Effect Of Arc Fusing On Microstructure And Hydrogen Damage Resistance Of CoCrFeMnNi High Entropy Alloy

CoCrFeMnNi high entropy alloy was been regarded as a potential hydrogen resistant alloy,but it has not been widely used due to the cost and preparation process limitations.In this paper,CoCrFeMnNi high entropy alloy was prepared by induction melting and then arc fused using arc,aiming to explore the feasibility of using CoCrFeMnNi high entropy alloy as a surfacing material with anti-hydrogen function.The effects of internal factors(structure state)and external factors(temperature)on the hydrogen resistance of CoCrFeMnNi high entropy alloy were investigated,and the mechanism was explained.Firstly,the effect of arc fusing on the microstructure of CoCrFeMnNi high entropy alloy was studied by metallographic microscope(OM),scanning electron microscope(SEM),X-ray diffraction(XRD),et al.The results show that the CoCrFeMnNi high entropy alloy before and after arc fusing all have the structure of FCC and precipitates phase,but there are differences in the quantity and distribution of precipitates.In terms of the characteristics of distribution,the precipitates in annealed high entropy alloy are dispersed,while those in arc fused high entropy alloy are intergranular.In terms of quantity,the precipitated phase in annealed high entropy alloy accounts for 11.59%,while in arc fused high entropy alloy the precipitated phase accounts for 24.96%.Secondly,the effect of arc melting on the sensitivity to hydrogen damage of CoCrFeMnNi high entropy alloy was investigated by slow strain rate tensile test and electrochemical hydrogen penetration test,and the mechanism was explained by combining with analyzing microstructure.Results show that the sensitivity of hydrogen damage increased significantly after arc melting.The reason is that after arc melting grain boundary and precipitated phase makes the function of internal hydrogen into the material more easily gathered at grain boundaries,making local high hydrogen content.And promoting local shape mechanism triggered the hydrogen,then hydrogen induced cracking.Finally,through slow strain rate tensile tests at different temperatures.The results show that when the temperature increases from 40℃ to 160℃,the hydrogen damage sensitivity of both annealed and arc fused high entropy alloys decreases.The hydrogen damage coefficient of arc fused high entropy alloy decreases from 43.01% to 13.00,while the hydrogen damage coefficient of annealed high entropy alloy decreases from11.62% to-63.47%.Hydrogen can improve the plasticity of annealed high entropy alloy at 160℃.The reason is mainly related to the interaction of temperature,hydrogen and dislocation,and the influence mechanism remains to be further studied.