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 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 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 The Effect of O2 H2O and N2 on the Fatigue Crack Growth Behavior of an alpha beta Titanium Alloy at 24 0C and 177 0C 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:
Download or read book The Effect of Oxygen Water and Nitrogen on the Fatigue Crack Growth Behavior of an Alpha and Beta Titanium Alloy at 24 Degrees Centigrade and 177 Degrees Centigrade 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:
Download or read book The Effect of 02 H20 and N2 on the Fatigue Crack Growth Behavior of an Alpha Beta Titanium Alloy at 24 C and Nasa written by United States. National Aeronautics and Space Administration and published by . This book was released on 2003* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 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 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 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 Effect of O x1B b2 x1B s H x1B b2 x1B sO and N x1B b2 x1B s on the Fatigue Crack Growth Behavior of an titanium Alloy at 24 x1B p0 x1B sC and 177 x1B p0 x1B sC 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:
Download or read book Influence of Metallurgical Factors on the Fatigue Crack Growth Rate in Alpha Beta Titanium Alloys written by J. C. Chesnutt and published by . This book was released on 1978 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research was conducted on two alpha-beta titanium alloys, Ti-6Al-4V and Ti-6Al-2Sn 4Zr-6Mo, as a function of alloy composition microstructure and strength level, environment, and fatigue loading conditions. A wide range of microstructural conditions, seven for Ti-6Al-4V and three for Ti-6Al-2Sn-4Zr-6Mo, was chosen to provide a full range of constituent types and morphologies and a range of mechanical properties. All the material for the program was obtained in the form of pancake forgings which were uniformly and weakly textured. The initial portion of the program consisted of material characterization and base line fatigue crack propagation (FCP) testing. Characterization included a full description of microstructures, as well as mechanical property testing, fracture toughness tests, S-N curve determination and measurement of other properties such as modulus and texture. Base line FCP testing in dry air at two stress ratios (R) of 0.1 and 0.3; and in a 3.5% NaCl solution at 1 and 20 Hz was conducted in this portion of the program. Results of this study included the determination that transformed beta microstructures generally exhibit the greatest fatigue crack propagation resistance and that increasing the load ration, R, can lead to significant increases in crack growth rate; the behavior in both cases was rationalized in terms of crack tip interaction with microstructural constituents.
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 and Crack growth Behavior in a Titanium Alloy Under Constant amplitude and Spectrum Loading written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A titanium alloy (Ti-6Al-4V STOA) plate material was provided by the University of Dayton Research Institute from a previous U.S. Air Force high-cycle fatigue study. Fatigue-crack-growth tests on compact, C(T), specimens have been previously performed at Mississippi State University on the same material over a wide range in rates from threshold to near fracture for several load ratios (R = Pmin/Pmax). These tests used the compression pre-cracking method to generate fatigue-crack-growth-rate data in the near-threshold regime. Current load-reduction procedures were found to give elevated thresholds compared to compression pre-cracking methods. A crack-closure model was then used to determine crack-front constraint and a plasticity-corrected effective stress-intensity-factor-range relation over a wide range in rates and load ratios. Some engineering estimates were made for extremely slow rates (small-crack behavior), below the commonly defined threshold rate. Single-edge-notch-bend, SEN(B), fatigue specimens were machined from titanium alloy plates and were fatigue tested at two constant-amplitude load ratios (R = 0.1 and 0.5) and a modified Cold-Turbistan engine spectrum. Calculated fatigue lives from FASTRAN, a fatigue-life-prediction code, using small-crack theory with an equivalent-initial-flaw-size (semi-circular surface flaw) of 9 æm in radius at the center of the semi-circular edge notch fit the constant-amplitude test data fairly well, but underpredicted the spectrum loading results by about a factor of 2 to 3. Life predictions made with linear-cumulative damage (LCD) calculations agreed fairly well with the spectrum tests.
Download or read book Fatigue Crack Growth and Surface Reactions for Titanium Alloys Exposed to Water Vapor written by S. J. Gao and published by . This book was released on 1983 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Parallel fracture mechanics and surface chemistry studies have been carried out to develop understanding of environmentally assisted fatigue crack growth in titanium alloys. Room temperature crack growth response in water vapor was determined for annealed Ti-5A1-2.5Sn alloy and for Ti-6A1-4V alloy in the solution treated and solution treated plus over-aged conditions as a function of water vapor pressure from 0.266 to 665 Pa at a frequency of 5 Hz and a load ratio of 0.1. Reference data were obtained in vacuum. The kinetics of reactions of water vapor and oxygen with fresh surfaces of Ti-5A1-2.5Sn alloy were measured at room temperature. The results showed that the reactions with water vapor and with oxygen are both rapid; with an initial sticking coefficient of 1.0 for water vapor and of 0.54 to 0.84 for oxygen. The reaction with water vapor produced a monolayer of oxide (TiO), whereas 2 to 3 layers of TiO resulted from the reaction with oxygen.
Download or read book Effect of Aging on Uniaxial Tensile Characteristics and Fatigue Crack Growth Behavior in the Near alpha Titanium Alloy TI 1100 written by Alec Madsen and published by . This book was released on 1993 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
