局部热处理对7B04铝合金口框零件成形性影响的模拟研究

Simulation and study on influence of local heat treatment on formability for 7B04 aluminum alloy frame parts

通过单向拉伸试验获得7B04铝合金原始O态和热处理T4态板材的力学性能参数。运用Dynaform有限元模拟软件,对原始O态板材及局部热处理差性板材(THTB)进行复杂口框零件的冲压成形及充液拉伸成形模拟,系统地研究了在两种成形工艺下局部热处理对口框零件成形性的影响。模拟结果表明:冲压成形口框零件时,原始O态板材局部减薄严重,破裂多发生在中间加强筋底部及圆角处等平面应变区域,局部热处理导致硬化区域周围的板材发生严重破裂,无法改善零件的整体成形性;充液拉深成形口框零件时,原始O态板材在拉深成形过程中,传力区圆角处发生破裂,合理的局部热处理方案引起材料局部硬化,使原始破裂位置的应变路径由平面应变转变成单拉应变,显著提高了口框零件的成形能力。

The mechanical property parameters of original O-state and heat-treated T4-state sheets for 7B04 aluminum alloy were obtained by uniaxial tensile tests,and the stamping process and hydroforming process of complex frame parts of original O-state sheet and tailored heat treated blank(THTB)were simulated by finite element simulation software Dynaform to systematically research the influence of local heat treatment on the formability of frame parts under different forming processes.The simulation results show that the local thinning of original O-state sheet is serious when the frame parts are formed by stamping,the fracture mostly occurs in the plane strain area such as the bottom of middle stiffener and the fillet,and the local heat treatment leads to the serious fracture of sheet around the hardening area,which is unable to improve the overall formability of frame parts.When the frame parts are formed by hydroforming,the original O-state sheet cracks at the fillet of force transmission zone during the deep drawing process,and the reasonable local heat treatment scheme causes local hardening of material,which changes the strain path at the original fracture position from plane strain to single tensile strain.Therefore,the forming ability of frame parts is improved significantly.