Bending fatigue properties of structural steel fabricated through wire arc additive manufacturing (WAAM)

Wire arc additive manufacturing (WAAM) has become an essential production method with advantages such as ease of application and economic benefits, along with high material savings and its ability to produce large parts close to their final form in a short time. In recent years, many studies have been carried out on WAAM, most of which have investigated the properties of the manufactured parts. Among these properties, the topic of fatigue was less frequently examined. The reasons for this may include difficulties such as the long duration of fatigue tests and the large number of test specimens required. However, since fatigue is responsible for most of the damage in metal components, it is important to determine the fatigue strength of the parts produced using WAAM. In this study, the WAAM process was applied to low alloy ER70S-6 steel, which is widely used in the metal industry and is also one of the most common materials used in WAAM processes. After the fabrication, horizontal and vertical specimens were obtained from the manufactured part and mechanical and metallurgical tests were applied, including, fatigue tests, with the fatigue properties of the produced WAAMed part determined using a specially designed and produced bending stress fatigue testing machine. Results demonstrated that the fatigue limits of the horizontal and vertical fatigue specimens at 107 cycles were very close to each other, as approximately 180 MPa. The fatigue strength values of the vertical and horizontal specimens were quite similar. However, the fatigue strength of the vertical specimens up to 106 cycles was found to be slightly higher.