Download or read book The Effect of O2 H2O and N2 on the Fatigue Crack Growth Behavior of an Alpha Beta Titanium Alloy at 24 C and 177 C written by Stephen W. Smith and published by . This book was released on 2001 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effect of O2 H2O and N2 on the Fatigue Crack Growth Behavior of an alpha beta Titanium Alloy at 24 C Anfd 177 C written by Stephen W. Smith and published by . This book was released on 2001 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: To study the effects of atmospheric species on the fatigue crack growth behavior of an ([alpha]+p titanium alloy (Ti 6-2-2-2-2) at room temperature and 177 °C, fatigue tests were performed in laboratory air, ultrahigh vacuum, and high purity water vapor, oxygen, nitrogen and helium at various partial pressures. Accelerated fatigue crack growth rates in laboratory air compared to ultrahigh vacuum are linked to the damaging effects of both water vapor and oxygen. Observations of the fatigue crack growth behavior in ultrahigh purity environments, along with surface film analysis using X-ray photoelectron spectroscopy (XPS), suggest that multiple crack-tip processes govern the damaging effects of air.
Download or read book The Effect of O2 H2o and N2 on the Fatigue Crack Growth Behavior of an Alpha Beta Titanium Alloy at 24 C and 177 C written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-17 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: To study the effects of atmospheric species on the fatigue crack growth behavior of an a+B titanium alloy (Ti 6-2-2-2-2) at room temperature and 177 C, fatigue tests were performed in laboratory air, ultrahigh vacuum, and high purity water vapor, oxygen, nitrogen and helium at various partial pressures. Accelerated fatigue crack growth rates in laboratory air compared to ultrahigh vacuum are linked to the damaging effects of both water vapor and oxygen. Observations of the fatigue crack growth behavior in ultrahigh purity environments, along with surface film analysis using X-ray photoelectron spectroscopy (XPS), suggest that multiple crack-tip processes govern the damaging effects of air. Three possible mechanisms are proposed: 1) at low pressure (less than 10(exp -1) Pa), accelerated da/dN is likely due to monolayer adsorption on crack-tip surfaces presumably resulting in decreased bond strengths at the fatigue crack tip, 2) for pressures greater than 10(exp -1) Pa, accelerated da/dN in oxygen may result from oxidation at the crack tip limiting reversible slip, and 3) in water vapor, absorption of atomic hydrogen at the reactive crack tip resulting in process zone embrittlement.Smith, Stephen W. and Piascik, Robert S.Langley Research CenterFATIGUE TESTS; FATIGUE (MATERIALS); CRACK PROPAGATION; TITANIUM ALLOYS; EMBRITTLEMENT; ATMOSPHERIC COMPOSITION; X RAY SPECTROSCOPY; WATER VAPOR; ULTRAHIGH VACUUM; PHOTOELECTRON SPECTROSCOPY
Download or read book Observations on the Generality of the Grain Size Effect on Fatigue Crack Growth in Alpha Plus Beta Titanium Alloys written by G. R. Yoder and published by . This book was released on 1980 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results obtained through analysis of the literature agree with those of our own as regards the effect of grain size (l) on region-II fatigue crack growth rates (da/dN) of alpha + beta titanium alloys in ambient air, viz. that for a given value of stress-intensity range (delta kappa), da/dN decreases as (l) is increased. The analysis indicates that when microstructural modification of a given alloy affects a reduction in da/dN, the reduction appears attributable to an increase in (l); conversely, when microstructural modification fails to affect a significant change in da/dN, the result appears attributable to a negligible change in (l). Comparison of fatigue crack growth behavior at stress-intensity ranges of 15, 21 and 40 MPa square root m indicates a diminution of the grain-size effect with increased delta kappa. As elucidated in terms of the reversed plastic zone size model, diminution of the grain-size effect follows as a consequence of the reduced portion of the structure-sensitive mode of crack growth present as delta kappa is increased.
