含钒超细晶双相钢的细化机制

Refinement mechanism of ultrafine-grain vanadium-containing dual phase steel

利用铁素体+马氏体+贝氏体的初始显微组织结合冷轧和连续退火的方法达到了细化晶粒的目的,通过这种方式制备的双相钢中有63.8%的铁素体晶粒尺寸分布于0.5～1μm,有53%的马氏体晶粒尺寸分布于0.5～1μm.针对该现象研究了基于铁素体+马氏体+贝氏体初始显微组织含钒超细晶双相钢的晶粒细化机制.分析认为,细化机制主要有三个方面:第一是形变对显微组织的细化,包括为了得到铁素体+马氏体+贝氏体的初始显微组织而进行的热轧和冷轧;第二是冷轧态显微组织的再结晶和快速奥氏体化;第三是钒的析出物阻碍奥氏体的长大.

Dual phase steel with 63.8% of ferrite grains and 53% of martensite grains in the size distribution of 0.5 to 1 μm was produced through adopting the initial microstructure of ferrite,bainite and martensite in combination with the cold rolling and continuous annealing process.The grain refining mechanism of vanadium-containing dual phase steel based on the initial microstructure of ferrite,martensite and bainite was investigated.It is found that the refining theory mainly has three aspects：（1） microstructure refinement by deformation including hot rolling and cold rolling for the initial microstructure of ferrite,martensite and bainite;（2） recrystallization and rapid austenitization of the as-cold rolled microstructure;and（3） vanadium precipitation preventing austenite from growing up.