ID: IJMET_09_04_035 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed AN EXPERIMENTAL INVESTIGATION ON A36 CARBON STEEL IN SUBMERGED ARC WELDED JOINTS Sachin Gupta, Sripati Varma Datla, Chandra Sekhar P and Nawaz Ali Shareef Student, Department of Mechanical Engineering, Koneru Lakshmaiah Education Foundation, Green Fields, Vaddeswaram, Guntur Dist., Andhra Pradesh, India ABSTRACT: In the present scenario of manufacturing process, welding plays an important role. As we all know that welding plays a significant role in metal joining process. The effectiveness of weld joint rely on its strength, heat distribution ability, etc. This experimental investigation concentrates on submerged arc welding control variables and process responses. The experiments were conducted based on Taguchi orthogonal array. The quality of weld joint is assessed through ultimate tensile strength, peak temperature, heat input and cooling rate. The response variations are monitored at different welding conditions of current, arc voltage and welding speed during SAW on A36 carbon steel. The effects of control variables on process responses are discussed. Keywords: Submerged arc welding, ASTM A36 Carbon Steel, Peak temperature, Ultimate tensile strength Cite this Article: Sachin Gupta, Sripati Varma Datla, Chandra Sekhar P and Nawaz Ali Shareef, An Experimental Investigation on A36 Carbon Steel in Submerged Arc Welded Joints, International Journal of Mechanical Engineering and Technology, 9(4), 2018, pp INTRODUCTION: In submerged arc welding process, local heating of weld plates causing non-uniform temperature distribution. The metallurgical transformation and thermo-plastic deformations during solidification lead to residual stresses and distortions in the weld component. Thus the submerged arc welding process becomes a very complex process involved with controlling of several process variables such as weld plates thickness, welding speed, welding current, welding voltage, work piece-electrode gap. Therefore, it is necessary to understand the significance of each process variable and to develop practical relations for the process, for which temperature distribution and the weld joint strength can be estimated within an acceptable tolerance editor@iaeme.com

2 An Experimental Investigation on A36 Carbon Steel in Submerged Arc Welded Joints Several investigations were reported in view of enhancing the submerged arc welding process efficiency. Cheong et al. [1] investigated on logical relationship on effect of current, polarity of electrode, diameter of electrode and electrode stand-off distance in melting speed, heel height, welding bead width and weld depth, in SAW. They have come to the conclusion that when a small electrode in terms of diameter is used, the increased in level of current do not have an eloquent effect on the percentage variation of the geometrical specifications of the welding. Basu et al. [2] completed investigation on the effect of the traditional wire, the current cable impulses and the welding rate on the welding proportions and the mechanical properties. The welding of HSLA steel submerged in single-phase tandem developed a series of mathematical relationships to estimate the dimensions of the welding seam and the mechanical properties rely on the welding circumstances. The investigational results exhibit that the width of the welding seam and the reinforcement level are altered mainly by current dragged bucket during penetration depth is under control of current of the main cable while the remaining conditions were same and the empirical relations develop according to the results of the Experimental studies on estimation of geometry of the welding seam and mechanical properties are in agreement. Mondal et al. [3] while investigating on the SAW process parameters presented another technique to enhance the SAW parameters is: 2062, Gr B MS (mild steel) with multiple response using the Taguchi approach and experiments using arc voltage, welding speed, current and electrode stand-off distance as control variables to evaluate multi-responses width and weld joint hardness. The optimal values were investigated using Taguchi method. The optimal values for cable lower width and greater hardness are 12.18A current, V arc voltage, mm\min speed and mm distance. Harish et al. [6]. studied the effect of cooling rate on microstructural changes in SIERRA welding and found that higher cooling rates form finer grains than low cooling rates; also the process parameters will show direct effect on the cooling speed. V. Gunaraj at al. [8] while a comparative investigation was done on the area affected by the heat for the union of weld bead on plate and on weld bead on joint of the submerged arc welding of the tubes, mathematical models were developed. It is found that the area of the area affected by the heat is more for the cable in the plate than the cable in the joint also the effect of the process variables follows the same trend. Aniruddha et al. [4] studying the effect of the heat entered welded submerged arc plates, they obtained an mathematical solution to predict the distribution of transient heat in the submerged arc welding plate with transient dimensional heat conduction equation and observed that the experimental results and the analytical solution results agree that the calculation of the width of the HAZ is also carried out with the help of analytical solutions. Graziano et al. [5] when preparing welded joints (MIG and SAW) in LDL 2101 D-SS (duplex stainless steel). the experiments are performed by welding using SAW and MIG techniques and HAZ, melting zone, metallographic characterization and mechanical properties have been found, and they have been compared with the SAW and MIG techniques. D.-W. Cho et al. [7] studied the behaviour of the molten pool by flowassisted metal transfer in a low current SAW during this study, a 3D heat transfers and a fluid flow was generated to find out heat distribution and behaviour of molten pool. Ravinder et al. [9] carried out a complete examination of SAW parameters and their effects on welding quality. McGrath et al. [10] examined the relationship between mechanical properties and microstructure of the welding metal and thermal areas of the SAW deposited on HSLA 80 steel by welding at different energy inputs and estimated in terms of microstructure and mechanical properties. in welded and stress-free conditions. X. R. Li, Y carried out the experiments to analyse which parameters influence the penetration of the welding. It was found that the current of the base plate was the most influential parameter that helps to calculate the penetration of the weld with sufficient precision [12] editor@iaeme.com

