Effect of Warm Rolling on the Evolution of Microstructure and Toughness in 100Cr6 Bearing Steel

Traditional spheroidization annealing of 100Cr6 bearing steel is time‐consuming and energy‐intensive. To address this, warm rolling is proposed as an efficient alternative for microstructure refinement and toughness enhancement. The influence of warm rolling at critical dual‐phase (760 °C) and ferrite (700 °C, 650 °C) temperatures is investigated. At 760°C, dynamic recrystallization dominated with 90% recrystallized area, yielding equiaxed ferrite grains of 4–6 μm and normally distributed carbides averaging 0.37 μm in size with 32 vol%. Lower‐temperature rolling at 650 °C intensified deformation bands to 3 μm spacing, promoting carbide precipitation to 47 vol% density at 15.7 particles μm −2 while suppressing recrystallization (90% area with GOS >2). Nanoscale carbides of 0.094 μm pinned grain boundaries, transitioning deformation mechanisms from grain‐boundary sliding to intragranular slip. Impact toughness increased by 30%–40% in ferrite‐zone rolled specimens due to crack deflection by laminated fibrous grains and fine carbides. This work clarifies how distortion energy storage drives deformation‐induced carbide precipitation, providing a pathway to achieve high toughness through tailored warm‐rolling processes.