再结晶对沉淀粒子尺寸及其分布的影响

本文通过碳萃取复型样品的电镜观察,研究了再结晶对沉淀粒子尺寸及其分布的影响。当10MnNb钢在1073—1373K温度范围内热压缩后等温停留时,NbC沉淀粒子随等温时间延长而粗化。在未再结晶期间,粒子尺寸分布曲线呈单峰;在再结晶期间,粒子粗化速率加快,改变了原来的粒子尺寸分布,使尺寸分布曲线呈双峰。再结晶时形变基体、再结晶前沿界面和再结晶晶粒三个区域中的粒子粗化机制不同,其平均尺寸和尺寸分布也不同,它们的叠加使尺寸分布曲线呈双峰。

EFFECT OF RECRYSTALLIZATION ON PRECIPITATE SIZE AND ITS DISTRIBUTION

The effect of recrystallization on precipitate size and its distribution was studied by carbon extraction replication in a Nb-bearing microalloyed steel which was aged in the temperature range from 1073 to 1373K after hot compression. It was found that there was a single peak distribution of precipitate size prior to recrystallization but a double peak distribution during recrystallization. To explain this a model based on precipitate coarsening kinetics has been proposed. The precipitate coarsening rate is greatly different in the unreerystallized grains, recrystallized grains and migrating grain boundaries. When recrystallization proceeds, an abnormal precipitate coarsening might be brought about by the passage of the recrystallization fronts. As a result, the precipitate size in the recrystallized grains. is much larger than that in the unrecrystallized grains, the overlap of which is supposed to be responsible for the double peak distribution.