Abstract This paper investigates the effect of overload and misalignment on crack propagation of laser welded T-joints. The results showed that the crack growth rates of these joints are like those of base material. For single overload, the increase of Δ K from 8.5 to 13 M P a m 1 / 2 multiplied the average retarded crack growth rate by 7.5 for R = 0.4. The highest crack retardation was caused by multiple overloads with overload ratio of 2 and interval of 10,000 cycles between overload peaks. According to fractographies, the size of plastic zone ahead of the crack tip and the crack branching governed for crack retardation.

中文翻译：

---

加载顺序对错位激光焊接T型接头疲劳裂纹延迟的影响

摘要 本文研究了过载和错位对激光焊接T 型接头裂纹扩展的影响。结果表明，这些接头的裂纹扩展速率与母材的裂纹扩展速率相似。对于单个过载，Δ K 从 8.5 增加到 13 MP am 1 / 2 使平均延迟裂纹扩展速率乘以 7.5，R = 0.4。最高的裂纹延迟是由多个过载引起的，过载率为 2，过载峰值之间的间隔为 10,000 次。根据断口学，裂纹尖端前塑性区的大小和裂纹分支决定了裂纹延迟。