Resistance Spot Welding of Additively Manufactured Maraging Steels—Part II: Failure Behavior

Abstract

Application of maraging steels via selective laser melting process in the automotive industry was unavoidably involved in the resistance spot welding with conventional steels. Due to the rapid cooling rate of welding process, selective laser melted maraging steels with unique chemical components and stack microstructure could induced the different microstructural evolution, resulting in the complicated fracture behavior in the spot welds. This paper developed a FEA model to predict the fracture mode of spot welds of DP600 to maraging steel and the effect of test conditions and printing orientations were studied. A method was proposed to calculate the material properties of fusion zone by introducing the combined effect of melting DP600 and maraging steels via selective laser melting, resulting in the accurate prediction of fracture mode and strength of spot welds. An interlayer with lower strength was found around the fusion zone and the fracture path propagated in the region, resulting in the partial interfacial failure of spot welds. Meanwhile, the printing orientation had no significant effect on the fracture mode and strength of spot welds, but the different material properties of maraging steels could affect the fracture displacement of spot welds. These findings could pave a way to guide the application of maraging steels via selective laser melting process in multiple industries, especially in the automotive industry.

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

“…Element types used in the model were C3D8R and C3D10 in different regions for a balanced computational efficiency and accuracy. The authors' previous work 18 provides a detailed description of the FE modeling method and the local material properties used in the current study.…”

“…Therefore, it is crucial to investigate the effects of printing orientation on the microstructure and mechanical properties of spot welds for SLMed MS1 parts, particularly when welded to conventionally produced steel to form dissimilar spot welds, such as the MS1 to DP600 spot weld. In our previous work, 11,18 we studied the weld nugget formation mechanism in MS1 RSWs with sheets of varying printing orientation, which revealed that the different material properties of maraging steels affect the fracture displacement in the tensile force-displacement curve of spot welds. Furthermore, the effect of printing orientation on the fracture mode and strength of MS1 RSWs were investigated, and results demonstrated that the printing orientation has no significant impact on the fracture mode and strength of spot welds.…”

“…Element types used in the model were C3D8R and C3D10 in different regions for a balanced computational efficiency and accuracy. The authors' previous work18 provides a detailed descriptionT A B L E 3 Fatigue test matrix. I G U R E 2 (A) Measurement method of weld nugget diameter and (B) comparison on weld diameters, A-F are test sets defined in Table 3.…”