60Si_2Mn钢变幅疲劳的扫描电镜直接观察

DIRECT OBSERVATION ON VARIABLE AMPLITUDE FATIGUE BEHAVIORS IN 60Si2Mn STEEL BY SEM

应用自制的扫描电镜疲劳加载台,对60Si2Mn 弹簧铜过载或欠载时疲劳裂纹扩展的延迟与加速效应进行了扫描电镜的直接观察.结果表明,尖峰载荷会使闭合力K_(c1) 发生明显变化.欠载会使 K_(c1) 下降,其与裂纹顶端的反转压缩塑性区有关.

Direct observation was accomplished on overload retardation and underload acceleration phenomena of fatigue crack growth in 60Si2Mn spring-steel by self-made SEM fatigue loading stage.Results showed that the spike load may cause the closure force,Kcl,to change obviously,and under-spike load may reduce Kcl.The acceleration effect is associated with the crack tip reversed compre-ssive plastic deformation zone.