Download or read book Creep Behavior of an Aluminum Alloy Under Transient Temperatures written by R. P. Mirro and published by . This book was released on 1966 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Creep of 2024-0 aluminum alloy was investigated under isothermal conditions and for several positive and negative inear rates of temperature change for the same temperature range and sigma = 10,000 P.S.I. The creep rates of the transient temperature tests were described using a time dependent viscosity coefficient. The temperature dependence of the elastic modulus was determined by resonant vibration tests. Using a time dependent viscosity coefficient having a nonlinear stress dependence for a Maxwell material possessing linearly elastic compressibility, explicit solutions for the stresses in a hollow sphere resulting from a step of internal pressure and steps of temperature at its boundaries (at t = 0) are presented. Numerically computed values are compared with values obtained for the same sphere in which, however, the viscosity coefficient is expressed by conventional activation energy theory.
Download or read book The Stress and Temperature Dependence of Creep in an Al 2 0wt Li Alloy written by Earl F. Goodson and published by . This book was released on 1989 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of stress and temperature on the creep behavior of an Aluminum-2.0 wt% Lithium alloy was investigated in the temperature range from 300 to 500 deg C. This temperature interval corresponds to a solid solution of Li in Al. Experimental results indicate that Al-2.0wt%Li behaves as a pure metal class alloy (class II). This is demonstrated by several creep characteristics including the value of the stress exponent (n approx. 5), the shape of the creep curve, and the nature of the creep transient after a temperature change. However, anomalous behavior of the activation energy was observed. Activation energies up to 55 kilocalories per mole, decreasing to approximately 33 kcal/mole at higher temperatures, were observed by the temperature cycling technique. Keywords: Activation energy, Creep behavior, Al-Li alloy, Theses, Metallurgy, Molecular structuring, Mechanical properties, Airframe construction, Materials. (jg).
Download or read book The Transient Creep Behavior of Aluminum and Aluminum 1 at Zinc Alloy written by Dinesh Kumar Shetty and published by . This book was released on 1970 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Stress and Temperature Dependence of Creep in an AL 2 0WT LI Alloy written by and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of stress and temperature on the creep behavior of an Aluminum-2.0 wt% Lithium alloy was investigated in the temperature range from 300 to 500 deg C. This temperature interval corresponds to a solid solution of Li in Al. Experimental results indicate that Al-2.0wt%Li behaves as a pure metal class alloy (class II). This is demonstrated by several creep characteristics including the value of the stress exponent (n approx. 5), the shape of the creep curve, and the nature of the creep transient after a temperature change. However, anomalous behavior of the activation energy was observed. Activation energies up to 55 kilocalories per mole, decreasing to approximately 33 kcal/mole at higher temperatures, were observed by the temperature cycling technique. Keywords: Activation energy, Creep behavior, Al-Li alloy, Theses, Metallurgy, Molecular structuring, Mechanical properties, Airframe construction, Materials. (jg).
Download or read book Thermoinelasticity written by Bruno A. Boley and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proposal for a Symposium on high temperature effects in solids originated in 1964, at which time a pilot committee, headed by Professor F. K. G. ODQVIST, was formed. Upon the recommendation of this com mittee, a site for the Symposium and a Scientific Organizing Committee were chosen, and some guidelines delineating the field to be covered were established. The Symposium was held at the National Engineering Laboratory in East Kilbride (Glasgow), Scotland, from June 25 to 28, 1968. The Scientific Organizing Committee was composed of the following mem bers: Professor B. A. BOLEY, Chairman (U. S. A.) Professor F. BUCKENS (Belgium) Professor F. K. G. ODQVIST (Sweden) Professor W. OLSZAK (Poland) Professor H. PARKUS (Austria) Dr. D. G. SOPWITH (U. K.) The Local Organizing Committee was subsequently formed; it was direct ed by Dr. SOPWTTH with Mr. R. BRODIE as Secretary, and Mr. C. E. PHILLIPS and Dr. J. GLEN as additional members. It deserves ample praise for excellent arrangements and hospitality. In the discussions concerned with the goals of the Symposium, it was decided that its principal aim should be the presentation of a comprehen sive view of the behavior of solids and structures at high temperature under any type of inelastic regime. It soon became apparent that this was a very wide field, since it would embrace questions ranging from those of basic thermodynamic to those of engineering analysis and design.
