本文较简要地介绍了利用在化学热处理前后进行的热循环处理细化20X钢的晶粒、提高其机械性能的研究成果。以5℃/min的速度加热到Ac_3以上5～10℃,随后缓慢冷却至Arl以下5～10℃,经过3～5次循环处理后,20X钢奥氏体晶粒可以细化至№11,最后空冷后其冲击韧性较经正火和快速加热循环处理的20X钢高50％～1.5倍。 This paper briefly introduces the research results of using the heat cycle before and after chemical heat treatment to refine the grains of 20X steel and improve its mechanical properties. Heated to 5 ~ 10 ℃ above Ac_3 at a rate of 5 ℃ / min, and then slowly cooled to 5 ~ 10 ℃ under Arl. After 3 ~ 5 cycles of treatment, the austenite grain size of 20X steel can be refined to №11, After the last air-cooled impact toughness compared with normalizing and rapid heating cycle of 20X steel 50% to 1.5 times higher.