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Microstructure Characteristics and Performance of a Novel Composite Stellite Alloy Fabricated by Laser Cladding
G-L. Wu, F-C. Ren, J. Zhang, Q-L. Zhang, R. Liu and J-H. Yao

Stellite 3 is an excellent wear-resistant material owing to its high carbon content, but has the serious problem of cracking during laser processing due to its extreme brittleness. To solve this problem a novel composite Stellite alloy which has comparable hardness and sliding wear resistance to Stellite 3 was prepared on 316 stainless steel by laser cladding using a mixed powder of major Stellite 3 and minor Stellite 21. The microstructure and phase of the new alloy was analysed by using a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The hardness, wear resistance and single-tip scratching behavior of the specimens were investigated experimentally. The results showed that no pores and cracks were formed in the new Stellite alloy laser clad layer. The main reinforcement phases in the microstructure consist of (Co,W)3C, Cr23C6, Cr7C3, Co3Mo. The hardness and wear resistance were improved not only by the carbides, but also by the Co3Mo in this new Stellite alloy. The butterfly valve switch test demonstrated that the sealing properties of the new alloy were significantly better than the existing Stellite 6 alloy.

Keywords: Diode laser, Stellite, 316 stainless steel, alloy, sealing valve, laser cladding, microstructure, phase, hardness, wear

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