scholarly journals FATIGUE CRACK GROWTH RATES IN UNIRRADIATED PRESSURE VESSEL STEEL.

1967 ◽  
Author(s):  
E Baldwin ◽  
D Mowbray
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Pressure Vessel ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Crack Growth Rates

Near-Threshold Fatigue Crack Growth in 2 1/4 Cr-1Mo Pressure Vessel Steel in Air and Hydrogen

1980 ◽  
Vol 102 (3) ◽  
pp. 293-299 ◽  
Author(s):  
R. O. Ritchie ◽  
S. Suresh ◽  
C. M. Moss
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Growth Rates ◽  
Pressure Vessel ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Argon Gas ◽  
Near Threshold

As part of an ongoing program to examine subcritical flaw growth in candidate steels for proposed coal gasifier pressure vessels, an initial study is made of characteristics of ultralow growth rate fatigue crack propagation in thick-section, normalized 2 1/4 Cr-1Mo pressure vessel steel (ASTM A387, Class 2 Grade 22). Crack propagation data are generated over a wide range of growth rates, from 10−8 to 10−2 mm/cycle, for load ratios between 0.05 and 0.80 at ambient temperatures in low pressure environments of moist air, dry hydrogen gas and dry argon gas. Particular emphasis is placed on behavior at near-threshold growth rates, below 10−6 mm/cycle, approaching the so-called threshold stress intensity for fatigue crack growth, ΔK0. Near-threshold growth rates, in addition to showing a marked sensitivity to load ratio, are found to be significantly enhanced in gaseous hydrogen compared to air. Similar environmentally-enhanced growth is observed in argon gas. To account for such results, previous models of threshold behavior based on environmental factors (e.g., hydrogen embrittlement) are questioned, and a new approach is presented in terms of the role of oxide debris from moist environments in promoting crack closure. This oxide-induced closure model is found to be consistent with most experimental observations of near-threshold fatigue crack propagation behavior and is proposed as a mechanism for environmental effects at ultra-low growth rates.

Modeling of fatigue crack growth in a pressure vessel steel Q345R

2015 ◽  
Vol 135 ◽  
pp. 245-258 ◽  
Author(s):  
Zhenyu Ding ◽  
Zengliang Gao ◽  
Xiaogui Wang ◽  
Yanyao Jiang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Pressure Vessel ◽  
Pressure Vessel Steel ◽  
Vessel Steel

An Evaluation of Fatigue Crack Growth in a Reactor Steel in Air and Water Environments Considering Closure Effects

2007 ◽  
Vol 348-349 ◽  
pp. 65-68
Author(s):  
Ivo Černý ◽  
Václav Linhart
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Water Environment ◽  
Pressure Vessel Steel ◽  
Crack Growth Behaviour ◽  
Vessel Steel ◽  
Reactor Pressure Vessel Steel ◽  
Crack Growth Rates

The paper contains results of an experimental programme aimed at an evaluation of fatigue crack growth rate and threshold conditions in a reactor pressure vessel steel. Though the main target of the work was to gain a data basis for possible future needs of defect and risk assessment, an emphasis was put on an evaluation of crack growth mechanisms, too. It was shown that despite some recent works infirming crack closure phenomenon itself or methods of its evaluation, crack closure explained near-threshold fatigue crack behaviour in the specific case of the reactor steel in air conditions and was in a direct consistency with results of fractographical analyses. A fairly recent model of partial crack closure was very suitable for an explanation of an unexpected fatigue crack growth behaviour in water environment, when fatigue crack growth rates were rather irregular and significantly lower that in air.

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.

scholarly journals Fatigue Crack Growth Testing of Sub-Clad Defects

1999 ◽  
Vol 121 (3) ◽  
pp. 269-275 ◽  
Author(s):  
D. P. Jones ◽  
T. R. Leax
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Pressure Vessel ◽  
Fatigue Testing ◽  
Repair Process ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Point Bend ◽  
Fatigue Crack Growth Testing

Fatigue crack growth tests were performed on four-point bend specimens with cracklike defects intentionally placed in A302B low-alloy pressure vessel steel clad with 308/309L weld-deposited stainless steel. The defects were placed in the base metal under the cladding by machining a cavity from the side opposite the cladding, electric-discharge machining a very sharp flaw, fatigue precracking the flaw, and then filling up the cavity by a weld repair process. The specimens were stress relieved before fatigue testing. The specimens were fatigue cycled at positive load ratios until the defects broke through to the surface. The specimens were then fractured at liquid nitrogen temperatures to reveal the fracture surfaces. Seven different sub-clad flaw specimens were tested in room temperature air and each test provides a record of cycles to defect breakthrough. Changes in defect size and shape as a function of applied load cycles were obtained by beach-marking the crack at various stages of the load history. The results provide a set of embedded defect data which can be used for qualifying fatigue crack growth analysis procedures such as those in Section XI of the ASME Boiler and Pressure Vessel Code. A comparison between calculated and measured values shows that the ASME B&PV Section XI fatigue crack growth procedures conservatively predict cycles to defect breakthrough for small sub-clad defects.

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