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本文探讨了45钢锻造余热淬火的工艺特性及其强韧化机理,分析了形变温度、锻后停留时间对形变后奥氏体晶粒再结晶与晶粒长大的影响。用透射电镜观察了组织形貌及亚结构。锻热淬火组织主要为细小板条马氏体和弥散析出的Fe_3C微粒,板条马氏体的亚结构主要由板条内部高密度缠结位错组成。回火析出的Fe_3C颗粒圆整细小,分布均匀;基体铁素体的回复再结晶要在较高回火温度下。在锻热淬火高温回火状态下,始锻温度低即形变温度低或锻后停留时间短时,有良好的强韧化效果,这是由于形变析出的碳化物在回火时促进了碳化物颗粒的细小均布,提高了α基体回火抗力,以及明显降低了脆性转变温度。
In this paper, the process characteristics of 45 steel forging residual heat quenching and the mechanism of strengthening and toughening were discussed. The effect of deformation temperature and forging residence time on recrystallization and grain growth of austenite after deformation was analyzed. Transmission electron microscopy was used to observe the microstructure and substructure. Forged hot-quenched microstructure is mainly small lath martensite and dispersed precipitated Fe_3C particles, lath martensite substructure mainly by the internal high-density entanglement dislocations. Tempering of Fe_3C particles rounded small, uniform distribution; matrix ferrite recovery recrystallization at a higher tempering temperature. In the forging quenching high temperature tempering, the initial forging temperature is low or low deformation temperature after forging residence time is short, have a good toughening effect, which is due to the precipitation of carbide during tempering to promote the carbide Small particles are uniformly distributed, improving the tempering resistance of the α matrix, and obviously reducing the brittle transition temperature.