Effects of multiple simulated weld repair cycles on the mechanical properties of a high strength, quenched and tempered steel

摘要

Corrosion damage to sea-going vessels can be repaired by removing the damaged metal and rebuilding the area with weld deposits. Over the life of a vessel, repair welding at the same location is often unavoidable and preferable to plate replacement, as it is more cost effective and timely procedure. In this study, the influence of the number of simulated weld repair thermal cycles (i.e. up to three repeated weld thermal cycles) on the microstructure and mechanical properties of a quenched and tempered (Q&T) steel was assessed. This assessment was undertaken through thermo-mechanical heat affected zone (HAZ) simulations, so as to isolate and assess the toughness of the different sub-zones in the HAZ over multiple thermal cycles. On all of the simulated samples, Charpy impact toughness and hardness tests were performed, followed by microstructural and fractographic analysis. The results attained were benchmarked against data from the original coarse grain (CG) and intercritically reheated coarse grain (CG-IC) HAZ thermal cycles. Although subtle differences in microstructure were observed, there was no significant degradation in toughness or hardness.