贝氏体三维形态及组织演化

在扫描电子显微镜（ＳＥＭ）较高分辨率条件下，用双磨面方法研究了贝氏体亚结构的三维（３－Ｄ）形态，发现上贝氏体及其亚片条的三维形态呈板条状。下贝氏体及其亚片条的三维形态呈片状，下贝氏体亚单元为块状。上，下贝氏体之间在三维形态上无明显界限。在存在过渡型的中间态贝氏体，其形态介于上、下贝氏体之间，这说明上、下贝氏体在本质上是统一的。用激发形核－台阶长大理论分析了上、下贝氏体组织形态演化机理，并提出演化过

THREE DIMENSIONAL MORPHOLOGY AND MICROSTRUCTURAL EVOLUTION OF BAINITE

The 3--D morphologies of bainite in steels have been studied by scanning electronmicroscopy (SEM) with high resolution, based on the dual--surface observation. The subplatescomposing uPPer berate sheaf are lath-like while the whole morphology of lower bainite andits subplates are plate--shaped. The subunits in lower bainite seem to be lumpish. There is noobvious difference between upper bainite and lower bainite. Between them elms transient bainite,whose 3--D morphology proves to resemble both opper and lower bainite on some aspects. Themicrostructural evolution of three types of bainite has been interpreted when the sympatheticnucleation ledgewise growth mechanism is employed, and the evolution model has been proposed.