Low-carbon S30C Steel with Superior Strength and Ductility Fabricated by Powder Bed Fusion-Electron Beam

This study demonstrates the potential of electron beam powder bed fusion (PBF-EB) for the fabrication of low-carbon S30C steel with superior strength and ductility. In addition to investigating the effect of preheating temperature on microstructural evolution, we examined the effect of subsequent quenching and tempering treatments. At 1033 K, equiaxed α-Fe grains dominated, whereas at 1173 K, elongated grains and side plates aligned with the build direction were more prevalent, resulting in a pronounced < 101 > texture. These microstructural features introduced anisotropy along the build direction, which was effectively mitigated by tempering. Compared with conventionally processed low-carbon S30C steel, the additively manufactured specimens exhibited higher yield and tensile strengths and improved ductility, achieving a maximum tensile strength of 1914 MPa and an elongation of 17%. The exceptional mechanical performance is attributed to the refined martensitic structures and high dislocation density induced by the PBF-EB process. These findings highlight the capability of PBF-EB to produce structural carbon steels with tunable properties by controlling the process parameters, thereby offering a cost-effective route for the industrial-scale additive manufacturing of steels.