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.

scholarly journals Fatigue-Crack Propagation Behavior of Incoloy 800 at Elevated Temperatures

1974 ◽  
Vol 96 (4) ◽  
pp. 249-254 ◽  
Author(s):  
L. A. James
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Fatigue Crack Propagation Behavior ◽  
Propagation Behavior ◽  
Incoloy 800 ◽  
Crack Growth Rates ◽  
Crack Propagation Behavior

Linear-elastic fracture mechanics techniques were used to characterize the fatigue-crack propagation behavior of Incoloy 800 in an air environment over the temperature range 75 to 1200 deg F (24 to 649 deg F). Crack growth rates were measured over the range 5×10−7 to 5×10−5 in./cycle. Material Grades 1 and 2 were found to exhibit essentially the same behavior over this range. In general, crack growth rates increased with increasing test temperature, although the increases were less then previously noted for austenitic stainless steels. This difference is probably related to the superior oxidation resistance of Incoloy 800.

Experimental Investigations of Fatigue Crack Propagation for Pipe Under Torsional Loading

2010 ◽  
Author(s):  
Motoki Nakane ◽  
Satoshi Kanno ◽  
Shota Hashimoto ◽  
Takayuki Watanabe ◽  
Yukio Takahashi
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Torsional Loading ◽  
Crack Growth Rates

This study discusses methods for evaluating fatigue crack propagation under torsional loading for pipes. To achieve this objective, fatigue crack propagation tests were carried out on both stainless steel and carbon steel used in piping systems of nuclear power plants. Two different kinds of pipes were tested in this study. These pipes had the same shape but the diameter and thickness of the larger pipe were twice those of the smaller pipe. The nominal shear stress amplitudes applied to the specimen were set between 50 and 100 MPa depending on the dimension of the specimen and desired crack growth rates. All fatigue tests were conducted under pure torsional loading with stress ratio R = −1 and at room temperature. The geometrical correction factors for the specimen were derived from elastic J-integral calculated by the FEM. The fatigue crack propagation tests results show that the crack growth rates estimated by the elastic stress intensity factor with the geometrical correction factor were much faster than curves prescribed in The Japan Society of Mechanical Engineers (JSME) codes. These results suggest that elastic plastic fracture parameters should be considered into the stress intensity factor because yield stresses for torsional loading would be smaller than those of uniaxial loading. The plastic zone correction method and modified reference stress method were examined as alternative methods. The crack growth rates estimated by the proposed methods almost totally correspond to the JSME curves. The two proposed methods were found to be quite effective at correctly evaluating the crack growth rates under torsional loading.

Transient Fatigue Crack-Growth Behavior and Damage Zones in Zr-Based Bulk Metallic Glass

2003 ◽  
Vol 806 ◽  
Author(s):  
Peter A. Hess ◽  
Reinhold H. Dauskardt
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Crack Closure ◽  
Growth Rates ◽  
Fatigue Loading ◽  
Structural Applications ◽  
Crack Growth Rates

ABSTRACTFatigue crack propagation mechanisms of bulk metallic glasses (BMGs) are not well understood, limiting their use in safety-critical structural applications particularly where complex fatigue loading may occur. Accordingly, the present study examines the effects of variable amplitude fatigue loading associated with block loading and tensile overloads on fatigue crack-growth rates in a Zr-based BMG. Crack growth studies were conducted on compact tension specimens using computer control of the applied stress intensity range, ΔK. Fatigue crack closure loads, which represent the initial contact of mating crack surfaces during the unloading cycle, were continuously monitored during testing. Abrupt drops in ΔK were found to significantly decrease fatigue crack-growth rates far below equilibrium values, arresting growth completely at a ΔK twice the nominal fatigue threshold ΔKTH. Conversely, an abrupt increase in ΔK was found to accelerate fatigue crack-growth rates. The effects of roughness-induced crack closure were assessed and found to be consistent with the suppression or acceleration of growth rates. However, in order to fully explain the observed transient growth rate response, other mechanisms that may be related to the fatigue mechanism itself were also considered. Specifically, the nature of the fatigue crack tip damage zone was also investigated. As BMGs lack distributed plasticity at low temperatures, the plastic zone differs greatly from that seen in ductile crystalline materials, and its role in fatigue crack propagation mechanisms is examined.

