摘要
为了提升980 MPa级高强钢局部成形性能,采用万能试验机、场发射扫描电镜(SEM)、电子背散射衍射(EBSD)及综合成形试验机等研究了不同退火工艺路径的980 MPa高强钢微观组织和力学性能,并评价了其扩孔及局部成形性能。结果表明,除了有铁素体和马氏体两相外,新型Q&T工艺的组织结构还存在回火马氏体中间相,铁素体和马氏体平均晶粒尺寸分别为3.14μm和2.62μm,马氏体面积分数为61.0%,而传统工艺下为典型的铁素体及马氏体双相组织,铁素体和马氏体平均晶粒尺寸分别为4.77μm和2.77μm,马氏体面积分数为35.8%。两种工艺伸长率相差不大,但屈服强度和扩孔率具有明显差异,新型Q&T工艺下获得了更高的屈强比及扩孔性能,得益于其更小铁素体晶粒尺寸及铁素体和马氏体硬度差。传统工艺下真实断裂应变(TFS)与真实均匀应变εu比值为7.0,而新型Q&T工艺下比值为15.2,因此新型Q&T工艺下具有更优异的局部成形特性。
In order to improve the local formability of 980 MPa high-strength steel,the microstructure and mechanical properties of 980 MPa high-strength steel with different annealing process paths were studied by means of universal testing machine,field emission scanning electron microscope(SEM),electron backscattering diffraction(EBSD)and comprehensive forming testing machine.Moreover,its effect on hole expansion ratio and local formability were evaluated.The results show that in addition to the two phases of ferrite and martensite,the microstructure of the new quenching&tempering(Q&T)process also contains tempered martensite,the average grain size of ferrite and martensitic is 3.14μm and 2.62μm,respectively,and the martensite area fraction is 61.0%,while the typical ferrite and martensitic dual phases are obtained under the traditional process,the average grain size of ferrite and martensite is 4.77μm and 2.77μm,respectively,and the martensite area fraction is 35.8%.The elongation of the two processes is comparable,but the yield strength and hole expansion ratio are significantly different,and the higher yield ratio and hole expansion ratio are achieved under the new Q&T process,which is attributed to its smaller ferrite grain size and the difference in ferrite and martensite hardness.The ratio of true fracture strain(TFS)to true uniform strain(εu)of the traditional process is 7.0,while the new Q&T process is 15.2,therefore the new Q&T process has excellent characteristics in local formability.
作者
邱木生
韩赟
滕华湘
白振华
Qiu Musheng;Han Yun;Teng Huaxiang;Bai Zhenhua(National Engineering Research Center for Equipment and Technology of Cold Strip Rolling,Yanshan University,Qinhuangdao Hebei 066004,China;Research Institute of Technology,Shougang Group Co.,Ltd.,Beijing 100043,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2023年第3期25-31,共7页
Heat Treatment of Metals
基金
河北省重点研发计划(20311004D)。
关键词
980
MPa级高强钢
组织
扩孔
局部成形性
980 MPa grade high-strength steel
microstructure
hole expansion
local formability
