PSI- Issue 9

12

Tareq RahmanMahmood, et al. / Structural Integrity Procedia 00 (2018) 000–000

Tareq Rahman Mahmood et al. / Procedia Structural Integrity 9 (2018) 71–85

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Fig. 14. 3D surface Interaction between electrode force and welding current

The tensile strength results for HSLA steel, 0.8 mm thickness are shown in Fig. 15. The red curve shows the tensile results. It’s occurs if the high current and high welding time are used. In this condition all failure will be pullout mode. The yellow curve represented the moderate strength of spot welded specimens. The experimental examinations show the partial interfacial failure mode. The lowest tensile strength due to using small welding current and small time is shown in grey curve. The fractured specimens show an interfacial failure mode. The green curve represented the optimum tensile strength that obtained due to using of the welding parameters from Design Expert.

Fig.15. Tensile test result for spot welded HSLA with 0.8 sheet thickness.

4.4. Process parameters analyzing The spot welded features like the size of fusion zone, weld penetration and electrode indentation are the most remarkable parameters controlling the mechanical performance. It has been shown that welding current and welding