Download or read book Technical Abstract Bulletin written by and published by . This book was released on with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of Creep in Metals and Alloys written by Michael E. Kassner and published by Elsevier. This book was released on 2004-04-06 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: * Numerous line drawings with consistent format and units allow easy comparison of the behavior of a very wide range of materials * Transmission electron micrographs provide a direct insight in the basic microstructure of metals deforming at high temperatures * Extensive literature review of over 1000 references provide an excellent reference document, and a very balanced discussionUnderstanding the strength of materials at a range of temperatures is critically important to a huge number of researchers and practitioners from a wide range of fields and industry sectors including metallurgists, industrial designers, aerospace R&D personnel, and structural engineers. The most up-to date and comprehensive book in the field, Fundamentals of Creep in Metals and Alloys discusses the fundamentals of time-dependent plasticity or creep plasticity in metals, alloys and metallic compounds. This is the first book of its kind that provides broad coverage of a range of materials not just a sub-group such as metallic compounds, superalloys or crystals. As such it presents the most balanced view of creep for all materials scientists. The theory of all of these phenomena are extensively reviewed and analysed in view of an extensive bibliography that includes the most recent publications in the field. All sections of the book have undergone extensive peer review and therefore the reader can be sure they have access to the most up-to-date research, fully interrogated, from the world's leading investigators.· Numerous line drawings with consistent format and units allow easy comparison of the behavior of a very wide range of materials· Transmission electron micrographs provide a direct insight in the basic microstructure of metals deforming at high temperatures· Extensive literature review of over 1000 references provide an excellent reference document, and a very balanced discussion
Download or read book Investigation of Three Analytical Hypotheses for Determining Material Creep Behavior Under Varied Loads with an Apllication to 2024 T3 Aluminum alloy Sheet in Tension at 400 F written by Avraham Berkovits and published by . This book was released on 1961 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Creep Behavior of Nano particle Strengthened Aluminum Alloy 6082 written by Mahmoud Abdu and published by . This book was released on 2011 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Creep characteristics of nano-particle strengthened AA6082 (Al-Mg-Si) alloy via precipitation hardening has been investigated in the present investigation. The precipitation hardening involved solution treatment at 843K for two hours followed by water quenching to room temperature. The alloy was then creep tested immediately after the elapse of the artificial aging period (5 hours) at the aging temperatures ranging from 673-803K. Creep data were obtained from carrying out tensile and double-shear creep tests. The range of strain rates employed in the creep data was 2x10−9 to 2x10−2 s−1. Examination of the creep data, which extended over seven orders of magnitude, showed a high apparent stress exponent, na = 7.4, and a high apparent activation energy, Qa = 206.5 kJ/mole, which was higher than the activation energy reported for lattice self-diffusion in Al (142 kJ/mole). These results implied that the rate-controlling creep mechanism was modified by the existence of a threshold stress. By analyzing the experimental data for the existence of the threshold stress at the different test temperatures, it was found that a threshold stress existed and that the modulus-normalized threshold stresses increased strongly with decreasing temperature. Transmission Electron Microscopy (TEM) investigation indicated that the threshold stress resulted from the interaction of dislocations with second phase particles. Theoretical explanation for the strong temperature-dependence of threshold stress was provided in terms of the interaction of lattice dislocations with impurity atoms segregating to the second phase precipitates at the detachment side. Energized dispersive Spectrometry (EDS) analysis showed that these precipitates were Mg2Si particles and that almost all the Mg in the alloy was consumed in forming the Mg2Si particles. On the basis of consideration of the experimental data, it was concluded that the alloy