Room temperature recovery of cryogenically deformed aluminium alloys

Materials & Design

Florian Grabner¹  Georg Falkinger²  Florian Spieckermann³  Stefan Pogatscher⁴  Belinda Gruber⁵  Peter J. Uggowitzer⁶  Alexander Schökel⁷ 

[1] Christian Doppler Laboratory for Advanced Aluminum Alloys, Chair of Nonferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef Straße 18, 8700 Leoben, Austria;Corresponding author at: Chair of Nonferrous Metallurgy, Montanuniversität Leoben, Franz-Josef-Str. 18, 8700 Leoben, Austria.;AMAG rolling GmbH, Postfach 32, Ranshofen 5282, Austria;Chair of Materials Physics, Montanuniversität Leoben, Jahnstr. 12, 8700 Leoben, Austria;Chair of Nonferrous Metallurgy, Montanuniversität Leoben, Franz-Josef-Str. 18, 8700 Leoben, Austria;Deutsches Elektronen Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany;LKR Light Metals Technologies Ranshofen, Austrian Institute of Technology, Lamprechtshausenerstr. 61, Ranshofen 5282, Austria;

关键词: Aluminium alloys;    Cryogenic temperature;    Recovery;    Softening;    Dislocation density;   

DOI  :  

来源: DOAJ

【 摘 要 】

Increased formability of aluminium alloys has been demonstrated via cryogenic deformation. In previous studies, the microstructures of samples deformed at low temperatures were analysed after reheating to room temperature (RT) and storage. However, after heating the dislocation structure and density of the deformed material do not reflect the cryogenic situation. In this work, we investigate the evolution of flow stress during recovery in Al-Mg and Al-Mg-Si alloys. We examine the RT recovery behaviour of samples pre-strained at 77 K to different strain levels, and evaluate the structural stability upon subsequent deformation. We also study microstructural evolution via in-situ synchrotron X-ray diffraction, starting from initial conditions at cryogenic temperatures to long-term RT-recovery. Recovery of cryogenically deformed samples at RT results in reduction of the flow stress, in dependence on RT storage. The recovery process can be divided into three distinct sections, each based on a different mechanism characterized by either the arranging or the annihilation of dislocations. Subsequent further straining at room temperature after cryogenic forming also generates plastic instabilities and premature fracture due to unfavourable hardening and recovery assisted softening interplay.

【 授权许可】

Unknown