Effect of Subcritical Quenching on Microstructure and Property of 20Cr Steel

The microstructure and property effects, mechanism and effect factors of subcritical quenching for 20Cr steel were overviewed. Also the feasibility of using normalization or annealing to replace the first time quenching was studied. Finally, the best subcritical quenching process was found. The results show that the optimal process for 20Cr steel is quenching at 820 ℃ and then tempering at 220 ℃. At this time, it owes better combination of high strength with good toughness. When the acicular ferrite is diffuse distribution, the material has better impact toughness. While normalizing or annealing replaces the first quenching, there will not have acicular ferrite that is diffuse distribution, which is bad for the impact toughness. It has certain guidance role in formulating the heat treatment of subcritical quenching for the steel owned similar performance with 20Cr steel.