Elaboration of oxide dispersion strengthened Fe-14Cr stainless steel by selective laser melting

Abstract

This study presents the influence of the main selective laser melting (SLM) processing parameters on the densification behavior and microstructure evolution of oxide dispersion strengthened (ODS) Fe-14Cr stainless steel. Optimization of the process parameters allows to manufacture ODS stainless steel parts, which present high densities up to 98% and a fine dispersion of nanosized Y-Ti rich oxide particles. Laser power and scan speed are found to strongly influence the density and the microstructure of SLM builds. The ratio power over scan speed controls the width and the depth of the molten pool. Low energy densities (i.e. a low laser power or a high scan speed), inferior to 100 J mm−3, cause lack of fusion of the powder and induce the presence of numerous pores. Finer microstructure can be achieved in this condition since grains receive less energy to growth. The hatch distance does not affect the density in the range of testing values. A decrease in hatch distance causes re-fusion of previous neighbor track but does not re-melt the previous layer since the ratio power over speed is kept constant when varying the hatch distance. A slight coarsening of the microstructure is observed in this case. A large range of hatch distance can be used and especially large values, which decrease the time of production. This study can be a guideline to achieve materials with specific microstructure for high temperature applications.