摘要
利用超快冷工艺在2250热连轧生产线生产X90管线钢,通过光学显微镜和扫描电镜观察组织,利用透射电镜观察微观结构和析出形貌,通过物理化学相分析及理论计算对析出规律进行研究,并对应变时效性能进行了研究。结果表明,X90管线钢屈服强度615-645 MPa,抗拉强度808-844 MPa,屈强比低于0.8,-20℃冲击功均在300 J以上;基体为由准多边形铁素体、粒状贝氏体、贝氏体铁素体及马氏体奥氏体组元构成的复相组织;析出为Ti、Nb的碳氮化物,超快冷工艺使管线钢中析出过程有效避开了析出鼻尖温度,从而使析出粒子更加细小弥散,析出沉淀强化作用理论计算值为92 MPa;经应变时效后拉伸曲线由Round-House形转变为Luders伸长型,出现明显的屈服平台,屈服强度增加250-280 MPa。
The X90 pipeline steel was produced on a 2250 hot strip mill line by the ultra fast cooling（ UFC） technology. Microstructure of the steel was studied by OM and SEM; TEM was used to observe the morphology and distribution of nano-precipitation particles.Precipitation behavior and strengthening mechanism were studied by theoretical calculation and physicochemical phase analysis. Besides,the strain aging properties of X90 steel was also studied. The results show that the yield strength of the X90 steel is 615-645 MPa,while the tensile strength is 808-844 MPa,the yield ratio is below 0. 8,and the charpy impact energy at- 20 ℃ is above 300 J; the microstructure of the X90 steel is composed of quasi-polygonal ferrite（ QF） 、granular bainite（ GB） 、bainite ferrite（ BF） and martensite /austensite island（ M / A）. The precipitated phases are Ti and Nb carbonitride; the nose temperature of PTT curve is avoided during the precipitation process through the application of UFC,making the precipitation particles more diffuse and finer; the contribution of precipitation on strength is 92 MPa; the stress-strain curve changes from Round-House shape to Luders shape after strain aging,and the yield strength increased by 250-280 MPa.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2015年第12期103-109,共7页
Transactions of Materials and Heat Treatment
基金
国家高技术研究发展计划(863计划)项目(2013AA031601)
国家"十二五"科技支撑计划项目(2012BAF04B01)
关键词
超快冷
X90
组织性能
强化机制
应变时效
ultra fast cooling
X90 pipeline steel
microstructure
strengthening mechanism
strain aging behavior
