等温淬火温度对40Si2MnCrV弹簧钢组织及性能的影响OA

40Si2MnCrV spring steel was subjected to austempering treatments at different temperatures.The microstructure was characterized using scanning electron microscopy,electron backscatter diffraction,and X-ray diffraction,while the mechanical properties were evaluated through tensile and impact tests.The experimental results show that the microstructure of the experimental steel quenched below the Ms mainly consists of martensite,bainite,and retained austenite,whereas the microstructure of the steel quenched above the Ms is primarily composed of bainitic ferrite,retained austenite,and martensite/austenite islands.Compared with the austempering samples above the Ms,the austempering samples below the Ms have higher retained austenite content and lower tensile strength.With the increase of austempering temperature,the tensile strength first decreases from 1.521 GPa at 230 ℃ to 1.074 GPa at 330 ℃,and then increases to 1.216 GPa at 370 ℃.At the austempering temperature of 310 ℃,the steel exhibits the optimal comprehensive mechanical properties,with the yield strength of 0.87 GPa,tensile strength of 1.135 GPa,elongation of 36.3％,reduction of area of 52.1％,and impact energy of 92.1 J.