Microstructure and fracture toughness of additively manufactured steels via directed energy deposition for pressure vessel application

The application of additively manufactured steels in pressure vessel components presents a promising opportunity for design flexibility, weight reduction, and material efficiency. This study investigates the mechanical performance and microstructural characteristics of various steel grades fabricated via laser directed energy deposition with wire, with a focus on their suitability for pressure vessel application. The mechanical behavior is evaluated through tensile testing and fracture toughness measurements. The results reveal distinct microstructural features as a direct consequence of the manufacturing technique, including a pronounced mesostructure and strong anisotropy. Mechanical testing demonstrated that the anisotropy in the microstructure also leads to anisotropy in the tensile properties of duplex stainless steels and austenitic stainless steels. Compared to wrought steels, the tensile properties are comparable or superior. Mode I fracture toughness measurements reveal excellent damage tolerance of all steels, not influenced by the microstructural anisotropy. These findings confirm that the processed steels possess the necessary structural integrity and mechanical robustness for use in pressure vessel applications, highlighting the viability of this manufacturing route.