Analysis of microstructure of additively manufactured stainless steel

Selective laser sintering was used for additive manufacturing of stainless steel parts. The microstructure of the initial powder and the as-processed part was investigated. It was found that high temperature gradients involved in selective laser sintering evolve non-equilibrium microstructures in the as fabricated state, e.g. retained austenite in martensite, significant dislocation density and residual stresses. The additively manufactured samples have an ultrafine grained structure with predominantly high angle grain boundaries and are free of a crystallographic texture and residual porosity.