Preparation And Properties Of Zinc Corrosion-resistant Laser-modified Layer

Steel materials have a series of advantages, such as good toughness, high strength,cost-effective. However, they are easily corroded in the air. Researchers have beenexploring measures to protect steel materials recently. Hot-dip galvanizing is one of themost effective measures to delay corrosion of steel materials in numerous protectionmethods. But most materials can react with zinc liquid which causes failure of materials orpollution of zinc liquid. Sink roll, stabling roll and bushings are important consumableparts in hot-dip galvanizing production line. In this issue, a variety of cobalt-based alloylayers are prepared by laser cladding process on316L stainless steel. The microstructure,microhardness and wear resistance of layers are studied, and the properties evaluation ofthe layer is conducted after corrosion-resistant of zinc test in liquid zinc. Get Co-basedlaser cladding layers which is applicable to Sink roll, stabling roll and bushings of stripcontinuous production line, and explore the optimal laser cladding process parameters.It was found that the microstructure of Co-based laser cladding layer is fine, and itformed a good metallurgical bonding between the layer and substrate. Preheatingprevented cracks inducing by laser irradiaditon produce phase change. Constant laserpower conditions, with increasing laser scanning speed, the finer microstructure. Constantlaser scanning speed conditions, with increasing laser power, the more coarsemicrostructure. The optimal parameters is laser power P=2kW, laser scanning speedV=1000mm/min, spot diameter D=3mm. The microstructure of CoCrMo laser claddinglayers mainly consists of γ-Co phase or γ-(Co,Cr) matrix phase and dendritic Cr7C3whichdistributes in matrix phase. In addition, Laves phase Co3Mo2Si which consists of Mo andSi is found in the microstructure increases corrosion-resistant of zinc.(Co,W)6C of thehigh content of W is obtained in CoCrW alloy laser cladding layers, so it caused the effect of dispersion strengthening and fine grain strengthening. The microhardness of Co-basedalloy powder laser cladding layers increases significantly microhardness than that ofsubstrate. The higest microhardness of CoCrMo alloys is4#which increases nearly5times than substrate. The higest microhardness of CoCrW alloys are7#and10#whichincreases nearly4times. The wear resistance of4#with a large amount of Cr is the best,and it is1/3of1#and1/2of2#in the same condition weight loss. The wear mechanismis oxidation. The ability of corrosion-resistant of zinc was as following:(3#,4#，5#，6#)>(1#，2#)>(7#，10#)>(8#，9#，11#)>(12#，13#). So the ability of corrosion-resistantof zinc of CoCrMo alloys laser cladding layer is better than that of CoCrW, and CoCrNiis the lowest...