An Overview of Hot- and Warm-Forming of Al-Mg Alloys

2010 ◽  
Vol 433 ◽  
pp. 259-265 ◽  
Author(s):  
Eric M. Taleff
Keyword(s):  
Solute Drag ◽  
Grain Boundary Sliding ◽  
Warm Forming ◽  
Mg Alloys ◽  
Transportation Industry ◽  
Forming Technology ◽  
Practical Engineering ◽  
Boundary Sliding ◽  
Solute Drag Creep ◽  
Al Mg Alloys

Al-Mg alloys exhibit remarkable hot and warm ductilities, which have made the 5000-series alloys a critical part of commercial hot gas-pressure forming operations for the transportation industry. A review of the metallurgical and practical engineering reasons for this success is presented, and new understanding for behaviors in these materials, expected to impact future advances in hot- and warm-forming technology, are described. The excellent formabilities in this material class are fundamentally attributable to two deformation mechanisms, grain-boundary-sliding and solute-drag creep. However, a number of failure mechanisms ultimately limit final ductility and formability. These include cavitation, flow localization and microstructure evolution. The interplay of these mechanisms is discussed in terms of the potential to improve processing windows in forming operations.

Characteristics of the GBS – SDC Transition during Bi-Axial Forming of AA5083

2012 ◽  
Vol 735 ◽  
pp. 43-48 ◽  
Author(s):  
Terry McNelley ◽  
Keiichiro Oh Ishi ◽  
Srinivasan Swaminathan ◽  
John Bradley ◽  
Paul Krajewski ◽  
...  
Keyword(s):  
Cold Working ◽  
Thermomechanical Processing ◽  
Rolling Texture ◽  
Solute Drag ◽  
Grain Boundary Sliding ◽  
Subsequent Evolution ◽  
Refined Grains ◽  
Boundary Sliding ◽  
Evolution Of Microstructure ◽  
Solute Drag Creep

Thermomechanical processing to enable superplasticity in AA5083 materials includes cold working followed by heating prior to hot blow forming. Upon heating for forming at 450°C, a B-type ({110}) rolling texture is replaced by a near-random texture with a weak superimposed cube orientation parallel to the sheet normal. The presence of refined grains 7 – 8μm in size reflects the predominance of particle-stimulated nucleation of recrystallization prior to forming. The subsequent evolution of microstructure, texture and cavitation behaviour during biaxial deformation in the solute drag creep (SDC) and grain boundary sliding (GBS) regimes will be presented.

Electron Microscopy Analysis of Grain Boundary Structure and Composition in Superplastically Deformed Al-Mg Alloys

1996 ◽  
Vol 54 ◽  
pp. 376-377
Author(s):  
J. S. Vetrano ◽  
S. M. Bruemmer
Keyword(s):  
Grain Boundary ◽  
Boundary Region ◽  
Grain Boundary Sliding ◽  
Mg Alloys ◽  
Boundary Structure ◽  
Temperature Structure ◽  
Boundary Composition ◽  
The Matrix ◽  
Boundary Sliding ◽  
Al Mg Alloys

Evaluation of grain boundary composition and structure in superplastically deformed AA5083-based alloys (AI-4.5Mg-1.6Mn-0.2Zr) was carried out in a field-emission gun transmission electron microscope (FEG-TEM). During superplastic deformation at high homologous temperatures materials undergo extensive grain boundary sliding (GBS) which creates a flow of defects in the near-boundary region. Recent literature has shown that the grain-boundary composition in Al-Mg alloys is not necessarily the same as the matrix, and that these differences can have an effect on GBS.Two alloy conditions were tested, with slightly different particulate content and superplastic deformability. Samples were tested at temperatures of 400°C and 450°C and a strain rate of 1x10-−3s−1 to vary the degree of grain boundary sliding, then quenched under load to preserve as much of the high-temperature structure as possible. TEM samples were prepared by carefully punching disks from the gage section of the deformed sample and electropolishing. Additionally, one sample was brought up to temperature and quenched but not deformed.

Characteristics of the Transition from Grain-Boundary Sliding to Solute Drag Creep in Superplastic AA5083

2007 ◽  
Vol 39 (1) ◽  
pp. 50-64 ◽  
Author(s):  
Terry R. McNelley ◽  
Keiichiro Oh-Ishi ◽  
Alexander P. Zhilyaev ◽  
Srinivasan Swaminathan ◽  
Paul E. Krajewski ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Solute Drag ◽  
Grain Boundary Sliding ◽  
Boundary Sliding ◽  
Solute Drag Creep

High-Temperature Deformation of Magnesium ElektronTM 43

2012 ◽  
Vol 735 ◽  
pp. 93-100
Author(s):  
Alexander J. Carpenter ◽  
Anthony J. Barnes ◽  
Eric M. Taleff
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Superplastic Forming ◽  
Solute Drag ◽  
Grain Boundary Sliding ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Fine Grained ◽  
Boundary Sliding

