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本文研究了7Cr7Mo3V2Si钢退火过程中的组织变化及球化退火机理,发现球化退火过程中,奥氏体的等温分解是以粒状碳化物的独立形核为主要机制。经过优化确定的快速球化退火工艺为:940～980℃加热2h,冷到780～800℃等温2.5h,再随炉冷至500℃出炉。采用此工艺可使7Cr7Mo3V2Si钢的硬度降至HBl94～202,从而大大改善了该钢的切削加工性和冷挤成型特性,并且用冷挤成型法成功地制造了模具。
In this paper, the microstructure evolution and spheroidizing annealing mechanism of 7Cr7Mo3V2Si steel during annealing were studied. It is found that the isothermal decomposition of austenite during the spheroidizing annealing is dominated by the independent nucleation of granular carbides. After the optimization of the rapid nodular annealing process: 940 ~ 980 ℃ heating 2h, cool to 780 ~ 800 ℃ isothermal 2.5h, and then cooled to 500 ℃ oven baked. The hardness of 7Cr7Mo3V2Si steel can be reduced to HBl94 ~ 202 by using this process, thereby greatly improving the machinability and cold extrusion properties of the steel, and successfully manufacturing the mold by the cold extrusion method.