含Nb船板钢再结晶行为及控轧工艺研究

在Φ450轧机上对含Nb船板钢进行阶梯轧制,研究不同变形温度和变形量下高温奥氏体再结晶行为,绘制出奥氏体形变再结晶区域图,根据再结晶区域图进行热轧实验,通过两种不同的控轧工艺实验对比,寻求力学性能稳定的含Nb船板钢控轧工艺。结果表明,变形温度为1000℃,20%的变形量可发生奥氏体再结晶;变形温度为900℃,低于30%的变形量不发生奥氏体再结晶,变形量增大至40%～50%,发生部分奥氏体再结晶;变形温度为850℃,50%的变形量也不发生奥氏体再结晶。终轧温度提高至910℃,利用超快速冷却技术,合理控制精轧阶段的变形量,可使含Nb船板钢获得与低温终轧条件相当的力学性能。

Recrystallization behavior and controlled rolling process of Nb microalloyed ship plate steel

With stepped rolling of Nb microalloyed ship plate steel on φ450 rolling mill, the recrystalli- zation behaviors of high-temperature austenite at different deformation temperatures and reductions were investigated. The recrystallization region graph of austenite deformation was plotted, on which basis hot rolling experiments were conducted. By comparing two different controlled rolling proces- ses, the controlling rolling process that can guarantee stable mechanical properties of Nb microalloyed ship plate steel was identified. The results show that： at the rolling temperature of 1000 ℃, recrys- tallization occurs when the reduction reaches 20%, and the austenite grains get refined; at 900 ℃, a reduction less than 30% will not lead to recrystallization of the austenite, yet under the reduction of 40% and 50% the austenite recrystallizes partially; but at 850℃, recrystallization does not occur e- ven under 50% reduction. When the finishing temperature is raised to 910 ℃, good mechanical prop erties of Nb ship plate steel can be gained by controlling pass reduction with ultra-fast cooling process.