Characterization of Elevated Temperature Crack Growth in Hastelloy-X Using Integral Parameters

1995 ◽  
Vol 117 (3) ◽  
pp. 299-304 ◽  
Author(s):  
K. S. Kim ◽  
R. H. Van Stone
Keyword(s):  
Crack Growth ◽  
Elevated Temperatures ◽  
Growth Data ◽  
Hastelloy X ◽  
Linear Elastic ◽  
Acceptable Accuracy ◽  
Elastic Fracture ◽  
Crack Growth Rates ◽  
Temperature Crack

Linear elastic fracture mechanics approaches are not suitable for prediction of fatigue crack growth in the nonlinear regime at elevated temperatures. The objective of this paper is to investigate the ability of the integral parameters by Blackburn (J*), by Kishimoto et al. (Jˆ), and by Atluri et al. (ΔTp*, ΔTp) to correlate crack growth data of Hastelloy-X at elevated temperatures under nominally elastic and nominally plastic loading. Crack growth is analyzed using a finite element method, and the integral parameters are computed from the results of analysis. The experimental crack growth rates are correlated with these parameters. It is found that J*, Jˆ, and ΔTp* can correlate crack growth data within an acceptable accuracy.

The Growth Rate of Semi-Elliptic Fatigue Cracks in Thick-Walled Cylinders

1983 ◽  
Vol 22 ◽  
Author(s):  
W. A. Lees ◽  
P. S. J. Crofton
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Internal Pressure ◽  
Crack Growth ◽  
Fatigue Cracks ◽  
Low Alloy Steel ◽  
Linear Elastic ◽  
Fatigue Data ◽  
Elastic Fracture ◽  
Crack Growth Rates

ABSTRACTThe rate of growth of fatigue cracks originating at the bore and at the outside surface of thick-walled low alloy steel cylinders has been measured for cylinders subjected to fluctuating internal pressure.Analysis of the results using linear elastic fracture mechanics relationships shows that crack growth rates found in air adequately predict the behaviour of cracks growing from the outside surface of a cylinder.Fatigue cracks growing from the bore of a cylinder subjected to fluctuating internal pressure are found to advance at a consistently higher rate than that predicted from crack growth rate tests carried out in air.These findings are discussed in relation to the proposed adoption of existent strain-life fatigue data for pressure vessel design.

Evaluation of Crack Growth in Oxygenated High Temperature Water Using Full Size Pipe Tests

1986 ◽  
Vol 108 (1) ◽  
pp. 50-56
Author(s):  
R. M. Horn
Keyword(s):  
High Temperature ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Crack Depth ◽  
Ultrasonic Inspection ◽  
Linear Elastic Fracture Mechanics ◽  
Growth Data ◽  
Full Size ◽  
Linear Elastic ◽  
Elastic Fracture

Full Size pipe tests have been conducted as part of EPRI research programs at the General Electric Company to verify IGSCC crack growth predictions made using a linear elastic fracture mechanics model. The tests on 10.16 cm (4″ pipes) were performed in oxygenated, high temperature, high purity water. The pipes were produced through standard manufacturing procedures which in turn led to characteristic field piping sensitization levels in the heat affected zones (HAZ) and characteristic through wall weld residual stresses. The tests were conducted at stresses equal to or below the yield strength under constant load with limited cycling. Ultrasonic inspection and metallography were used to characterize crack depth after several test phases and used to verify model predictions. Significant cracks were detected and radial and circumferential growth were documented. These test results support the predictions made using linear elastic fracture mechanics modeling, and are discussed in terms of crack growth data developed in CT specimens in the laboratory. The stress level and oxygen level are shown to influence the crack growth rates. Rates of circumferential crack growth are also evaluated. The paper discusses the results in the context of other stress corrosion evaluations as well.

