空冷弛豫对铌微合金化热轧多相钢组织性能的影响

来源期刊：钢铁2011年第4期

论文作者：郑东升 朱伏先 李艳梅 陈炳张

文章页码：70 - 75

关键词：铌微合金钢； 热轧多相钢； 弛豫； 显微组织； 力学性能

Key words：Nb microalloyed steel； hot-rolled multiphase steel； relaxation； microstructure； mechanical property

摘    要：研究了铌微合金化试验钢控冷过程空冷弛豫温度对其组织和力学性能的影响,结合金相、电镜观察以及XRD技术分析了弛豫过程铁素体组织的演变、基体中的应变诱导析出行为以及组织中的残余奥氏体量变化。结果表明,轧后采用弛豫+超快冷的控冷工艺可以得到含有铁素体、贝氏体和残余奥氏体的多相组织,弛豫终止温度显著影响铁素体晶粒尺寸、铁素体量以及铁素体基体上的沉淀析出量。随着弛豫终止温度的降低,试验钢的屈服强度和抗拉强度呈降低趋势,而屈强比均保持在0.7左右的较低水平。当弛豫终止温度为720℃时,试验钢的抗拉强度、伸长率和强塑积分别达到820MPa,37.5%和30.750GPa·%的最大值。

Abstract: Effect of air-cooling relaxation temperature during the controlled cooling on the microstructure and mechanical properties of hot-rolled Nb microalloyed steel was investigated.The results show that the multiphase microstructure containing ferrite,bainite and retained austenite can be obtained by relaxation and ultra-fast cooling after rolling,while the final temperature of relaxation significantly influences the ferrite grain size,ferrite content,dislocation density and precipitation amount on the ferrite matrix.The yield and tensile strengths decrease and the yield ratio approximately remains the low level of 0.7 with the reduction of relaxation stop temperature.When the final temperature of relaxation is 720℃,tensile strength,total elongation and product of tensile strength and ductility reach the maximum values,ie.,820MPa,37.5% and 30.750GPa·%,respectively.