高强度钢板热成形性预测研究进展

高强度钢板热冲压成形是实现车身轻量化、保证安全性的重要途径,近年来得到汽车和钢铁工业的广泛关注与应用。由于高温工况的引入,高强度钢板的力学行为表现出明显的应变率和温度相关性,为准确评价板料的热成形性带来了挑战。概述了热冲压技术的工艺特点,从热成形极限实验和理论预测两方面展开讨论,介绍了国内外学者的相关研究工作,分析了应变成形极限方法存在的不足,引出了基于损伤力学理论的板材成形性评价方法,分别介绍了连续介质损伤和细观损伤理论在板材成形性方面的若干研究,以及材料损伤参数的识别方法。结合热冲压技术的工艺特点,指出热冲压高强度钢的损伤研究应采用实验、理论及数值仿真相结合的方式,并充分考虑温度、加载速率以及应力状态对损伤演化的影响。本研究可为完善损伤理论在金属板材热冲压中的应用提供借鉴。

Research progress of the prediction method for thermal formability of high strength steel

Hot stamping of high strength steel is an approach to achieve the lightweight of auto-body and guarantee the security of automobile simultaneously, and it has been widely used in the automobile and steel industry in recent years. Due to the high temperature process, the mechanical behaviors of high strength steel are strongly dependent on the deformation temperature and strain rate, which presents a challenge to evaluate the thermal formability accurately. On the basis of the review of the process characteristics of hot stamping, the experimental and theoretical predicted research on the thermal forming limit diagram (FLD) published by overseas and domestic scholars is analyzed. The deficiencies of FLD are discussed, then the evaluation methods for formability based damage mechanics are introduced, which include the continuum damage mechanics and mesoscopic damage mechanics. The calibration methods for damage parameter are also discussed. Finally, some suggestions are given: to accurately study the damage evolution of high strength steel in hot stamping, the influence of deformation temperature, strain rate and stress state must be fully considered. To achieve this, the method combined experiment, theory and numerical simulation must be adopted based on the technological characteristics of the hot stamping technology. This work can provide a reference for the improvement of damage theory in hot stamping of sheet metal, and the related research results can be used to guide process optimization of actual hot stamping, which can effectively shorten the development cycle of new products.