Influence of PBF-LB Process Atmosphere on the Fatigue Strength of Hot Isostatically Post-Densified Duplex Steel Parts Produced via the Shell Core Approach

Abstract

Laser-based additive manufacturing is a great manufacturing technology for producing parts of any geometry. To also increase the strength and reliability of parts produced via powder bed fusion with laser beam (PBF-LB), hot isostatic pressing (HIP) is often used to densify residual porosity or lack-of-fusion defects. When components are post-densified via HIP, they do not require a high density beforehand, only a closed porosity or a dense shell. By building up samples with increased porosity, the PBF-LB process can be accelerated and productivity increased. HIP post-treatment gives the material its full density and good mechanical properties. However, with this approach, the influence of the process gases becomes important. Either argon or nitrogen is used in the PBF-LB process. It is assumed that these process gases are trapped in the pores and thus have an influence on the HIP process and also the mechanical properties after HIP. In this study, the influence of argon and nitrogen as process gases on the properties of duplex AISI 318LN steel after powder bed fusion with laser beam and hot isostatic pressing is investigated for the case of very high initial porosities.

Compactability Regularities Observed during Cold Uniaxial Pressing of Layered Powder Green Samples Based on Ti-Al-Nb-Mo-B and Ti-B

“…Powder metallurgy methods serve as the primary technologies for manufacturing composite materials. These methods encompass various techniques, including selective laser sintering [31][32][33][34][35], hot isostatic pressing [36][37][38], spark plasma sintering [39][40][41][42], selfpropagating high-temperature synthesis (SHS) [43][44][45][46], and several other methods [47][48][49][50], wherein pressed powder green samples serve as precursors. The quality of the green sample, which encompasses factors like uniform density along its height and radius, relative density across the entire batch, and technological strength, significantly influences the physical, mechanical, and operational properties of the resulting products.…”