scholarly journals Relation of threshold levels fatigue crack development in low-alloy steel under harmonic and operational loading

2021 ◽  
Vol 1023 ◽  
pp. 012015
Author(s):  
S Lebedinsky ◽  
O Naumov
Keyword(s):  
Fatigue Crack ◽  
Alloy Steel ◽  
Crack Development ◽  
Low Alloy Steel ◽  
Threshold Levels ◽  
Fatigue Crack Development

Test Stand for Analysis of Fatigue Crack Propagation under Bending with Torsion

2008 ◽  
Vol 144 ◽  
pp. 90-93 ◽  
Author(s):  
Grzegorz Gasiak ◽  
Grzegorz Robak
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Digital Camera ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Test Stand ◽  
Crack Development ◽  
Fatigue Crack Propagation Rate ◽  
Fatigue Crack Development

The paper presents a test stand for measurements of fatigue crack propagation. The stand includes a fatigue machine MZGS–100 and a device for registration of the crack length. The test stand is equipped with a stereoscopic microscope with fluent magnification of 7× – 67.5×. The microscope can be applied for observation of fatigue crack development. The microscope is also equipped with a digital camera, which enables continuous observation of fatigue crack development on the computer monitor and it is not necessary to stop the machine. The test results obtained at this stand can be used for determination of fatigue life and fatigue crack propagation rate.

Further Development of a Model for Predicting Corrosion Fatigue Crack Growth in Reactor Pressure Vessel Steels

1987 ◽  
Vol 109 (3) ◽  
pp. 340-346 ◽  
Author(s):  
J. D. Gilman
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Alloy Steel ◽  
High Stress ◽  
Time Dependent ◽  
Crack Advance ◽  
Low Alloy Steel ◽  
Time Rate ◽  
Paris Law

Analysis of fatigue crack growth data for low-alloy steel shows that the influence of cyclic frequency in simulated LWR environments can be interpreted as the superposition of a time-dependent, corrosion-assisted crack growth rate upon an increment predicted by a Paris law. The time-dependent component increases monotonically to a maximum of about 6×10−5 mm/s as stress cycling becomes more aggressive. A useful measure of aggressiveness is the average time rate of crack advance due to the Paris law component alone; i.e., AΔKn × frequency. The result suggests that current ASME Code methods for flaw assessment are highly conservative in some regimes of stress and frequency, but there is a possibility of growth rates well above the ASME XI, Appendix A curves in a very low-frequency, high-stress regime. An upper bound to the time rate of corrosion-assisted crack growth in low-alloy steel is well supported by the data. The threshold conditions for the onset of this high rate are less well defined and require further investigation.

Fatigue Crack Thresholds Significantly Affected by Thermo-Mechanical Loading Histories in an Austenitic and a Ferritic Low Alloy Steel

2014 ◽  
Vol 891-892 ◽  
pp. 1295-1301
Author(s):  
Masakazu Okazaki ◽  
M. Muzvidziwa ◽  
R. Iwasaki ◽  
Naoto Kasahara
Keyword(s):  
Fatigue Crack ◽  
Alloy Steel ◽  
Mechanical Loading ◽  
Structural Reliability ◽  
Repair Process ◽  
Fluid Temperature ◽  
Low Alloy Steel ◽  
History Effects ◽  
High Temperature Structural Material ◽  
High Cycle Thermal Fatigue

High cycle thermal fatigue failure of pipes induced by fluid temperature change is one of interdisciplinary issues to be concerned for long term structural reliability of high temperature structural material and components in energy systems. In order to get basic understanding on this article. the fatigue crack propagation tests were carried out in a low alloy steel and an austenitic stainless steel those were subjected to typical kinds of thermo-mechanical loading histories those included a simulated weld repair process. It was shown experimentally that the thermo-mechanical histories left their individual effects along the prior fatigue crack wake, resulting in significant change in the fatigue crack threshold. Some proposes are presented to predict those history effects.

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