High-temperature stability and mechanical property optimization of laser powder bed fusion 316L steel after controlled annealing

Abstract

The research demonstrated that laser powder bed fusion (LPBF) coupled with controlled annealing at 1200 °C, could significantly increase the proportion of coincidence site lattice (CSL) grain boundary, thereby achieving an outstanding synergy of enhanced strength and exceptional ductility. The plastic deformation behavior, strain hardening behavior, and fracture behavior of LPBF 316L steel annealing at 1200 °C for 20 h were studied through quasi-in-situ tensile process. It was found that LPBF 316L steel formed a certain proportion of deformation twins during the tensile process, and the formation of twins changed the crystal orientation, thus promoting further slip and crystal deformation. The synergistic effect of slip and twin promoted higher plasticity. LPBF process coupled with controlled annealing at 1200 °C for 20 h leads to a ultimate tensile strength of 613 MPa and total elongation of 73.8%.

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Central South University