Determination of corrosion-assisted stress crack growth rate in 304L stainless steel welds

2007 ◽  
Vol 58 (1) ◽  
pp. 25-28 ◽  
Author(s):  
A. Díaz-Sánchez ◽  
V. M. Castaño
Author(s):  
Kokleang Vor ◽  
Catherine Gardin ◽  
Christine Sarrazin-Baudoux ◽  
Jean Petit ◽  
Claude Amzallag

The scope of this study is to investigate the effect of tensile prestrain on crack growth behavior in a 304L stainless steel. Fatigue crack propagation tests were performed on single-edge notched tension (SENT) raw specimens (0% of prestrain) and on prestrained specimens (2% and 10%). On one hand, it is found that the different levels of prestrain exhibit no significant influence on crack propagation in the high range of Stress Intensity Factor (SIF), where there is no detectable crack closure. On the other hand, a clear effect of prestrain on crack growth rate can be observed in the near threshold region where closure is detected. Thus, it can be concluded that the prestrain mainly affects the crack growth rate through its influence on the crack closure.


Author(s):  
David Tice ◽  
Norman Platts ◽  
Keith Rigby ◽  
John Stairmand ◽  
David Swan

The rate of growth of flaws in reactor circuit components by fatigue is usually determined using the reference crack growth curves in Section XI of the ASME Boiler and Pressure Vessel Code. These curves describe the rate of crack propagation per cycle (da/dN) as a function of the applied stress intensity factor range (ΔK). No reference curves for water-wetted defects in austenitic stainless steels are currently available. This paper describes the results of testing of Type 304L stainless steel in simulated PWR primary coolant over a range of temperatures and mechanical loading conditions. The data on wrought stainless steel presented in this paper demonstrate that crack growth rates can be significantly enhanced by the PWR primary environment at temperatures between 150°C and 300°C. The degree of enhancement increases significantly with reducing loading frequency and decreases with decreasing water temperature. The environmental influence on fatigue is also smaller at very high R ratio (≥0.85). At long rise times the maximum enhancement of crack growth rate over inert crack growth rates was between 1 and 2 orders of magnitude at 250–300°C. However there is evidence that at very long rise times the environmental effect starts to decrease again. The conditions under which this occurs are influenced by temperature and water flowrate, with turbulent flow conditions appearing to have a limited beneficial effect. Due to the strong time dependence of crack growth rate, the data are best rationalized using a time domain (a˙e–a˙i) approach.


2021 ◽  
Author(s):  
Koji Miyoshi ◽  
Masayuki Kamaya

Abstract The effect of a single overload on the fatigue crack growth rate was investigated for Type 316 stainless steel. Fatigue crack growth tests were conducted by controlling strain and load. Tensile and compressive overloads were applied during constant amplitude cycling. The overload ratio, which was defined as the ratio of overload size to baseline constant amplitude, was also changed. The constant amplitude tests were conducted at the strain or the stress ratio of −1.0 which was defined as the ratio of the minimum value to the maximum value. The crack opening point was obtained by the unloading elastic compliance method. The crack growth rate increased after the single compressive overload. The accelerating rate increased with the overload ratio. In contrast, not only the acceleration but also the retardation of the crack growth rate was observed for some tensile overload cases. The crack growth rate increased for relatively small tensile overload cases and decreased for relatively large tensile overload cases. The change in the crack opening level was examined. The crack growth rates after tensile and compressive single overloads correlated with the effective strain and stress intensity factor ranges both for load and strain controlling modes.


Sign in / Sign up

Export Citation Format

Share Document