Download or read book Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6 2 2 2 2 written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-31 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth rates of Ti 6-2-2-2-2 as a function of stress ratio, temperature (24 or 177 C), tensile orientation and environment (laboratory air or ultrahigh vacuum) are presented. Fatigue crack growth rates of Ti 6-2-2-2-2 are also compared with two more widely used titanium alloys (Timetal 21S and Ti 6Al-4V). The fatigue crack growth rate (da/dN) of Ti 6-2-2-2-2 in laboratory air is dependent upon stress ratio (R), particularly in the near-threshold and lower-Paris regimes. For low R (less than approximately 0.5), da/dN is influenced by crack closure behavior. At higher R (> 0.5), a maximum stress-intensity factor (K(sub max)) dependence is observed. Fatigue crack growth behavior is affected by test temperature between 24 and 177 C. For moderate to high applied cyclic-stress-intensity factors (delta-K), the slope of the log da/dN versus log delta-K curve is lower in 177 C laboratory air than 24 C laboratory air. The difference in slope results in lower values of da/dN for exposure to 177 C laboratory air compared to room temperature laboratory air. The onset of this temperature effect is dependent upon the applied R. This temperature effect has not been observed in ultrahigh vacuum. Specimen orientation has been shown to affect the slope of the log da/dN versus log delta-K curve in the Paris regime.Smith, Stephen W. and Piascik, Robert S.Langley Research CenterCRACK PROPAGATION; FATIGUE (MATERIALS); TITANIUM ALLOYS; CORROSION; STRESS RATIO; TEMPERATURE EFFECTS; CRACK CLOSURE; STRESS INTENSITY FACTORS
Download or read book Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6 2 2 2 2 written by and published by . This book was released on 2001 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Crack Growth Behavior of Two Titanium Alloys at Room and Elevated Temperature written by Todd P. Albertson and published by . This book was released on 1996 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Crack Growth Behavior of Titanium Aluminide Ti 25Al 25Nb written by SJ. Balsone and published by . This book was released on 1993 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fatigue crack growth rate of an orthorhombic + beta titanium aluminide, nominally Ti-25Al-25Nb, was studied as a function of temperature (25 to 750°C), environment (air and vacuum), frequency (0.001 to 1.0 Hz), and superimposed hold times (1 to 1000 s) under computer-controlled constant Kmax testing conditions. In addition, fatigue crack growth rates from the near-threshold region to rates greater than approximately 10-7 m/cycle were determined at room and elevated temperatures. Results show that the fatigue crack growth rate exhibits a combination of cycle- and time-dependent behavior and is sensitive to environment over the entire temperature range. At elevated temperature, crack growth per cycle is found to increase with decreasing frequency in both laboratory air and vacuum, suggesting a contribution from environmentally assisted crack growth. Growth rates in vacuum are as much as an order of magnitude lower than those obtained in air. Further, hold times of increasing duration are found to slightly decrease and then increase the crack growth rate at elevated temperature. At elevated temperatures, crack growth behavior appears to be a complex interaction of environmental degradation at the crack tip, crack-tip blunting due to creep, and cyclic fatigue (resharpening of the crack tip). An attempt was made to correlate the observed fatigue crack growth rates with the mechanism, or mechanisms, of fracture. The crack growth characteristics were compared with those of the alpha-2 titanium aluminide, Ti-24Al-11 Nb, and a conventional high-temperature titanium alloy, Ti-1100.
Download or read book Atmospheric Influence on Fatigue Crack Propagation in Titanium Alloys at Elevated Temperature written by S. Lesterlin and published by . This book was released on 1997 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fatigue crack propagation behavior of a Ti-6Al-4V alloy has been investigated at room temperature and at 300°C. Tests were run in air, high vacuum, and some other environments with controlled partial pressure of water vapor and oxygen. The enhancement of the fatigue crack growth rates observed in air in comparison to high vacuum, considered as an inert environment, is clearly attributed to the presence of water vapor. Tests in a controlled environment demonstrate that very low partial pressure can accelerate crack propagation. On the basis of previous studies on Al alloys and steels, two controlling mechanisms are considered and discussed, namely, a propagation-assisted water vapor adsorption and a hydrogen-assisted propagation.
