Effect of surface modification through GTAW on high-temperature performance of 4Cr5MoSiV steel

Abstract

In the study, the surface modification of 4Cr5MoSiV steel through gas tungsten arc welding (GTAW) was carried out. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the evolution of phases and microstructures before and after the GTAW surface modification treatment. The microhardness, tribological behavior, and high-temperature oxidation property were systematically investigated using the tests regarding microhardness, high-temperature wear, and high-temperature oxidation. GTAW remelting process generated (FCC + BCC) dual phase, which created mutual restriction between the two phases in plastic deformation. Continuous distribution of hard Cr3C2 carbides at grain boundaries could disperse local stresses. The microhardness of the GTAW remelting layer was significantly improved, and the GTAW remelting increased the V element of the free state and formed V2O5 oxide with unique lattice structure in the oxide layer. The high-temperature oxidation performance of the GTAW remelting layer was slightly deteriorated. The high-temperature oxidation duration for the high-temperature wear test was short, and the high hardness of remelting layer and the connective carbides together played the major roles, so GTAW remelting layer had excellent resistance to high-temperature wear resistance.