Cyclic Crack Growth Behavior of Reactor Pressure Vessel Steels in Light Water Reactor Environments

1986 ◽  
Vol 108 (1) ◽  
pp. 26-30 ◽  
Author(s):  
W. A. Van Der Sluys ◽  
R. H. Emanuelson
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Rates ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Loading Frequency ◽  
Water Reactor ◽  
Pressure Vessel Steels ◽  
Crack Growth Rates

During normal operation light water reactor (LWR) pressure vessels are subjected to a variety of transients resulting in time varying stresses. Consequently, fatigue and environmentally assisted fatigue are growth mechanisms relevant to flaws in these pressure vessels. In order to provide a better understanding of the resistance of nuclear pressure vessel steels to flaw growth process, a series of fracture mechanics experiments were conducted to generate data on the rate of cyclic crack growth in SA508-2 and SA533B-1 steels in simulated 550°F Boiling Water Reactor (BWR) and 550°F Pressurized Water Reactor (PWR) environments. Areas investigated over the course of the test program included the effects of loading frequency and R ratio (Kmin/Kmax) on crack growth rate as a function of the stress intensity factor (ΔK) range. In addition, the effect of sulfur content of the test material on the cyclic crack growth rate was studied. Cyclic crack growth rates were found to be controlled by ΔK, R ratio, and loading frequency. The sulfur impurity content of the reactor pressure vessel steels studied had a significant effect on the cyclic crack growth rates. The Higher growth rates were always associated with materials of higher sulfur content. For a given level of sulfur, growth rates were higher in a 550°F simulated BWR environment than in a 550°F simulated PWR environment. In both environments cyclic crack growth rates were a strong function of the loading frequency. Further, the loading frequency at which the highest cyclic crack growth rate was observed was found to be a function of the applied ΔK level. In most cases, all cyclic crack growth rates were on or under the ASME Section XI high R water reference flaw growth line and above the Section XI air reference flaw growth line, supporting the position of these lines on the growth rate–ΔK level graph.

Influence of PWR Primary Coolant Environment on Corrosion Fatigue Crack Growth of Austenitic Stainless Steel

2005 ◽  
Author(s):  
David Tice ◽  
Norman Platts ◽  
Keith Rigby ◽  
John Stairmand ◽  
David Swan
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Rates ◽  
Environmental Influence ◽  
304L Stainless Steel ◽  
Loading Frequency ◽  
Primary Coolant ◽  
Crack Growth Rates

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.

Effect of Constraint Induced by Specimen Geometries on Crack Growth Behavior Under Creep-Fatigue Interaction

2018 ◽  
Author(s):  
Lei Zhao ◽  
Lianyong Xu
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Tip ◽  
Crack Growth Behavior ◽  
Growth Behaviour ◽  
Crack Growth Behaviour ◽  
Creep Fatigue ◽  
Crack Growth Rates

Creep-fatigue interaction would accelerate the crack growth behaviour and change the crack growth mode, which is different from that presenting in pure creep or fatigue regimes. In addition, the constraint ahead of crack tip affects the relationship between crack growth rate and fracture mechanics and thus affects the accuracy of the life prediction for high-temperature components containing defects. In this study, to reveal the role of constraint caused by various specimen geometries in the creep-fatigue regime, five different types of cracked specimens (including C-ring in tension CST, compact tension CT, single notch tension SENT, single notch bend SENB, middle tension MT) were employed. The crack growth and damage evolution behaviours were simulated using finite element method based on a non-linear creep-fatigue interaction damage model considering creep damage, fatigue damage and interaction damage. The expression of (Ct)avg for different specimen geometries were given. Then, the variation of crack growth behaviour with various specimen geometries under creep-fatigue conditions were analysed. CT and CST showed the highest crack growth rates, which were ten times as the lowest crack growth rates in MT. This revealed that distinctions in specimen geometry influenced the in-plane constraint level ahead of crack tip. Furthermore, a load-independent constraint parameter Q* was introduced to correlate the crack growth rate. The sequence of crack growth rate at a given value of (Ct)avg was same to the reduction of Q*, which shown a linear relation in log-log curve.

Fatigue Crack Growth Behavior of Titanium Alloy Ti-6Al-4V and Weldment

2001 ◽  
Vol 123 (3) ◽  
pp. 141-146 ◽  
Author(s):  
Mamdouh M. Salama
Keyword(s):  
Growth Rate ◽  
Titanium Alloy ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Titanium Alloys ◽  
Crack Growth ◽  
Growth Rates ◽  
Offshore Structures ◽  
Crack Growth Rates

Optimization of weight, cost, and performance of deepwater offshore structures demands the increased utilization of high strength, light weight, and corrosion resistant materials such as titanium alloys. Titanium alloy Ti-6Al-4V has been considered for several critical components such as risers and taper joints. Because of the novelty of use of titanium alloys in the offshore industry, there is currently no standard governing design of titanium components for offshore structures. Since these structural components are subjected to a complex spectrum of environmental loading, assessment of defect tolerance using fatigue crack growth analysis is generally considered an important design parameter. In this paper, more than 60 crack growth data sets from 20 independent laboratories were collected and analyzed to develop crack growth rate equations for use in defect assessment. These data include the results of fatigue testing of both base material and welded joints in air and seawater with and without cathodic protection and at different R-ratios and test frequencies. The results suggest that for crack growth rates above 10−7 in./cycle, crack growth of Ti-6Al-4V appears to be independent of testing condition and materials processing. At the low crack growth rate (below 10−7 in./cycle), the review revealed that data are very limited. These limited data, however, suggest that the crack growth threshold is dependent on the R-ratio and slightly dependent on material processing. Comparison between crack growth rates of steel and titanium alloy (Ti-6Al-4V) showed that the two materials have very similar behavior.

Fatigue Crack Growth in Type 316 Stainless Steel at High Temperature

1971 ◽  
Vol 93 (4) ◽  
pp. 976-980 ◽  
Author(s):  
P. Shahinian ◽  
H. H. Smith ◽  
H. E. Watson
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
316 Stainless Steel ◽  
Arrhenius Relation ◽  
Crack Growth Rates

The dependence of fatigue crack growth rates on range of stress intensity factor (ΔK) in Type 316 stainless steel was investigated over the temperature range of 75 to 1100 deg F. The data for the most part could be described by a power law relationship. An increase in temperature generally increased crack growth rate for a given ΔK and decreased fatigue life. The dependence of crack growth rate on temperature is not described adequately by an Arrhenius relation over the range investigated. On the other hand, by normalizing ΔK with respect to Young’s modulus, E, the crack growth rates for the various temperatures tend to fall within a single band.

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