Microstructures and mechanical properties of additively manufactured Fe–30Mn–3Al–3Si TWIP steel using laser powder bed fusion

Twinning induced plasticity (TWIP) high manganese steel demonstrates high ultimate tensile strength (UTS) and ductility, but its low yield strength limits its applications. This study presents the additive manufacturing of Fe–30Mn–3Al–3Si TWIP steel using laser powder bed fusion (LPBF) with enhanced mechanical properties. The average grain size of the LPBF-fabricated Fe–30Mn–3Al–3Si was 5.4 ± 1.3 μm, which was only one-tenth of that of a wrought one. In-situ formed Al-rich oxide nanoparticles were observed to be uniformly distributed in the matrix. The size of the oxide nanoparticles was about 30 nm with a volume fraction of about 0.9 %. The tensile yield strength was 554 ± 3 MPa and the UTS was 837 ± 7 MPa with an elongation of 41.5 ± 2.6 % for horizontal direction. Low anisotropy was observed for LPBF-fabricated Fe–30Mn–3Al–3Si. Compared with the wrought Fe–30Mn–3Al–3Si, the yield strength was increased by 140 %. This work provides a benchmark for the additive manufacturing of high manganese steel. • A systematic study of microstructures and properties of LPBF Fe–30Mn–3Al–3Si. • Mechanical properties are improved. • Al-rich oxide nanoparticles are firstly discovered in Fe–30Mn–3Al–3Si. • High strength is attributed to grain boundary, dislocation and dispersion strengthening.