Download or read book Environment dependent Fatigue Crack Growth in Alloy 718 written by Dian Zheng and published by . This book was released on 1992 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanisms and Modelling of Environment Dependent Fatigue Crack Growth in a Nickel Based Superalloy written by H. Ghonem and published by . This book was released on 1991 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: At loading frequencies below that of the transitional frequency level, which is typical of mission cycles of jet engines, the elevated temperature fatigue crack growth process in Alloy 718 is viewed to be fully environment-dependent. Of all the crack growth stages, this process, while is the most critical in high temperature application due to its highly accelerated crack growth rate, is the least studied or understood. The objective of this research program is to focus on the understanding or the mechanism controlling this oxidation-dependent stage in order to develop the ability to predict its associated crack growth performance under different environment conditions. For this purpose, three major studies have been carried out; the first was to provide evidence of the existence of the fully environment-dependent stage in which the crack growth rate would be equal to the oxygen penetration rate at the crack tip. The second study was to establish a crack tip oxidation mechanism on the basis of material, environmental and loading parameters interactions in the crack tip region. The last objective of this program is to establish a micromechanical based quantitative model to predict the environmentally-dominated crack growth stage.
Download or read book Fatigue Crack Propagation in Metals and Alloys written by Ulrich Krupp and published by John Wiley & Sons. This book was released on 2007-04-09 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive overview of the whole field of fatigue and fracture of metallic materials covers both the theoretical background and some of the latest experimental techniques. It provides a summary of the complex interactions between material microstructure and cracks, classifying them with respect to the overall damage process with a focus on microstructurally short cracks and dynamic embrittlement. It furthermore introduces new concepts for the numerical treatment of fatigue microcrack propagation and their implementation in fatigue-life prediction models.This comprehensive overview of the whole field of fatigue and fracture of metallic materials covers both the theoretical background and the latest experimental techniques. It provides a summary of the complex interactions between material microstructure and cracks, classifying them with respect to the overall damage process. It furthermore introduces new concepts for the numerical treatment of fatigue microcrack propagation and their implementation in fatigue-life prediction models.
Download or read book Experimental Study of Oxygen Assisted Crack Growth in Alloy 718 and Alloy TI 1100 written by and published by . This book was released on 1993 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: The high Temperature fatigue crack growth behavior of alloy 718 is reviewed and investigated. FCGR have then been measured under constant K and various oxygen partial pressures. A transition pressure associated with an important increase of the FCGR is found. At this transition pressure (10-2mbar) the crack propagation path changes from transgranular to intergranular. From this study it is concluded, that intergranular crack growth requires the formation of Ni based oxide during the early stage of the oxidation as well as high intergranular internal stresses promoted by an inhomogeneous distribution of the deformation. The crack growth behavior of TI-1100 is investigated for loading frequencies ranging from 30 Hz to 0.005 Hz at temperature levels extending from 23 Cto 650 C in both air and vacuum environments. Two types of time-dependent damage mechanisms have been identified; oxidation and creep effects. It is concluded that effect of oxidation on the crack growth acceleration is rapid and constant in relation to the frequencies tested and is weekly dependent on cycle time. Creep effects, on the other hand, are dominant at low frequencies in both air and vacuum and are loading-rate dependent.
Download or read book Near Threshold Fatigue Crack Growth Behavior of Fine Grain Nickel Based Alloys written by John A. Newman and published by . This book was released on 2003 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Crack Growth Rate of Inconel 718 Sheet at Cryogenic Temperatures written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-24 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inconel 718 sheet material was tested to determine fatigue crack growth rate (FCGR) at cryogenic conditions representative of a liquid hydrogen (LH2) environment at -423 degree F. Tests utilized M(T) and ESE(T) specimen geometries and environments were either cold gaseous helium or submersion in LH2. The test results support a significant improvement in the fatigue crack growth threshold at -423 degree F compared to -320 degree F or 70 degree F. Wells, Douglas and Wright, Jonathan and Hastings, Keith Langley Research Center; Marshall Space Flight Center NASA/TM-2005-213948, L-19198
Download or read book Effect of Microstructure on Creep Fatigue Crack Growth in Alloy 718 written by K. Sadananda and published by . This book was released on 1979 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crack Growth in Alloy 718 Under Thermal Mechanical Cycling written by and published by . This book was released on 1986 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation was conducted to evaluate and model the crack growth rates in a nickel-base super-joy under load controlled thermal-mechanical cycling. Experiments were conducted on center-cracked panel specimens of Inconel 718 with temperature limits of 427 C to 649 C. closed-loop temperature control in the cracked region of the specimen was maintained by a microcomputer and four quartz heating lamps. A D.C. electric potential drop method was used to monitor crack lengths. The elastic stress intensity factor, K, was used to correlate all crack growth data. & A linear cumulative damage model was developed which sums cycle-dependent, mixed-mode, and time-dependent damage terms to predict thermal-mechanical fatigue crack growth rates. The model was developed entirely from isothermal baseline test data. The cycle-dependent term was based on low temperature (427 C) high frequency (10 Hz) crack growth data. The mixed-mode term was developed from low frequency (0.01 Hz) fatigue crack growth tests at 538 C and 649 C. The time-dependent term was developed from sustained-load crack growth tests at 538 C, 593 C, and 649 C. All thermal and mechanical cycles used during thermal-mechanical fatigue (TMF) testing were symmetric, triangular, and 96 seconds long. Crack growth rates were determined over a range of Sigma K using a stress ratio, R, of 0.1. Tests were conducted with the maximum load leading the maximum temperature by phase angles of 0, 90%, 180, 225, 270, and 315. The in-phase test (0') produced the highest crack growth rates, with the 315', 270', 225', 180', and 90' tests following in order. The 0' and 90' crack growth rates were separated by over a factor of ten at all AK values tested.% All TMF crack growth rates were bracketed by the isothermal growth rates at 427 C and 649 C.
