Influence Of Remelting Process On Thestructure And Performance Of The Iron-based Composite Coating By Flame Spraying

In this paper, Iron-based alloy coating containing Fe、Cr、W、Ni、Mo、B、Si elements wasprepared using flame spraying technology on the surface of45steel. Different spraying processparameters and the performance after remelting were investigated. The Microstructure andProperties of Iron-based alloy coating both before and after remelting were analyzed by opticalmicroscope、microhardness tester、scanning electron microscope、X-ray diffusion、energydisperse spectroscopy.The results show that the mechanical bond played a dominant role between theoxy-acetylene flame spraying coating and substrate, metallurgical bond played only a subsidiaryrole. The coating consists of deformed particles,undissolved particles,oxides and a small amountof porosity.When the preheating temperature was about200℃,the roughness was40mesh sandpaper roughening treatment,the spraying distance was100mm,the porosity was1.763%,themicrohardness of the coatings reaches579.35HV,the bond strength reaches46.82MPa,thecomprehensive properties were optimal.The flame spraying coating was remelted by argon arc process.The bond betweenIron-based alloy remelting layer and substrate was metallurgical bond.The microstructure wasdense and there are few poles.The remelting layer after arc remelting was divided into threezones: the molten zone,the bonding zone,the heat-affect zone.The microstructure of the moltenzone from surface to close to the bonding zone successively were the tiny Reticular dendrites,size uniform equiaxed crystal, coarse dendritics.The bonding zone was relatively bright andnarrow, grew with planar crystal.The heat-affect zone was coarse widmanstatten structure。Interms of alloy ratio:the enhancement of Iron-based alloy powder hardness and wear resistancehad close touch with the composition of alloy powder.With the adding of chromium iron,thehardness of the remelting layer increases at the first,then remain stable.At the same time,with theadding of WC,the hardness of the remelting layer increases at the first,then decreases.When theFe55Self-fluxing Alloy Powder Contained13%chromium iron,10%WC,the hardness and wearresistance were the best.The hardness of the coatings reaches62.6HRC,the wear loss was0.0952g.