GCr15钢超高周的疲劳行为

以GCr15钢为试验材料进行旋转弯曲超高周疲劳行为的试验研究,用电子显微镜对试样断口进行观察.结果表明:疲劳裂纹的萌生机制可以分为两种,一种为表面裂纹萌生机制,发生在高应力幅短寿命区,是由试样表面晶体滑移或表面夹杂引起的;另一种为内部裂纹萌生机制,发生在低应力幅长寿命区,是由试样内部的非金属夹杂物引起的.通过对试验结果的分析和处理,描绘出了GCr15钢的S-N曲线.通过对裂纹萌生位置处尺寸参数的计算和评估,阐述了裂纹萌生于内部的破坏机理,提出了基于裂纹尺寸参数的超高周疲劳极限的推定方法.

Fatigue Behavior of GCr15 Steel in Ultra-High Life Region

For the sake of revealing the ultra-high cycle fatigue behavior,GCr15 bearing steel was used as testing material and rotating bending fatigue test was adopted.The fracture part of the sample was observed by using SEM.Test results show that fatigue crack initiation has two different mechanisms.One is called the surface crack initiation mechanism.It is governed by a crystal slip or nonmetallic inclusion on the specimen surface,which occurs in the region of short fatigue life and high stress amplitude level.The other is called the internal crack initiation mechanism.It is governed by nonmetallic inclusion at subsurface which occurs in the region of long fatigue life and low stress amplitude.Through the analysis and disposal of the experimental results,the S-N curve was depicted.Through the calculation and evaluation of crack initial size parameter,mechanism for internal fracture mode where fatigue crack occurs at specimen subsurface was discussed and fatigue life prediction procedures were indicated based on crack initial size parameter.