淬火态45号钢在等通道角挤压过程中晶粒演化

Grain-refining Evolution for Quenched Medium-carbon Steel by Equal-channel Angular Pressing

将马氏体相变与强塑性变形工艺相耦合,开发了基于等通道角挤压快速制备亚微米级中碳钢工艺。试验采用45号钢,就淬火态在不同回火温度和回火时间条件下进行挤压。试验结果表明,由马氏体相变得到的过饱和铁素体为动态再结晶和应变诱导碳化物析出作了能量和组织准备,并在一定的回火温度下进行等通道角挤压使位错密度快速增加,实现了动态再结晶,形成了细小晶粒,同时应变诱导碳化物从过饱和的铁素体中以弥散形式析出,使亚微米铁素体基体上均匀分布着细小碳化物。这种组织结构具有较高的稳定性,在550℃退火30min后,晶粒尺寸仍保持在1μm以内。

A technique coupled martensite transformation with severe plastic deformation （SPD） has been developed for rapid producing submicron grain medium carbon steel based on equal channel angular pressing （ECAP）. Experiments were conduced on medium-carbon steel,and quenched steel was pressed at different tempering temperatures and time. The results indicted that the homogeneous supersaturated ferrites by martensite transformation was prepared for dynamic recrystallization and strain induced carbide precipitation, accumulated higher dislocation density in the crystal structure during ECAP at given tempering temperature urged to recrystallize and induced carbide particles to precipitate in dispersed phase. Homogeneous ultra-fined grain ferrites with fine carbide particles distributed grain boundaries could be achieved. These submicron microstructures possessed thermal stability and they remained grain size of less than 1 μm after annealing at 550℃ for 30 min.