Effect of Cold Rolling Aging Process on the Precipitation Behavior of S44660 Super Ferritic Stainless Steel

Super ferritic stainless steel S44660 tends to precipitate brittle phases during medium‐temperature aging, though the quantitative effect of cold rolling pretreatment is not yet well understood. This study systematically investigates the effects of different cold rolling reductions (0–9%) on the microstructural evolution and mechanical properties of this steel during aging at 800 °C. The experimental results show that cold rolling causes a slight elongation of the grains along the rolling direction, leading to a more complex strain distribution within the grains and an increased dislocation density. During aging, precipitation of the sigma (σ) phase, Laves phase, and chi (χ) phase was observed. The sigma phase content increased significantly with aging time and rolling reduction, reaching 13.32% after 3 h of aging at a 9% reduction. Furthermore, the initiation of microcracks within the sigma phase occurred 1 h earlier with increasing cold rolling deformation. Vickers hardness analysis revealed that the material's average hardness increased from 206.58 HV in the solution‐treated state to 219.66 HV after 3 h of aging. Specimens with higher cold rolling reductions generally exhibited higher hardness both before and after heat treatment. The hardness of the material showed a linear increase with the amount of sigma phase.