Dissolution and Precipitation Behaviour during Continuous Heating of Al–Mg–Si Alloys in a Wide Range of Heating Rates

Materials

Julia Osten¹  Benjamin Milkereit¹  Christoph Schick²  Olaf Kessler¹ 

[1] Chair of Materials Science, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Albert-Einstein-Str. 2, 18059 Rostock, Germany; E-Mails:;Polymer Physics Group, Institute of Physics, University of Rostock, Wismarsche Str. 43-45, 18057 Rostock, Germany; E-Mail:

关键词: continuous heating;    differential scanning calorimetry (DSC);    aluminium alloys;    Al–Mg–Si;    sheet;    dissolution;    precipitation;    enthalpy change;   

DOI  :  10.3390/ma8052830

来源: mdpi

【 摘 要 】

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 °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.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.