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Direct creep curve assessment and optimization of creep equations for high temperature alloys
Author(s) -
Kloos Karl Heinz,
Granacher Joachim,
Pfenning Andreas
Publication year - 1996
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199605473
Subject(s) - creep , materials science , diffusion creep , distortion (music) , mechanics , structural engineering , composite material , engineering , physics , amplifier , microstructure , grain boundary , optoelectronics , cmos
The conventional use of a time temperature parameter method for the basic assessment of a multi‐heat creep data set facilitates the establishment of a creep equation for a material type. However, the parameter can introduce some distortion to the creep data and hence the creep equation. To avoid this disadvantage, a new method for the direct creep curve assessment of multi‐heat data was developed. Systematic deviations in creep behaviour of individual test materials in respect to the mean behaviour of the multi‐heat data set are reduced and the creep curves for individual stresses are transformed to mid creep curves of a limited number of stress classes. With this method large multi‐heat creep data sets of Alloy 100 and Alloy 738 LC could be reduced to mean creep curves. On this basis, existing parameter based creep equations were examined and optimized, if necessary. Further, the confidence limits of these equations were determined. With a stress modification the creep behaviour of a material similar in structure can be described. In finite element analyses some verification experiments which simulate typical loading conditions of components could be successfully recalculated with the optimized creep equations.