Study Of Modified Layer By Different Processes On Valve Materials

A valve is one of the important parts in the equipment and manufacturing, it is also principal controlled components in the fluid transportation system. Superior or inferior quality and performance of valves have a substantive effect on safety in production and economic benefits for enterprises in the long run. In order to adapt to objective requirements with the rapid development of modern industry, it can improve the performance to conform the use demand and work standards by different processes on the traditional valve materials so that production can be run smoothly and enterprises can develop stably. Consequently, different components modified layer were fabricated used M2 and Ni-based series alloy by different processes on 316 stainless steel and Monel 400 alloy respectively. The microstructure, chemical composition, microhardness, wear-resisting property of the coatings have been investigated by using scanning electron microscope, energy spectrometer, X-ray diffraction, microhardness tester and pin-on-disk wear tester.The testing results indicated that the microstructure of modified layer by laser cladding is compact and fine, its microhardness much higher than that of plasma surfacing. The laser modified layer is mainly composed ofα-Fe, Fe6W6C, Fe3C, Cr₇C₃ and Fe₂MoC, the microhardness and wear resistance increased obviously with add to Y₂O₃, WC particles and C powder. The best wear resistance performance increased nearly 12 times than that of 316 stainless steel. WC particles are dissolved properly and quality of the whole modified layer is best when process parameters of laser irradiation is P = 2.5kW, D = 4mm, V = 6mm/s. Research on the Ni based alloy by laser cladding on Monel shows that, no cracks, pore-free modified layer with good bonding with substrate was obtained when it is fabricated a transition layer on Monel 400 alloy by micro-arc spark deposition in advance and then it is treated by laser cladding on the transition layer. The laser modified layer is mainly composed ofγ-Ni,CrB,Ni3B,Ni3Fe,Cr₇C₃ and Cr23C6, the microhardness and wear resistance increased obviously with add to Y₂O₃ and WC. The best wear resistance performance increased nearly 24 times than that of Monel 400 alloy. WC particles are dissolved properly and quality of the whole modified layer is best when laser process parameters is P = 4kW, D = 1×10mm, V = 6mm/s.