Influence of the in situ pulsed current on the microstructure and performance of composite roller fabricated by the wire arc additive manufacturing

Continuous casting composite rolls play a critical role in slab casting systems, with the Section 0 roll near the slab exit subjected to immense mechanical loads and thermal cycling. The harsh environment often leads to roll failure, adversely affecting production efficiency. Currently, post-service repair of continuous casting composite rolls often employs wire arc additive manufacturing (WAAM). But WAAM always form coarse microstructures and high residual stresses in the deposited layer, resulting in uneven coating wear and spalling during service. To address microstructural heterogeneity and poor interfacial integrity in continuous casting composite rolls, the study developed a novel in-situ electropulsing treatment-assisted wire arc additive manufacturing (EPT-WAAM) technique, investigating the effects of different EPT parameters on the molten pool morphology, microstructure, and mechanical properties of 414N alloy deposited on 42CrMo substrate. The results demonstrate that EPT-WAAM can induce periodic oscillation of the arc, enhance molten pool flow, and improve the wettability of molten metal on the substrate. X-ray micro-computed tomography scanning confirms that EPT-WAAM significantly decreases internal porosity within deposited layers. Microstructure shows grain orientation, substantial refinement, and improved hardness homogeneity throughout the 414N cladding's top and middle sections. By employing synergistic strengthening mechanisms such as defect reduction, grain refinement, and hardness uniformity, a high–strength–ductility sample has been successfully fabricated. These results demonstrate that the EPT-WAAM can produce high-performance samples directly in the as-deposited state, thus offering a viable technical pathway for the development of various high-performance alloys in the field of additive manufacturing.