7Cr7M03V2Si钢球化退火机理及其快速退火工艺的研究

Study on the Mechanism of Spheroidizing Annealing for7Cr7Mo3V2Si Steel and the Technology for ItsQuick Annealing

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。

The structure transformations of 7Cr7Mo3V2Si steel in its annealing process and the mechanism of the spheroidizing annealing have been studied. It was found that the major mechanism was the isothermal decomposition of austenite being in independent nucleations of granular carbides, during spheroidizing annealing process. The optimized quick annealing technology is as follows: heating at 940-980℃ for 2h, then cooling to 780-800℃ for 2. 5h followed by cooling in furnace to 500 C, then for air cooling. Using this new technology, the hardness of 7Cr7MO3V2Si steel could reduce to HB194-202, so that the abilities for cold extrusion forming and cutting machining have been obviously improved, and the making of dies being very successful by cold extrusion forming.