THREE DIMENSIONAL MORPHOLOGY AND MICROSTRUCTURAL EVOLUTION OF BAINITE
贝氏体三维形态及组织演化

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.