A Physical-Based Plane Stress Constitutive Model for High Strength AA7075 under Hot Forming Conditions

Metals

Wei Wu¹  Haitao Qu¹  Fulong Chen¹  YujieHan and Kailun Zheng¹  Shuguang Qu²  Jing-Hua Zheng³ 

[1] AVIC Manufacturing Technology, Beijing 100024, China;Department of Mechanical Engineering, Dalian University of Technology, Dalian 116024, China;Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK;

关键词: hot forming;    constitutive model;    7075 aluminum alloy;    flow behavior;    microstructure validation;    plane stress;   

DOI  :  10.3390/met11020314

来源: DOAJ

【 摘 要 】

Physicallybased constitutive equations are increasingly used for finite element simulations of metal forming processes due to the robust capability of modelling of underlying microstructure evolutions. However, one of thelimitations of current models is the lack of practical validation using real microstructure data due to the difficulties in achieving statistically meaningful data at a sufficiently large microstructure scale. Particularly, dislocation density and grain size governing the hardening in sheet deformation are of vital importance and need to be precisely quantified. In this paper, a set of dislocation mechanics-based plane stress material model is constructed for hot forming aluminum alloy. This material model is applied to high strength 7075 aluminum alloy for the prediction of the flow behaviorsconditioned at 300–400°C with various strain rates. Additionally, an electron backscatter diffraction (EBSD) technique was applied to examine the average grain size and geometrical necessary dislocation (GND) density evolutions, enabling both macro- and micro- characteristics to be successfully predicted. In addition, to simulate the experienced plane stress states in sheet metal forming, the calibrated model is further extended to a plane stress stateto accuratelypredict the forming limits under hot conditions.The comprehensively calibrated material model could be used for guidinga better selection of industrial processing parameters and designing process windows, taking into account both the formed shape as well as post formed microstructure and, hence, properties.

【 授权许可】

Unknown