研究了深冷处理时间和深冷循环次数对SDC99冷作模具钢内耗行为的影响,采用耦合模型理论对SKK(Snoek-Kê-K9ster)弛豫强度的变化机制进行了解释。结果表明:对于深冷未回火试样和深冷后回火试样,随着深冷时间的增加,SKK峰升高,其中深冷8 h后SKK峰最高,而深冷时间继续延长,SKK峰逐渐降低;随着深冷循环次数的增加,SKK峰升高,但仍低于深冷8 h的SKK峰。结合TEM结果发现,深冷处理可以促进回火过程析出更多的细小碳化物。 The effect of cryogenic treatment time and cryogenic cycle on the internal friction of SDC99 cold die steel was studied. The coupling mechanism was used to explain the relaxation mechanism of SKK (Snoek-Kê-K9ster). The results show that the SKK peak rises with the increase of cryogenic time for cryogenic and non-tempering samples, and the SKK peak is the highest after 8 h of cryogenic treatment, while the cryogenic time continues to extend, The SKK peak gradually decreased. As the number of cryogenic cycles increased, the SKK peak increased but remained below the SKK peak for 8 h. Combined with the TEM results, it is found that cryogenic treatment can promote the precipitation of more fine carbides during the tempering process.