| In this paper,Co-28Cr-6Mo alloy was treated through high pressure torsion(HPT)and high-pressure heat treatment.The microstructural evolution of Co-28Cr-6Mo alloys was characterized by optical microscope,X-ray diffraction,scanning electron microscope,electron backscatter diffraction analyzer and transmission electron microscopy,and the mechanical properties were tested by micro-hardness tester and universal tensile tester.The experimental results show that,after HPT,martensite phase transformation was promoted,hardness increased,and with the rotation numbers increasing,grains were obviously refinement,the hardness increased,the yield strength and tensile strength increased first and then decreased.The grains of the original Co-28Cr-6Mo alloys through HPT,after high-pressure heat treatment,were grown,austenite content increased,hardness increased first and then decreased,yield strength and tensile strength increased,plastic decreased with increasing temperature;with pressure increasing,austenite content first decreased and then increased,and the hardness was opposite,the yield strength and tensile strength decreased,and the plasticity was poor;with time increasing,austenite content first decreased and then increased,and the hardness was opposite.The best performance of Ori-HPT(2)samples was obtained at 5 GPa,1050℃,holding 10 min.The grain of the heat treatment alloys after high-pressure heat treatment,were refined,austenite content and hardness increased,yield strength and tensile strength decreased with increasing temperature;with pressure increasing,grain were refined,austenite content increased,hardness increased,yield strength and tensile strength decreased;with time increasing,grain were refined,hardness first increased and then decreased,yield strength and tensile strength decreased.The best performance was obtained at 5 GPa,950℃,holding 30 min.The grain of the heat treatment alloys under HPT,after high-pressure heat treatment,were grown,hardness decreased,yield strength and tensile strength increased and the elongation decreased with temperature increasing;with pressure increasing,martensite phase transition was promoted and hardness increased first and then decreased;with time increasing,grain were grown,hardness first increased and then decreased,yield strength and tensile strength increased and the elongation decreased.The best performance of HT-HPT(2)samples was obtained at 1 GPa,1050℃,holding 30 min. |
