Microstructures And Mechanical Properties Of High Entropy Alloy After Hot Rolling

Fe_49.5Mn₃₀Co₁₀Cr₁₀C_0.5 is a kind of typical two-phase high entropy alloy designed by German scientist D.Raabe,and the plastic effect induced by phase transformation is introduced,so it has higher strain hardening ability and tensile strength.The alloy overcomes the strength–ductility trade-off,and significantly reduces the cost,however,the research on the microstructure and mechanical properties of the alloy after hot rolling annealing has not been reported up to now.This research is innovative and provides theoretical and technological basis for the application of the alloy,which has important scientific significance and engineering value.The as-cast Fe_49.5Mn₃₀Co₁₀Cr₁₀C_0.5 alloy was pretreated by forging,hot rolling and homogenizing annealing to obtain a high entropy alloy with uniform composition and almost single phase FCC structure.By OM,XRD,SEM,EBSD,TEM,hardness measurement and tensile property measurement,the effects of hot rolling temperature,hot rolling reduction,hot rolling passes,cooling method after hot rolling and initial grain size before hot rolling on the microstructure and mechanical properties of the alloy were studied for the first time.After homogenization annealed Fe_49.5Mn₃₀Co₁₀Cr₁₀C_0.5 high entropy alloy at 1200?×2h was hot rolled at six passes(600??1000?)with total reduction of 60%,with the increasing rolling temperature,the recrystallization degree increases gradually,and the micro hardness,yield strength and ultimate tensile strength decrease from 345 HV_0.2 to279 HV_0.2,811 MPa to 569 MPa and 1043 MPa to 887 MPa,respectively,and the elongation increases from 36%to 52%.After homogenization annealed Fe_49.5Mn₃₀Co₁₀Cr₁₀C_0.5 high entropy alloy at 1200?×2h was hot rolled at 1000?for different passes(1-6 passes)with total reduction of 60%,with the increasing rolling passes,the recrystallization degree increases,and the hardness and yield strength decrease from 313 HV_0.2 to 279 HV_0.2 and702 MPa to 569 MPa,respectively,and the ultimate tensile strength and elongation first increase and then decrease.The comprehensive tensile properties of the alloy after hot rolling at four passes are better,and its yield strength,ultimate tensile strength and elongation are 635 MPa,950 MPa and 58%,respectively.After homogenization annealed Fe_49.5Mn₃₀Co₁₀Cr₁₀C_0.5 high entropy alloy at 1200?×2h by hot rolling at 800?with total reduction of 60%was air cooled,water cooled and air cooled after holding temperature for10min,respectively,the water cooled and air cooled microstructure did not recrystallize,however,the partially recrystallization microstrcture occurs after holding temperature for10min and has excellent comprehensive mechanical properties.Its yield strength,ultimate tensile strength,elongation and strength-plasticity product are 399 MPa,852 MPa,68%and57936 MPa`%,respectively.After homogenization annealed Fe<sub>49.5</sub>Mn<sub>30</sub>Co<sub>10</sub>Cr<sub>10</sub>C<sub>0.5</sub> high entropy alloy at 1200?×2h was air cooled by hot rolling at 1000?with total reduction of 60%,its yield strength,ultimate tensile strength,elongation and strength-plasticity product are 658 MPa,1022 MPa,58%and 59276 MPa`%,respectively.These results provide theoretical and technological basis for the application of the alloy.