LNG储罐用高锰钢中厚板生产技术开发

Production technology development of high manganese steel plate for liquefied natural gas tanks

为实现高锰钢良好的强韧性能匹配,对高锰钢中厚板进行了控轧控冷工艺试验,通过金相显微镜、扫描电镜和透射电镜观察了高锰钢中厚板的显微组织,采用拉伸和冲击试验机测定了高锰钢中厚板的综合力学性能。结果表明:高锰钢中厚板显微组织为单相奥氏体,奥氏体晶粒尺寸为10~20μm,碳化物弥散分布在奥氏体晶界处,且奥氏体晶粒内部存在较大尺寸的孪晶;高锰钢中厚板纵向屈服强度、抗拉强度、断后伸长率和-196℃冲击功分别为508 MPa、862 MPa、50.07%和124 J,高锰钢中厚板横向屈服强度、抗拉强度、断后伸长率和-196℃冲击功分别为511 MPa、856 MPa、51.67%和97 J;奥氏体晶界处弥散分布的硬相(Cr, Mn)_(23)C_(6)型碳化物,可有效提高高锰钢中厚板的强度;孪晶诱导塑性(TWIP)效应产生大量形变孪晶,增加了均匀伸长率,是高锰钢主要的增塑机制;软相奥氏体中形成的机械孪晶促进位错滑移和增殖,同时产生较强的晶粒细化效应,是高锰钢主要的韧化机制。

In order to achieve good strength and toughness matching of high manganese steel plate,the controlled rolling and controlled cooling test was conducted.The microstructure of the high manganesesteel plate was observed by optical microscope,scanning electron microscope and transmission electron microscope,and the comprehensive mechanical properties of the high manganese steel plate were measured by tensile and impact testing machines.The results showed that the microstructure of high manganese steel plate was single-phase austenite,the austenite grain size was 10-20μm,and the carbides were dispersed at the austenite grain boundaries.Moreover,there were large twins in the austenite grain.The longitudinal yield strength,tensile strength,elongation and impact absorbed energy at-196℃of the high manganese steel plate were 508 MPa,862 MPa,50.07%and 124 J,respectively.The transverse yield strength,tensile strength,elongation and impact absorbed energy at-196℃of the high manganese steel plate were 511 MPa,856 MPa,51.67%and 97 J,respectively.The hard phase(Cr,Mn)_(23)C_(6) carbides distributed at the austenite grain boundaries could effectively improve the strength of the high manganese steel plate.Twinning induced plasticity(TWIP)effect produced a large number of deformation twins and increased the uniform elongation,which was the main plasticizing mechanism of high manganese steel.The mechanical twins formed in soft phase austenite promoted the slip and multiplication of dislocation,and leading to stronger dynamic grain refinement effect,which was the main toughening mechanism of high manganese steel.