低碳钢中超细铁素体的长大倾向

在热模拟单向压缩条件下考察了四个不同C,Mn含量的低碳钢中通过形变强化相变产生的超细铁素体在模拟卷取温度下的长大倾向.结果表明,不同C,Mn含量的四种钢中的超细铁索体在～500℃的保温0～10min过程中都很稳定,没有明显的长大过程,也未明显观察到铁素体的静态再结晶.超细铁素体稳定的主要原因是由于稳定的第二组织(珠光体或渗碳体颗粒)的有效钉扎,它既阻止了铁素体的明显长大,也抑制其静态再结晶的充分进行.但不同C,Mn含量的四种钢中的第二组织有不同的演变规律,保温过程中形变奥氏体内形成离异珠光体并缓慢粗化.另外,利用背散射电子衍射取向成像技术还测定了08钢保温过程中的取向(差)变化.

Coarsening Tendency of Ultra-fine Ferrite in Low Carbon Steels

The coarsening tendency of ultra-fine ferrite grains produced by deformation-enhanced transformation was investigated at simulated coiling temperatures by thermal simulating tests in four low carbon steels containing different C and Mn contents. Results show that the ultra-fine microstructures are quite stable. No apparent coarsening and static recrystallization of ferrite grains were detected and they are ascribed to the effective pinning by the second/minor phases. The evolution of second phases in four steels was different. During holding at coiling temperatures the transformation of austenite to perlite proceeded in a divorced manner owing to the strong deformation of austenite. Orientation mapping in EBSD measurements was also applied to reveal the changes of (mis)orientations of ferrite grains during holding.