中碳低合金空冷贝氏体铸钢的组织与性能研究

Study on the Microstructure and Properties of Air Cooled Bainite Cast Steels with Low-Alloy and Medium Carbon

以A3钢边角料为原料添加锰铁、硅铁、铬铁和钼铁以及少量的稀土，通过中频感应熔炼及相应的炉前处理，设计了1种铸钢，通过不同的热处理工艺制度，在空冷条件下获得了贝氏体组织．通过16种不同的热处理工艺研究热处理对组织的影响规律，借助光学金相显微镜（OM）、扫描电子显微镜（（SEM）、硬度计和冲击试验机等手段分析研究了试验钢热处理态、回火态以及不同热处理工艺规范下的力学性能，利用透射电子显微镜（TEM）分析研究了空冷贝氏体组织组成以及析出的碳化物的成分．结果表明：合金元素C，Si．Mn，Mo，Cr的合理有效配合，可使钢在空冷条件下，在较宽的成分范围内得到以贝氏体为主的显微组织．TEM分析证明基体组织以下贝氏体为主，兼有部分上贝氏体，同时还有少量的残余奥氏体存在，贝氏体中的碳化物有渗碳体和ε-碳化物．贝氏体钢的硬度在40～49HRC范围内变化，冲击韧性在44～70J／cm2范围内变化；

A new kind of air cooled bainite east steel （medium carbon air cooled bainite east steel） was obtained by adding ferro - manganese iron, ferro - silicon iron, chromic iron and ferromolybdenum , a few rare earths in the raw A3 steel, east through medium frequency induction furnace, designed consisting of low alloy medium carbon by element alloying in the paper. In the subject, we study the effect of the alloys on the mierostructure and mechanical property of low alloy systematically and synthetically, using 16 diffirent heat treatment method to find the relation between heat treatment and microstmcture. Microstructure and mechanical property of heat - treated, and treated in different heat treating processes experimental steel were were performed by OM, SEM, hardness tester and impact machine. Mierostructure changes of Granular bainite and chemical constitution of carbide precipitated when tempered were performed by TEM . The influences of mierostrueture on strength - toughness as well as wear resistance of the steel un- der low stress conditions were investigated, through the study, the following conclusions were obtained： Medium Carbon air eooled bainite cast steel is bainite , martensiteadn little retained austenite mixed mierosture, and keeping 2 hours time in 980℃ austenitizing temperature then air cooled , and keeping 1 hours time in 880℃ anstenitizing then cooled in normal temperature temperature and keeping 2 hours time in 250℃ anealing, the hardness is 49.7 HRC,the impact toughnes is 52.53J/cm2.