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冷轧低碳钢在快速加热之后进行临界退火,EBSD和TEM研究了该退火过程中的微结构演变。α相初次再结晶完成之前将试样加热至Ac1以上并且退火,初次再结晶具有严重的迟滞现象,导致α相的晶粒大小不一、分布不均匀。由于这种迟滞现象,在非再结晶α相中形成的亚晶不能被再结晶形成的α相抑制,因而在退火过程中可以不断的长大,最终使α相的晶粒尺寸相当统一、分布均匀。基于公式rn-ron=Kt的分析说明非再结晶α相中的亚晶增长从保温时间的第100秒延续至1000秒,n=3,亚晶的增长受Mn体积扩散控制,Mn分布在α和γ的界面上。保温时间1000秒之后,n从3转变为2,这可能是由于在亚晶界面中更小的γ相的逐渐消失造成的。
Cold-rolled mild steel is subjected to critical annealing after rapid heating. EBSD and TEM studies the microstructure evolution during the annealing process. Before the primary recrystallization of α phase was completed, the sample was heated to above Ac1 and annealed. The primary recrystallization had a serious hysteresis, resulting in uneven grain size distribution and uneven distribution of α phase. Due to this hysteresis, the subgrains formed in the non-recrystallized α phase can not be suppressed by the α phase formed by recrystallization, and therefore, can grow continuously during the annealing process, resulting in a fairly uniform grain size of the α phase Evenly. The analysis based on the formula rn-ron = Kt shows that the subgrain growth in the non-recrystallized α phase is extended from the 100th second to 1000 seconds of the holding time, n = 3, the growth of the subgrain is controlled by the Mn volume diffusion, And γ at the interface. After a holding time of 1000 seconds, n changed from 3 to 2, probably due to the gradual disappearance of the smaller γ phase in the subgrain interface.