Nb和时效时间对热轧中锰TRIP钢中P偏聚的影响

热轧态中锰TRIP钢首先经650 ℃退火2 h,随后在550 ℃进行等温时效热处理,采用场发射扫描电镜(FE-SEM)研究该钢中P的偏聚和时效析出行为的变化情况。结果表明,中锰TRIP钢中P在晶界的偏聚是一种非平衡偏聚现象,临界时间约为50 h,与理论计算结果48 h较为吻合。在局部偏聚区域内,C与P存在共偏聚的关系,即P偏聚量高的地方,C含量也高。而合金元素Nb具有抑制P偏聚的效果,在20~70 h时效时间内,可以相对降低6.57%~19.5%的最大P偏聚量。根据电子背散射衍射(EBSD)菊池线分析,P偏聚量低于2.28at%时,P为固溶状态,高于2.28at.%时,P为析出状态。

Effect of Nb and aging time on phosphorus segregation in hot-rolled medium-manganese TRIP steel

The phosphorus segregation and precipitation behavior in a hot-rolled medium-manganese TRIP steel treated with 650℃annealing for 2 h+550℃isothermal aging were investigated by field emission scanning electron microscopy(FE-SEM).The results show that the grain boundary segregation of P is a non-equilibrium phenomenon.The critical time is about 50 h,which is consistent with the theoretical calculation result of 48 h.C and P co-segregation exists in certain local regions,where the segregations of C and P are both higher.The alloying element Nb has an inhibitory effect on phosphorus segregation in the steel,the maximum P segregation content can be reduced relatively by 6.57%-19.5%within the aging time of 20-70 h.According to the Kikuchi line analysis in the electron backscatter diffraction,P is in solid solution when the content of segregation is less than 2.28 at%,while P will be in the precipitated phase when the content of segregation is more than 2.28 at%.