High Temperature Deformation and Associated 3D Characterisation of Damage in Magnesium Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 1128-1133 ◽  
Author(s):  
Pierre Lhuissier ◽  
A. Villanueva Fernandez ◽  
L. Salvo ◽  
Jean Jacques Blandin
Keyword(s):  
High Temperature ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
X Ray ◽  
Plastic Stability ◽  
Micro Tomography ◽  
3D Information ◽  
Deformation Tests

A way to overcome the low deformability of magnesium alloys at room temperature is toincrease the temperature of forming operations. The stress exponent n, which is known to be a keyparameter in the control of plastic stability, generally decreases when temperature increases.Nevertheless, low n-values are not enough to ensure large capacity of deformation since fracturecan also result from strain induced cavitation. In the present investigation, both the mechanisms ofhigh temperature deformation and damage were studied in selected Mg alloys. Since damage datacan also give information on the deformation mechanisms, the strain induce cavitation behaviourwas mainly studied thanks to X-ray micro tomography which provides 3D information like thecavity shapes or the variation with strain of the number of cavities. Moreover, additionally toconventional post mortem analyses, it was attempted to perform the 3D damage characterisation inin situ conditions, namely directly during high temperature deformation tests.

Parameters Controlling High Temperature Deformability of Wrought Magnesium Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 352-357
Author(s):  
Pierre Lhuissier ◽  
Luc Salvo ◽  
Jean Jacques Blandin
Keyword(s):  
High Temperature ◽  
Magnesium Alloys ◽  
Solute Drag ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Fine Grained ◽  
Significant Damage ◽  
Micro Tomography ◽  
Superplastic Properties ◽  
Deformation Tests

Due to limited deformability at room temperature, high temperature forming of magnesium alloys appears as an interesting alternative. Superplastic properties can be obtained in the case of fine grained magnesium alloys and in this regime, due to significant damage sensitivity, fracture strain is mainly controlled by nucleation, growth and coalescence of cavities. Magnesium alloys with large grained alloys can also exhibit interesting deformabilities at high temperature since dislocation movements can be controlled by a solute drag effect promoting plastic stability. Examples of such situations are presented in the case of wrought magnesium alloys, the associated damage mechanisms being investigated thanks to 3D X-ray micro tomography performed in continuous mode, namely directly during high temperature deformation tests.

4D Damage Characterization during Superplastic Deformation of Magnesium Alloys

2012 ◽  
Vol 735 ◽  
pp. 61-66 ◽  
Author(s):  
Pierre Lhuissier ◽  
Mario Scheel ◽  
Luc Salvo ◽  
Elodie Boller ◽  
Marco Di Michiel ◽  
...  
Keyword(s):  
Magnesium Alloys ◽  
Aluminium Alloys ◽  
Superplastic Deformation ◽  
Fracture Process ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Efficient Tool ◽  
X Ray ◽  
Micro Tomography ◽  
Deformation Tests

As for aluminium alloys, magnesium alloys are generally sensitive to strain induced cavitation when they are deformed in superplastic conditions. It has been widely shown that X-ray micro tomography is a particularly efficient tool for studying in 3D damage mechanisms during superplastic deformation. However, such characterisations are generally performed in post mortem conditions, namely on samples first deformed up to given strains and then characterised. In the present investigation, thanks to particularly short acquisition times offered by ESRF, damage induced by superplastic deformation of a magnesium alloy is studied thanks to tomography analyses performed in 4D conditions, namely directly during high temperature deformation tests. Such conditions provide unique opportunities for investigating nucleation, growth and coalescence of cavities since it is thus possible to follow each cavity up to the fracture process.

