进行超声波疲劳和疲劳裂纹扩展速率实验, 研究了3种60Si2CrVA弹簧钢的超高周疲劳破坏行为.结果表明, 60Si2CrVA弹簧钢的超高周疲劳性能主要与其中夹杂物的尺寸有关,即随着夹杂物尺寸的减小, 钢的疲劳寿命和疲劳强度均逐渐提高.对于内部夹杂物引起的疲劳破坏, 在低应力幅、高循环周次(约大于106 cyc)条件下,在夹杂物周围的鱼眼处往往存在粗糙的粒状区域(GBF). 对于A-60钢,随着疲劳源夹杂物处应力场强度因子幅的减小, 疲劳寿命增加;而GBF处的应力场强度因子幅并不随疲劳寿命变化而变化,基本为一常数(平均值为4.6 MPa×m1/2),与疲劳裂纹扩展门槛值(4.3 MPa×m1/2)接近.
The very high cycle fatigue fracture behavior of three heats commercial spring steels 60Si2CrVA were studied by using ultrasonic fatigue test and fatigue crack propagation rate test. The experimental results indicate that fatigue failures originated mainly from large oxide inclusions. There was significant difference of the very high cycle fatigue properties of the tested three heats, although their oxygen content is equal. Further investigation reveals that this difference was mainly caused by the difference of inclusion size. That is to say, both fatigue life and fatigue strength increase with decreasing inclusion size. It was also found that in the case of internal inclusion-induced fractures at cycles beyond about 1×106, a fish-eye area was usually seen on the fracture surface, and inclusion was usually observed inside the fish-eye and a granular bright facet (GBF) was found in the vicinity around the inclusion. Further investigation of heat A-60 reveals that the stress intensity factor range at crack initiation site of inclusion ΔKinc had the trend to decrease gradually with increasing the number of cycles to failure Nf. However, the stress intensity factor range of GBF ΔKGBF had the trend to be almost constant with Nf with an average value of about 4.6 MPa•m1/2, which is very close to the fatigue crack propagation threshold of about 4.3 MPa•m1/2.
参考文献
| [1] |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%