高强度钢板的热塑性成形极限

以22MnB5为研究对象,通过试验与数值模拟相结合的方式研究了高强度硼钢在高温下的热塑性成形极限. 开发了基于Nakajima测试的成形极限试验装置TFLD300,进行了高温条件下的成形极限试验并获得了不同温度下的成形极限曲线,由此建立了考虑温度影响的三维成形极限图3D-TFLD(thermal forming limit diagram). 在自主开发的商业金属成形软件KMAS(king mesh analysis system)基础上,结合热成形热、力及相变多物理场耦合关系开发了热成形分析模块,并将三维成形极限图作为高温成形性的判断准则引入到热成形数值模块中. 以一款汽车B柱为例,通过KMAS软件对其热成形过程中的破裂情况进行了数值模拟,并与试验进行对比,结果证明KMAS软件热成形分析模块和3D-TFLD能够准确地预测板料在热成形过程中的破裂情况.

Thermoplastic Forming Limit of High Strength Steel

The thermoplastic forming limit of high strength boron steel, 22MnB5 at high temperature was studied by both experimental research and numerical simulation. Firstly, the device, TFLD300, was developed for the forming limit test based on the Nakajima test. A series of forming limit tests at high temperature were carried out and forming limit curves at different temperatures were obtained. Then a 3-D thermal forming limit diagram with temperature history and strain path was constructed accordingly. Based on the independently developed metal forming commercial software KMAS (king mesh analysis system), the thermoforming analysis module used to deal with the coupling relationship among thermoforming, force, and phase-change was developed with the 3-D thermal forming limit diagram as the criterion for the formability at high temperature. Finally, the typical B-pillar's hot forming process was simulated and the simulated results were compared with the corresponding experiment results. The comparison show that the KMAS thermoforming numerical analysis results are in an accurate agreement with the 3-D TFLD measured results, indicating that both of them can be applied to analyze and measure the fracture of high strength sheet metals in their hot forming.