Selective laser melting

Hardening (computing)

Peening

Residual stress

Metallurgy

Materials science

Layer (electronics)

Shot peening

Microstructure

Fractography

Composite material

Fatigue limit

Brittleness

Laser peening

Hardness

Additive manufacturing

The effect on fatigue resistance of additively manufactured (AM) AlSi10Mg specimens fabricated by selective laser melting (SLM) following surface treatment by shot-peening was investigated. Specimen surface was shot-peened with either steel or ceramic balls. Nano-indentation measurements revealed that shot-peening caused surface hardening, with the hardness profile from the surface to the interior of the bulk disappearing 50 μm below the surface. Surfaces polished before shot-peening or following removal of about 25–30 μm from the surface after shot-peening by either mechanical or electrolytic polishing showed improved fatigue resistance and fatigue limit. Fractography of broken specimens demonstrated that for shot-peened specimens, the site of fatigue crack initiation was deeper than that for specimens that had not undergone shot-peening. The fracture area of AM-SLM AlSi10Mg specimens before and after shot-peening displayed a ductile fracture with relatively deep dimples. In contrast to AM specimens, the final fracture area of die-cast samples exhibited a brittle fracture surface, containing numerous cleavage facets and micro-cracks.

On the effect of shot-peening on fatigue resistance of AlSi10Mg specimens fabricated by additive manufacturing using selective laser melting (AM-SLM)