Dissolution and Precipitation Behaviour during Continuous Heating of Al-Mg-Si Alloys in a Wide Range of Heating Rates
Dissolution and Precipitation Behaviour during Continuous Heating of Al-Mg-Si Alloys in a Wide Range of Heating Rates
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DOI：
10.3390/ma8052830
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发表时间：
2015-05-01
期刊：
影响因子：
3.4
通讯作者：
Kessler, Olaf
中科院分区：
文献类型：
--
作者：
Osten, Julia;Milkereit, Benjamin;Kessler, Olaf
在宽动态范围内，研究了四种不同的铝合金（EN AW-6005A、EN AW-6082、EN AW-6016和EN AW-6181）在四种不同的初始热处理条件（T4、T6、过时效和软退火）下的溶解和析出行为。用差示扫描量热法（DSC）记录了20 ~ 600℃的升温曲线，升温速率为0.01 K/s ~ 5 K/s。我们特别注意控制基线的稳定性，生成平坦的基线，并允许对结果DSC曲线进行准确的定量评估。随着升温速率的增加，单个的溶解和沉淀反应向更高的温度转移。加热过程中的反应明显重叠，部分反应同时进行。随着升温速率的增加，析出反应和溶解反应受到的抑制越来越大，放热析出反应比吸热溶解反应受到的抑制更早。积分加热曲线可以量化不同初始微观结构条件下的焓值。参考钢的时间-温度-奥氏体化图，构建了铝合金的连续加热溶解图，以图形形式总结了结果。这些图表可以支持热处理车间的工艺优化。
In the present study, the dissolution and precipitation behaviour of four different aluminium alloys (EN AW-6005A, EN AW-6082, EN AW-6016, and EN AW-6181) in four different initial heat treatment conditions (T4, T6, overaged, and soft annealed) was investigated during heating in a wide dynamic range. Differential scanning calorimetry (DSC) was used to record heating curves between 20 and 600 degrees C. Heating rates were studied from 0.01 K/s to 5 K/s. We paid particular attention to control baseline stability, generating flat baselines and allowing accurate quantitative evaluation of the resulting DSC curves. As the heating rate increases, the individual dissolution and precipitation reactions shift to higher temperatures. The reactions during heating are significantly superimposed and partially run simultaneously. In addition, precipitation and dissolution reactions are increasingly suppressed as the heating rate increases, whereby exothermic precipitation reactions are suppressed earlier than endothermic dissolution reactions. Integrating the heating curves allowed the enthalpy levels of the different initial microstructural conditions to be quantified. Referring to time-temperature-austenitisation diagrams for steels, continuous heating dissolution diagrams for aluminium alloys were constructed to summarise the results in graphical form. These diagrams may support process optimisation in heat treatment shops.