Microstructure and mechanical characterization of additively manufactured Fe11Cr8Ni5Co3Mo martensitic stainless steel

Abstract

This study investigates the impact of various printing processes on the microstructure, grain orientation, dislocation density, residual stresses, and mechanical properties of Fe11Cr8Ni5Co3Mo0.2Si0.16Al0.12 V martensitic aged stainless steels produced through laser-based powder bed fusion (LPBF) using different processing parameters. The LPBF samples displayed varying densities, dislocation densities, and grain orientations with different combinations of process parameters. Sample 3 showed the highest densification effect, dislocation density ranged from 6.23 × 1013 m−2-1.164 × 1014 m−2. The horizontally crystallographic texture is primarily 〈111〉 orientation, it was observed that sample 3 also had a 〈001〉 orientation. The building direction has strong Gaussian texture {110} 〈001〉. The residual stress is compressive residual stress, and the maximum residual stress is depicted in sample 6, which is −222.8 ± 16.8 MPa. The optimal combination for the ultimate tensile strength and elongation was achieved using a laser power of 200 W, scanning speed of 1000 mm/s, hatch spacing of 100 μm, layer thickness of 30 μm, and laser energy density of 66.7 J/mm3. The total yield strength increase in the LPBF MSS samples, 60% can be attributed to the intensification of dislocations, with the contributions to intensity ranked in the order of σd>σt>σgb>σp.