Effect of TIG remelting on microstructure, corrosion and wear resistance of coating on surface of 4Cr5MoSiV1 (AISI H13)

This study aims at surface modification of the 4Cr5MoSiV1 (AISI H13) steel through the TIG (tungsten inert gas) remelting process. TIG remelting process was conducted using the major parameters, i.e. 250 A welding current and 120 mm/min welding speed (3.0 mm electrode diameter), under the protection of Argon. After remelting, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to analyze phases, microstructure and element distribution, respectively. After TIG remelting on the surface of 4Cr5MoSiV1 steel, the phase transition from body-centred cubic (BCC) to face-centred cubic (FCC) has occurred, and a great amount of Cr3C2 segregated along the grain boundaries, which resulted in eutectic structures. The results illustrated that the TIG remelting layer has better corrosion resistance than the original steel, which is related to the grain boundaries with Cr3C2, and result in wider passivation. Further, the microhardness of the TIG remelting layer has been increased to a great extent, which has leaded to lower friction coefficient and better wear resistance. And then, the small punch tests exhibit the morphology of intergranular fracture at the remelting layer, and this situation testified the role of grain boundaries in this study. To summarize, in the study, including the phase transition, precipitation, and change of grain boundary, have improved the performance of the TIG remelt-ed 4Cr5MoSiV1 greatly, which can develop its innovative applications. •TIG remelting process imoproved the corrosion and wear properties of the 4Cr5MoSiV1 (AISI H13) steel.•TIG remelting promoted the phase on the surface of 4Cr5MoSiV1 steel transited from BCC to FCC.•A lot of Cr3C2 precipitates extensively segregated at the grain boundaries after TIG remelting.•The protection of grain boundaries resulted in the better hardness but worse impact toughness of the TIG remelting layer.