渗氮及表面增碳对3Cr2W8V钢冷热疲劳行为的影响

Effect of Surface Nitriding and Carburizing on Behavior of Thermal Fatigue in Steel 3Cr2W8V

用板状缺口试样研究了在自约束条件下，表面增碳和渗氮对3Cr2W8V钢冷—热疲劳裂纹萌生、扩展及裂纹形态特征的影响。结果表明，表面增碳及渗氮均使钢的热疲劳裂纹萌生及扩展抗力降低，渗氮尤为显著。经渗氮处理的试样在冷—热疲劳试验中除缺口尖端出现主裂纹外，试样表面较早出现大量裂纹，最后形成龟裂；表面增碳的试样在试验中也出现少量表面裂纹，而表面化学成分无变化的试样则未出现表面裂纹。

Using noched flat specimens under self-restrained condition,the effect of carbon and nitrogen content increased on steel 3Cr2W8V surface on thermal fatigue crack initiation and propagation and shape characteristics has been studied. The results show that the resistances thermal fatigue crack initiation and propagation in steel are reduced due to the Carburizing and nitriding, and nitrogen has the prominent effect. For nitrided specimens,the main crack and a lot of surface cracks appear on the notch top in the thermal fatigue test, and finally network cracks are formed. For the carburized specimen,some cracks appear on the surface, but surface crack is not happened for those without chemical composition change