Preparation,Microstructure And Properties Of Precipitation Enhanced Co_1.5CrFeNi_1.5W_x High Entropy Alloy Cladding

Roll,conveying roll and slitting guide wheel are prone to wear,oxidation and corrosion during rolling.The hardness of traditional high chromium cladd-ing layer is insufficient,while the machinability of cemented carbide cladding layer is poor.Based on this,a precipitation strengthened high entropy alloy cl adding layer with oxidation resistance,corrosion resistance,easy machining and high hardness is developed on the basis of Fe-Co-Mo type carbon free precipi tation hardening high speed steel in the early stage.A series of were prepared by argon arc cladding Co_1.5CrFeNi_1.5W_xhigh entropy alloy cladding layer,and introduce aging treatment for precipitation strengthening to further optimize its microstructure and properties.The effects of W content and aging treatment on microstructure,phase composition,Laves phase transformation,mechanical pro-perties,corrosion resistance and high temperature oxidation resistance of clad-ding layer were studied.Precipitation strengthening mechanism of Co_1.5CrFeNi_1.5W_xhigh entropy alloy cladding layer.The preliminary conclusions are as fo-llows:1.Study the high-entropy alloy cladding layer of cladding Co_1.5CrFeNi_1.5W _x（x=0,0.5,1,1.5,2）and find that the cladding alloy is composed of white W-rich phase,grayμphase（Fe₇W₆and Co₇W₆）and the dark gray matrix FCC phase composition.A large number of network dendritic structures and a smal l amount of flocculentμphase exist at the cladding grain boundaries.After he at treatment,the network dendritic structure disappears,and a large number of flocculentμphases exist at the grain boundaries.The hardness of the cladding layer increases with the increase of W content,and the hardness of W1.5 is t he highest,up to 682.18HV.2.To study the effect of heat treatment process on the microstructure and properties of Co_1.5CrFeNi_1.5W_x（x=0,0.5,1,1.5,2）high-entropy alloy claddin g layer.The optimum tempering time of the cladding layer is 30min,and the optimum tempering temperature is 610℃.The cladding layer was directly temp ered after cladding,and all cladding layers showed precipitation strengthening.After tempering at 610℃ for 30 min,the microhardness of W1.5 was as hig h as 945.01HV,but with the increase of tempering temperature,the microhardn ess was as high as 945.01HV.With the increase of high temperature and temp ering time,the hardness gradually decreased.4.Electrochemical tests were carried out on Co_1.5CrFeNi_1.5W_x（x=0,0.5,1,1.5,2）cladding state and heat-treated high-entropy alloy cladding layers respe ctively,and it was found that the W1.5 Has the best corrosion resistance.After heat treatment,the uniformity of the structure has been greatly improved,the number of pitting pits is significantly reduced compared with the cladding state,and the size of the pitting pits is also significantly smaller than that of the cl adding state.5.Co_1.5CrFeNi_1.5W_x（x=0,0.5,1,1.5,2）cladding and heat-treated high-ent ropy alloy cladding layers were oxidized at 500℃,600℃,and 700℃,resp ectively,and found that 500℃ When oxidized at 600℃,the oxidation weigh t gain of the cladding and heat-treated high-entropy alloy cladding layers is not obvious,indicating that the high-temperature oxidation resistance is better at t his temperature.When oxidized at 700℃,the oxidation weight gain of the cl adding and heat-treated high-entropy alloy cladding layers is quite different.Ex cept for W1.5,the high-temperature oxidation resistance of other high-entropy a lloy cladding layers is poor.