Failure Investigation for QP Steel Sheets under uniaxial and Equal-Biaxial Tension Conditions

10th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes

Zou, Danqing^1,2 ; Li, Shuhui^1,2 ; He, Ji^1,2 ; Cui, Ronggao^1,2

Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures, Shanghai Jiao Tong University, Shanghai

200240, China^1

State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai

200240, China^2

关键词: D. digital image correlation (DIC);    Equal biaxial tension;    Failure behaviors;    Failure investigation;    Quenching and partitioning;    Surface strain field;    Uniaxial tensions;    Volume fraction of retained austenite;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/734/3/032017/pdf
DOI  :  10.1088/1742-6596/734/3/032017

来源: IOP

【 摘 要 】

The Quenching and Partitioning (QP) steel sheet is new generation material to induce phase transformation for plasticity in forming vehicle parts. The phase transformation is strongly stress state dependent behavior in experiments, which should affect the failure timing and limit strain in forming processes. In this paper, Nakajima test with QP980 and DP1000 steel sheets under equal-biaxial loading condition is performed for failure behavior. X-ray diffraction (XRD) is adopted to obtain the volume fraction of retained austenite (fA). Digital Image Correlation (DIC) is used to record the surface strain field and its evolution during equal-biaxial tension deformation. The same level Dual Phase (DP) steel is also employed for the purpose of comparison. The results show that phase transformation in QP steel gives small impact on failure strain under equal biaxial tension condition which is contradicted with our understanding. It suggests that failure behavior under uniaxial tension of QP980 is strongly phase transformation dependent. But it shows almost independent under equal biaxial tension condition.