Retrogression and Reaging of AA7075 and AA6013 Aluminum Alloys

Retrogression and Reaging of AA7075 and AA6013 Aluminum Alloys
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DOI：
10.1007/s11661-020-06133-0
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发表时间：
2021-01
期刊：
Metallurgical and Materials Transactions A
影响因子：
--
通讯作者：
K. Rader;J. Carter;L. Hector;E. Taleff
K. Rader;J. Carter;L. Hector;E. Taleff
中科院分区：
其他
文献类型：
--
作者：
K. Rader;J. Carter;L. Hector;E. Taleff

文献摘要

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倒退与再时效(RRA)是汽车工业对制造高强度铝合金零件的一项重要技术。对AA7075-T6和AA6013-T6材料的RRA热处理进行了研究。回归被证明是一个热激活过程，具有单一活化能的合理特征。测得AA7075-T6和AA6013-T6的回归活化能分别为97±7和160±30 kJ/mol。在一定的回归温度范围内，定义并测量了临界回归时间tR*和tRmax。这些数据与缩短时间的概念一起用来预测产生成功的倒退热处理的温度和时间的组合。建议对AA7075-T6进行200℃，持续3-12分钟，对AA6013-T6进行240℃，持续7分钟。来自再老化热处理的数据证实了AA6013中显著的RRA响应。对于退化的AA7075，建议的再老化热处理为120℃，持续24小时；对于退化的AA6013，建议的再老化热处理为190℃，持续1小时。模拟汽车油漆烘烤循环的再老化热处理，185摄氏度，持续25分钟，几乎与推荐的AA6013再老化热处理一样有效，但明显不如推荐的AA7075再老化热处理有效。
Retrogression and reaging (RRA) is of interest to the automotive industry for manufacturing components of high-strength aluminum alloys. RRA heat treatments are investigated for AA7075-T6 and AA6013-T6 materials. Retrogression is demonstrated to be a thermally activated process reasonably characterized with a single activation energy. Activation energies for retrogression are measured as 97 ± 7 and 160 ± 30 kJ/mol for AA7075-T6 and AA6013-T6, respectively. Critical retrogression times,tR* andtRmax, are defined and measured across a range of retrogression temperatures. These data are used with the concept of reduced time to predict combinations of temperature and time that produce successful retrogression heat treatments. Recommended retrogression heat treatments are 200 °C for 3 to 12 minutes for AA7075-T6 and 240 °C for 7 minutes for AA6013-T6. Data from reaging heat treatments confirm a significant RRA response in AA6013. Recommended reaging heat treatments are 120 °C for 24 hours for retrogressed AA7075 and 190 °C for 1 hour for retrogressed AA6013. A reaging heat treatment that simulates the automotive paint-bake cycle, 185 °C for 25 minutes, is almost as effective as the recommended reaging heat treatment for AA6013 but is significantly less effective than the recommended reaging heat treatment for AA7075.