热处理对 14Cr14Co12Mo5 低碳马氏体轴承钢组织性能的影响

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 M₂₃C₆ and M₇C₃ 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/mm² respectively, achieving a good match of strength and toughness.