钢中贝氏体组织控制工艺研究-材料加工工程专业论文.docxVIP

钢中贝氏体组织控制工艺研究Abstract 钢中贝氏体组织控制工艺研究 Abstract The bainite morphologies and fo册ation mechanism of bainite ln 60S12Mn and T1 O steels under quench hot(970℃)were studied by optic microscope，transmission electron microscope(TEM) and micro-character． The bainite morphologies and formation mechani§m of bainite were compaired with normal quench(870℃)．The bainitic morphologies and bainitic transformation in tow steels were influenced with austenization temperature and austenization time。 Some martensite—like bainites，such as regular t“angular，crossed，”N”一and butterfly-type were obserVed in the alloys．The bainite microstructure and morphologies in steels under diff色rent isothermaI temperature and isothermal time condition were inVestigated．The hardness of steels were investigated by the sclerometer．The t1‘ansition characte“stics of bainite phase transformation were discussed from perspectiVe of self．organization theory．The results show that bainite phase transformation in the middle temperature area is transitiVe，and it has double character of the pearlite decomposition and the martensite transfbrmation．transition characte ristics The valence electron structufes of austenite and the critical resistance of bainitic transformation in bainite phase transformation area of Fe—C alloy are calculated by the empi“cal electron theory of solid and molecules．The effect on bainite phase transformation by elements Si、Mn is discussed．Since the behaViour of elements Si and Mn during isothermaltransfomation depends on the segregation force of C—Si、 C—Mn， the complexity of the microstructure and morphology are appeared．Based on the empirical elecn’on theory of solids and molecule，this paper sets up the valence electron structure of bainitic crystal cells in Fe—C alloys and analyses the effect of a110ying elements Mn，Si etc，on strength and toughness in bainitic steels．It shows that there are segregation structure units of C—Si and C—Mn in the alloying bainitic steels which haVe higher