大变形管线钢中F/B多相组织应变硬化行为和应力比研究  

Strain Hardening Behavior and Stress Ratio of High Deformability Pipeline Steel with Ferrite/Bainite Multi-phase Microstructure

作　　者：汤忖江[1] 尚成嘉[1] 关海龙[1,2] 王学敏[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]建龙集团,遵化064200

出　　处：《材料研究学报》2016年第6期409-417,共9页Chinese Journal of Materials Research

基　　金：国家重点基础研究发展计划2010CB630801资助项目~~

摘　　要：采用TMCP工艺获得了5种不同贝氏体体积分数的铁素体/贝氏体(F/B)多相钢。通过纵向力学性能分析,并结合修正C-J分析方法研究了以F/B多相组织为特征的大变形管线钢的应变硬化行为,获得了F/B多相钢中贝氏体体积分数与应力比、屈强比的关系,并通过修正C-J分析对此现象的机理进行了合理的阐释。结果表明,大变形管线钢的弹性形变阶段主要对应修正C-J分析中的第I阶段,塑性形变阶段包括修正C-J分析第Ⅱ和第Ⅲ阶段,屈服点(应变0.5%)附近阶段可跨越第I和第Ⅱ阶段。F/B多相钢中各阶段的应变硬化能力存在显著差异,并且其应变硬化行为呈现出与贝氏体体积分数相关的特性。通过适宜的组织调控可以实现管线钢强度和塑性的最佳匹配。应力比Rt_(1.5)/Rt_(0.5)适宜用于表征管材屈服点附近的应变硬化能力,应力比R_(t2)/R_(t1)、R_(t5)/R_(t1)均适宜用于表征X70级管线钢塑性阶段应变硬化能力,R_(t2)/R_(t1)较适宜用于表征X80级管线钢塑性阶段应变硬化能力。Five ferrite/bainite（F/B） multi-phase steels with different volume fractions of bainite were obtained by TMCP process.The strain hardening behavior of high deformability pipeline steel with F/B multi-phase was studied by the analysis of longitudinal mechanical properties and modified C-J analysis.The relationships between volume fraction of bainite and stress ratio as well as yield ratio were analyzed,and relevant mechanisms were illustrated by modified C-J analysis.The results show that the stage of elastic deformation of high deformability pipeline steel mainly corresponds to stage I in modified C-J analysis,and the stage of plastic deformation consists of stage Ⅱ and stage Ⅲ;and the stage near yield point（0.5% strain） can go across stage I and stage Ⅱ.However,the strain hardening capability of each stage is obviously different from each other,and the strain hardening behavior is closely related to the volume fraction of bainite in F/B multi-phase steel.The optimal matching between strength and plasticity of pipeline steel can be achieved by controlling the microstructure suitably.The stress ratio of Rt_（1.5）/Rt_（0.5）is appropriate to describe the strain hardening capability near the yield point,and the stress ratios of R_（t2）/R_（t1） and R_（t5）/R_（t1） are appropriate to represent the strain hardening capability of plastic deformation stage in X70grade pipeline steel.The stress ratio of R_（t2）/R_（t1） is suitable to characterize the strain hardening capability of plastic deformation stage in X80 grade pipeline steel.

关 键 词：金属材料 铁素体/贝氏体多相钢 大变形管线钢 应变硬化行为 修正C-J分析 贝氏体体积分数 应力比 屈强比 

分 类 号：TG142.1[一般工业技术—材料科学与工程]