Numerische Lösung gewöhnlicher Differentialgleichungen

Oelschlägel, Dieter; Matthäus, Wolf-Gert

doi:10.1007/978-3-322-96433-5_5

Cited by 1 publication

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“…An alternative approach to achieve high tensile strains uses transformation superplasticity, which has no grain-size requirement because it relies on the biasing of internal stresses produced by cyclical phase transformation. [7] A variety of polymorphic metals and alloys exhibit transformation superplasticity, including iron and steel, [7][8][9][10][11][12][13] titanium and Ti alloys, [7,[14][15][16][17][18][19][20][21] zirconium and Zr alloys, [7,[22][23][24] cobalt, [7,25] and uranium. [7,26,27] Among these metals, titanium and its alloys are particularly suitable for transformation superplasticity because they are commercially important and are difficult to shape by other methods.…”

Section: Introductionmentioning

confidence: 99%

Transformation Superplasticity of Cast Titanium and Ti-6Al-4V

Chen

Bice

et al. 2007

Metall Mater Trans A

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Samples of unalloyed titanium and Ti-6Al-4V with a cast, coarse-grain structure were subjected to simultaneous mechanical loading and thermal cycling about their transformation range to assess their capability for transformation superplasticity. Under uniaxial tensile loading, high elongations to failure (511 pct for titanium, and 265 pct for Ti-6Al-4V) and an average strainrate sensitivity exponent of unity are observed. Samples previously deformed superplastically to a strain of 100 pct show no significant degradation in room-temperature mechanical properties as compared to the undeformed state. Biaxial dome bulging tests confirm that transformation superplasticity is activated under thermal cycling and faster than creep deformation. The cast, coarse-grained titanium and Ti-6Al-4V have similar transformation-superplasticity characteristics as wrought or powder-metallurgy materials with finer grains. This may enable superplastic forming of titanium objects directly after the casting step, thus bypassing the complicated and costly thermomechanical processing steps needed to achieve fine-grain superplasticity.

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