残余压应力场对B780CF钢焊接接头疲劳裂纹扩展的影响

为了明确不同强度残余压应力场对裂纹扩展速率及寿命的影响，采用埋弧自动焊通过不同焊接热输入控制不同焊缝宽度，从而在制备标准CT试样时通过机械加工时的残余应力释放得到各组不同强度残余压应力场的各组焊接接头，并根据裂纹闭合原理，提出基于Elber的三参数分段公式，根据分段公式条件从MTS试验机采用柔度法获得的试验数据中提取、归纳数据，利用断裂力学方法和数理统计方法进行分析，得出结论，裂尖存在的焊接残余压应力场在一定程度上可以明显降低裂纹扩展速率，提高裂纹扩展寿命，对焊接接头裂纹扩展有着关键性作用。

Effect of residual compressive stress field on fatigue crack growth of B780CF steel welded joints

In order to know the effect that residual pressure stress field with different strength to the crack growth rate and life, The standard CT samples of welded joints are prepared through mechanical processing, which coming from the automatic submerged arc welding with different welding line energy and grouping with different residual compressive stress field. Then put forward a three-parameters formula based on the Elber according to the principle of crack closure, which is used to analyze the closure test data from MTS testing machine by the method of fracture mechanics and mathematical statistics. Then get the conclusion, in a certain extent, the welding residual pressure stress field can significantly reduce the crack growth rate, improve the crack propagation life, which plays a key role in crack propagation of welded joint.