深冷处理对EA4T车轴钢马氏体组织及短裂纹行为的影响  

Effect of deep cryogenic treatment on the martensite structure and short crack behavior of EA 4 T axle steel

作　　者：苏畅 杨冰[1] 宋江杰 肖守讷[1] 阳光武[1] 朱涛[1] SU Chang;YANG Bing;SONG Jiangjie;XIAO Shoune;YANG Guangwu;ZHU Tao(State Key Laboratory of Traction Power,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学牵引动力国家重点实验室,四川成都610031

出　　处：《中南大学学报（自然科学版）》2023年第4期1300-1310,共11页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51675446);四川省国际科技创新合作项目(2022YFH0075);牵引动力国家重点实验室自主课题(2022TPL-T03)。

摘　　要：利用光学显微镜(OM)、维氏硬度计、X射线衍射(XRD)和电子背散射衍射(EBSD)技术等,开展深冷处理与回火顺序对EA4T车轴钢马氏体组织及其疲劳断裂性能影响的研究。研究结果表明:无论是“回火+深冷”处理还是“深冷+回火”处理,均能有效细化材料的微观组织,从而提高硬度和位错密度,但组织中含量较少的残余奥氏体无法通过深冷处理继续向马氏体转化;相对而言,经“深冷+回火”处理的试样晶粒尺寸细化效果最佳,且小角度晶界占比最多,可有效抑制裂纹的萌生;经“深冷+回火”处理后,材料微观组织对裂纹扩展的阻碍作用最强,裂纹扩展速率的下降更明显,疲劳断裂性能相对更优。The effect of deep cryogenic treatment and tempering sequence on the martensite structure and fatigue properties of EA 4 T axle steel were investigated by optical microscopy(OM),Vickers hardness tester,X-ray diffraction(XRD)and electron backscatter diffraction(EBSD).The results show that both"tempering+deep cryogenic"treatment and"deep cryogenic+tempering"treatment can effectively refine the microstructure of the material,thus improve the hardness and dislocation density.However,the retained austenite with less content in the structure cannot continue to transform into martensite by deep cryogenic treatment.The sample treated by"deep cryogenic+tempering"treatment has the best grain size refinement effect,and the proportion of low angle grain boundary is the largest,which effectively inhibits the initiation of cracks.It can be seen that after the"deep cryogenic+tempering"treatment,the microstructure of the material has the strongest inhibitory effect on crack growth,the decrease of the crack growth rate is more obvious,and the fatigue fracture performance is relatively better.

关 键 词：深冷处理 马氏体 位错密度 组织细化 裂纹扩展 

分 类 号：U270.41[机械工程—车辆工程]