超快冷下X65管线钢微观组织演变及强化机制分析  

Microstructural Evolution and Strengthening Mechanism of X65 Pipeline Steel Processed by Ultra-fast Cooling

作　　者：王学强[1,2] 赵金华[3] 袁国[1] 王国栋[1] WANG Xue-qiang;ZHAO Jin-hua;YUAN Guo;WANG Guo-dong(State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China;Shougang Qian'an Iron & Steel Co.,Ltd.,Qian'an 064404,China;School of Materials Science and Engineering,Taiyuan University of Science and Technology,Taiyuan 030024,China)

机构地区：[1]东北大学轧制技术及连轧自动化国家重点实验室,辽宁沈阳110819 [2]首钢股份公司迁安钢铁公司,河北迁安064404 [3]太原科技大学材料科学与工程学院,山西太原030024

出　　处：《东北大学学报（自然科学版）》2019年第3期334-338,355,共6页Journal of Northeastern University(Natural Science)

基　　金：国家科技支撑计划项目(2012BAF04B01)

摘　　要：基于热连轧生产线开发了X65管线钢超快冷新工艺,系统表征了该工艺下实验钢的微观组织特征,并进一步讨论了其强化机制.结果表明,超快冷下X65管线钢微观组织为细小针状铁素体(AF)+准多边形铁素体(QPF)+M/A岛+弱化珠光体(DP)混合组织,有效晶粒尺寸为2. 93μm,大角晶界百分比为31. 5%;实验钢组织亚结构为细小的块状铁素体,铁素体尺寸分布在200～1 000 nm;在铁素体基体上析出了大量尺寸<10 nm的Nb(C,N)粒子;实验钢各项力学性能均满足API SPEC 5L标准要求.超快冷工艺下X65管线钢的主要强化机制为细晶强化、固溶强化、位错强化及纳米析出强化的耦合强化,其中纳米析出强化强度贡献值为96. 1 MPa.Based on the hot-rolling production line,a novel processing of ultra-fast cooling(UFC)was developed to produce X65 pipeline strip.Microstructure of the experimental steel after the new processing was studied and the strengthening mechanism was further discussed.The results showed that microstructure of the UFC processed X65 pipeline strip primarily consists of fine acicular ferrite(AF),quasi-polygonal ferrite(QPF),martensite/austenite(M/A)and degenerate pearlite(DP).The effective grain size is 2.93 μm and the proportion of the high-angle boundary in the microstructure is 31.5 %.Small block ferrite with the size ranging from 200 to 1 000 nm is observed in the substructure.A large fraction of nano-sized Nb(C,N)particles(<10 nm)are observed in the ferrite matrix.Moreover,mechanical properties of the experimental steel met to the API SPEC 5L standard.The main strengthening mechanism for the UFC processed X65 pipeline strip is composed by grain refining strengthening,solid solution strengthening,dislocation strengthening and precipitation strengthening,where the strengthening contributed by nano-sized precipitations is 96.1 MPa.

关 键 词：热连轧 超快冷 X65管线钢 针状铁素体 强化机制 

分 类 号：TG142.1[一般工业技术—材料科学与工程]