Fatigue-Crack Propagation in Steels of Various Yield Strengths

1971 ◽  
Vol 93 (4) ◽  
pp. 1190-1196 ◽  
Author(s):  
J. M. Barsom
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Structural Steels ◽  
Martensitic Steels ◽  
The Relationship ◽  
Crack Growth Rates

The useful life of highly constrained welded structures subjected to cyclic loads often depends on the crack-propagation behavior of the material. Thus, to predict the service life of many structures and to establish safe inspection intervals, an understanding of the rate of fatigue-crack propagation in steel is required. Accordingly, an investigation was conducted to determine the fatigue-crack-growth rates in structural steels ranging in yield strength from 36 to 191 ksi; for this study, wedge-opening-loading (WOL) specimens were used. The tests were conducted at room temperature in an air environment, and the results were compared with published fatigue-crack-growth data for steels having similar yield strengths. The results showed that the primary factor affecting fatigue-crack-growth rates in structural steels is the applied stress-intensity-factor range, ΔKI, and that conservative estimates of fatigue-crack growth per cycle of loading, da/dN, for martensitic steels are obtained from the relationship dadN=0.66×10−8(ΔKI)2.25 where a is in inches and ΔKI is in ksi in. Similarly, the data showed that conservative estimates of da/dN for ferrite-pearlite steels are obtained from the relationship dadN=3.6×10−10(ΔKI)3 As indicated in these equations, the fatigue-crack-growth rates were higher for martensitic steels than for ferrite-pearlite steels. The data also showed that the fatigue-crack growth per cycle accelerated for all the steels, and that this transition from the above relationships to increased rates occurred when the crack-opening-displacement range, Δδ, which is a measure of the strain range at the crack tip, reaches a critical value. The fatigue-rate transition in martensitic steels occurred when Δδ was about 1.6 × 10−3 in. However, the fatigue-rate transition in ferrite-pearlite steels occurred at a Δδ value slightly higher than 1.6 × 10−3 in. A model based on micro structural considerations is presented, which accounts for these differences in the fatigue-crack-growth behavior between martensitic and ferrite-pearlite steels.

Fatigue Properties of Casting TC4 Alloys Treated by Hot Isostatic Pressing

2011 ◽  
Vol 197-198 ◽  
pp. 1668-1673
Author(s):  
Yu Hong Yao ◽  
Xiao Feng Shangguan ◽  
Jiang Nan Liu ◽  
Zheng Pin Wang ◽  
Jian Feng Wei
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Stress Ratio ◽  
Fatigue Properties ◽  
Stress Ratios ◽  
Crack Growth Rates

With the aircraft structure design criterion from traditional static strength design to damage tolerance design and with the independent research and development of new-type civil turbofan regional aircraft and the implement of the plan to develop the country's own large passenger jets in China, it is essential to do some researches on casting TC4 alloys for the lack of the data of fatigue properties. The detail fatigue rating cut-off (DFRcutoff) values of casting TC4 alloys are measured and calculated by double dots method, the thresholds in fatigue crack propagation and the fatigue crack growth rates at different stress ratios are studied and the fatigue fracture at different stress ratios are observed by scanning electron microscopy. The results show that DFRcutoff value by double-dot method is 375.83 Mpa. The thresholds of fatigue crack propagation decrease with the increase of the stress ratio, whereas the fatigue crack growth rates increase with the increment of the stress ratio and the relationship curves between fatigue crack propagation rates and the stress intensity factor range have been obtained. Moreover, SEM observations indicate that the fatigue trips become wide with the increasing of the stress ratio.

