Quenched and tempered (Q&T) steels are known for relatively high strength, hardness and wear resistance combined with a comparatively good toughness. One of the most used Q&T steels is the low-alloyed structural steel grade 42CrMo4 (AISI 4140), as it offers a wide range of applications, representing one of the most universal grades for the Q&T heat treatment. In this context, near-net shape additive manufacturing (AM) processes represent promising candidates to overcome prevailing limitations, e.g. for small series, as these processes enable a considerable reduction in costs, as subsequent machining steps can be significantly reduced. For processing of metallic materials, the focus is particularly on powder bed-based AM processes such as laser-based powder bed fusion of metals (PBF-LB/M) and electron beam-based powder bed fusion of metals (PBF-EB/M). However, with respect to manufacturing of the low-alloyed Q&T steel 42CrMo4 by powder bed-based AM techniques, studies employing the PBF-EB/M process are still limited. The present study, thus, focuses on assessing the structural integrity of Q&T steels manufactured via PBF-EB/M technique.

Near-fully dense components were fabricated by optimizing key process parameters, such as beam current, scanning speed (v) and hatch distance (h), aiming on an enhanced microstructure and mechanical properties. For mechanical characterization, hardness and quasi-static mechanical properties in both, as-built and heat-treated conditions, were assessed in order to examine the effects of post-processing routes. In direct comparisons with conventionally manufactured 42CrMo4 steel, the PBF-EB/M material revealed that tailored properties can be achieved. This work demonstrates the potential of PBF-EB/M to produce high-strength, wear-resistant steel components with the added benefits of design flexibility and reduced efforts in post-processing, making 42CrMo4 suitable for demanding engineering applications.