Structure and Properties of R18U Surfacing of Highspeed Steel After its High Tempering.

Using plasma surfacing in a nitrogen environment with a PP-R18U non-current-carrying flux-cored wire, the layers up to 10 mm thick were formed on a 30HGSA steel, followed by an additional high-temperature tempering (at 580°C for 1 hour in 4 tempers). It is shown that the deposited layer has a frame-type structure formed by α-iron grains with extended layers of the Fe₃W₃C (M₆C) carbide phase located along the boundaries. Nanosized particles of carbides of the V₄C₃, Cr₇C₃, Fe₃C, Cr₂₃C₆ and WC_1–x types are identified in the grain volume. It is found out that high tempering increases the microhardness of the deposited PP-R18U layer by 13% (up to 5.3 GPa) and decreases its wear resistance by 12.3% the friction coefficient by 7.7%. [ABSTRACT FROM AUTHOR]