Fatigue Crack Growth in Flow Formed INCONEL 718

2016 ◽  
Vol 879 ◽  
pp. 374-379
Author(s):  
Costa Coleman ◽  
Martin R. Bache ◽  
Carl Boettcher
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Inconel 718 ◽  
Longitudinal Direction ◽  
Test Pieces ◽  
Crack Growth Rates

Fatigue crack propagation has been measured in flow formed Inconel 718 (IN718). Test pieces were extracted from a flow formed tubular structure in the longitudinal direction, retaining the tube curvature across their width. Crack growth rates (da/dN) were measured at 20, 300, and 400oC. For comparison, tests were repeated on specimens with an identical geometry but machined from conventionally forged IN718. Detailed metallurgy of the flow formed material is presented.

scholarly journals Studies on Quasi-Static and Fatigue Crack Propagation Behaviours in Friction Stir Welded Joints Using Peridynamic Theory

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Fei Wang ◽  
Yu’e Ma ◽  
Yanning Guo ◽  
Wei Huang
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Crack Path ◽  
Friction Stir ◽  
Welding Direction ◽  
Crack Growth Rates ◽  
Crack Turning

The friction stir welding (FSW) technology has been widely applied in aircraft structures. The heterogeneity of mechanical properties in weld and the hole in structure will lead the crack to turn. Peridynamics (PD) has inherent advantages in calculating crack turning. The peridynamic theory is applied to study the crack turning behaviour of FSW joints in this work. The compact tension (CT) samples with and without a hole are designed. The crack propagation testing under quasistatic and fatigue loads are performed. The peridynamic microplastic model is used and a three-stage fatigue calculation model is developed to simulate the quasistatic fracture and the fatigue crack growth. The results predicted by the peridynamic models are compared with the experimental ones. The effects of welding direction on quasistatic and fatigue crack propagation behaviours are investigated and the effect of hole position on crack path geometry is also studied. It is shown that the crack turning in FSWed CT samples can be captured by the peridynamic microplastic and the three-stage fatigue calculation models. The peridynamic crack growth rates agree with the experimental results. For CT specimen without a hole, the crack turns into the weld zone where the material is softer. The effect of welding direction on crack growth rates is not obvious. For CT sample with a hole, the crack propagation direction has been mainly controlled by the hole location and the welding direction has a slight effect on crack path.

Fatigue Crack Propagation in Low-Alloy Heat-Treated Steels

1967 ◽  
Vol 89 (1) ◽  
pp. 19-25 ◽  
Author(s):  
A. J. Brothers ◽  
S. Yukawa
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Heat Treated ◽  
Alloy Steels ◽  
Alloy Heat ◽  
Accelerate Crack Growth ◽  
Crack Growth Rates

The rates of fatigue crack propagation in several heat-treated steels were determined for several alloy steels heat-treated to yield strengths in the range 70,000 to 125,000 psi. For one steel crack growth rates were determined for both a thick notch bend specimen and for thin notched plate specimens. It is observed that the concepts of Griffith-Irwin fracture mechanics successfully correlate crack growth rates in the various geometry and thicknesses employed. However, the specific relationship is dependent on yield strength level. Microscopic examination suggests in some instances that inclusion segregates act effectively to locally accelerate crack growth rates.

Fatigue Crack Propagation in A533B Steels—Metallographic and Fractographic Analyses

1979 ◽  
Vol 101 (2) ◽  
pp. 155-164 ◽  
Author(s):  
A. D. Wilson
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Nonmetallic Inclusion ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Electron Microscopic ◽  
Alloy Plate ◽  
Crack Growth Rates

Metallographic and fractographic analyses are performed on A533B low alloy plate steels made by three steelmaking practices. The fatigue crack growth rates of these steels had been previously established in all six possible testing orientations. By using quantitative image analysis to quantify the nonmetallic inclusion structures of these steels, graphical and statistical correlations were established between the two material constants of the fatigue crack growth rate equation and various inclusion parameters. The average area of an inclusion on the metallographic cross section corresponding to the plane of fracture was found to be the best single parameter for establishing a correlation applying to all testing orientations. Scanning electron microscopic investigations of the fracture surfaces of the fatigue crack propagation specimens indicated that the inclusions (Type II manganese sulfides and alumina galaxies) exerted a predominant effect on the fatigue crack propagation behavior. Both studies provide additional evidence that the differences in fatigue crack growth rates between and within the steels of this investigation can be a result of the nonmetallic inclusion structures of the materials.

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