Figure 13 Main effects plot for S/N ratio- Tensile test
Related Figures (24)
Figure 2: dissimilar materials welded using TIG welding Stainless steel316L and Mild steel IS 2062 are selected over other materials because of its distinct properties, its availability in market and cheaper cost. It has high corrosion resistance and can be operated at elevated temperature. Specimen of 300x20x3: dimension was prepared and welded according to the ASTM E8 standards. The chemical composition of SS 316L and IS 2062 shown in the table 1 and 2. The selected welding parameters and levels for each factor are given in Table 3. chart as shown in the Figure 1. For any project, there should be a proper methodology. Methodology is precise order in which we carry out the project. It starts from the selection of the material to the conclusion of the project. The methodology that is adopted is explained in the form of a flow chart as shown in the Figure 1. Table 1: Chemical Composition of stainless steel 316L Table 2: Chemical Composition of Mild steel IS 2062 Table 3: Process parameters and their values at different level Orthogonal arrays are the standard arrays which are selected based on the number of selected parameters and levels. L9 orthogonal array is chosen from Minitab 18 software and the welding was carried out in sequential order with the parameters as shown in the table 4 Table 4: L9 Orthogonal array Figure 3: Experimental set up of TIG Welding Seer es NESE Aere SANA ERAN ae OSORNO Ma cone one me eeMh es IPO NCI SHO me? It is engineered range of inverter based, TIG machine, which is in compliance with industrial benchmarks. It is used to weld stainless steel, mild steel, copper and titanium. It is known for accurate dimension and capability to deliver optimum performance. Figure 5: Vickers Hardness Tester Machine In this experimental work, the tests have been investigated on Hardness and Tensile strength by varying various process parameters like Current, Voltage and Gas flow rate. Figure 4: prepared specimen after machining Figure 6: UTM Tensile Testing Machine Table 5: welding process parameters It is evident from fig 8 that failure has occurred in the mild steel of grade IS 2062 and not in the welded region, welded region formed by TIG welding has strong joint and reduces cracks and pores on the surface which shows Tungsten inert gas welding is most significant than other welding process. The values of welding process parameters are given below in the table 5. Hardness test and tensile tests are performed on 9 specimens. After welding operation and mechanical tests were performed, the microstructural study was made in order to understand the effect of welding heat across the specimen. Table 7: ANOVA Result for Hardness Table 6: Response Table for SN ratio Figure 11: Main Effect plot for SN ratio Figure 10: input parameters versus Tensile strength Figure 9 shows the comparison of input parameters and Hardness. It is observed that hardness increases with increase in voltage. Maximum hardness is obtained at 120(Amp) current, 60V voltage and 9Lit/min gas flow rate. Sample 6 has highest Hardness. Figure 10 shows the comparison of the input parameters and tensile strength. It is noticed that as current increases, tensile strength of the specimen increases. Current has reasonably large effect on tensile strength. Maximum Tensile strength is obtained at 130A current, 50V Voltage and 10 Lit/min gas flow rate Table 7: Response Table for Signal to Noise Ratios — Tensile test Table 8: ANOVA Result for tensile test From the results of Response table and ANOVA table of tensile strength , welding current is found to be the major factor affecting ultimate tensile strength since its F value is 18.11 and Voltage is found to be second ranking since its F value is 9.68 and Gas flow rate ranks last since its F value is 1.75. From ANOVA table it is also noted that Percentage contribution of current is 50%, Voltage is 36% and Gas flow rate is 10%. So it is clear that welding current only has significant effect at 95% confidence level. Figure 14 shows pie chart for Percentage Contribution of different parameters for tensile test. Confirmation experiment is done at optimal process level and the value of Hardness and Tensile Strength after optimization is 187 and 480 N/mm’? respectively. Thus effectiveness of Taguchi Optimization method was verified. Figure 17: Microstructure of Parent Zone 500X Figure 15: Microstructure of Parent Zone 100X Microstructural observation is performed on the optimized specimen, followed by welding operation .This study is to make a view of the material properties in the grain growth at the welded area. Figure 16: Microstructure of Weld Zone 100x
