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

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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104 licrostructural Refinement and its High Temperature Deformation by Friction Stir Process Technology

The Proceedings of the Materials and processing conference ◽

10.1299/jsmemp.2013.21._104-1_ ◽

2013 ◽

Vol 2013.21 (0) ◽

pp. _104-1_-_104-5_

Author(s):

Tsutomu ITO ◽

Takeo YOKOTA

Keyword(s):

High Temperature ◽

High Temperature Deformation ◽

Temperature Deformation ◽

Process Technology ◽

Friction Stir Process ◽

Friction Stir

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.1128 ◽

2012 ◽

Vol 706-709 ◽

pp. 1128-1133 ◽

Cited By ~ 3

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.

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Ductility and Stability in Metallic Materials

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.2319 ◽

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.

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Parameters Controlling High Temperature Deformability of Wrought Magnesium Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.783-786.352 ◽

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.

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