Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9795803 | Materials Science and Engineering: A | 2005 | 9 Pages |
Abstract
The superplastic properties and microstructural evolution of a 7055 aluminum alloy was examined in tension at temperatures ranging from 300 to 450 °C and strain rates ranging from 2.7 Ã 10â5 to 5.6 Ã 10â2 sâ1. A refined microstructure with an average grain size of â¼1.4 μm and a portion of high-angle grain boundaries (HAGBs) of â¼67% was produced in sheets by equal channel angular extrusion (ECAE) followed by isothermal rolling (IR) at 250 °C. The alloy exhibited a maximum elongation-to-failure of â¼820% at a temperature of 450 °C and an initial strain rate of 5.6 Ã 10â3 sâ1. Superplastic elongation of â¼670% was recorded at strain rates higher than 10â2 sâ1, where the strain rate sensitivity coefficient was around 0.44. The relationship between superplastic ductilities and microstructure stability was analyzed. It was shown that increasing the portion of HAGBs by IR results in enhancement of superplastic properties.
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Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
I. Nikulin, R. Kaibyshev, T. Sakai,