3 Sachin Gupta, Sripati Varma Datla, Chandra Sekhar P and Nawaz Ali Shareef Owing to the above experimental investigations, this investigation deals with an experimental investigation on heat affected zone and depth of penetration, length. The results of submerged arc welding were analyzed and reported. 2. EXPERIMENTATION 2.1. Experimental setup: All the welding performances are performed in "SPARKLINE make invertor based" submerged arc welding machine that is equipped with a copper coated mild steel electrode of 2.4mm and granulated flux of high silica gel. Welding setup is connected to a full and semiautomatic movement of submerged arc welding line figure 1 shows a complete experimental setup for submerged arc welding conducted in the investigation. Figure 1 Experimental setup for submerged arc welding Granulated high silica gel is used as shielding to protect the weld zone from atmospheric contamination Materials Used Work piece Workpiece is selected for submerged arc welding is A36 OF rectangular shape with dimension of 120*50*10. The composition, mechanical and physical properties of work material are given in Table 1 Chemical Composition Element C% Cu% Fe% Mn% P% Si% S% Composition Table 2 Mechanical Properties and physical properties Elastic Modulus 200 Gpa Bulk Modulus 140 Gpa Poisson Ratio.260 Shear Modulus 79.3 Gpa Density 7.85g/cm editor@iaeme.com

4 An Experimental Investigation on A36 Carbon Steel in Submerged Arc Welded Joints Electrode used Copper coated mild steel wire electrode having diameter of 2.4mm. Granulated high silica gel which is supplied from hopper during welding Welding Procedure: Welding was done on plates. Numerous tests have been performed based on the knowledge of literature to find out how it works a range of controllable variables of the heat source independently. Welding current, voltage and welding speed. That was observed a high heat supply causes undercutting and very low heat value is not able to give to appreciable bead-on-joint. Furthermore, it was reported that the thermal behavior of the weld during The cooling phase has a non-linear nature. In view of above, to include the non-linear effect of thermal behavior, three levels are selected for each parameter. Based on these tests, the selected ranges for each selected parameter selected for experimentation are given in Table 1. After selecting the welding parameters, a design matrix was prepared. In general design of experiments is too complex and too difficult to apply. In addition, number of experiments to perform will increase with increase in number of variables. With full factorial experimental design require 27 experiments as there are 3 factors and 3 levels in this investigation but the cost of experimentation will not be economical so, we used Taguchi method for design of experiments to reduce the number of experiments obtain similar results and conducted for 15 set of experiments. Figure 2 preparation of work piece Table 3 experimentation parameters S no parameters Units symbols Low level(-) Medium level(0) High level(+) 1 Current Amp A Voltage Volts V Speed mm/min S S no Table 4 Design Matrix for Different Processes Parameters Current (Amps) Voltage (Volts) Speed (mm/min) editor@iaeme.com

