Arts et Métiers institute of technology – LAMPA, France
Marion Auffray
Biography
Marion Auffray is a PhD researcher in Materials Science, currently based at LAMPA—the Angers laboratory of the Arts et Métiers Institute of Technology. Her research primarily investigates the fatigue behavior of metallic alloys through both experimental and numerical approaches. After earning a bachelor’s and master’s degree in general engineering with a specialization in mechanics and advanced materials, her doctoral work has focused on decorrelating the effects of surface condition, defects, residual stresses, and microstructure on the fatigue strength of 316L stainless steel produced via Laser Powder Bed Fusion additive manufacturing.
Conferences
Room |
Date |
Hour |
Subject |
|---|---|---|---|
| Room 6 |
25-03-2026 |
6:20 pm – 6:40 pm |
50 Leading role of the sub-surface microstructure over the surface topography on the fatigue strength of stress-relieved L-PBF 316L parts |
Conferences Details
50 Leading role of the sub-surface microstructure over the surface topography on the fatigue strength of stress-relieved L-PBF 316L parts
The Laser Powder Bed Fusion (L-PBF) process allows to manufacture parts with both a complex geometry and a high mechanical performance. The as-built and netshape L-PBF 316L parts – i.e. without any heat nor surface treatment, have tensile residual stresses, sub-surfaces pores, a rough surface and a contour-core microstructure that lead to a low fatigue strength. Residual stresses can be relieved with a heat-treatment to enhance the fatigue properties, but the best performance is obtained after machining and polishing. The differences between the polished and the heat-treated net-shape conditionslie in the sub-surface microstructure, the surface topography, and the population of sub-surface pores. This study aims to quantify the impact of each of these subsurface parameters on the fatigue behaviour. To do so, the sub-surface microstructure of the net-shape condition is
characterized. Then, uni-axial fatigue tests are carried out on stress-relieved specimens with the following surface conditions: net-shape, partially polished, and machined and polished. For defects smaller than 200 µm, the sub-surface microstructure is the most influential parameter on the
fatigue strength. The grain size under the surface is considered in the Kitagawa-Takahashi diagram relatively to the killer defect size. This allows to align all the batches.
Keywords: Sub-surface microstructure; Surface topography; Fatigue; L-PBF; 316L SS
