Evaluation of the process parameters and cladding effects on the microstructure and mechanical properties of SA516 GR70 steel welded joints

Abstract

The current study aims to evaluate the mechanical and microstructure properties of SA516 GR70 medium carbon steel having cladding of stainless steel SS316 using shielded metal arc welding (SMAW) technique. The mechanical and microstructure properties have been evaluated at three process parameters such as welding electrode material, electrode diameter, and welding current. The ultimate tensile strength (UTS), impact strength and micro hardness (MH) have been selected as output responses. A full factorial design having 27 combinations of experiments has been employed to analyze the effect of process parameters on output responses. Optical microscopy has been used to analyze the microstructure of the welded joints. The analysis of variance (ANOVA) results revealed that the type of welding electrode is found to be the most significant parameter for all three output responses. The 3D mesh contour plots demonstrated that optimal values of UTS of 640 MPa, MH of 380 HV, and impact strength of 120 Joules have been achieved at the experimental settings such as welding electrode of SS 312, electrode diameter 3.8 to 4 mm, and welding current ranges between 70 to 90 amps. Microstructural analysis revealed that finer austenite grains appeared in the interface region of the joints at the optimal experimental settings which enhanced the weld mechanical properties. Furthermore, validation test has been depicted that mathematical models of these combination of process parameters and responses are validated due to the low percentage error.