Localization of Strain Rate at Mesoscale and Its Effect on the Measured Strain Rate Sensitivity During Superplastic Deformation

Abstract

Microstructural observations on specimens deformed in regions I, II and III of superplasticity suggest that the dislocation activity is restricted to limited grains in region I but spreads to almost all grains in the region III. Analysis has been carried out to show that the transition from the localized plastic flow in region I to relatively homogeneous plastic flow in region III significantly contributes to the high strain rate sensitivity observed in region II.

Keywords:

• Superplasticity
• Region II
• Grain boundary sliding
• Localization
• Mesoscopic
• Strain rate sensitivity
• Grain size
• Dislocation density
• Atomistic mechanism
• Accommodation
• Plane stress
• Intragranular
• Effective strain rate sensitivity
• Slip line
• Ultrafine grain