摘要
采用国产工业态5083铝合金,通过气胀成形方式试制高铁车窗零件。对5083铝合金原始金相组织进行分析,发现其平均晶粒尺寸为24μm,远大于国外细晶材料的晶粒尺寸,很难进行超塑成形,因此选择合适的成形参数(成形温度、应变速率、压力加载曲线)来弥补材料在超塑性能上的不足。在不同温度和应变速率条件下对试样进行高温拉伸试验,结果表明:当温度小于475℃,伸长率普遍小于100%;当温度为550℃时,伸长率受应变速率影响变化剧烈,不适合作为成形温度。因此选择气胀成形的温度为525℃,应变速率为6. 56×10~(-4)s~(-1)。通过对成形过程中圆角的应力应变状态进行分析,得到了圆角成形的恒应变速率压力加载方式,并研究了当圆角两边夹角角度变化时恒应变速率压力加载曲线的差别。
A high-speed-railway window part was made in the way of air bulging using domestic industrial state 5083 aluminum alloy. By analyzing the original metallographic microstructure of 5083 aluminum alloy,it is found that the average grain size is 24 μm,which is more coarse than the fine-grained foreign material,making it difficult to realize the superplastic forming. Therefore,appropriate forming parameters,such as temperature,strain rate and loading curve are imperative to compensate for the drawback of the poor superplasticity of the material. The high-temperature tensile tests at different temperatures and strain rates were carried out. The results show that the elongation rate is lower than 100% when the temperature is below 475 ℃; the elongation rate fluctuates acutely with the change of strain rate when the temperature is 550 ℃,making it unsuitable to use as a forming temperature. Thus,the forming temperature and strain rate are set at 525 ℃ and 6. 56 × 10~(-4) s~(-1),respectively. By analyzing the stress and strain state of the fillet in the forming process,the pressure loading curve at a constant strain rate was formulated,and the difference of the constant strain rate pressure loading curves was researched when the angle of the fillet varied.
引文
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