Study on High Temperature Friction and Wear Properties of Austenitic Hot Working Die Steel at 750 ℃

The high temperature friction and wear properties of SDHA hot working die steel under different loads at 750 ℃were studied by high temperature friction and wear testing machine. Meanwhile,the widely used martensioned hot working die steel SDDVA was used for comparison.The wear surface,cross section morphology and surface phase composition of the two materials were analyzed by optical profilometer,SEM and XRD.The results show that the wear rate of SDHA steel is in the range of 1.22-4.11×10^-5 mm³/ (N·m)and that of SDDVA steel is in the range of 18.9-23.3×10^-5 mm³/ (N·m)under 10-20 N load at 750 ℃. The oxidation layer of the two materials undergoes the process of "deformation →cracking →spalling →reoxidation of the spalling region" under the action of load.In addition,the oxides of SDHA steel are composed of Fe₂O₃ and Fe₃O₄,and the oxides of SDDVA steel are composed of FeO,Fe₂O₃ and Fe₃O₄.At 750 ℃,SDHA steel has higher compressive strength and microhardness than SDDVA steel. The maximum compressive strength and microhardness of SDHA steel are 590.21 MPa and 432 HV0.2,respectively,and the maximum compressive strength and microhardness of SDDVA steel are 390.24 MPa and 290 HV0.2.