Crack initiation and crack growth behavior of carbon and low-alloy steels

Gavenda, D. J.; Luebbers, P.R.; Chopra, O.K.

doi:10.2172/505296

Cited by 15 publications

(26 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During cyclic loading of smooth test specimens, surface cracks 10 mm or longer form quite early in life (i.e., <10% of life) at surface irregularities or discontinuities either already in existence or produced by slip bands, grain boundaries, second-phase particles, etc. 5,[40][41][42][43][44] Consequently, fatigue life may be considered to be composed entirely of propagation of cracks from 10 to 3000 mm long. A schematic illustration of the two stages, i.e., initiation and propagation, of fatigue life is shown in Fig.…”

Section: Formation Of Engineering-size Cracksmentioning

confidence: 99%

“…The growth of MSCs is very sensitive to microstructure. 41,42 Fatigue cracks greater than the critical length of MSCs show little or no influence of microstructure, and are termed mechanically small cracks. Mechanically small cracks correspond to Stage II (tensile) cracks, which are characterized by striated crack growth, with a fracture surface normal to the maximum principal stress.…”

Section: Formation Of Engineering-size Cracksmentioning

confidence: 99%

“…The data obtained by Orbtlik et al 43 for Type 316L SS in air at 25°C and ª0.2% strain range were used to estimate the crack growth in air at 0.75% strain range. Studies on carbon and low-alloy steels 41,42,49 indicate that the fatigue crack size at various life fractions is independent of strain range, strain rate, and temperature; consequently, the depth of the The results show that at the same number of cycles, the crack length is longer in low-DO water (PWR) than in air, e.g., after 1500 cycles the crack length in air, high-DO water (BWR), and PWR water is ª40, 300, and 1100 mm, respectively. The growth of cracks during the initiation stage, i.e., growth of MSCs, is enhanced in water; fatigue cycles needed to form a 500-mm crack are a factor of ª12 lower in low-DO water than in air.…”

Section: Growth Of Small Cracks In Lwr Environmentsmentioning

confidence: 99%

“…5,42 Metallographic evaluation of the specimens indicates that the growth of MSCs in carbon and low-alloy steels occurs predominantly by the slip oxidation/dissolution process. 5 However, for SSs, fatigue lives are lower in low-DO water than in high-DO water; such results are difficult to reconcile in terms of the slip oxidation/dissolution mechanism.…”

Section: Equation 13mentioning

confidence: 99%

See 3 more Smart Citations

Mechanism and estimation of fatigue crack initiation in austenitic stainless steels in LWR environments.

Chopra¹

2002

View full text Add to dashboard Cite

The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life (e-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of fatigue crack initiation in austenitic stainless steels in LWR coolant environments. The existing fatigue e-N data have been evaluated to establish the effects of key material, loading, and environmental parameters (such as steel type, strain range, strain rate, temperature, dissolved-oxygen level in water, and flow rate) on the fatigue lives of these steels. Statistical models are presented for estimating the fatigue e-N curves for austenitic stainless steels as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are presented. The influence of reactor environments on the mechanism of fatigue crack initiation in these steels is also discussed. Executive SummarySection III, Subsection NB, of the ASME Boiler and Pressure Vessel Code contains rules for the design of Class 1 components of nuclear power plants. Figures I-9.1 through I-9.6 of Appendix I to Section III specify the Code design fatigue curves for applicable structural materials. However, Section III, Subsection NB-3121, of the Code states that effects of the coolant environment on fatigue resistance of a material were not intended to be addressed in these design curves. Therefore, the effects of environment on fatigue resistance of materials used in operating pressurized water reactor (PWR) and boiling water reactor (BWR) plants, whose primary-coolant pressure boundary components were designed in accordance with the Code, are uncertain.The current Section-III design fatigue curves of the ASME Code were based primarily on strain-controlled fatigue tests of small polished specimens at room temperature in air. Best-fit curves to the experimental test data were first adjusted to account for the effects of mean stress and then lowered by a factor of 2 on stress and 20 on cycles (whichever was more conservative) to obtain the design fatigue curves. These factors are not safety margins but rather adjustment factors that must be applied to experimental data to obtain estimates of the lives of components. They were not intended to address the effects of the coolant environment on fatigue life. Recent fatigue-strain-vs.-life (e-N) data obtained in the U.S. and Japan demonstrate that light water reactor (LWR) environments can have potentially significant effects on the fatigue resistance of materials. Specimen lives obtained from tests in simulated LWR environments can be much shorte...

show abstract

Section: Formation Of Engineering-size Cracksmentioning

confidence: 99%

Section: Formation Of Engineering-size Cracksmentioning

confidence: 99%

Section: Growth Of Small Cracks In Lwr Environmentsmentioning

confidence: 99%

Section: Equation 13mentioning

confidence: 99%

See 2 more Smart Citations

Mechanism and estimation of fatigue crack initiation in austenitic stainless steels in LWR environments.

Chopra¹

2002

View full text Add to dashboard Cite

show abstract

“…11). 20 In air and low-DO water, g r o w of surface cracks occurs initially as shear cracks -45" to the stress axis, and then as tensile cracks normal to the stress axis when slip is no longer confined to planes at 45" to the stress axis. Also, for C S s , Stage I crack growth in air and low-DO water occur entirely along the soft ferritegrains, whereas in high-DO water and AIO6-Gr B steels in air, simulated PWR environment, and high-DO water the cracks propagate across both ferrite and pearlite regions.…”

Section: A533-gr B Steelmentioning

confidence: 99%

Environmentally assisted cracking in light-water reactors: Semi-annual report, January--June 1997. Volume 24

Chopra¹,

Chung²,

Gruber

1998

Self Cite

View full text Add to dashboard Cite

Hydrogen-involved tensile and cyclic deformation behavior of low-alloy pressure vessel steel

Katada

Kim

et al. 2004

Metall Mater Trans A

View full text Add to dashboard Cite

The temperature-and strain-rate-dependent tensile behavior of hydrogen-charged low-alloy pressure vessel steel ASTM A508 C1.3 has been investigated. The fatigue crack initiation and propagation behavior of the steel in high-temperature water environments has also been evaluated. It was found that hydrogen played significant roles in both tensile and cyclic deformation processes, especially in the temperature and strain-rate region of dynamic strain aging (DSA). The presence of hydrogen resulted in a distinct softening in tensile strength and a certain loss in tensile ductility in the DSA region. Remarkable degradation in fatigue crack initiation and propagation resistance in high-temperature water environments was observed in the DSA strain-rate region. Typical hydrogen-induced cracking features also appeared on the corresponding fatigue fracture surfaces. The interactions between hydrogen and DSA in tensile and cyclic deformation processes are discussed as well as their combined effects on the environmentally assisted cracking (EAC) mechanism of pressure vessel steels in high-temperature water environments.

show abstract

Crack initiation and crack growth behavior of carbon and low-alloy steels

Cited by 15 publications

References 6 publications

Mechanism and estimation of fatigue crack initiation in austenitic stainless steels in LWR environments.

Mechanism and estimation of fatigue crack initiation in austenitic stainless steels in LWR environments.

Environmentally assisted cracking in light-water reactors: Semi-annual report, January--June 1997. Volume 24

Hydrogen-involved tensile and cyclic deformation behavior of low-alloy pressure vessel steel

Contact Info

Product

Resources

About