Download or read book Proceedings of the 8th International Symposium on Superalloy 718 and Derivatives written by The Minerals, Metals & Materials Society (TMS) and published by John Wiley & Sons. This book was released on 2014-12-02 with total page 951 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Microstructure and Environment on the Elevated Temperature Creep and Low Cycle Fatigue Crack Growth Rates in Inconel 718 written by and published by . This book was released on 1986 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue crack Propagation Behavior of Inconel 718 written by and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The techniques of linear-elastic fracture mechanics were used to characterize the effect of several variables (temperature, environment, cyclic frequency, stress ratio, and heat-treatment variations) upon the fatigue-crack growth behavior of Inconel 718 base metal and weldments. Relevant crack growth data on this alloy from other laboratories is also presented. (33 fig, 39 references) (auth).
Download or read book Mechanical Behaviour of Materials at High Temperature written by C. Moura Branco and published by Springer Science & Business Media. This book was released on 1996-06-30 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the edited version of lectures and selected research contributions presented at the NATO ADVANCED STUDY INSTITUTE on MECHANICAL BEHA VI OUR OF MATERIALS AT HIGH TEMPERATURE, held in Sesimbra, Portugal, 12th-22nd September 1995, and organized by 1ST-Lisbon Institute of Technology, PortugaL The Institute was attended by 88 participants, including 15 lecturers from 17 countries including five CP countries. The lecturers were leading scientists and technologists from universities, research institutions and industry. The students were mainly young PhD students and junior academic or research staff with postgraduate qualifications (MSc or PhD). Fourteen students were from the five CP countries. The students presented research papers or posters during the Institute reporting the current progress of their research projects. A total of thirty three lectures, ten research papers and fifty posters were presented. This book does not contain the poster presentations and seven research papers were selected for publication. All the sessions were very active and quite extensive discussions on scientific aspects took place during the Institute. The Advanced Study Institute provided a forum for interaction among scientists and engineers from different areas of research, and young researchers.
Download or read book Fatigue Crack Growth Rate of Inconel 718 Sheet at Cryogenic Temperatures written by Douglas Wells and published by BiblioGov. This book was released on 2013-07 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inconel 718 sheet material was tested to determine fatigue crack growth rate (FCGR) at cryogenic conditions representative of a liquid hydrogen (LH2) environment at -423 degree F. Tests utilized M(T) and ESE(T) specimen geometries and environments were either cold gaseous helium or submersion in LH2. The test results support a significant improvement in the fatigue crack growth threshold at -423 degree F compared to -320 degree F or 70 degree F.
Download or read book Effect of Frequency on Fatigue Crack Growth Rate of Inconel 718 at High Temperature written by and published by . This book was released on 1987 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth was studied at 650 deg. C as a function of frequency for several ratios of minimum-to-maximum stress intensity, and for two values of maximum stress intensity factor. Crack lengths were monitored at low frequencies from compliance calculations based on crack mouth opening displacement measurements. At higher frequencies, crack length was measured using a d.c. electric potential system. It was found that fatigue crack growth rate can be characterized in three distinct frequency regions. These three regions represent fully cycle dependent, mixed, and fully time dependent crack growth behavior and each region can be modeled by a power law function. Observation of micro mechanisms support the existence of these three different regions of crack growth. Keywords: Fatigue crack growth, Time dependent growth, Cyclic-dependent growth, Nickel base superalloy, Crack growth rate model, Frequency effects.
Download or read book A Model for Creep Fatigue Interactions in Alloy 718 written by NE. Ashbaugh and published by . This book was released on 1985 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted to evaluate the crack growth rates in Inconel 718 at 649°C under symmetric and unsymmetric triangular waveshapes and triangular waves with hold times at maximum load. Data are presented as crack growth rate per cycle as a function of total cycle time. An analytical model is developed which predicts crack growth rate from an integration of the sustained load crack growth rates over the cycle when time-dependent behavior is dominant. The data show that the loading portion of a cycle is the major contributor to the time-dependent crack growth behavior. At low unloading frequencies or high load ratios, however, the unloading portion of the cycle is found to become increasingly important. The model utilizes minimum baseline data and is proposed for predictions of crack growth rate over a variety of loading cycle types.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Cryogenic Engineering Materials written by Richard P. Reed and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the Tenth International Cryogenic Materials Conference (ICMC) held in Albuquerque, New Mexico, July 12-16, 1993.
