热处理对14Cr14Co12Mo5低碳马氏体轴承钢组织性能的影响

Effect of heat treatment on microstructure and properties of 14Cr14Co12Mo5 low carbon martensitic bearing steel

通过光学显微镜、扫描电镜、X射线衍射、透射电镜、洛氏硬度、冲击测试和拉伸试验等研究了淬火+冷处理和高温回火循环热处理工艺对14Cr14Co12Mo5低碳马氏体轴承钢组织性能的影响。结果表明:经淬火、两次冷处理及高温回火后,不仅可以细化试验钢中的马氏体板条,而且能有效促进残留奥氏体向马氏体转变,马氏体板条宽度从511.5 nm细化至116.0 nm,马氏体体积分数从78.4%增加至87.9%。此外,在高温回火过程中板条马氏体内的M_(23)C_(6)和M_(7)C_(3)细小碳化物不断析出,不仅可以提高试验钢的强度和硬度,而且细小弥散分布的碳化物也可以提高其韧性。经淬火+冷处理和高温回火工艺处理后,试验钢的抗拉强度为1624 MPa,硬度为49.5 HRC,冲击韧性为136 J/mm^(2),实现了强韧性的良好匹配。

Effect of quenching+cryogenic treatment and high-temperature tempering cyclic heat treatment on microstructure and properties of 14Cr14Co12Mo5 low carbon martensitic bearing steel was studied by means of optical microscope,scanning electron microscopy,X-ray diffraction,transmission electron microscopy,Rockwell hardness,impact test and tensile test.The results show that after quenching,twice cryogenic treatment and high-temperature tempering,not only the martensite lath in the experimental steel can be refined,but also the transformation of retained austenite to martensite can be promoted effectively.The width of martensite lath is refined from 511.5 nm to 116.0 nm,and the volume fraction of martensite is increased from 78.4% to 87.9%.In addition,the M_(23)C_(6) and M_(7)C_(3) fine carbides in the lath martensite are continuously precipitated during the high-temperature tempering,which can not only improve the strength and hardness of the experimental steel,but also improve the toughness of the steel due to the fine dispersed carbides.After being quenched,cryogenic treated,and high-temperature tempered,the tensile strength,hardness and impact toughness of the experimental steel are 1624 MPa,49.5 HRC and 136 J/mm^(2) respectively,achieving a good match of strength and toughness.