为解决颗粒增强铝基复合材料塑性加工困难的问题,采用脉冲电流辅助热拉深成形工艺。利用脉冲电流产生的焦耳热效应加热坯料,加热速度快、效率高,极大减少了坯料在加热过程中的热损耗。脉冲电流密度达到21.7A.mm-2时,坯料温度达到成形温度400℃。同时,铜电极和坯料之间安装的高电阻、低热传导率的不锈钢隔热片,有效地减小了坯料与电极间的热传导,提高了坯料的温度场分布均匀性。成形的工件表面质量光滑、形状精确、厚度均匀、无明显划伤和褶皱,圆角处无显微裂纹出现,尺寸精度达到±0.2mm。脉冲电流辅助热拉深成形工艺为SiCp/2024Al复合材料板材的塑性加工提供了一种高效、节能的绿色工艺方法。
The feasibility of pulse current auxiliary thermal deep drawing was designed and investigated to form the SiC particle reinforced Aluminum composites sheet.This technique set the sheet directly into the die and inputted high-intensity pulse current to heat sheet,which had many advantages,including high-speed heating,lower heat loss and reducing oxidation.The average pulse current density was achieved at 21.7 A·mm-2 with temperature of SiCp/2024Al composites reaching around 400 ℃.During electrification,the stainless steel was inserted between the sheet and the copper electrodes successfully prevented heat dissipation and promoted temperature uniformity.The workpiece shows good shape retention,surface quality and high geometry accuracy.The present investigation has successfully verified the feasibility of process procedure for PCATDD of SiCp/2024Al composites sheet.