Analysis of Intragranular Misorientation Related to Deformation in an Al-Mg-Mn Alloy

2005 ◽  
Vol 495-497 ◽  
pp. 1049-1054 ◽  
Author(s):  
Yoshimasa Takayama ◽  
Jerzy A. Szpunar ◽  
Hajime Kato
Keyword(s):  
Electron Microscope ◽  
High Temperature ◽  
Room Temperature ◽  
Electron Back Scatter Diffraction ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Stored Energy ◽  
Kernel Average Misorientation ◽  
Dislocation Glide ◽  
Scanning Electron

Intragranular misorientation reflects strain generated during deformation with dislocation glide. The SEM/EBSP (scanning electron microscope/ electron back scatter diffraction pattern) technique provides is “kernel average misorientation (KAM)” as the most appropriate quantity to evaluate the strain or the stored energy for a given point. The KAM is defined for a given point as the average misorientation of that point with all of its neighbors. In the present paper two analyses of the intragranular misorientation using the SEM/EBSP technique for a cyclic deformation at room temperature and a high temperature deformation in an Al-Mg-Mn alloy are reviewed.

scholarly journals Effect of Annealing on Structure and Mechanical Behavior of an AA2139 Alloy

2014 ◽  
Vol 783-786 ◽  
pp. 258-263 ◽  
Author(s):  
Damir Tagirov ◽  
Daria Zhemchuzhnikova ◽  
Marat Gazizov ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Flow Stress ◽  
Room Temperature ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Aged Alloy ◽  
Coarse Particles ◽  
Initial Material ◽  
High Ductility

An AA2139 alloy with a chemical composition of Al–4.35Cu-0.46%Mg–0.63Ag-0.36Mn–0.12Ti (in wt.%) and an initial grain size of about 155 μm was subjected to annealing at 430°C for 3 h followed by furnace cooling. This treatment resulted in the formation of a dispersion of coarse particles having essentially plate-like shape. The over-aged alloy exhibits lower flow stress and high ductility in comparison with initial material in the temperature interval 20-450°C. Examination of microstructural evolution during high-temperature deformation showed localization of plastic flow in vicinity of coarse particles. Over-aging leads to transition from ductile-brittle fracture to ductile and very homogeneous ductile fracture at room temperature.

Ductility and Stability in Metallic Materials

2018 ◽  
Vol 941 ◽  
pp. 2319-2324
Author(s):  
Oscar A. Ruano ◽  
Fernando Carreño ◽  
Manuel Carsí
Keyword(s):  
High Temperature ◽  
Magnesium Alloys ◽  
Deformation Mechanisms ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Metallic Materials ◽  
Stability Criteria ◽  
New Concepts ◽  
Stability Maps ◽  
The Stability

Ductility is the property of a given material to deform without fracture. In other words, is the capacity to maintain a structural stability under stresses. It is an important property that is difficult to predict since many microstructural and experimental factors play a role. A review of the most important approaches on ductility is given in this work with special emphasis in the high temperature deformation and the deformation mechanisms. The stability of materials is also analyzed and new concepts on the conditions for hot working are included. Stability maps are analyzed and conclusions on the various stability criteria are given on the base of magnesium alloys.

Grain Refinement and High Temperature Deformation in Friction Stir Processed Sheets of Magnesium Alloys

2007 ◽  
Vol 551-552 ◽  
pp. 55-60 ◽  
Author(s):  
Yoshimasa Takayama ◽  
Y. Otsuka ◽  
Toshiya Shibayanagi ◽  
Hajime Kato ◽  
Kunio Funami
Keyword(s):  
High Temperature ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Maximum Stress ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Rolled Sheet ◽  
Friction Stir ◽  
Fine Grain ◽  
Elongation To Failure

Grain refinement and high temperature deformation in two kinds of magnesium alloys subjected to friction stir processing (FSP) have been investigated. One was a rolled sheet of LA141Mg and another was a cast plate of AZ91Mg. FSP was developed by adapting the concepts of friction stir welding to obtain a fine grain size in a stirred zone. Grain refinement was achieved by FSP to give fine grain sizes of 11.4μm and 8.4μm for LA141 and AZ91 alloys, respectively. For LA141 alloy, the maximum stress of the FSPed sample was higher than that of the as-received one in the range of 300K to 523K while the elongation to failure of the former was considerably smaller than that of the latter. On the other hand, the elongation for the FSPed sample of AZ91Mg showed three times larger elongation with a lower maximum stress than the as-received cast one at 523K and 2.8×10-3s-1. Further difference in high temperature deformation for both magnesium alloys was discussed based on microstructural change and stress-strain curves.

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