双相高强钢板烘烤硬化力学性能的各向异性  

Anisotropic mechanical properties of dual phase high strength steel sheets accounting for bake hardening process

作　　者：张颖 李文凯 蒋华源 何霁 ZHANG Ying;LI Wen-kai;JIANG Hua-yuan;HE Ji(State Key Laboratory of Mechanical System and Vibration,Shanghai Jiao Tong University,Shanghai 200240,China;Integrated Computational Material Engineering Laboratory,Department of Engineering,Zhejiang University City College,Hangzhou 310015,China;College of Mechanical Engineering,Rensselaer Polytechnic Institute,New York 12180,USA;Shanghai Key Laboratory of Digital Manufacture for Thin-Walled Structures,Shanghai Jiao Tong University)

机构地区：[1]上海交通大学机械系统与振动国家重点实验室,上海200240 [2]浙大城市学院工程学院集成计算工程研究中心,浙江杭州310015 [3]伦斯勒理工学院机械工程学院,美国纽约州12180 [4]上海交通大学上海复杂薄板结构数字化制造重点实验室,上海200240

出　　处：《塑性工程学报》2022年第7期129-139,共11页Journal of Plasticity Engineering

基　　金：国家自然科学基金面上项目“超高强钢板断裂行为的各向异性和断裂极限预测”(51975364);上海市自然科学基金面上项目“金属/碳纤维复合结构热冲压的多源热力交互行为及断裂极限预测”(19ZR1425800);中国航空科学基金“金属板/碳纤维复合结构热冲压共固化成型工艺研究”(201936057001)。

摘　　要：以常应用于车门防撞梁的双相钢DP600板材为研究对象,设计考虑烘烤工艺影响的力学性能实验,分别针对初始状态、无预应变烘烤、6%预应变烘烤以及15%预应变烘烤条件下沿板材轧制方向0°~90°共7个方向进行单向拉伸实验,通过应力-应变曲线研究了不同预应变条件下烘烤后由烘烤引起的屈服应力增加量(BH值)、抗拉强度和均匀伸长率等力学性能的变化。建立了基于单拉实验数据的板材力学性能标定识别方法,采用先进屈服方程对DP600烘烤前和不同预应变烘烤之后的屈服行为、塑性流动行为和硬化行为进行了定量表征和对比研究。结果表明:DP600在预应变条件下烘烤后具有显著的烘烤硬化特性,6%及15%预应变的引入直接引起BH值增大约100和200 MPa,且不同预应变条件下的BH值在不同方向上均呈现出各向异性特征,DP600的均匀伸长率在烘烤后有一定程度的下降。预应变水平对伸长率变化有较大影响,且在不同方向上也呈现出各向异性。抗拉强度在烘烤前后基本无变化,6%预应变烘烤后抗拉强度增大约20 MPa, 15%预应变烘烤后增大约60 MPa。相比初始状态,DP600烘烤后各个方向的r值会有所增大,但是6%预应变烘烤后r值又降低,而更高的预应变则又会导致r值增大。通过参数优化标定,YLD2000方程所确定的屈服轨迹与实验数据点有更好的拟合度,使用YLD2000方程能够更加准确地描述DP600线性加载条件下烘烤前后的屈服行为。The dual phase steel DP600 sheets commonly used in door anti-collision beam was taken as the research object, and the mechanical properties experiments considering the influence of baking process were designed. The unidirectional tensile experiments were carried out in seven directions from 0 ° to 90 ° along the rolling direction under the conditions of initial state, no prestrain baking, 6% pre-strain baking and 15% pre-strain baking, respectively. The changes of mechanical properties such as the increase of yield stress caused by baking(BH value), tensile strength and uniform elongation after baking under different pre-strain conditions were studied by stress-strain curves. The calibration and identification method for mechanical properties of sheets based on unidirectional tensile experiments data was established. The yield behavior, plastic flow behavior and hardening behavior of DP600 before baking and after different pre-strain baking were quantitatively characterized and compared by using the advanced yield equation. The results show that DP600 has significant baking hardening characteristics after baking under pre strain conditions. The introduction of 6% and 15% pre-strain directly increases BH value by about 100 and 200 MPa. BH values show anisotropic characteristics in different directions under different pre-strain conditions, and the uniform elongation of DP600 decreases to a certain extent after baking. The pre-strain level has a great influence on the change of uniform elongation and it also shows anisotropy in different directions. The tensile strength basically has little change before and after baking. The tensile strength increases by about 20 MPa after 6% pre-strain baking and about 60 MPa after 15% pre-strain baking. Compared with the inital state, the r value of DP600 in all directions increases after baking, but decreases after 6% pre-strain baking, and higher pre-strain leads to increase of r value. Through parameter optimization calibration, the yield trajectory determined by YLD2000 eq

关 键 词：双相高强钢 烘烤硬化 预应变 屈服方程 

分 类 号：TG156[金属学及工艺—热处理]