On the Low Strain Rate Regime of Structural Superplasticity - an Internal Variable Approach

Won Kyu Bang; J.E. Park; Yong Nam Kwon; Chong Soo Lee; Young Won Chang

doi:10.4028/www.scientific.net/MSF.475-479.3007

Paper Titles

Superplastic Behavior and Cavitation for WC-Co Cemented Carbides
p.2991

Microstructural Evolution and Deformation Mechanisms for Superplasticity of NiAl Intermetallic
p.2995

The Effects of Free Space in Mould Cavity on Sandglass Extrusion
p.2999

The Influence of Deformation Condition on Microstructure and Properties of GH4169 Alloy
p.3003

On the Low Strain Rate Regime of Structural Superplasticity - an Internal Variable Approach
p.3007

Threshold Stress for Super Plastic Flow in Spatially Extended Crystalline Systems
p.3013

Influence of Stress State on Superplastic Deformation Behavior in a Zn-Al Eutectoid Alloy
p.3017

Application of Superplastic Flow to Manufacturing of Microcellular Aluminum Foams
p.3021

Superplastic Forming of Aluminum Alloy Car Body Panels
p.3025

HomeMaterials Science ForumMaterials Science Forum Vols. 475-479On the Low Strain Rate Regime of Structural...

On the Low Strain Rate Regime of Structural Superplasticity - an Internal Variable Approach

Abstract:

The superplastic deformation behavior of a fine-grained 7075 Al has been investigated to clarify the issue of threshold stress. A series of mechanical tests has been conducted at various temperatures for the specimens with various grain sizes. The quantitative constitutive parameters have been determined from load relaxation test by applying the internal variable theory of structural superplaticity (SSP) proposed by Chang et al. The GBS flow could be formulated as a viscosity-type equation, characterized by the Newtonian exponent of 1.0. The unresolved issue of threshold stress is clarified and identified as a critical stress required for the GBS. The micro-mechanical roll of grain size refinement has also been manifested in terms of proposed constitutive parameters.