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Metallurgical and Materials Transactions A

, Volume 34, Issue 10, pp 2377–2386 | Cite as

Microstructure evolution during alpha-beta heat treatment of Ti-6Al-4V

  • S. L. Semiatin
  • S. L. Knisley
  • P. N. Fagin
  • D. R. Barker
  • F. Zhang
Article

Abstract

A framework for the prediction and control of microstructure evolution during heat treatment of wrought alpha/beta titanium alloys in the two-phase field was established via carefully controlled induction heating trials on Ti-6Al-4V and accompanying mathematical modeling based on diffusion-controlled growth. Induction heat treatment consisted of heating to and soaking at a peak temperature T p=955 °C, controlled cooling at a fixed rate of 11 °C/min, 42 °C/min, or 194 °C/min to a variety of temperatures, and final water quenching. Post-heat-treatment metallography and quantitative image analysis were used to determine the volume fraction of primary (globular) alpha and the nucleation sites/growth behavior of the secondary (platelet) alpha formed during cooling. The growth of the primary alpha during cooling was modeled using an exact solution of the diffusion equation which incorporated diffusion coefficients with a thermodynamic correction for the specific composition of the program material and which took into account the large supersaturations that developed during the heat-treatment process. Agreement between measurements and model predictions was excellent. The model was also used to establish a criterion for describing the initiation and growth of secondary alpha as a function of supersaturation, diffusivity, and cooling rate. The efficacy of the modeling approach was validated by additional heat treatment trials using a peak temperature of 982 °C.

Keywords

Material Transaction Titanium Alloy Supersaturation Continuous Cool Beta Phase 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© ASM International & TMS-The Minerals, Metals and Materials Society 2003

Authors and Affiliations

  • S. L. Semiatin
    • 1
  • S. L. Knisley
    • 2
  • P. N. Fagin
    • 3
  • D. R. Barker
    • 3
  • F. Zhang
    • 4
  1. 1.the Air Force Research Laboratory, Materials and Manufacturing DirectorateAFRL/MLLMWright-Patterson Air Force Base
  2. 2.the Chemical Engineering DepartmentUniversity of DaytonDayton
  3. 3.UES, Inc.Dayton
  4. 4.Compu Therm LLCMadison

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