scholarly journals Superplastic Behavior of Al-Mg-Mn Alloy: An Experimental & Numerical Investigation

2018 ◽  
Vol 778 ◽  
pp. 45-52
Author(s):  
Tayyaba Zaman ◽  
Rehan Qayyume ◽  
Amjad Ali ◽  
Shaheed Khan ◽  
Chaoli Maa
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Deformation Mechanism ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
Uniaxial Tensile ◽  
Sensitivity Index ◽  
Deformation Response ◽  
Surface Optical ◽  
Dominant Deformation Mechanism

Deformation response of Al-4.46Mg-0.48Mn alloy under uniaxial tensile loading was investigated at temperatures ranging from 400°C - 525°C and at strain rates of 3x10-3s-1, 1x 10-3s-1& 10-4s-1. The alloy exhibited a maximum elongation >480% at a strain rate of 10-3s-1and 525°C. At all conditions, the dominant deformation mechanism governing the superplastic deformation was investigated as a function of strain rate and temperature. The contributions of strain-rate sensitivity and strain hardening were analyzed in relation to the observed tensile ductility. The strain rate sensitivity index (m) and average activation energy (Q) values revealed that the dominant deformation mechanism is grain boundary sliding (GBS). The GBS phenomenon was further confirmed through high magnification examination of deformed surface. Optical microscopy (OM) and Scanning Electron Microscopy (SEM) showed that dynamic re-crystallization occurs during hot deformation of the alloy which causes reasonable enhancement of plasticity.

Determination of Material Parameters during Superplastic Forming of AZ31B Magnesium Alloy at Elevated Temperatures in Uniaxial Tensile Test

2015 ◽  
Vol 787 ◽  
pp. 437-441
Author(s):  
S. Ramesh Babu ◽  
Vijul Shah ◽  
M.P. Shyam
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Elevated Temperatures ◽  
Rate Sensitivity ◽  
Superplastic Forming ◽  
Uniaxial Tensile ◽  
Sensitivity Index ◽  
Percentage Elongation ◽  
Strain Rate Sensitivity Index

Superplasticity is the ability of the material to produce neck free elongations within a material before fracture. For the past three decades superplastic forming has gained a major development in many industries to produce complex shapes. To perform the superplastic forming at elevated temperatures, the material parameters such as strain rate and strain rate sensitivity index has to be determined. These parameters affect the formability in such a way that higher the strain rate during deformation, lesser will be the percentage elongation and which in turn increases the flow stress of the material there by limiting the formability. Similarly, the strain rate sensitivity index is a measure of resistance to neck formation during deformation. Lesser the strain rate sensitivity value, more will be the neck formation thereby limiting the formability. Hence in this work, an experimental setup is designed to perform the uniaxial tensile testing at elevated temperatures to determine the flow stress, percentage elongation, strain rate and strain rate sensitivity. The determination of these parameters will be helpful in executing the forming at certain temperature and pressure to attain maximum formability. Also the SEM photographs of the fractured specimen were analysed to determine at what temperature and strain rate, the cavitation density increases.

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.

Evolution of plasticity, strain-rate sensitivity and the underlying deformation mechanism in Zn–22% Al during high-pressure torsion

2014 ◽  
Vol 75 ◽  
pp. 102-105 ◽  
Author(s):  
In-Chul Choi ◽  
Yong-Jae Kim ◽  
Byungmin Ahn ◽  
Megumi Kawasaki ◽  
Terence G. Langdon ◽  
...  
Keyword(s):  
High Pressure ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Deformation Mechanism ◽  
High Pressure Torsion ◽  
Rate Sensitivity

A Model for the Effects of Strain Rate and Temperature on the Deformation Behavior of Ultrafine-Grained Metals

2011 ◽  
Vol 291-294 ◽  
pp. 1173-1177
Author(s):  
Zi Ling Xie ◽  
Lin Zhu Sun ◽  
Fang Yang
Keyword(s):  
Grain Boundary ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Boundary Diffusion ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
Dislocation Slip ◽  
Deformation Response ◽  
Ultrafine Grained ◽  
Boundary Sliding

A theoretical model is developed to account for the effects of strain rate and temperature on the deformation behavior of ultrafine-grained fcc Cu. Three mechanisms, including dislocation slip, grain boundary diffusion, and grain boundary sliding are considered to contribute to the deformation response simultaneously. Numerical simulations show that the strain rate sensitivity increases with decreasing grain size and strain rate, and that the flow stress and tensile ductility increase with either increasing strain rate or decreasing deformation temperature.

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