用Q390C连铸坯轧制Q460qE的工艺研究

用Nb+V+Ti微合金化的Q390C连铸坯,通过TMCP工艺,成功升级到Q460qE,钢板力学性能达到Q460qE标准要求.两次工业试验的主要工艺为:粗轧温度范围1000~1100℃;精轧开轧温度(890±10)℃,终轧温度(820±10)℃;开冷温度(780±10)℃,终冷温度(630±10)℃,水冷冷速12℃/s;精轧段总压下量不小于60%.由于奥氏体未再结晶区累积大压下量轧制有利于形成高密度的奥氏体晶界,从而增加铁素体形核速率,细化晶粒.此工艺得到的组织表面层为细小多边形铁素体加贝氏体,中间层为铁素体加珠光体.检测表明此组织的钢板具有良好的拉伸与冲击性能.

Rolling Process Investigation on Upgrading Q390C Continuous Casting Slab to Q460qE Plate

The Nb+V+Ti microalloyed Q390C continuous casting slabs were upgraded successfully to Q460qE via TMCP (thermo-mechanical controlled process) with all mechanical properties up to the relevant plate standard. The main parameters of rolling schedule in two pilot tests were as follows: rough rolling temperature range 1000-1100°C; finishing rolling onset at (890±10)°C and terminating at (820±10)°C; starting temperature for cooling is at (780±10)°C and ending at (630±10)°C, cooling rate about 12°C/s and the total reduction in finishing section not less than 60%. The cumulative heavy reduction in the austenite unrecrystallized region benefits the formation of high-density austenite grain boundary, thus increasing the ferrite nucleation rate with grain refining. Furthermore, it was found that the surface structure of the steel plate thus rolled is composed of tiny polygonal ferrite plus bainite and that the structure of intermediate layer is composed of ferrite plus pearlite. Such a structure can provide high tensile strength and impact toughness.