Effect of WC Additions on Microstructure and Properties of Fecrnisib Surfacing Layer Prepared by Plasma Surfacing

FeCrNiSiB surfacing layers with different mass fractions of WC powders are prepared on surface of Q235 low-carbon steel used in ships by plasma surfacing method, and the effects of WC addition on the microstructure, hardness and friction and wear properties of the FeCrNiSiB surfacing layer are investigated. Results show that the cross section of the surfacing specimen consists of three parts, which are the surfacing layer, fusion zone and matrix. The phases in the surfacing layer include Cr₂₃C₆, Cr₃Fe₁₄C, C and WC. Black and white phases are alternately distributed in the surfacing layer. The white phase is alloy binding phase with low melting point, which has a large amount of Fe and C elements, and a small amount of Cr and W. Compared with the white phase, the black phase is carbide strengthening phase with high melting point, with a small amount of Fe element and a large amount of W, C and Cr elements, and the addition of WC powders promote the volume ratio of the carbide strengthening phase. The hardness of the surfacing layer rises with the increase of the WC addition, and the hardnesses in the lower zone of the surfacing layer are higher than that in the upper part. The friction coefficient of the surfacing layer remains between 0.55 and 0.65, and with the increase of WC addition, the friction coefficient decreases first and then increases. The FeCrNiSiB surfacing layer prepared with WC addition of 30% and the welding current of 130 A has the best friction and wear performance.