基于DEFORM–3D的7A85大规格铸锭镦粗拔长工艺优化研究

Study on Upsetting and Drawing Process Optimization of 7A85 Large Size Ingot Based on DEFORM-3D

目的为满足结构舱段用高强高韧铝合金宽幅薄壁高筋整体成形壁板挤压制备需求,在保证组织与性能均匀性的同时,进一步提高铸锭利用率。方法采用万能力学性能试验机测试力学性能,结合金相显微镜与扫描电镜完成组织与断口形貌观察。结果7A85半连续铸锭在300℃砧板模具温度下拔长与4.0长径比镦粗时,铸锭整体应力分布最为均衡。晶界处残存的耐热高温相由连续线状转变为分散点状与折线状,铸锭显微组织和性能一致性较高,利于后续挤压制备。结论利用DEFORM–3D数值模拟软件,可对7A85大规格半连续铸锭拔长与镦粗过程的流变应力与等效应变分布进行有效预测,结合铸锭不同区域的受力分析与整体全速度矢量分布,可以准确判断工艺的合理性和可行性。砧板模具温度与铸锭长径比,对7A85半连续铸锭400℃拔长镦粗过程流变应力分布影响明显,可有效改善晶界处残存耐热高温相的分布形态,提高材料的组织均匀性与力学性能。

The influence of the mold temperature and aspect ratio on the flow stress and equivalent strain was studied in this paper.The stress distribution attains the most balanced value when the mold temperature and the L/D ratio reaches 400℃and 4.0,the residual heat-resistant phases distributed nearby the grain boundary change from continuous linear to dispersed dot and polyline,a higher consistency is beneficial to an extrusion process for 7A85 aluminum ingot.DEFORM-3D numerical simulation software can effectively predict the flow stress and equivalent strain distribution in the upsetting and drawing process,also the rationality and feasibility of the process can be accurately judged by combining the force analysis in different regions of the ingot and the total velocity distribution.The flow stress distribution was significantly affected by the mold temperature and the L/D ratio when the ingot was heated at 400℃,which could effectively improve the distribution morphology of the residual heat-resistant phases,improving the microstructure uniformity and mechanical properties.