Effect of quenching temperature on performance of chromium-molybdenum steel
The microstructure and mechanical properties of quenching at different temperatures(860～920℃)and tempering process were studied by optical microscope,electron microscope,universal testing machine and impact testing machine.The results showed that under the premise of keeping the tempering temperature unchanged at 580℃,the chromium-molybdenum steel pipe material had good comprehensive mechanical properties when it was quenched from 900℃ for 30 min.Its tensile strength was 933 MPa,yield strength was 857 MPa,elongation after fracture was 24％,and the impact energy at room temperature was 194.8 J,which meet the normal use needs of drill pipe.After 30 minutes of holding at 860-920℃,followed by water cooling and 50 minutes of holding at 580℃,the microstructure of the material was found to be tempered martensite.However,when quenching from 860℃,a certain amount of ferrite appeared,resulting in poor overall mechanical properties;By observing the impact fracture surface under an electron microscope,the fracture surfaces quenched from different temperatures(860-900℃)and tempered were all characterized by dimples.However,when hold at 900℃for 30 minutes,then water cooling,and hold at 580℃for 50 minutes,the dimples were the smallest and most dense.When the quenching temperature increased to 920℃,the dimple characteristics of the fracture surface were no longer obvious,and it was in the transition stage from toughness to brittleness.
万方数据
维普
