Strain Rate Effects on the Fatigue Crack Growth of SA508 Cl.3 Reactor Pressure Vessel Steel in High-Temperature Water Environment

2000 ◽  
Vol 123 (2) ◽  
pp. 173-178 ◽  
Author(s):  
S. G. Lee ◽  
I. S. Kim
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Strain Rate ◽  
Crack Growth ◽  
Pressure Vessel Steel ◽  
Strain Rate Effects ◽  
Vessel Steel ◽  
Reactor Pressure Vessel Steel ◽  
Rate Effects ◽  
Reactor Pressure

Corrosion fatigue tests were performed in air saturated hot water to assess fatigue crack growth behavior of reactor pressure vessel steel at the LWR operating condition. The main test parameter was loading frequency. Crack growth rate was increased with decreasing frequency until a critical frequency. It was found through fractographic study that the enhancement of crack growth rate was environmentally assisted by the hydrogen embrittlement, since brittle striations and cleavagelike facets with microvoid were formed in the crack growth process. The strain rate effects on crack growth rate were investigated through da/dt versus dε/dt curves. At intermediate range, there is a transient point which corresponds to an onset of dynamic strain aging and abruptly increases the crack growth rate; above the transient point, small-size-particle-enhanced brittle cracks, while only large-size-particle-enhanced brittle cracks before the transient. From the fractography, it is suggested that EAC may be enhanced by specific strain rate, and that EAC may be related to interactions of hydrogen with oxide film and to Luders band movement with a high strain gradient at inclusion/matrix interface.

The Effect of Specimen Thickness Upon the Fatigue Crack Growth Rate of A516-60 Pressure Vessel Steel

1977 ◽  
Vol 99 (2) ◽  
pp. 248-252 ◽  
Author(s):  
A. M. Sullivan ◽  
T. W. Crooker
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Pressure Vessel ◽  
Specimen Thickness ◽  
Pressure Vessel Steel ◽  
Vessel Steel

Fatigue crack growth rate studies on A516-60 pressure vessel steel indicate no effect of specimen thickness in stress-relieved specimens ranging in thickness from 0.25 to 2.0 in. (6.35 to 50.8 mm). A regression curve equation for all thicknesses relating cyclic crack growth rate (da/dN) to crack-tip stress-intensity factor range (ΔK) is obtained. The significance of these results is discussed in the light of current engineering practice and previous studies on size effects in fatigue crack propagation.

Fatigue Crack Growth in Large Specimens With Various Stress Ratios

1984 ◽  
Vol 106 (3) ◽  
pp. 255-260 ◽  
Author(s):  
F. Ellyin ◽  
H.-P. Li
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stress Ratio ◽  
Type Equation ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Stress Ratios

An experimental investigation has been carried out on large plates made of pressure vessel steel A516 Gr.70, to determine the fatigue crack growth rate. The specimen size was 914.4 × 304.8 × 12.7 mm (36 × 12 × 0.5 in.) with an initial central through crack of about 92 mm (3.6 in.). The stress ratio, R, applied to the specimens varied from zero to 0.4. This ratio was maintained constant during a test, but the stress amplitude, Δσ, at times was increased in order to obtain data under a large range of stress intensity factor, ΔK. The crack growth rate, da/dN, is expressed in terms of stress intensities, ΔK and Kmax, through a power-law-type equation. The variation of material constants with the applied stress ratio is discussed. From the data analysis, a general equation for the crack propagation rate is suggested in the form of da/dN = C (Kmax)n where C and n are functions of ΔK, Kmax and material parameters. The results are also compared with the recommended ASME Code formula and are found to be in fairly good agreement.

Studies on Strain Fatigue Crack Growth Rate Controlled by Displacement or Load of 16MnR Steel

2011 ◽  
Vol 243-249 ◽  
pp. 5680-5685
Author(s):  
Yan Yan ◽  
An Zhong Liu ◽  
Dao Xiang Zhou
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Plastic Energy ◽  
Weighted Means

In order to understand the strain fatigue crack growth rate of pressure vessel steel controlled by displacement or load, we did experiments on strain fatigue of 16MnR steel and describe the fatigue with the energy method. We have obtained delayed cycle curve of strain fatigue controlled by displacement or load and calculated the J-integral at crack tip. In order to compare strain fatigue crack growth rates of 16MnR steel on two conditions，we compute weighted means of the strain fatigue controlled by displacement or load. Comparing two kinds of fatigue growth rate, it is obvious that the crack growth rate of fatigue controlled by displacement is greater than that controlled by load. All experiments show that compress plastic energy is higher, the fatigue growth rate of 16MnR is lower.

An Experimental Study of the Crack Growth Behavior of 16MnR Pressure Vessel Steel

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Xiaogui Wang ◽  
Zengliang Gao ◽  
Tianwen Zhao ◽  
Yanyao Jiang
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Stable Crack Growth ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Pressure Vessel Steel ◽  
Constant Amplitude ◽  
Vessel Steel ◽  
R Ratio

An experimental investigation was conducted on the crack growth behavior of a pressure vessel steel, 16MnR, in ambient air. Standard compact tension specimens were subjected to Mode I loading with several R-ratios and loading amplitudes. Three circular notch sizes ranging from very sharp notch to blunt notch were used. In addition to constant amplitude loading, experiments were conducted to study the influences of overload and loading sequence on crack growth. The results show that the R-ratio has an insignificant influence on the crack growth of the material. The size of the notch together with the R-ratio and loading amplitude has a great influence on the early crack growth from the notch. A single tensile overload during a constant amplitude loading experiment retards the crack growth significantly. Right after the application of an overload, the crack growth rate is higher than that of the stable crack growth observed in the constant amplitude loading. The crack growth rate decreases and reaches a minimum value before it gradually increases and reaches the stable crack growth curve. In high-low sequence loading with the maximum load in the second step lower than that of the first loading step, the preceding higher constant amplitude loading results in a significant crack growth retardation in the second loading step. This phenomenon is similar to the effect of a single tensile overload on the constant amplitude loading. An existing model making use of the stress intensity factor is discussed with respect to its capability to describe the observed crack growth behavior with the influence of overload and sequence loading.

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