Study on Post‐Forging Cooling Process of 100CrMnSi6‐4 Bearing Steel

This study employed a Gleeble‐3500 thermal simulation tester to analyze the dynamic CCT behavior of 100CrMnSi6‐4 bearing steel, revealing phase transformation patterns during continuous cooling. Based on the CCT curve, two post‐forging cooling processes were designed: rapid cooling + slow cooling + air cooling (RSC‐AC) and rapid cooling + slow cooling (RSC), with focus on studying the effects of final cooling temperature, slow cooling rate in the pearlitic transformation zone, and post‐slow cooling rate. The results showed that lower final cooling temperatures refined grain structure and pearlite interlamellar spacing while suppressing secondary carbide precipitation; reduced slow cooling rates in the pearlitic transformation zone led to coarsening of pearlite colonies but promoted dispersed carbide distribution; the RSC process demonstrated better microstructural homogeneity, while the RSC‐AC process achieved finer grains and pearlite lamellae with improved mechanical properties. The optimal process parameters were: after high‐temperature deformation, rapid cooling at 3°C/s to 630°C, followed by slow cooling at 0.15°C/s to the pearlite transformation finish temperature and subsequent air cooling to room temperature, ultimately obtaining fine lamellar pearlite microstructure free from carbide networks, fully meeting the requirements for pre‐spheroidization annealing treatment.