Author: C. M. HudsonPublisher:
ISBN:
Category : Materials at high temperatures
Languages : en
Pages : 40
Book Description
Fatigue-crack Propagation in Several Titanium and Stainless-steel Alloys and One Superalloy
Author: C. M. HudsonPublisher:
ISBN:
Category : Materials at high temperatures
Languages : en
Pages : 40
Book Description
Fatigue Crack Propagation in Titanium Alloys
Author: Jean K. GregoryFatigue Crack Propagation in Titanium Alloys
Author: A. J. McEvilyPublisher:
ISBN:
Category :
Languages : en
Pages : 7
Book Description
This Annual Report covers the period Aug. 1, 1976 through Sept. 30, 1977, and deals with the topics fatigue crack initiation and growth in Ti-6Al-4V forging alloy. Subsurface crack initiation has been related to the presence of severe dislocation pile-ups and perhaps to the influence of internal hydrogen. In the fatigue crack growth progress it has been shown that different mechanism are operative in various regions of the da/dN versus delta K plot. The retardation effect associated with overload has been shown to be primarily a surface related effect due to the higher degree of crack closure which exists in the surface regions of a specimen. (Author).
The Effects of an Aqueous Environment on the Fatigue Crack Propagation Characteristics of Titanium Alloys
Author: T. W. CrookerPublisher:
ISBN:
Category :
Languages : en
Pages : 19
Book Description
Fatigue crack propagation was studied in Ti-6Al-4V, Ti-7Al-2Cb-1Ta, Ti-6Al-6V-2Sn-1Cu-0.5Fe, Ti-6Al-3V-1Mo, and Ti-7Al-2.5Mo alloys. These materials possess yield strengths in excess of 100 ksi, combined with favorable levels of fracture toughness, and they are currently under evaluation for application in large welded structures. Where an application involves repetitive loading, a knowledge of fatigue crack propagation characteristics is required for failure-safe design against fracture. Fabrication and non-destructive testing procedures cannot guarantee that cracklike defects, which can grow to a critical size, will not be present in plate-thickness sections containing welded joints. In addition, the role of an aggressive environment, such as salt water, in this failure mechanism is of the utmost importance. Fatigue crack propagation data were taken in both ambient room air and 3.5% salt-water environments. Surface-notched plate bend specimens were cycled in full-reverse (tension-to-compression) sinusoidal loading. The fatigue crack was observed optically, and the crack growth rate was described as an empirical power-law function of the total (elastic-plus-plastic) strain range. Fatigue crack growth rate relationships were first developed in an air environment and then employed as baselines for establishing the effect of the salt-water environment. Comparisons were made among the fatigue crack propagation characteristics of the several titanium alloys and among a broad spectrum of high-strength structural alloys, both ferrous and nonferrous, previously studied. (Author).
Atmospheric Influence on Fatigue Crack Propagation in Titanium Alloys at Elevated Temperature
Author: S. LesterlinPublisher:
ISBN:
Category : Environment
Languages : en
Pages : 23
Book Description
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.
Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6-2-2-2-2
Author: A Review and Analysis of Fatigue Crack Propagation in Titanium Alloys at Room Temperature
Author: R.J.H. WanhillThe Effect of O2, H2O, and N2 on the Fatigue Crack Growth Behavior of an Alpha + Beta Titanium Alloy at 24 C and 177 C
Author: Stephen W. SmithFatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6-2-2-2-2
Author: National Aeronautics and Space Adm NasaPublisher: Independently Published
ISBN: 9781723951589
Category : Science
Languages : en
Pages : 76
Book Description
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
Author: