冷轧中锰钢退火过程中硬度及组织的演化

Microstructure Evolution and Hardness of Cold Rolled Medium Manganese Steel

利用EBSD技术研究了冷轧中锰钢在退火过程中的组织演化规律,从而揭示了其硬度变化的原因。研究结果表明:冷轧中锰钢在650℃退火,获得了0.3～0.6μm等轴状奥氏体和铁素体的超细晶组织,且随着退火时间的延长组织结构没有发生明显粗化;在550～650℃退火,随着温度的升高,奥氏体含量不断增加;在700℃退火时,奥氏体稳定性降低,出炉空冷过程中发生了马氏体转变,硬度升高;逆转变奥氏体相的稳定性主要受其碳含量控制,碳含量越高越容易获得大量稳定的逆转变奥氏体。

In order to reveal the reason for the change of hardness,the evolution of microstructure in cold rolled medium manganese steel was investigated by means of EBSD.The investigation indicate that cold rolled medium manganese steel annealing at 650 ℃ can be obtained 0.3-0.6 μm equiaxed austenite and ferrite ultrafine grain structure,and no obvious coarsening takes place with as extension of annealing time.The volume fraction of austenite increases with increase in temperature from 550 ℃ to 650 ℃.Annealing at 700 ℃,the stability of austenite is reduced for martensite transformation,and the hardness increases.Reverted austenite phase stability is mainly controlled by its carbon content.The higher of the carbon content,the easier access to a large number of stable reverted austenite.