Fatigue Crack Propagation in an HSLA Steel (MF-80) in Air and in Salt Water

1990 ◽  
Vol 27 (04) ◽  
pp. 221-224
Author(s):  
S. J. Gill ◽  
T. W. Crooker
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Salt Water ◽  
Hsla Steel ◽  
Water Environment ◽  
High Strength Steels ◽  
Load Ratio ◽  
Chloride Salt ◽  
Region Ii

Fatigue crack propagation was studied in MF-80 HSLA steel in ambient room air and in 3.5 percent sodium chloride salt water. Region II fatigue crack growth rate (da/dN) data were obtained at two load ratios, R = 0.10 and R = 0.67. da/dN values were found to be affected by both load ratio and environment, with the greatest effect being caused by the combination of high load ratio and salt-water environment. Overall, the results of this study suggest that MF-80 HSLA steel may have slightly less Region II fatigue crack propagation resistance than other high-strength steels of comparable strength.

50-Fold Difference in Region-II Fatigue Crack Propagation Resistance of Titanium Alloys: A Grain-Size Effect

1979 ◽  
Vol 101 (1) ◽  
pp. 86-90 ◽  
Author(s):  
G. R. Yoder ◽  
L. A. Cooley ◽  
T. W. Crooker
Keyword(s):  
Grain Size ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Load Ratio ◽  
Plastic Zone Size ◽  
Crack Propagation Resistance ◽  
Order Of Magnitude ◽  
Region Ii

Fatigue crack growth rates (da/dN) in ambient laboratory air have been determined for a wide variety of materials from four basic α + β titanium alloy systems. Each material was cyclically loaded with a haversine waveform and a load ratio, R = 0.10. The results indicate that, at a constant value of stress-intensity range (ΔK), the width of the da/dN data band exceeds an order of magnitude. For example, at ΔK = 21 MPa·m1/2, a 50-fold difference in fatigue crack propagation rates is observed. Analysis of the crack growth rate data at this point indicates a systematic dependence on grain size (l), viz. that da/dN decreases with increasing l. An interpretation of this effect is offered in terms of reversed (cyclic) plastic zone size considerations.

Fatigue Crack Propagation Limit Curves for S690QL and S960M High Strength Steels and their Welded Joints

2018 ◽  
Vol 1146 ◽  
pp. 44-56 ◽  
Author(s):  
János Lukács ◽  
Ádám Dobosy ◽  
Marcell Gáspár
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Welded Joints ◽  
High Strength Steels ◽  
High Strength ◽  
Base Materials ◽  
Propagation Limit

The objective of the paper is to present the newest results of our complex research work. In order to determination and comparison of the fatigue resistance, fatigue crack growth tests were performed on different grades of S690QL quenched and tempered, and S960TM thermomechanically rolled high strength steels.15 mmand30 mmthick base materials were used for our investigations. Welded joints were made from these base materials, using gas metal arc welding with matching, overmatching, and undermatching filler metals. In the paper, the performance of the welding experiments will be presented, especially with the difficulties of the filler material selection; along with the results of the fatigue crack growth examinations executed on the base materials and its welded joints. Statistical aspects were applied both for the presenting of the possible locations of the cracks in the base materials and the welded joints and for the processing of the measured data. Furthermore, the results will be compared with each other, and the possibility of derivation of fatigue crack propagation limit curves will be referred.

Fatigue Crack Propagation Limit Curves for High Strength Steels and their Application for Engineering Critical Assessment Calculations

2014 ◽  
Vol 891-892 ◽  
pp. 563-568 ◽  
Author(s):  
János Lukács ◽  
Marcell Gaspar
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Welded Joints ◽  
Research Work ◽  
High Strength Steels ◽  
High Strength ◽  
Critical Assessment ◽  
Propagation Limit

There are different prescriptions containing fatigue crack propagation limit curves and rules for the prediction of the crack growth. The research work aimed (i) to determine fatigue crack propagation limit curves for high strength steels and their welded joints, based on the Paris-Erdogan law; (ii) to use the determined limit curves for engineering critical assessment (ECA) calculations. Experiments were performed on different high strength steels and their welded joints; and the propagating cracks in the specimens represent the different possible locations of the real cracks in the structural elements. Fatigue crack growth tests were executed byΔK-decreasing and constant load amplitude methods. The evaluation process consists of six steps, and by means of the selected values a statistical method can be proposed for determination of the limit curves. Engineering critical assessment calculations were performed on a welded structural element having crack like defects.

Corrosion Fatigue Crack Propagation Behavior of a C-Mn-Cb Steel

1984 ◽  
Vol 106 (3) ◽  
pp. 233-241 ◽  
Author(s):  
A. D. Wilson
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Salt Water ◽  
Water Solution ◽  
Transgranular Fracture ◽  
Specimen Orientation ◽  
Sulfur Level

The fatigue crack propagation properties of a C-Mn-Cb plate steel (SA633 Grade C) in a 3.5 percent NaCl solution have been evaluated for loading frequencies of 10, 1.0, and 0.1 Hertz. To reveal the influence of test specimen orientation and steel cleanliness, both a conventional sulfur level and a low sulfur-calcium treated plate were examined in the three major testing orientations. In addition to other basic testing of the plates, the elastic-plastic fracture toughness properties were also established. The fatigue crack growth rates at 0.1 Hz of both steels were increased by factors of 2–5 over air data, depending on the ΔK level and specimen orientation; some increase was also noted at 1.0 Hz. The acceleration due to the salt water environment was a result of a hydrogen embrittlement mechanism which resulted in bursts of faceted, cleavage-like, transgranular fracture of ferrite grains in this ferrite-pearlite steel. At higher ΔK levels, the calcium treated steel showed slower growth rates than the conventional sulfur level steel for all testing conditions. It was found that higher oxygen contents of a salt water solution could lead to corrosion product wedging at low ΔK levels, which could retard crack growth.

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