Evaluation of microstructure,crystallographic texture,crystal orientation,grain boundary characteristics,and mechanical characteristics of dissimilar joints of ASTM A240 and alloy 625 in different welding techniques for high temperature applications

Abstract

Graphical abstract

The current study focuses on the welding of dissimilar joints between ASTM A240 and alloy 625 for high temperature applications, particularly in the manufacturing of CSP storage tanks. Two welding techniques, Double pulse – MIG and Single Pulse -MIG, were utilized. When comparing the two techniques, Double pulse -MIG demonstrated a 65% grain refinement and 30% lower heat input compared to Single pulse – MIG. Double pulse – MIG also showed a reduction of 17.7% in high angle grain boundaries (HAGB). The presence of a strong texture in weld center (WC) was confirmed by a maximum pole intensity of 7.7 in the normal direction (ND) direction. Double pulse – MIG exhibited a higher amount of strong texture in WC compared to Single pulse – MIG. Additionally, Double pulse – MIG resulted in a 75 MPa reduction in residual stress compared to Single pulse – MIG. Due to its ability to produce finer grains, Double pulse – MIG exhibited superior mechanical properties and higher tensile strength. Overall, the research highlights the advantageous mechanical properties of Double pulse – MIG over Single pulse – MIG welding methods.