Handling Uncertainty in the Remnant Fatigue Life Assessment of Offshore Process Pipework

2016 ◽  
Author(s):  
Arvind Keprate ◽  
R. M. Chandima Ratnayake
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Life Assessment ◽  
Assessment Process ◽  
Linear Elastic ◽  
Fatigue Life Assessment ◽  
Process Piping ◽  
Growth Laws ◽  
Elastic Fracture ◽  
Offshore Industry

A typical procedure for a remnant fatigue life (RFL) assessment is stated in the BS-7910 standard. The aforementioned standard provides two different methodologies for estimating RFL; these are: the S-N curve approach and the crack growth laws (i.e. using Linear Elastic Fracture Mechanics (LEFM) principles) approach. Due to its higher accuracy, the latter approach is more commonly used for RFL assessment in the offshore industry. Nevertheless, accurate prediction of RFL using the deterministic LEFM approach (stated in BS-7910) is a challenging task, as RFL prediction is afflicted with a high number of uncertainties. Furthermore, BS-7910 does not provide any recommendation in regard to handling the uncertainty in the deterministic RFL assessment process. The most common way of dealing with the aforementioned uncertainty is to employ Probabilistic Crack Growth (PCG) models for estimating the RFL. This manuscript explains the procedure for addressing the uncertainty in the RFL assessment of process piping with the help of a numerical example. The numerically obtained RFL estimate is used to demonstrate a calculation of inspection interval.

Effect of Salt Water Temperature on the Crack Growth Characteristics of 12 Chrome Steel

1974 ◽  
Vol 96 (2) ◽  
pp. 81-87 ◽  
Author(s):  
R. Eisenstadt ◽  
K. M. Rajan
Keyword(s):  
Stress Intensity ◽  
Crack Growth ◽  
Corrosion Fatigue ◽  
Growth Rates ◽  
Salt Water ◽  
Water Solution ◽  
Correction Term ◽  
Growth Data ◽  
Rotating Beam ◽  
Crack Growth Rates

The corrosion fatigue crack growth rates on 12 chrome steels of typical composition, 12Cr, 0.2C, 1Mo, 1W, of 150,000-ksi yield is relatively unaffected by 4.5 percent NaCl salt water solution at room temperature. There is a significant rise in the crack growth rates of 12 chrome steels with increasing temperature for salt water corrosion fatigue of about 4 to 1 for 160 deg F—4.5 percent solution. In correlating rotating beam understressing data on average crack growth rate versus stress intensity factor with 0-maximum data generated by other techniques, the value 1−R Kmax equivalent to n = 0.5 in the expression Keff = Kmax (1 − R)n correlates the rotating beam data adequately with the 0-Max data for other techniques. A correction factor for eccentric crack fronts on solid round specimens for rotating beam crack growth data to calculate stress intensity factors for solid notched round bars has been developed. The correction term is 4rd2 for the following stress intensity expression. K1=2.257Mr3+4rd20.80t+7.12r−1/2

Experimental Investigation of Constraint Effects on Creep Crack Growth

2002 ◽  
Author(s):  
Adam D. Bettinson ◽  
Noel P. O’Dowd ◽  
Kamran M. Nikbin ◽  
George A. Webster
Keyword(s):  
Stainless Steel ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Growth Data ◽  
Creep Crack ◽  
Low Constraint ◽  
Constraint Effects ◽  
Crack Growth Model ◽  
Crack Growth Rates

In this work the effects of specimen size and type on creep crack growth rates in stainless steel are examined. Experiments have been carried out on high constraint compact tension specimens (CT) and low constraint centre cracked panels (CCP) of ex-service 316H stainless steel. All testing was carried out at 550°C. Constraint effects have been observed in the data, with the large CT specimens having the fastest crack growth rate and the small CCP specimens the slowest. These trends are consistent with those that would be predicted from two parameter (C*–Q) theories. However, it is found that a constraint dependent creep crack growth model based on ductility exhaustion overpredicts the constraint dependence of the crack growth data.

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