Cost-Affordable Technique Involving Equal Channel Angular Pressing for the Manufacturing of Ultrafine Grained Sheets of an Al–Li–Mg–Sc Alloy
✍ Scribed by Rustam Kaibyshev; Damir Tagirov; Anna Mogucheva
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 334 KB
- Volume
- 12
- Category
- Article
- ISSN
- 1438-1656
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✦ Synopsis
Abstract
A two‐step process consisting of modified equal channel angular pressing (ECAP) and subsequent isothermal rolling (IR) was developed to produce thin sheets of aluminum alloys with ultra‐fine grained (UFG) structure. Significant increase in the efficiency of ECAP was attained by using flat billets and a back pressure system. The incorporation of final IR into technologic route provides a reduced strain which is necessary to impose for the fabrication of thin sheets with UFG structure. In addition, it allows producing relatively “long billets.” In order to demonstrate the feasibility of this technique an Al–5.1Mg–2.1Li–0.17Sc–0.08Zr (wt %) alloy was subjected to ECAP at 325 °C to a total strain of ∼8 using processing route CX. The operation time of this processing did not exceed 15 min. Subsequent IR at the same temperature with a total reduction of 88% was applied to produce thin sheets with a 1.8 mm thickness and an average size of recrystallized grains of ∼1.6 µm. These sheets exhibit extraordinary high superplastic ductilities. In addition, this material demonstrated almost isotropic mechanical behavior at room temperature. The maximum elongation‐to‐failure of ∼2700% was attained at a temperature of 450 °C and an initial strain rate of 1.4 × 10^−2^ s^−1^. Thus it was demonstrated that the two‐step processing consisting of ECAP with a back pressure followed by IR was a simple technique providing potential capability for the fabrication of superplastic sheets from an Al–Mg–Li–Sc alloy on a commercial scale.