摘要
通过调控微观组织形貌及各相组织配比,进一步优化超高强复相钢的综合力学性能,并采用扫描电镜(SEM)、电子探针(EPMA)、透射电镜(TEM)等表征手段,研究其强塑性提升机理。研究结果表明,在820℃的(γ+α)临界区温度退火工艺条件下,显微组织由约37%铁素体、49%贝氏体以及14%残余奥氏体(体积分数)组成,其中铁素体组织以再结晶铁素体和先共析铁素体两种形态存在;贝氏体呈块状;残余奥氏体呈不规则颗粒状,主要分布在铁素体晶界处或铁素体与贝氏体相界面间,其晶粒大小与其周围“贫碳区”BCC晶粒尺寸大致成正比。在910℃奥氏体单相区退火时,显微组织由约19%先共析铁素体、61%板条束状贝氏体型铁素体以及厚度在60~130 nm范围的20%片层状残余奥氏体组成,其中贝氏体铁素体以再结晶γ晶粒作为相变的块状基准单元且呈不同位向分布;大角度晶界所占比例达85.4%;基体中V(C,N)第二相粒子为相间析出,析出粒子直径为3~9 nm,平均列间距约31 nm,对材料的强度贡献计算值约为281 MPa。超高强复相钢的综合力学性能与其微观形貌特征、晶体结构和晶体取向、第二相析出粒子、高密度位错以及残余奥氏体的TRIP效应贡献均密切关联,单相奥氏体区退火工艺条件下,复相钢的抗拉强度达到1226 MPa,同时伸长率和扩孔率分别提高至19.1%和51%,强塑积达到23.42 GPa·%。研究结果可为高强化材料综合性能的提升提供参考。
The comprehensive mechanical properties of ultra-high strength complex phase steel were optimized furtherly by regulating the microstructure morphology and the ratio of each phase structure.The enhancement mechanism of strength-plasticity was studied by characterization methods of scanning electron microscopy(SEM),electronic probe micro-analysis(EPMA)and transmission electron microscopy(TEM).The results show that the microstructure is composed of about 37%ferrite,49%bainite and 14%retained austenite(volume fraction)when the annealing temperature is 820℃which is in the(γ+α)two-phase critical region.The ferrite structure is composed of recrystallized ferrite and proeutectoid ferrite,bainite is blocky.Retained austenite is irregularly granular and mainly distributed at the ferrite grain boundary or between the ferrite and bainite phase interface,and its grain size is basically proportional to the BCC structure of the"carbon-poor region"around it.When the annealing temperature is 910℃which is in the single-phase austenite region,the microstructure is composed of about 19%proeutectoid ferrite,61%lath-like bainite ferrite and 20%lamellar retained austenite with a thickness of 60-130 nm.The bainite ferrite is a massive reference unit with recrystallized austenite grains as the phase transition and distributes in different directions.The proportion of high angle grain boundaries reaches 85.4%.The second phase particles of V(C,N)in the matrix are interphase precipitated,the diameter of the precipitated particles is 3-9 nm,the average column spacing is about 31 nm,and the calculated contribution to the strength of the material is about 281 MPa.The comprehensive mechanical properties of ultra-high strength complex phase steel are closely related to its micro-morphology,crystal structure and crystal orientation,second-phase precipitated particles,high-density dislocations and the TRIP effect contribution of retained austenite.When the annealing temperature is in the single-phase austenite region,the tensile strength of
作者
侯晓英
刘万春
王军
丁明凯
初林
王业勤
HOU Xiaoying;LIU Wanchun;WANG Jun;DING Mingkai;CHU Lin;WANG Yeqin(Rizhao Co.,Ltd.,Shandong Iron&Steel Group,Rizhao 276805,Shandong,China)
出处
《中国冶金》
CAS
CSCD
北大核心
2024年第1期61-71,共11页
China Metallurgy
基金
日照市自然科学基金(优秀青年基金)资助项目(RZ2021ZR10)。
关键词
复相钢
组织调控
强塑性机理
相间析出
晶体学结构
complex phase steel
microstructure control
mechanism of strength-plasticity
interphase precipitation
crystallography structure
