夹杂物对超高强度钢低周疲劳裂纹萌生及扩展影响的原位观测

SEM IN SITU OBSERVATIONS TO THE EFFECTS OF INCLUSIONS ON INITIATION AND PROPAGATION OF THE LOW CYCLIC FATIGUE CRACK IN SUPER STRENGTH STEEL

采用扫描电镜原位观测了数微米大小夹杂物对超高强度钢疲劳裂纹萌生及扩展的影响,并用有限元法解释了夹杂物尺寸 和形状对疲劳裂纹萌生及初期扩展的影响程度,得到了超高强度钢低周疲劳裂纹萌生与扩展特性和夹杂物对疲劳破坏的关键尺寸的 估计值．同时,讨论了现行实验方法对确定铁基材料裂纹扩展速率的作用．

SEM in situ observations for the effects of inclusions on the fatigue crack initiation and propagation behaviors of super strength steel indicate that the inclusion size and shape affect not only on the fatigue crack initiation location but also on the crack growth behavior. At the same time, the effects of inclusions on the fatigue crack initiation are discussed by finite element method （FEM） analysis. The critical size of inclusion in low cyclic fatigue crack propagation is proposed and the influence of fatigue crack growth rate is estimated.