Welding processes often produce high levels of tensile residual stress. Low transformation temperature (LTT) welding wires utilise phase transformation strains to overcome the thermal contraction of a cooling weld. In this paper, the residual stress within each weld was quantified using the milling/strain gauge method, being the strain change measured as the weldment was milled away. The fatigue tests were conducted under uniaxial loading considering two types of LTT materials. The results show that the crack propagation of all samples was similar in cycles although both LTT materials extended the crack initiation, and, therefore, the overall life of the part. It was found that both LTT materials reduced the residual tensile stresses, increased the residual compressive stresses, leading to increase in fatigue life about 30%.

焊接工艺通常会产生高水平的拉伸残余应力。低转变温度 (LTT) 焊丝利用相变应变来克服冷却焊缝的热收缩。在本文中，使用铣削/应变仪方法量化每个焊缝内的残余应力，即在铣削焊件时测量的应变变化。疲劳试验是在考虑两种 LTT 材料的单轴载荷下进行的。结果表明，尽管两种 LTT 材料都延长了裂纹萌生时间，因此延长了零件的整体寿命，但所有样品的裂纹扩展周期相似。结果发现，两种 LTT 材料都降低了残余拉应力，增加了残余压应力，导致疲劳寿命增加约 30%。