Notched specimens thermo-mechanical fatigue of a 1CrMoV turbine steel

• Published in: Nuclear engineering and design Vol. 234; no. 1; pp. 11 - 24
• Main Authors: MAZZA, E, HOLLENSTEIN, M, HOLDSWORTH, S, SKELTON, R. P
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2004; Elsevier
• Subjects: Applied sciences; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Nuclear fuels; Near field; Stress concentration; Inspection; Turbine; Steel; Stress strain; Crack propagation; Nuclear reactor; Finite element method; Fatigue test; Fatigue strength; Crack initiation; Damaging
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2004.06.009

Isothermal (N-LCF) and thermo-mechanical fatigue (N-TMF) tests have been performed on circumferentially notched bars made of 1CrMoV. The main purpose of the investigation has been to evaluate the suitability of uniaxial fatigue data for the damage assessment of components with stress raising features. Service-cycle N-TMF tests (with low strain rates and long hold periods at peak temperature) reproduced at the notch root the strain and temperature histories of corresponding uniaxial TMF tests performed in previous studies. It is therefore possible to directly compare the notch root endurances with uniaxial data lines. The experimental results have been complemented by detailed finite element calculations and metallurgical analysis from post-test inspections. Under the assumption of a very short crack initiation length, the endurances of the notched tests can be rationalized from the uniaxial data. Measurements of short crack growth within the notch near field have been analysed using stress-strain loops in the notch near field calculated by finite elements. For the same surface equivalent strain range short crack growth is slower in notched tests than in uniaxial tests and is faster in the present N-TMF tests as compared with the N-LCF tests.