喷丸处理对马氏体时效超高强度钢疲劳性能的影响

通过喷丸处理改善固溶+时效态某马氏体时效超高强度钢的疲劳性能。采用成组法和升降法对喷丸前后试样进行应力比R=-1的旋转弯曲疲劳试验,得到喷丸前后试样的疲劳寿命及1×10⁷周次下的疲劳极限,采用双加权最小二乘法拟合喷丸前后试样S-N曲线。采用X射线衍射法测定喷丸后试样残余应力,并结合ANSYS有限元数值分析,研究了喷丸残余应力对某超高强度钢疲劳性能的影响。结果表明:喷丸可显著提高某超高强度钢的疲劳寿命和疲劳极限,喷丸后的疲劳极限约为喷丸前的1.37倍;喷丸后产生的残余应力使疲劳源远离表面,且外载应力越小,疲劳源距离表面越远,寿命提高的效果越明显。

Influence of shot peening on fatigue property of maraging ultra-high strength steel

Fatigue property of a maraging ultra-high strength steel in solution treated and aged state was improved by shot peening. A rotating bending fatigue experiment of the specimens before and after shot peening was performed at stress ratio R =-1. Fatigue lives and fatigue limit at 1 × 10^7 cycles were tested using the group method and staircase method,and the S-N curves were fitted with a double weighted least square method. Using X-ray diffraction to determine the residual stress of the shot peening samples,and combined with the results of finite element,the effect of residual stress on fatigue property of the ultra-high strength steel was studied. The results show that shot peening can significantly improve the fatigue life and fatigue limit of the ultra-high strength steel,and the fatigue limit after shot peening is 1. 37 times higher than that of the unshot-peened specimens. The residual stress caused by shot peening makes the fatigue source far away from the surface,and the smaller the loading stress,the farther the distances of the fatigue source from the surface,and the effect of fatigue life improvement is more obvious.