Download or read book The influence of slip character and microstructure on fatigue crack growth in Alpha and Alpha Beta Titanium alloys written by John E. Allison and published by . This book was released on 1982 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Fatigue Crack Growth Behavior of Ti 24A1 11Nb as a Function of Temperature and Load Ratio written by Richard Joseph Bernard and published by . This book was released on 1991 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Crack Growth of Two Advanced Titanium Alloys at Room and Elevated Temperature written by TP. Albertson and published by . This book was released on 1997 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper provides fatigue crack growth information at low crack growth rates for two sheet titanium alloys: ?-21S, a ? alloy, and Ti-62222, an ? + ? alloy. Room (25°C) and elevated temperature (175°C) fatigue crack growth tests at two different stress ratios, R = 0.1 and 0.5, were performed. Effects of temperature and stress ratio were evaluated in order to study the complex interaction between fatigue, environment, and loading conditions. Crack-opening load was measured throughout the test from automated compliance measurements and was used to adjust fatigue crack growth data for crack closure. For ?-21S, fatigue crack growth rates were similar at 175 and 25°C at a stress ratio of 0.1, while crack growth rates were lower at 175 versus 25°C at a stress ratio of 0.5 for the same nominal ?K. Concepts associated with crack closure accounted for this as crack growth rates were found to be higher at 175°C than 25°C for both stress ratios when plotted as a function of ?Keff, showing a temperature dependency on crack growth rate. For Ti-62222, fatigue crack growth rates were comparable between 25 and 175°C for R = 0.5, but were different at R = 0.1 where crack closure was observed at 175°C. Fatigue crack growth behavior of these two titanium alloys was comparable for all loading and temperature conditions.
Download or read book Effect of Microstructure Strength and Oxygen Content on Fatigue Crack Growth Rate of Ti 4 5Al 5 0Mo 1 5Cr CORONA 5 written by G. R. Yoder and published by . This book was released on 1983 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth rate behavior in CORONA 5, an alloy developed for applications requiring high fracture toughness, has been examined for eight material conditions. These conditions were designed to give differences in microstructure, strength level, and oxygen content, in such a manner that the separate effects of these variables could be defined. For all eight conditions, fatigue crack growth rates (da/dN) are virtually indistinquishable over the full all spectrum of stress-intensity range (Delta K) examined. Concomitantly, it is noted that over the sizeable solution annealing range studied, the primary alpha-phase morphology was substantially invariant. A change in microfractographic appearance occurs at delta KT, as extensive secondary cracking along Alpha/Beta interfaces is observed at all hypertransitional levels of Delta K, but not for Delta K
Download or read book The Effect of Load Excursions on Fatigue Crack Growth in a Titanium Alloy written by David Eugene Lemm and published by . This book was released on 1997 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Crack Propagation of Metastable Beta Titanium Vanadium Alloys written by Saghana B. Chakrabortty and published by . This book was released on 1978 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fatigue crack propagation behavior of three titanium-vanadium alloys (24, 28 and 32 wt.% V) which have (tensile) deformation modes ranging from coarse twinning to wavy and planar slip has been measured in laboratory air and correlated with their low cycle fatigue properties and microstructure. The fatigue crack growth rate of alloys with similar microstructures but different deformation modes, and of alloys with similar deformation modes but different microstructures have been compared. Increasing the deformation barrier mean free path and improving low cycle fatigue properties has been observed to reduce the fatigue crack growth rate at low and intermediate Delta K levels. The fatigue crack growth data have been compared with that calculated from equations which use microstructure and low cycle fatigue parameters. The predictive capability of these equations which contain only measurable parameters has been found to be quite adequate. (Author).
Download or read book Influence of Alpha Beta Interface Phase on Fracture Toughness and Fatigue Crack Growth Rate in Ti 6Al 4V written by C. G. Rhodes and published by . This book was released on 1980 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: The alpha/beta interface phase is a microstructural feature which occurs in two-phase, alpha/beta, titanium alloys under certain processing conditions. Interface phase can grow to widths of up to approx. 500 nm and has been shown to exert an influence on tensile properties. In this work, its influence on fracture toughness and fatigue crack growth rate in Ti-6Al-4V has been examined. (Author).
Download or read book Fatigue Crack Propagation in Titanium Alloys written by A. J. McEvily and published by . This book was released on 1975 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report summarizes the research accomplishments in the first year's program of a study of fatigue crack growth in Ti-6Al-4V alloys. Fatigue crack growth rates have been determined in the mean threshold regions, and data for the effect of mean stress on the threshold level indicate that the dependency may be interpretable in terms of a constrant crack opening criterion. Additional work on high cycle fatigue indicates that there are two regions for the Coffin-Manson relation and that cyclically developed residual stresses may be responsible for this behavior.
