多元微合金钢中的应变诱导复合析出

Strain-Induced Precipitation in a Multi-microalloyed Steel

采用透射电子显微镜结合纳米束能谱技术,研究了含Nb,Ti,Mo等多种微合金元素的超低碳贝氏体钢在奥氏体非冉结晶区终轧后弛豫阶段的应变诱导析出行为.实验结果表明:经30％预变形后,在850℃和900℃等温弛豫时,钢中析出开始主要有纯Nb及Nb-Ti复合的两类,以后者为主.随弛豫时间延长,纯Nb型析出物消失,复合夹杂中铌钛比增加.弛豫阶段后期,Mo会以置换原子形式进入(Ti,Nb)(C,N)的面心立方晶格中,其量随弛豫时间的延长而增加.析出物形状以不规则外形为主,其密度及平均尺寸与变形温度和弛豫时间密切相关.

Transmission electron microscopy (TEM) and nanobeam EDS technique were used to investigate the strain induced precipitation behavior during relaxation process after deformation in the non-recrystallization temperature range of a ultra-low carbon steel containing Nb, Ti and Mo. The experiment results indicate that after 30% predeformation at 850°C and 900°C, two kinds of precipitates, combination of Nb and Ti and a few pure Nb, occur in the steel during isothermal holding. The atomic ratio of Nb to Ti in particles increased and pure Nb particles disappeared with the relaxation extended. After longer holding, some Nb and Ti atoms in the lattice sites of the precipitates were replaced by Mo atoms. The content of Mo in the precipitates rose with the relaxation time increased. The shape of the precipitates is mainly irregular and the density and average size of precipitates are related to deformation temperature and relaxation time.