【摘要】 采用光学显微镜、扫描电镜和透射电镜研究了20Cr2Ni4、45CrNi、30CrMnSi钢中(1200℃进行固体渗碳20 h后淬火)蝶状马氏体的几种形貌。根据马氏体晶体学和相变力矩原理,提出了蝶状马氏体的形成机理,并用它对蝶状马氏体的特性进行了合理的解释;同时发现蝶状马氏体只发生在马氏体比容大、迁移激活能高而导致形核和核长大困难的合金里。当形核困难时,尤其是在压力场下,"伴生核"相变的形核功和核长大功较低,比"普通核"相变更容易发生。核长大功高的合金,当粗大的马氏体片因过高的应变能而停止长大时,可以通过两种方式继续相变:1)在粗马氏体片一侧,沿另一个惯习面长出分支;2)发生"伴生核"相变,在残留的奥氏体中形成蝶状马氏体。更多还原

【Abstract】 Several morphologies of butterfly martensite in 20Cr2Ni4、45CrNi、30CrMnSi steels( solid carburization at 1200℃ and subsequent quenching) were studied by means of optical microscope,scanning electron microscope and transmission electron microscopy. The formation mechanism of butterfly martensite has been proposed in the light of analysis of the martensitic crystallography and transformation moment,and interpreted satisfactorily the characteristic of butterfly martensite. The results show that butterfly martensite only occurs in alloys of which specific volume is large,migrating activation energy is very high,the formation of nucleation and nucleus growth is extremely difficult. When the formation of nucleation is hard,particularly under the pressure stress field,the forming nucleus energy and nucleus growth energy of "associated nucleation"transformation are lower and more easily take place than the"commonnucleation " transformation. In alloys of which nucleus growth energy is high,when coarse martensite plate stops to growing up because of extremely high volume strain energy,martensite transformation can continue through two kinds of methods: 1) in one side at the coarse martensite plate,growing out many noodles branch; 2) happening an "associated nucleation"transformation,and forming butterfly martensite in surplus retained austenite.更多还原