Effect of welding parameters on tensile and impact strength of dissimilar Hardox 450–St 52 steel joints

This study investigates the influence of welding parameters and joint configuration on the mechanical efficiency and microstructural evolution of dissimilar Hardox 450–St 52 steel joints. These materials are commonly used together in excavator and backhoe loader buckets to optimize wear performance and cost-effectiveness. The joint integrity was evaluated through optical microscopy, SEM analysis, tensile tests, and Charpy U-notch impact tests. Results indicated that the welding thermal cycle induced a distinct heat-affected zone (HAZ) and significant grain growth, leading to localized softening, particularly on the Hardox 450 side. In single-sided welds, mechanical performance deteriorated with increasing welding current. However, double-sided welding configurations partially mitigated this degradation by providing a more balanced thermal distribution and improved structural homogeneity. Notably, the double-sided specimen welded at 190 A achieved a tensile strength of 485.30 ± 1.92 MPa, nearly matching the St 52 base metal. Furthermore, the welded joints exhibited favorable energy-absorption behavior under impact loading, particularly in the double-sided configuration. Specifically, the 190 A double-sided joint reached an absorbed energy of 62 ± 0.71 J, surpassing the impact toughness of the Hardox 450 base metal (60 J). These findings demonstrate that optimized double-sided welding parameters can effectively minimize the softening issues in high-strength abrasion-resistant steels, providing useful guidance for the fabrication of heavy-duty components.