Hot deformation behavior and hot rolled properties of Gd-rich 316 L austenitic stainless steel neutron shielding material for spent nuclear fuel storage and transportation

Abstract

Gd-rich austenitic stainless steel as a low-cost neutron shielding structural-functional integrated material is considered the most promising material to replace boron neutron shielding materials. However, as-cast Gd-rich austenitic stainless steel neutron shielding materials are affected by high hardness, low melting point, net-like, brittle intermetallic compound (Fe,Ni,Cr)₃Gd, and its hot workability and mechanical properties are very poor. In this paper, Gd-rich 316 L austenitic stainless steel neutron shielding material hot deformation behavior was revealed, and the constitutive equation and hot processing maps were established and verified. On this basis, the effects of hot rolling on material microstructure and properties were studied, mainly discussing the effects of rolling temperature and subsequent solution treatment on the microstructure, recrystallization, mechanical properties, and neutron shielding properties. Studies have shown that Gd-rich 316 L austenitic stainless steel neutron shielding material has good hot workability at deformation temperatures of 950 ∼ 1050 °C and strain rates of 0.01 ∼ 0.1 s⁻¹. Compared with before hot rolling, the strength, elongation and neutron shielding properties of 1050 °C hot-rolled 316 L-2.5wt%Gd neutron shielding material are increased by 1.79 times, 1.96 times and 1.31 times, respectively. After solution treatment at 1100 °C × 60 min, the elongation further increased to 39.53 %, which was 4.32 times than before hot rolling. This study provides valuable insights for high Gd content austenitic stainless steel neutron shielding materials thermo-mechanical processing and improving the strength and plasticity.