
Stephanie contributed to a great paper by our collaborators at University of Pittsburg (Wei Xiong’s group). This paper is titled A Design Strategy for Surface Modification and Decarburization to Achieve Enhanced Mechanical Properties in Additively Manufactured Stainless Steel and was recently published in the Journal of Manufacturing and Materials Processing (doi: 10.3390/jmmp8060264). For this paper Sridar et. al. developed a decarburization heat-treatment to that can be applied after the carbon-based sensitization and etching process we use to post-process Power Bed Fusion (PBF) printed stainless steel parts. The decarburization process they developed increased the ultimate tensile stress from 500 MPa to 700 MPa.
Abstract: Post-processing of additively manufactured components, including the removal of support structures and the reduction in surface roughness, presents significant challenges. Conventional milling struggles to access internal cavities, while the Self-Terminating Etching Process (STEP) offers a promising solution. STEP effectively smooths surfaces and dissolves supports without substantial changes in geometry. However, it can lead to compositional changes and precipitation, affecting the material properties and necessitating a design strategy to mitigate them. In this study, STEP is applied to stainless steel 316L (SS316L) produced via laser powder bed fusion, reducing surface roughness from 7 to 2 μm. After STEP, the surface carbon exhibited a threefold increase, leading to the formation of M23C6 clusters. This significantly impacted the yield strength, resulting in a 37% reduction compared to the as-built condition. The key to overcoming this challenge was using computational simulations, which guided the determination of the decarburization conditions: 1000 ◦C for 60 min, ensuring maximum M23C6 dissolution and surface carbon reduction with minimal grain coarsening.Following these conditions, the yield strength of SS316L was restored to the level observed in the as-built condition. These findings underscore the potential of the proposed design strategy to enhance the mechanical performance of additively manufactured components significantly.