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Investigations on intercrystalline creep crack growth of the austenitic steels X 6 CrNi 18 11 and X 8 CrNiMoNb 16 16
Author(s) -
ElMagd Essam,
Walkenhorst HansWerner
Publication year - 1990
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199000294
Subject(s) - creep , austenitic stainless steel , materials science , metallurgy , austenite , finite element method , composite material , structural engineering , microstructure , engineering , corrosion
The aim of the investigations was to get information about the behaviour of intercrystalline creep cracks during creep deformation from the evaluation of metallographic micrographs and finite element calculations. Two austenitic steels, X 8 CrNiMoNb 16 16 and X 6 CrNi 18 11, were investigated by carrying out creep tests at a temperature of 973 K with varying nominal stresses leading to times of failure from 1 to 3 783 h, as well as to certain creep strains in the tertiary creep stage. These creep tests were followed by analyzing metallographic micrographs of the creep tested specimens and by carrying out finite element calculations, which simulated creep crack growth. It was found that intercrystalline creep cracks in austenitic steel grow independently from momentary crack length but dependent on applied nominal stress and time. Finite element calculations show that local creep strain is a criterion for intercrystalline creep crack growth, contrary to stress‐dependent fracture mechanical results.