Plasma wire arc additive manufacturing (PWAAM) of high-strength steel on a high-carbon steel, consideration and characterization of the transition area

In hybrid metal structures where high-strength steel (10NiMnMoCr8-7-6) is added onto a high-carbon (C55E) steel substrate using plasma wire arc additive manufacturing (PWAAM), the transition area remains critical due to the complex interactions between the alloys and their thermal histories. This study uses a combination of high-resolution characterization methods to investigate the local mechanical properties and microstructural gradients in the unaffected substrate, the heat-affected zone (HAZ), the dilution zone (DZ), and the all-weld metal (AWM). Carbon content and microstructure were systematically characterized and linked to the respective microstructural zones of the transition area to evaluate the differences in microstructure and mechanical properties. In addition to micro-tensile tests and hardness measurements, nanoindentation and indentation plastometry-based imprint testing (IPIT) were applied to capture local mechanical properties at a high resolution across the transition area. The different carbon content in combination with the altering thermal history establishes a complex microstructure gradient, correlating with local mechanical properties — a relationship that was clearly revealed by the combined characterization methods.