Fatigue properties of resistance spot-welded maraging steel produced by selective laser melting

This research study investigates the fatigue properties of resistance spot welds (RSWs) made from selective laser-melted (SLMed) maraging steel (MS1) and compares them with dual-phase (DP) steel RSWs. The findings reveal that MS1 spot welds exhibit superior fatigue properties compared with DP steel RSWs, regardless of the printing orientation of the MS1 substrate. Furthermore, fatigue fracture occurs at the MS1 substrate, with a transition of fracture location observed from MS1 to itself and MS1-to-DP600 dissimilar welds. The results of structural stress analysis indicate that the weld nugget diameter is not the only factor affecting the fatigue life. The study also highlights the importance of considering materials inhomogeneity and fracture modes in fatigue life assessment. Based on the findings, the study recommends the development of a new fatigue life prediction curve for spot welds of additive manufacturing (AM) materials. Such a curve would be beneficial in promoting the further application of AM technology for functional parts of design verification vehicles (DCV) and production cars. Overall, the research contributes to the understanding of the fatigue properties of RSWs made from SLMed MS1 and DP steel, which has implications for the design and manufacturing of parts in the automotive industry.