The Influence of Post-Weld Heat Treatment on High-Pressure Vessel Steel ASTM A285 Grade C with Gas Metal Arc Welding Process

The objective of this research was to study the influence of the post-weld heat treatment of a high-pressure vessel steel ASTM A285 Grade C with a gas metal arc welding process on its hardness and microstructure of the Weld Metal (WM) and Heat-Affected Zone (HAZ). In a welding process, the 4 mm high-pressure vessel steel ASTM A285 Grade C was welded by a gas metal arc welding robot arcing. Then, the post-weld heat treatment (stress relieving process) was continued at 520, 570, and 670 degrees Celsius for 30 and 60 minutes at each temperature level, compared with the as-weld specimens. After that, optical microscopy was tested. The hardness was also tested by using the Vickers hardness test. The result showed that temperature and time in the stress relieving process significantly affected the hardness in WM and HAZ (p˂0.05). The WM and HAZ microstructures of stress-relieved specimens were Pearlite, Acicular ferrite, and Widmanstatten ferrite which showed coarser grain than as-weld specimens.