STP765: A Deformation Model for Elevated Temperature Including Grain Size Distribution Effects

    Ghosh, AK
    Manager, Metals Processing, Rockwell International Science Center, Thousand Oaks, Calif.

    Raj, R
    Rockwell International Science Center, Thousand Oaks, Calif.

    Pages: 20    Published: Jan 1982


    Abstract

    It is widely believed that grain boundary sliding, accommodated by diffusion, which leads to a Newtonian viscous behavior (σ ∝ ˙ε) and grain matrix deformation exhibiting a power law creep behavior (α ∝ ˙εm), are the two concurrent deformation phenomena occurring at elevated temperatures in metals, particularly during superplastic flow. A deformation model for this combined behavior has been developed in which the grain size and its distribution are taken into account. Strain compatibility relations have been utilized to predict material flow behavior under loading, load relaxation, and steady-state conditions. Comparison with experimental results shows that the sigmoidal σ-˙ε relationship for superplastic metals is explained well by the model. The model also simulates other experimental aspects as well as internal stress development during elevated temperature flow.

    Keywords:

    superplasticity, creep, high temperature flow, grain boundary sliding, strain rate sensitivity, grain size distribution


    Paper ID: STP28900S

    Committee/Subcommittee: E28.10

    DOI: 10.1520/STP28900S


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