Formation of Submicrocrystalline Structure in Large-Scale Ti-6Al-4V Billets during Warm Severe Plastic Deformation

  1. Prof. Dr. Michael Zehetbauer3 and
  2. Prof. Ruslan Z. Valiev4
  1. S.V. Zherebtsov1,
  2. G.A. Salishchev1,
  3. R.M. Galeyev1,
  4. O.R. Valiakhmetov1 and
  5. S.L. Semiatin2

Published Online: 28 JAN 2005

DOI: 10.1002/3527602461.ch15h

Nanomaterials by Severe Plastic Deformation

Nanomaterials by Severe Plastic Deformation

How to Cite

Zherebtsov, S.V., Salishchev, G.A., Galeyev, R.M., Valiakhmetov, O.R. and Semiatin, S.L. (2004) Formation of Submicrocrystalline Structure in Large-Scale Ti-6Al-4V Billets during Warm Severe Plastic Deformation, in Nanomaterials by Severe Plastic Deformation (eds M. Zehetbauer and R. Z. Valiev), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, FRG. doi: 10.1002/3527602461.ch15h

Editor Information

  1. 3

    Institut für Materialphysik, Universität Wien, Boltzmanngasse 5, 1090 Wien, Austria

  2. 4

    Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, 12 K. Marks Str., Ufa, 450 000, Russia

Author Information

  1. 1

    Institute for Metals Superplasticity Problems, Ufa, Russia

  2. 2

    Air Force Research Laboratory, Wright-Patterson Air Force Base, USA

Publication History

  1. Published Online: 28 JAN 2005
  2. Published Print: 25 FEB 2004

ISBN Information

Print ISBN: 9783527306596

Online ISBN: 9783527602469

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Keywords:

  • formation of submicrocrystalline structure;
  • large-scale titanium billet products;
  • warm severe plastic deformation;
  • low-temperature superplasticity;
  • superplastic forming (SPF);
  • isothermal forging

Summary

Materials with a submicrocrystalline (SMC) structure have an average grain size less than 1 µm and show enhanced mechanical properties such as increased strength and fatigue resistance [1]. They also exhibit superplastic behavior at temperatures much below the temperature range typical for materials with micron-sized grains [1, 2], thereby leading to a decrease in processing tool costs and material savings due to reduced contamination [3]. Specifically, low-temperature superplasticity in titanium alloys can be used to produce structural components by superplastic forming (SPF) or isothermal forging at much lower temperatures (600–700 °C) than those used presently (850–950 °C) [4]. However, this requires methods by which an SMC structure can be developed in large-scale billets. A submicrocrystalline structure can be produced in bulk material by severe plastic deformation (SPD) using methods such as equal channel angular extrusion [1] or multi-step isothermal forging [5]. In either case, the development of the SMC structure requires lower working temperatures than those commonly used in the conventional manufacture of semi-finished products. In addition to determining the deformation-temperature regime, the initial (perform) microstructure should also be established, for it can have a substantial effect on the kinetics of grain refinement. For two-phase (alpha/beta) titanium alloys, the perform microstructures are typically globular, bimodal, or lamellar. After hot- or warm-working, the characteristics of these alloys and their final microstructures will be different. However, there is no information in the literature concerning the influence of the initial microstructure on the development of a homogeneous SMC structure during SPD.

The objective of the present work was to establish a method for creating an SMC structure in large-scale titanium billet products by means of multi-step isothermal forging. In particular, the effect of SPD processing conditions and initial microstructure on the formation of a homogeneous SMC structure in large-scale billet of the titanium alloy Ti-6Al-4V was to be determined.