20Mn2SiVB钢在两相区加热贝氏体区等温过程中的组织与性能  

Microstructures and properties of 20Mn2SiVB steel heated in two-phase region and austempered in the bainite zone

作　　者：龙秀慧[1] 霍颜秋[2] 刘廷明[1] 周振华[3] 

机构地区：[1]山东滨州学院自动化系,山东滨州256600 [2]上海交通大学材料科学与工程学院,上海200030 [3]长春工业大学材料科学与工程学院,吉林长春130012

出　　处：《金属热处理》2008年第9期74-76,共3页Heat Treatment of Metals

摘　　要：采用光学显微镜、扫描电镜和X射线衍射仪对20Mn2SiVB钢在两相区加热贝氏体区等温不同时间所获得的组织形态和相结构进行了研究,并进行了拉伸试验。结果表明,20Mn2SiVB钢经760℃两相区加热后在420℃贝氏体区等温过程中,首先在奥氏体晶界析出贝氏体铁素体,随着等温时间的延长,铁素体板条增多,分割奥氏体晶粒,形成贝氏体铁素体和其板条间的富碳奥氏体小岛。所获得组织为先共析铁素体、无碳化物贝氏体、粒状贝氏体、残留奥氏体和马氏体。拉伸试验表明,在760℃加热420℃等温5 min后,试样可获得较好的综合性能,其抗拉强度σb≈970 MPa,伸长率δ≈14.9%。The microstructures and phase structure of 20Mn2SiVB steel heated in two-phase region and austempered in hainite zone were studied by means of optical microscope, scanning electron microscope and X-ray diffraetometer, and a tensile test was carried out. The results show that the bainitic ferrites precipitate first at the boundary of the austenite grains when 20Mn2SiVB steel heated at 760℃ in the two-phase region and austempered at 420℃ in the bainite zone,and with the prolongation of the isothermal time ,the amount of lath-shaped bainitic ferrites increase, which decollate the austenite grain and form rich carbon island-shaped austenite falling among bainitic ferrites and the lathes. The proeutec-toid ferrite, carbide-free bainite, granular bainite, retained austenite and martensite are the microstrueture obtained in the process. The tensile test shows that better comprehensive properties can be gained at 760℃ heating and at 420℃ isothermal holding for 5 min：σb ≈970 MPa and δ≈14.9% .

关 键 词：20Mn2SiVB钢 贝氏体 粒状贝氏体 马氏体 

分 类 号：TG142.31[一般工业技术—材料科学与工程]