表面疲劳短裂纹在残余压应力场中的扩展

SMALL SURFACE CRACK PROPAGATION IN THE RESIDUAL STRESS FIELDS

研究Ｉｎｃｏｎｅｌ７１８镍基合金表面短裂纹在喷丸残余应力场中的扩展行为。用扫描电镜中的疲劳加载装置对表面裂纹的闭合行为进行原位观察和测量。研究表明，表面短裂纹具有较穿透短裂纹更低的扩展门槛值，表面短裂纹的闭合与残余压应力场的大小和分布密切相关，残余压应力场中的表面短裂纹扩展及形状变化完全可以通过其闭合行为的变化进行解释。

The propagation of small surface crack in a shot peening residual stress field for Inconel 718 nickel base alloy was carried out in this paper. Closure of small surface cracks was studied by means of in situ SEM observation. The results show that small surface cracks have lower threshold comparing with through\|thickness small crack, the propagation and shape change of surface cracks in compressive residual stress field can be totally explained by its closure behaviour, which is related to magnitude and distribution of the compressive residual stress field.