Grains growing by simultaneous recrystallization and grain growth mechanisms near the surface of shot peened Al
Year: 2025
Type: article
Abstract: Surface treatments like shot peening (SP) are frequently applied to laser powder bed fusion (LPBF) alloys to introduce beneficial compressive residual stresses, but this process simultaneously creates a gradient microstructure near the surface. The thermal stability of this SP-induced microstructure is critical, as any microstructural evolution during in-service thermal exposure could compromise the beneficial properties. This study analyzes the microstructural evolution of SP-treated LPBF AlSi10Mg during annealing at 500 °C using scanning electron microscopy and electron backscatter diffraction. It is found that the as-built Si network is fragmented by SP and a microstructural gradient is induced: The grains are ultrafine (0.8 μm) at the surface and transition towards coarser sizes reaching 3.0 μm at a depth of 40 μm. Consequently, the annealing response is heterogeneous: The surface layer undergoes rapid coarsening (the high-angle boundary spacing increases from 0.8 μm to 3.4 μm in 5 min), while at the subsurface a few nuclei grow rapidly to an abnormally large size. Subsequently, these grains grow to dominate both the surface and the layer below, facilitated by a reduction in Zener pinning as the Si particles coarsen. This study provides critical insight into a series of competing microstructural mechanisms, which are essential for predicting performance evolution when an SP treated LPBF AlSi10Mg component is in use.
Authors: P. Snopiński, K. Matus, X. Zhang, T. Yu, D. Juul Jensen
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,640
Awards: G2375618255, G7243732840, G8933019563
OpenAlex ID: W4416958216