5 Sachin Gupta, Sripati Varma Datla, Chandra Sekhar P and Nawaz Ali Shareef Temperature Measurement: Cooling time (in seconds) is recorded for the calculation of cooling rate.in this investigation, K-type thermocouple of 1mm diameter with data acquisition device is used. The temperature is recorded at four different locations. The First thermocouple is placed exactly below the weld arc and other three thermocouples are placed 2.4 mm away from each other from the central position along the transverse direction. The thermocouples are inserted into the drilled holes two ensure perfect contact with the metal. Four holes (each hole was 5 mm deep) were drilled opposite to weld surface of each plate, for placing of thermocouples during welding. Figure 3 insertion of thermocouples into specimen 2.4. Cutting of specimen for test: After welding, a horizontal cross-section of the weld was cut from the plates as specimens. These specimens were prepared were prepared as per ASTM standards for tensile Figure 4 portion removed for tensile test studies editor@iaeme.com

6 An Experimental Investigation on A36 Carbon Steel in Submerged Arc Welded Joints Figure 5 dimensions for tensile test specimen 3. RESULTS AND DISCUSSION: In the present study peak temperatures, ultimate tensile strength, and heat input was found for each of the specimens. Properties of the steel weld are affected by the process parameters applied to the base plate 3.1. Peak temperatures, Ultimate tensile strength, Cooling rate and Heat input: S no Current (C) Voltage (V) Speed (mm/sec) Ultimate Tensile Strength(N\mm 2 ) Peak Temperature ( o C) Heat Input (KJ\mm) Cooling rate o C/sec Peak temperatures, Ultimate tensile strength, Heat input, and cooling rate have been found out for all specimen Variation of responses due to increase in current: By keeping voltage and welding speed and with increase in welding current peak temperature and heat input increases with this cooling rate and ultimate tensile strength is decreased editor@iaeme.com

7 Sachin Gupta, Sripati Varma Datla, Chandra Sekhar P and Nawaz Ali Shareef Figure 6 variation of ultimate tensile strength, peak temperature, heat input and welding speed with respect to current 3.3. Variation of responses due to increase in voltage: By keeping current and welding speed constant with the increase in voltage heat input increases while ultimate tensile strength, peak temperature and heat input decreases. Figure 7 variation of ultimate tensile strength, peak temperature, heat input and welding speed with respect to voltage 3.4. Variation of responses due to increase in welding speed: By keeping current and voltage constant with the increase in welding speed cooling rate increasing while ultimate tensile strength, peak temperature and heat input decreases Figure 8 variation of ultimate tensile strength, peak temperature, heat input and welding speed with respect to welding speed 3.5. TEMPERATURE PLOTS At the time of welding, the temperature is recorded using data logger, by a thermocouple at different points. These temperature readings are useful in draw temperature plots. These plots used for calculating the cooling rate of weldment editor@iaeme.com

8 Temperature (c) Temperature (C) Temperature (C) An Experimental Investigation on A36 Carbon Steel in Submerged Arc Welded Joints a Time(Sec) 0mm 2.4mm 4.8mm 7.2mm b Time (Sec) 0 mm 2.4 mm 2.8 mm 7.2 mm c Time (Sec) 0 mm 2.4 mm 4.8 mm 7.2 mm Figure 9 (a) low, (b) medium, (c) High ultimate tensile strength temperature histories editor@iaeme.com

