强化机制对高强度桥梁钢Q500qE屈强比的影响

Effect of strengthening mechanism on yield ratio of high strength Q500qE bridge steel

通过化学成分设计以及TMCP过程控制研究了不同的强化机制对高强度桥梁钢Q500QE屈强比的影响。结果表明,通过增加固溶元素Mn、Cr的含量和降低析出强化元素Nb的含量,可有效降低屈强比。晶粒细化有利于强度和韧性的提高,但对屈强比不利。相比之下,相变强化是实现高强度和低屈强比的最佳途径。热轧后采用分段冷却工艺可获得铁素体+贝氏体的双相组织。通过调整铁素体和贝氏体相的比例和硬度,可有效控制屈强比。

Through chemical composition design and TMCP process control,the effects of different strengthening mechanisms on the yield ratio of high strength Q500 qE bridge steel were studied.The result indicated that the yield ratio was effectively lowered by increasing the content of solid solution elements such as Mn and Cr and decreasing the content of precipitation element Nb.Grain refinement was beneficial to the improvement of strength and toughness,but it is detrimental to the yield ratio.In comparison,transformation strengthening was found to be the best way to achieve high strength and low yield ratio.A dual-phase microstructure of ferrite plus bainite could be generated by an interrupted cooling process after hot rolling.The yield ratio could be effectively controlled by adjusting the proportion and hardness of ferrite and bainite phases.