Academic Articles | |||||
Regular Paper | Vol.9 No.3 (2017) p.152 - p.163 | ||||
LCF and HCF of Austenitic Stainless Steels |
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Gerd DOBMANN1,* | |||||
1 Chair of Nondestructive Testing and Quality Assurance, Saar-University, Campus Dudweiler, Saarbrücken, 66125, Germany |
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Abstract | |||||
The need to reliably perform a fatigue life assessment is obvious, if we have the ageing infrastructure in our power plants in view. Concerning components manufactured in austenitic stainless steel, in Germany, in PWR, we do not have in the primary circuit, as main cooling line (MCL), an austenitic component. The German design is based on pipes, made from the same steel grade as the reactor pressure vessel (RPV) – but cladded on the inner side by austenitic stainless steel. Therefore, Germany, for instance, has not the NDT inspection problems, other countries have, with the dissimilar metal weld between RPV nozzle and MCL. However, the surge line and the pressurizer spray line are fully made from austenitic stainless steel and they are exposed to thermomechanical fatigue. Concerning their fatigue behavior over lifetime of a NPP, many open questions still exist. The paper describes fatigue experiments, monitoring the material in the servo-hydraulic fatigue machine and the development of the PHYBAL procedure for physically based life evaluation. This new technology, in contrast to the standardized SN-Curve evaluation, only asks for a small number of specimens. In case of a homogeneous material, only three tests, 1 incremental step test and 2 constant amplitude tests, are required for the estimation of a complete S-N-fatigue curve by calculation. | |||||
Keywords | |||||
LCF, HCF, austenitic stainless steel, phase transformation, Villari effect, GMR sensor, PHYBAL | |||||
Full Paper: PDF
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