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透射电镜(TEM)对40CrMnSiMoV 钢310℃下贝氏体转变研究发现,该钢下贝氏体铁素体由亚单元组成。亚单元内存在中脊,其惯习面为(0.424,0.738,0.526)f,fcc/bcc 间位向关系为(111)f//(011)b,[01],与[1]b 差3±1°。短时间等温时,组织中无碳化物析出,而存在两种不同取向分布的残余奥氏体薄膜。一定等温时间后,发现三种不同形态的碳化物同时或先后自贝氏体铁体素和奥氏体内析出。上述实验结果仅当认为下贝氏体按切变方式转变时,方能得到很好理解。
Transmission electron microscopy (TEM) study of bainite transformation of 40CrMnSiMoV steel at 310 ℃ found that the bainitic ferrite consists of subunits. Sub-unit exists in the ridge, the habitus surface of (0.424,0.738,0.526) f, fcc / bcc between the direction of the relationship of (111) f (011) b, [ 01], and [ 1] b poor 3 ± 1 °. When isothermal for a short time, no carbides precipitate in the microstructure, but there are two kinds of retained austenite films with different orientation distributions. After a certain isothermal time, three different forms of carbides were found to precipitate from bainitic ferritin and austenite simultaneously or successively. The above experimental result can only be well understood when it is considered that the lower bainite is transformed in a shear manner.