Effect of Annealing and Hot Isostatic Pressing on the Structure and Hydrogen Embrittlement Resistance of Powder-Bed Fusion-Printed CoCrFeNiMn High-Entropy Alloys

As an additive-manufacturing (AM) technique, powder-bed fusion (PBF) shows tremendous potential in both the research and industrial communities. Research on the post-treatment of PBF-prepared products is a hot topic. Hydrogen embrittlement (HE) resistance is a practical necessity, especially in microstructures. Here, the effect of annealing and hot isostatic pressing (HIP) on the properties of PBF technology-printed CoCrFeNiMn high-entropy alloys (HEAs) is investigated. The results show that these two post-thermal treatment approaches can release residual stress (from approximately 338 to 44 MPa) from PBF-printed samples, which is the main reason for declines in hardness (from approximately 211 to 194 HV). In addition, both annealing and HIP can reduce HE sensitivity, thus improving resistance to HE, with elongation increasing by 75.4% and 85.4% after annealing and HIP, respectively. In summary, both post-thermal treatments are of great significance to the development of HEAs with optimized structures and protection against HE, which can contribute to the development of these behaviors during application.