INFLUENCE OF THE SOFT ZONE ON THE STRENGTH OF WELDED MODERN HSLA STEELS

The objective of this study was to investigate the influence of softening in the heat-affected zone of welds and the constraint effect on the transverse tensile strength of a microalloyed, thermomechanically controlled processed (TMCP) high-strength steel grade. The welding was performed with three different levels of energy input to establish soft zones with varied extensions to investigate the dimension of softening and to determine the constraint effect on various widths of the soft zone. The results showed that the tensile strength was not significantly compromised by softening in the HAZ. The reason for this is the constraint effect of the base metal and the high strength of the weld metal. In conclusion low heat input welding processes keep the soft zone small and the strength high.