| As a advanced production technology,laser cladding technology has been widely used in aerospace,metallurgy,chemical industry and transportation industry in recent years.Playing a role as a kind of surface modification technique,laser cladding can produce high resistance of corrosion,wear,oxidation and hardness of the various properties of surface strengthening coating on the surface of low-cost motearal.Due to its good plasticity toughness and corrosion resistance,304 stainless steel is widely used in machinery,light industry,medical durable household consumption and construction.But the general stainless steel materials need additional measures to achieve the purpose of protecting the surface of stainless steel products for it’s low hardness and abrasion resistance.Therefore,there is great practical significance to study on laser cladding of Stellite Alloy and its composite coatings on 304 stainless steel.This paper is about the research on laser cladding stellite 12 coating and stellite 12/TiC coating on 304 stainless steel.Through several experiments to optimize the parameters,single-channel cladding layer with higher quality,fewer defects were formed ultimately.A larger area of the cladding was prepared by multi-track lap with optimal parameters.The microstructure,the composition and distribution phase of the cladding layer was observed and analysed through by using optical microscopy,scanning electron microscopy,and X-ray diffraction.The microhardness and friction and wear tests of different coatings were tested,and the wear resistance of the coatings was evaluated.The microstructure and composition analysis showed that on 304 stainless steel substrate,Stellite 12 coating forming looks good,some slightly slags are on surface,a good metallurgical bond with the substrate.The cross section of the coating shows a convex shape,and its microstructure is fine and uniform.Different power and scanning speed processing of Stellite 12 coatings have similar microstructure of dendrite crystal and cellular crystal appeared.The scanning speed has a significant effect on the microstructure of the coating.The faster the scanning speed,the smaller the dendrite and the more the more the crystalline grains.The scanning speed has a significant effect on the microstructure of the coating.The faster the scanning speed is,the less dendrite and the more crystalline grains apear.The result of stellite 12/TiC show fine but is not continuous and have some splash.No.1 and No.3 coating have more pores and larger transverse cracks.With the same composition of Stellite 12/TiC composite coating,relatively close to the laser cladding layer microstructure,the dendrite and cellular crystal composition,and contains a relatively close phase.The hardness test and wear test results show that the hardness of Stellite 12 coating was higher than 304 stainless steel substrate with 2 times.When the laser power is high,the microstructure of the cladding layer is uniform,and the grain size of the recrystallized grains is basically the same,and no obvious clusters are formed.The hardness of the cladding layer can be improved by the lower scanning speed.When the laser power is higher,the cladding layer has higher hardness.At the same time also has good friction and wear,coating dense and uniform,the strength and toughness of the coating was enhanced to the maximum extent to avoid the friction and wear process of Coating Cracking and spalling.The high hardness of the coating can not only reduce the grinding effect on the friction surface during the subsequent friction,but also prevent the adhesive wear.Different components of Stellite 12 and TiC composite coating,relatively close to the laser cladding layer microstructure,the dendrite and cellular crystal composition,and contains a relatively close phase.The residual TiC particles reinforced effect on coating microstructure,microhardness and wear resistance of Stellite 12 and TiC composite coating compared with 304 stainless steel substrate has been significantly improved. |
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