... its quench-hardening ability is higher, to join the steel grain refinement of vanadium, reduce the sensitivity of overheating, ... )Elongation δ 5 (%) : 10 frequencyArea reduction ψ (%) : 40 frequencyHardness: hot rolling, than 321 HB; Cold pull + heat treatment, than 321 HB4 ... (special needs, 30 °C ±).5.Delivery status:the hot rolling steel heat treatment or not heat treatment with state delivery, cold ...