Theses and Dissertations Collection

Additive manufacturing is a relatively new industrial technique for the manufacturing of desired shapes layer upon layer, which has, in recent years, begun to garner significant interest due to its potential, showing new possibilities in both part design and logistical trains. Because of the new way the materials are manufactured, new modeling techniques and a verification of material characteristics are required to ensure safe and economical design. Direct metal laser sintering (DMLS) is a powder bed, laser based additive manufacturing technique that already has industrial machines active and available. DMLS is popular because of its relatively high accuracy, ability to manufacture multiple parts simultaneously, and the low amount of waste produced during manufacture.

15-5 PH SS is a martensitic precipitation hardening stainless steel, used in aerospace, chemical, and other industries because of its high strength, excellent corrosion resistance, and good forgeablility. Even though this steel has been made via DMLS, there has been a lack of detailed examination of the additively manufactured material in comparison with its traditionally manufactured counterpart. In this study, tensile and creep tests performed on additively manufactured 15-5 PH showed an improvement of approximately 30% in elevated temperature tensile strength. This increase in tensile strength came at a reduction in ductility by 50%. Further, the creep life of the additively manufactured material was 30% greater when tested at 593 oC and 211 MPa. Examination of potential heat treatments of the additively manufactured alloy was also carried out, with the additively manufactured material exhibiting smaller precipitate sizes and higher Vickers hardness.