Effect of laser process parameters on crack rate and microstructure of Ni60/WC clad coating

doi:10.13251/j.issn.0254-6051.2021.09.045

Abstract

Abstract: Effects of laser power (P), scanning speed (v), overlap rate (O) and powder feeding rate (Q) on the crack rate and microstructure of Ni60 /WC coating were studied by single factor test. The phase composition and element distribution of the coating were analyzed by means of energy spectrometer and X-ray diffraction. The results show that the crack rate is directly proportional to the P and inversely proportional to the v. Under the appropriate P and v, the effect of both O and Q on crack rate is not obvious. Both the coating and the substrate can form a good metallurgical bond, and each parameter has no obvious influence on the crystal growth pattern. The whole molten pool is successively composed of planar crystal region, cellular crystal region, relatively fine dendrite region and fine equiaxial crystal region from bottom to top. The grain size is mainly determined by the cooling rate ε. The grain size is directly proportional to the P and inversely proportional to the v and O. However, with the increase of Q, the grain size first decreases and then increases. The Ni60/WC coating is mainly composed of γ-(Fe, Ni), W₂C, Fe₃W₃C, M₇C₃, M₂₃C₆ and Ni₄W, etc, among which the WC part exists in the form of particles, playing the role of second phase strengthening, and part of WC form alloy carbide with Fe, Ni and other elements in the molten pool, in the grain boundary precipitation network, playing the role of grain boundary strengthening.

Key words: laser cladding, Ni60/WC coating, crack rate, microstructure

CLC Number:

TG174.4

Zhou Jianbo, Zhang Jing, Zhang Leitao, Li Haitao, Fan Shuaiqi, Xu Jinfu. Effect of laser process parameters on crack rate and microstructure of Ni60/WC clad coating[J]. Heat Treatment of Metals, 2021, 46(9): 252-257.

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