Complex sheet metal components can be formed from lightweight aluminum and magnesium sheet alloys using superplastic forming technologies. Superplastic forming typically takes advantage of the high strain-rate sensitivity characteristic of grain-boundary-sliding (GBS) creep to obtain significant ductility at high temperatures. However, GBS creep requires fine-grained materials, which can be expensive and difficult to manufacture. An alternative is provided by materials that exhibit solute-drag (SD) creep, a mechanism that also produces elevated values of strain-rate sensitivity. SD creep typically operates at lower temperatures and faster strain rates than does GBS creep. Unlike GBS creep, solute-drag creep does not require a fine, stable grain size. Previous work by Boissière et al. suggested that the Mg-Y-Nd alloy, essentially WE43, deforms by SD creep at temperatures near 400°C. The present investigation examines both tensile and biaxial deformation behavior of ElektronTM 43 sheet, which has a composition similar to WE43, at temperatures ranging from 400 to 500°C. Data are presented that provide additional evidence for SD creep in Elektron 43 and demonstrate the remarkable degree of biaxial strain possible under this regime (>1000%). These results indicate an excellent potential for producing complex 3-D parts, via superplastic forming, using this particular heat-treatable Mg alloy.

Damage Development During Superplasticity of Light Alloys

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
R. Boissière ◽  
J. J. Blandin ◽  
L. Salvo
Keyword(s):  
Superplastic Deformation ◽  
Superplastic Forming ◽  
Grain Boundary Sliding ◽  
Mg Alloys ◽  
Damage Development ◽  
Light Alloys ◽  
Irregular Shapes ◽  
Complex Shapes ◽  
Boundary Sliding ◽  
Damage Processes

Superplastic forming (SPF) of metallic alloys allows the production of components with particularly complex shapes since in this regime, due to the predominance of grain boundary sliding (GBS), the material exhibits a high plastic stability. However, in many light alloys (i.e., Al or Mg alloys), superplastic deformation induces damage leading to premature fracture. Despite extensive work in the past, the mechanisms of damage induced by superplastic deformation remain under debate. In particular, due to the important contribution of GBS, voids with very irregular shapes frequently develop, resulting in a difficulty to obtain reliable experimental data from conventional quantitative metallography. It is the reason why the use of X-ray microtomography, providing 3D images of material bulk, is a particularly fruitful technique to investigate damage processes in superplastic materials. Thanks to this technique, damage development during superplastic deformation of Al and Mg alloys is investigated and the three main steps of damage development (nucleation, growth, and coalescence) are discussed.

Accommodation of Grain Boundary Sliding in AZ31 Alloy

2007 ◽  
Vol 345-346 ◽  
pp. 581-584
Author(s):  
Yong Nam Kwon ◽  
Young Seon Lee ◽  
S.W. Kim ◽  
Jung Hwan Lee
Keyword(s):  
Grain Boundary ◽  
Tensile Deformation ◽  
Texture Evolution ◽  
Grain Morphology ◽  
Superplastic Forming ◽  
Az31 Alloy ◽  
Grain Boundary Sliding ◽  
Processing Technique ◽  
Mg Alloys ◽  
Boundary Sliding

Mg alloys could be the lightest alloys among the industrially applicable engineering alloys. Since wrought Mg alloy has limited applications due to the poor formability, casting is currently the main processing technique to fabricate Mg components even though wrought alloys are superior in terms of mechanical properties and reliability. While a lot of research and development has been focused on warm forming under the temperature condition of around 250°C where more formability could be expected, superplastic forming could be another way to get over the low formability of Mg alloys. Like other superplastic materials grain boundary sliding is the main deformation mechanism of Mg superplasticity. Accommodation of stress concentration around triple point of grain boundary should be done favorably if grain boundary sliding continues without any fracture. In the present study, superplastic behavior of AZ31 alloys with several grain sizes was examined firstly. Accommodation of grain boundary sliding of AZ31 alloy would be discussed on the basis of grain morphology and texture evolution after tensile deformation.

Basic Study on Thixo-Co-Extrusion of Multi-Layer Tube with Al/Mg Alloys

2008 ◽  
Vol 141-143 ◽  
pp. 73-78 ◽  
Author(s):  
Kai Kun Wang ◽  
Peng Zhang ◽  
Yan Mei Du ◽  
Zeng Pan ◽  
Hong Gao Li
Keyword(s):  
Fem Simulation ◽  
Mg Alloys ◽  
Electric Resistance ◽  
Basic Study ◽  
Electric Resistance Furnace ◽  
Forming Technology ◽  
Material Forming ◽  
New Processing ◽  
Semi Solid ◽  
Al Mg Alloys

Thixo-forming is in the forefront of metal processing technology in the 21st century. The research on thixo-co-extrusion of multi-layer tube as extension and development of the semi-solid forming technology is a completely new processing method for the composite material forming and is of great significance, in which different semi-solid billets (slurries) are extruded at the same time to form multi-layer tubes. In this study, different sizes of column-shaped and ring-shaped billets of Al/Mg alloys were firstly prepared by using specially designed molds. Then they were reheated by electric-resistance furnace，microstructures from different heating laws were investigated. Lastly, FEM simulation on thixo-co-extrusion of double-layer tube with A356/AZ91 was conducted.

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