Microstructure and properties of Cr12MoV cold work mold steel repaired by wire arc additive manufacturing

Abstract

The build-up welding repair belongs to the typical wire arc additive manufacturing technology, and can effectively repair the mold, significantly extend the life of the mold, is widely used in the field of mold repair. In this study, Cr12MoV cold work mold steel was repaired using wire arc additive manufacturing. Three build-up welding layers Ni625 (Inconel 625) layer, D322 (CrWMoV steel) layer, and Ni625/D322 double-layer composite build-up layer were designed on the Cr12MoV surface. Temperature field simulation and thermodynamic simulation calculations were used to provide the theoretical basis for microstructural analysis of the build-up welding specimens. The practicality of D322 build-up joint is best. The microstructure of D322 build-up joint is D322 layer (acicular martensite)/PHZ (the fusion zone)/HAZ (the heat-affected zone) Ⅰ (Ld + carbides)/HAZ Ⅱ (martensite + residual austenite + carbides (primary + spherical)/HAZ Ⅲ (martensite + lower bainite)/HAZ Ⅳ (tempered sorbite)/BMZ (the base material). The gradient of hardness distribution in different zones of the D322 build-up joint is the smallest, and the hardness of martensite D322 layer is the highest (702 HV), with the best wear resistance (the friction coefficient and the mass loss are lowest). Moreover, D322 build-up joints in the D322 layer and HAZ Ⅱ brittle fracture, shear strength of 464 MPa. The application of this technology can effectively repair Cr12MoV cold work mold steel and provide guidance for the mold repair industry.