淬火态中碳钢温锻成形行为的研究

Investigation into Warm Forging Behavior of Plain Medium-carbon Steel with Martensite Microstructure

将相变与形变晶粒细化有效地结合，开发了中碳钢在马氏体状态下的温锻塑性成形工艺。研究表明，马氏体相变钢在500～600℃保温适当时间后快速形变，其塑性指标、成形性能比传统的退火态钢要好，变形抗力基本相同。形变时通过位错运动、孪晶及动态再结晶使铁素体组织得到细化，平均晶粒尺寸小于1μm，通过应变诱导使碳化物以颗粒状形态在晶界和晶内析出，并均匀弥散地分布在细小的铁素体基体中，使材料具有较高的强韧性和热稳定性。

A new warm forging process which integrates phase transition with heavy plastic deformation was developed in plain medium-carbon steel with martensite starting microstructure. It has been clarified that the steel with martensite structure which is forged soon at warm temperature around 500-600℃ possesses higher plastic level and better formability than that of normal annealed steel, and their deformation resistances are approximately the same. The ultrafine grained （UFG）ferrite with mean grain size being smaller than 1μm can be obtained by the interaction between the dynamic recrystallization ,dislocation slip and twinning and spheroidized cementite particles can be uni formly precipitated by strain-induced and dispersed in an ultrafine ferrite matrix during heavy plastic deformation. These multi-phased uhrafine microstructures perform superior mechanical properties and thermal stability.