Nowadays, the use of different classes of materials in the same structure is increased to keep pace with innovation and high structural performances. In this context, structural components made of different materials need to be joined together and a possible solution is given by arc welding. Dissimilar welded joints must often be able to withstand fatigue loads; however, Design Standards provide fatigue strength categories only for homogeneous welded joints. The aim of the present paper is to compare the fatigue behaviour of EN-GJS-1050 austempered ductile iron-to-S355J2 steel dissimilar joints to the categories of the corresponding homogeneous steel welded joints, as suggested in International Standards and Recommendations. For this purpose, experimental fatigue tests were performed on a selection of dissimilar welded details. First, the microstructure was identified by metallographic analysis; micro-hardness measurements were collected and residual stress profiles were obtained by using the X-ray diffraction technique on a selection of joints. Misalignments were quantified for all specimens. Then, experimental fatigue tests have been performed on a number of joint geometries subject to axial or bending fatigue loadings and tested in the as-welded conditions. The fracture surfaces of the joints have been analysed to locate fatigue crack nucleation sites.

如今，在同一结构中增加使用不同类别的材料以跟上创新和高结构性能的步伐。在这种情况下，需要将由不同材料制成的结构部件连接在一起，并通过弧焊给出可能的解决方案。异种焊接接头通常必须能够承受疲劳载荷。但是，设计标准仅提供了均匀焊接接头的疲劳强度类别。本文的目的是按照国际标准和建议书，将EN-GJS-1050奥氏体球墨铸铁与S355J2钢异种接头的疲劳性能与相应的均质钢焊接接头的类别进行比较。为此，对一系列不同的焊接细节进行了实验疲劳测试。第一的，通过金相分析鉴定组织；收集显微硬度测量值，并通过使用X射线衍射技术对选定的接头获得残余应力曲线。对所有样本的错位进行了量化。然后，已经对许多承受轴向或弯曲疲劳载荷的几何形状进行了实验疲劳测试，并在焊接条件下进行了测试。已经分析了接头的断裂表面以定位疲劳裂纹成核位置。已经对许多承受轴向或弯曲疲劳载荷的几何形状进行了实验疲劳测试，并在焊接条件下进行了测试。已经分析了接头的断裂表面以定位疲劳裂纹成核位置。已经对许多承受轴向或弯曲疲劳载荷的几何形状进行了实验疲劳测试，并在焊接条件下进行了测试。已经分析了接头的断裂表面以定位疲劳裂纹成核位置。