热处理工艺对NM500耐磨钢组织和力学性能的影响

通过扫描电子显微镜,电子背散射衍射、透射电子显微镜以及力学分析等方法研究了在线淬火-回火(DQ-T)和再加热淬火-回火(RQ-T)对NM500耐磨钢组织和性能的影响,并讨论了不同热处理工艺的强化机理.发现试样经过不同的热处理工艺后在较高的强度下均能保持良好的韧性.由于位错密度的增加和更细的马氏体板条束尺寸,DQ-T试样的抗拉强度和硬度明显高于RQ-T试样,但是强度的增加并没有造成韧性和塑性急剧的降低.再加热淬火温度对RQ-T试样的强度影响较大,当淬火温度较低时,马氏体板条束得到细化,这种细晶强化作用有效地提高了RQ-T试样的强度. 

Heat treatment influence on the microstructure and mechanical properties of NM500 wear resistant steel

The effects of direct quenching-tempering (DQ-T) and reheat quenching-tempering (RQ-T) on the microstructure and mechanical properties of NM500 wear resistant steel were studied by scanning electron microscopy, electron back-scattered diffraction, transmission electron microscopy, and mechanical testing. The strengthening mecha-nisms of these heat treatment processes were also discussed in the paper. It is found that samples treated by DQ-T and RQ-T both have good ductility and high strength. The tensile strength and hardness of the DQ-T sample are superior to those of the RQ-T sample due to higher densities of dislocations and smaller sizes of martensite blocks, but the impact toughness and ductility of the DQ-T sample do not drop significantly. For the RQ-T sample, reheat quenching temperature has a remarkable effect on the strength, and fine blocks can be obtained when the quenching temperature is not high. This grain refinement strengthening can be an effective method to increase the strength of the RQ-T sample.