薄带连铸取向硅钢的热轧孪生行为

薄带连铸流程下取向硅钢粗大λ晶粒(〈100〉//ND，normal direction)的“遗传”会导致磁性能恶化.为解决这一问题，针对取向硅钢的热轧孪生行为开展研究，结果表明:凝固组织粗大的取向硅钢在650℃热轧时可产生大量112〈111〉形变孪晶，这与具有高层错能的硅钢在较高温度下难以孪生变形的传统认知不同.热轧过程中复杂的应力状态降低了变形孪晶的取向依赖性，由于具有更高的储存能，孪晶界/孪晶界及孪晶界/晶界交叉点成为再结晶形核的优先位置，大大提高了常化过程中的再结晶率，受沿孪晶界应变分布及孪晶间距离的限制，沿孪晶界形核的再结晶晶粒通常呈“饼状”，最终形成以细小且取向漫散的再结晶晶粒为主的常化组织，消除了初始凝固组织中有害的粗大λ晶粒.

Hot Rolling Twinning Behavior of Strip Casting Grain-Oriented Silicon Steel

In strip casting grain-oriented silicon steels， the inheritance of coarse λ grains (〈100〉//ND， normal direction) can deteriorate their magnetic properties. To solve the problem， twinning behaviors in strip casting grain-oriented silicon steels during hot rolling were investigated in this work. It is found that after rolling at 650℃， a number of 112〈111〉deformation twins are formed in the coarse solidification microstructure of the steels， in contrast to the well-accepted view that it is difficult to trigger twinning at relatively high temperature in the grain-oriented silicon steels with high stacking-fault energy. The results indicate that the complex stress state during hot rolling may weaken the orientation dependence of deformation twinning. Due to higher stored energy， the intersections of twin/twin boundaries and twin/grain boundaries can act as the preferential nucleation sites for the recrystallized grains during normalizing annealing， leading to a significant increase of recrystallization rate. Because of the restriction from local strain partitioning and the limited size between the twins， the shape of new-formed recrystallized grains is mainly plate-shaped. Consequently， the fine grains with scattered orientations are formed in the normalized microstructure and the coarse λ grains in the solidification microstructure are eliminated.