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The creep curve of austenitic steels X 6 CrNi 1811 and X 8 CrNiMoNb 1616 after stress changes
Author(s) -
ElMagd Essam,
Shaker Chaled
Publication year - 1990
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199000345
Subject(s) - creep , materials science , dislocation , austenite , stress (linguistics) , thermodynamics , aluminium , metallurgy , enthalpy , mechanics , composite material , physics , microstructure , linguistics , philosophy
The present investigation aims at a better understanding of the relation between creep rate and time in terms of the internal back stress as a structural parameter. The formulation of the creep rate is based on the fundamental Orowan equation. The average dislocation velocity was derived by a theoretical consideration of the required effective stress in dependence of free activation enthalpy. A relation for the mobile dislocation density was determined by fitting the experimental results to calculated data. The determination of the internal back stress in the different creep stages was carried out on austenitic steel X 6 CrNi 18 11, X 8 CrNiMoNb 16 16 and on pure aluminium. It was found, that the knowledge of the behaviour of the internal stress after stress changes allows an exact description of the corresponding creep rate curve.