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Deformation characteristics of isothermally forged UDIMET 720 nickel-base superalloy

Monajati, H ; Sharif University of Technology | 2005

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  1. Type of Document: Article
  2. DOI: 10.1007/s11661-005-0284-z
  3. Publisher: Minerals, Metals and Materials Society , 2005
  4. Abstract:
  5. The hot deformation behavior of nickel-base superalloy UDIMET 720 in solution-treated conditions, simulating the forging process of the alloy, was studied using hot compression experiments. Specimens were deformed in the temperature range of 1000 °C to 1175 °C with strain rates of 10-3 to 1 s-1 and total strain of 0.8. Below 1100 °C, all specimens showed flow localization as shear band through the diagonal direction, with more severity at higher strain rates. A uniform deformation was observed when testing between 1100 °C and 1150 °C with dynamic recrystallization as the major flow softening mechanism above 1125 °C. Deformation above γ' solvus temperature was accompanied with grain boundary separation. The hot working window was determined to be in the interval 1100 °C to 1150 °C. Thermomechanical behavior of the material was modeled using the power-law, the Sellars-Tegart, and an empirical equation. The flow stress values showed a nonlinear dependence of strain rate sensitivity to strain rate. The analysis indicated that the empirical method provides a better constitutive equation for process modeling of this alloy. The apparent activation energy for deformation was calculated and its variations with strain rate and temperature are discussed
  6. Keywords:
  7. Activation energy ; Compression testing ; Deformation ; Forging ; Grain boundaries ; Hot working ; Mathematical models ; Plastic flow ; Recrystallization (metallurgy) ; Strain rate ; Superalloys ; Thermal effects ; Flow localization ; Hot deformation ; Strain rate sensitivity ; Thermomechanical behavior ; Nickel alloys
  8. Source: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 36, Issue 4 , 2005 , Pages 895-905 ; 10735623 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s11661-005-0284-z