9 Sachin Gupta, Sripati Varma Datla, Chandra Sekhar P and Nawaz Ali Shareef 3.6. MICROSTRUCTURE: According to ultimate tensile (high, medium and low), 3 specimens are selected plates 1,8 and 13 these specimens were polished and etched with 2% nital solution for 7 seconds, which was used for investigation of the microstructure. The microstructure is conducted at 200X Fig 4 shows the microstructure of weldment at different ultimate tensile strength (low, medium and high) specimen with high ultimate tensile strength has more fine grains at HAZ than low tensile strength. Finer grains are formed at weld zone of high tensile strength specimen. It is also observed that grain size is larger at HAZ for high tensile strength specimen. Heat affected zone Weld Metal Parent Metal a) Plate 1 Microstructure (Low UTS) Heat affected zone Weld Metal Parent Metal b) Plate 13 Microstructure (Medium UTS) Figure 10 Showing Microstructure at (a) low, (b) High Ultimate Tensile Strength (200X Magnification) 4. CONCLUSION: Submerged arc welding conducted on A36 low carbon steel at varied current, voltage and welding speed the following conclusions were obtained: 1. Tensile strength decreased by increase in current and voltage and welding speed. 2. Peak temperature increased by increase in current and decreased by increase in voltage and welding speed. 3. Heat input increased by in voltage and current and decreased by increase in welding speed. 4. Cooling rate increases with increase in welding speed and decreased in current and voltage editor@iaeme.com

10 An Experimental Investigation on A36 Carbon Steel in Submerged Arc Welded Joints REFRENCES: [1] Chandel, R.S, H.P.Seow and F.L.Cheong. Effect of increasing deposition rate on the bead geometry of submerged arc welds. Journal of Materials Processing Technology 72.1 (1997): [2] kiran, D.V., B.Basu and A.De, Influence of process variables on weld bead quality in two wire tandem submerged arc welding of HSLA steel, Journal of Materials Processing Technology (2012): [3] Saha, Abhijit, and Subhas Chandra Modal. Optimization of process parameters in submerged arc welding using multi-objective taguchi method. Advance in Material Forming and Joining. Springer, New Delhi, [4] Ghosh, Aniruddha, Somnath Chattopadhyay and R.K.Das. Effect on heat input on Submerged arc welded plates. procedia engineering 10 (2011): [5] Graziano, Ubertalli, Donato Firrao and Giamancro Taveri. Characterization of welded Joints (MIG and SAW) on LDX 2101 Duplex SS. procedia engineering 109 (2015): [6] Cho, Dae-Won, Degalal Venkata Kiran, and Suck-Joo Na. Analysis of Molten pool behaviour by flux-wall guided metal transfer in low-current submerged arc welding arc process. International Journal of Heat and Mass Transfer 110 (2107): [7] Gunaraj, V., and Murugan. Prediction and Comparison of the area of heat affected zone for the bead-on-plate in submerged arc welding of pipes. Journal of Materials Processing Technology (1999): [8] Singh, Ravinder pal, R. k. Garg, and D.K. Shukla. parametric Effect on Mechanical Properties in Submerged arc welding process-a review. International Journal of Engineering Science and Technology 4.2 (2012):11. [9] Smith, N.J., et al. Microstructure/mechanical property relationships of submerged arc welds in HSLA 80 steel. Welding Journal68.3(1989):11. [10] Tadavi, T., et al. Microscopic Analysis of Heat Affected Zone (HAZ) of submerged Arc Welding (SAW) Joints for 1018 Mild Steel Sheet. (2017) [11] Li, X.,Y. Zhang, and L. Kvidhal, Penetration depth monitoring and control in submerged arc welding. Weld. J 92.2 (2013): S48-S56. [12] Nagesh, D.S., and G.L. Datta, Prediction of weld bead geometry and penetration in shielded metal-arc wielding using artificial neural networks. Journal of Materials Processing Technology 123.2(2002): [13] Arya, Harish Kumar, Kulwant Singh, and R.K.Saxena. cooling time (t8/5)model for Submerged Arc Welded Pressure Vessel Steel Using Dimensional Analysis. Journal of Pressure Vessel Technology 139.6(2017): editor@iaeme.com