Effect of Deformation Temperature on High Strain Rate Superplastic Properties in PM 2024Al-Fe-Ni Alloys

AbstractSuperplastic properties of magnesium alloys and their composites were reviewed with a special emphasis on the achievement of high strain rate superplastic forming. The role of grain size on superplastic deformation mechanisms was particularly addressed. Commercial Mg-Al-Zn alloys and a ZK60-based composite are used as model materials to illustrate the underlining principles leading to the observation of high strain rate superplasticity. In this paper, experimental results from several processing routes, including thermomechanical processing, severe plastic deformation, and extrusion of machined chips and rapidly solidified powders, are presented. High strain rate superplasticity (HSRS) is demonstrated in ZK60-based composites.

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Study of Flow Softening Mechanisms of a Nickel-Based Superalloy With Δ Phase

Archives of Metallurgy and Materials ◽

10.1515/amm-2016-0251 ◽

2016 ◽

Vol 61 (3) ◽

pp. 1537-1546 ◽

Cited By ~ 8

Author(s):

Y.C. Lin ◽

Dao-Guang He ◽

Ming-Song Chen ◽

Xiao-Min Chen ◽

Chun-Yang Zhao ◽

...

Keyword(s):

High Strain Rate ◽

Strain Rate ◽

Deformation Temperature ◽

High Strain ◽

Flow Softening ◽

Compression Tests ◽

Electron Backscattered Diffraction ◽

Deformation Heating ◽

Nickel Based Superalloy ◽

Δ Phase

AbstractThe flow softening behaviors of a nickel-based superalloy with δ phase are investigated by hot compression tests over wide ranges of deformation temperature and strain rate. Electron backscattered diffraction (EBSD), optical microscopy (OM), and scanning electron microscopy (SEM) are employed to study the flow softening mechanisms of the studied superalloy. It is found that the flow softening behaviors of the studied superalloy are sensitive to deformation temperature and strain rate. At high strain rate and low deformation temperature, the obvious flow softening behaviors occur. With the increase of deformation temperature or decrease of strain rate, the flow softening degree becomes weaken. At high strain rate (1s−1), the flow softening is mostly induced by the plastic deformation heating and flow localization. However, at low strain rate domains (0.001-0.01s−1), the effects of deformation heating on flow softening are slight. Moreover, the flow softening at low strain rates is mainly induced by the discontinuous dynamic recrystallization and the dissolution of δ phase (Ni3Nb).

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Microstructure Change During High Strain Rate Superplastic Deformation in a PM 7475 AL-0. 7ZR Alloy

MRS Proceedings ◽

10.1557/proc-196-265 ◽

1990 ◽

Vol 196 ◽

Author(s):

K. Matsuki ◽

M. Tokizawa ◽

Y. Murakami

Keyword(s):

High Strain Rate ◽

Strain Rate ◽

High Strain ◽

Subgrain Size ◽

Early Stage ◽

Strain Rate Range ◽

Al Alloy ◽

Subgrain Structure ◽

Superplastic Properties ◽

Rapidly Solidified

ABSTRACTImprovements of superplasticity in the high strain rate range have been achieved in a 7475 Al alloy with 0. 7 wt% Zr produced from rapidly solidified powder (PM7475-0.7Zr alloy), and the superplastic properties and microstructural changes with strain have been investigated.The PM 7475-0.7 Zr alloy has a cold rolling structure, but on heating to the superplastic temperature of 520°C, the alloy developed a very fine subgrain structure of average subgrain size of less than 1 μm. The fine structure was stabilized with metastable cubic Al3Zr precipitate dispersions, and there exist a large number of less than 5° misorientation subboundaries together with a small number of highly misoriented ones.After 117% strain at the high strain rate of 2. 5×10−1 S−1 the subboundaries with the misorientation of 5° – 15° Were observed to increase. During the initial stage of the deformation, m value and the contribution of boundary sliding to the deformation also increased with strain, and thus the alloy behaved superplastically during the following deformation.The improvements of superplasticity with strain in the early stage of the high strain rate deformation of the alloy were interpreted to be closely related with the increase in misorientation of subboundaries stabilized with finely dispersed metastable Al3Zr precipitates.

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Microstructural Evolution Deformed Heavily by High Strain Rate at High Temperature Range in Ultra Low Carbon Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.558-559.523 ◽

2007 ◽

Vol 558-559 ◽

pp. 523-528

Author(s):

Joo Hee Kang ◽

Shiro Torizuka ◽

Toshihiro Hanamura

Keyword(s):

Grain Size ◽

High Temperature ◽

Carbon Steel ◽

High Strain Rate ◽

Strain Rate ◽

Deformation Temperature ◽

High Strain ◽

Low Carbon Steel ◽

Low Carbon ◽

Ultra Low Carbon Steel

The microstructural change was observed during large strain high Z deformation with high strain rate in high temperature range using ultra low carbon steel. The finer grains were obtained as decreasing the deformation temperature and increasing the strain rate. And the fraction of high angle grain boundaries became higher in low deformation temperature and strong texture of ferrite recrystallized dynamically was measured such as ND//<100>,<111> and RD//<110>. The change of grain size could be analyzed by Zener-Hollomon parameter, whereas the duration has large effect on the deviation of expected grain size in deformation with high strain rate.

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