考虑单向拉伸预应变的DP780高强钢成形极限  

Forming limit on high strength steel DP780 considering uniaxial tensile pre-strain

作　　者：蔡达[1] 欧航 蒋浩[1] 丁小娜 李光耀[1,2] 崔俊佳 Cai Da;Ou Hang;Jiang Hao;Ding Xiaona;Li Guangyao;Cui Junjia(State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle,Hunan University,Changsha 410082,China;Shenzhen Automotive Research Institute(Shenzhen Research Institute of National Engineering Laboratory for Electric Vehicles),Beijing Institute of Technology,Shenzhen 518118,China)

机构地区：[1]湖南大学整车先进设计制造技术全国重点实验室,湖南长沙410082 [2]北京理工大学深圳汽车研究院(电动车辆国家工程实验室深圳研究院),广东深圳518118

出　　处：《锻压技术》2024年第7期90-96,共7页Forging & Stamping Technology

基　　金：国家自然科学基金资助项目(52375331);深圳市科技计划项目(KQTD20200820113110016)。

摘　　要：为了建立双相钢DP780单向拉伸预应变条件下的成形极限曲线。对厚度为1.6 mm的DP780高强钢进行考虑单向拉伸预应变的力学性能测试。首先,在大试样上制造不同程度的单向拉伸预应变,随后在预变形后的大试样中心截取小试样进行单向拉伸测试并获取各向异性系数、断后伸长率和硬化系数等材料参数,从而基于半经验公式推导得到单向拉伸预应变条件下的成形极限曲线。单向拉伸预应变对材料性能参数和成形极限有显著影响。随着预应变程度的提升,断后伸长率逐步下降,当预应变达到12%时,断后伸长率下降幅度为35.4%。随着预应变的提升,平面应变到等双拉一侧区域内,成形极限点逐渐减小;单向拉伸一侧的成形极限曲线受预应变的影响向右偏移,但不随预应变的增加而改变。基于两步变形的物理实验和预测模型,能够高效地分析材料受特定预应变载荷下的力学性能,并建立准确反映预应变效应的成形极限图,便于工程技术人员在实际生产中对预应变板材的成形性能进行判断。In order to establish the forming limit curve of dual phase steel DP780 under uniaxial tensile pre-strain condition,the mechanical properties of high-strength steel DP780 with a thickness of 1.6 mm were tested considering uniaxial tensile pre-strain.Firstly,different degrees of uniaxial tensile pre-strain were manufactured on the large sample,and then,a small sample was intercepted at the center of pre-deformed large sample for uniaxial tensile test and the material parameters such as anisotropy coefficient,elongation after fracture and hardening coefficient were obtained.Furthermore,based on semi empirical formulas,the forming limit curve considering uniaxial tensile pre-strain was derived.The results show that the uniaxial tensile pre-strain has a significant impact on material performance parameters and forming limits.As the pre-strain increases,the elongation after fracture gradually decreases.When the pre-strain reaches 12%,the elongation after fracture decreases 35.4%.As the pre-strain increases,the forming limit point gradually decreases in the regions of plane strain and biaxial tensile strain.The forming limit curve on one side of uniaxial tension is shifted to the right due to the influence of pre-strain,but the forming limit does not change with the increasing of pre-strain.Based on two-step deformation physical experiments and prediction model,the mechanical properties of materials under specific pre-strain loads can be analyzed very efficiently,and an accurate forming limit diagram reflecting the pre-strain effect can be established,which is convenient for engineering technologist to judge the forming performance of pre-strain plates in actual production.

关 键 词：高强钢 单向拉伸 预应变 力学性能 成形极限 

分 类 号：TG306[金属学及工艺—金属压力加工]