behaved as metal-class (Class M) alloy strengthened with nano-particles. This conclusion has been supported by two pieces of evidence: (a) the shape of the creep curves that showed extensive transient creep, and (b) the formation of subgrains in the investigated TEM substructure. In addition, an examination of the transition criterion from viscous glide to dislocation climb revealed that the Mg content in the alloy should have decreased from 1%Mg (initial composition) to a value less than or equal to 0.17%Mg in the final composition. By incorporating, the threshold stress into the rate equations, it has been demonstrated that the true activation energy was reasonably close to 142 kJ/mole (activation energy for lattice self-diffusion in Al) and that the true stress exponent was 4.6 (the stress exponent reported for Al and Class M Al-based solid solution alloys). These findings led to conclude that the rate-controlling mechanism is high-temperature climb of dislocations which can be described by a modified power-law creep due the presence of threshold stress. Comparison of the creep data obtained from the present alloy with those reported for pure Al indicated that the investigated alloy was more creep-resistant than pure Al. Analysis of the creep data at very low stresses (ơ = 2.1-3.99 MPa) at 803 K indicated that the stress exponent rapidly increased with decreasing the stress, and that the threshold analysis gave a threshold stress of 2.0 MPa similar to that obtained at the same temperature from the higher stress range (ơ = 5.88-35.11 MPa) where the creep deformation is controlled by the high temperature climb of dislocations. It has been shown that the creep deformation showed explicit threshold behavior and that the creep rate appeared to be controlled by Harper-Dorn creep. The data on Harper-Dorn creep provide the first report on the possible occurrence of Harper-Dorn creep in a nano-particle strengthened Al-Mg-Si alloy. However, the data presented herein is still preliminary and further future work is required.
Download or read book Inelastic Deformation of an Aluminum Alloy Under Combined Stress at Elevated Temperature written by George Malcolm Brown and published by . This book was released on 1970 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biaxial stress tests were performed on thin wall tubes of polycrystalline 2024-T81 Aluminum at temperatures of 150 and 250c. The nominal metallurgical stabilization temperature for this alloy is 190c. Transient and steady state creep strain rates exhibited a considerable depenence on load path history. For a prescribed history it is possible to determine unique surfaces of constant creep strain rate. For the zero history, involving a single loading from the origin to a prescribed point in stress space, surfaces of constant steady state strain rate, at elevated temperature, have the same shape as room temperature yield surfaces of moderate offset. In the temperature and small strain regions considered here, room temperature yield surfaces were found to be unaffected by elevated temperature deformation. The changes in shape of room temperature yield surfaces, due to room temperature plastic deformation caused corresponding changes in the elevated temperature surfaces of constant steady state creep rate. At a given stress point, an outward local motion of the yield surface resulted in a corresponding outward local motion of the steady state creep rate surfaces. The experimental determination of surfaces of constant flow potential was also attempted. (Author).
Download or read book Some Static Longitudinal Stability Characteristics of an Overlapped type Tandem rotor Helicopter at Low Airspeeds written by Robert J. Tapscott and published by . This book was released on 1958 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flight measurements of some longitudinal static stability characteristics with an overlapped-type tandem-rotor helicopter at low airspeeds are presented. The data show that a critical amount of longitudinal control is required to maintain trimmed flight at certain combinations of airspeed and rate of descent. Estimates based on theoretically predicted interference effects indicate that the front rotor downwash acting on the rear rotor could cause variation of the longitudinal moments of the same order of magnitude as the measured variation.
Download or read book The Creep Properties of Metals Under Intermittent Stressing and Heating Conditions written by Lawrence A. Shepard and published by . This book was released on 1954 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tensile Properties and Creep Strength of Three Aluminum Alloys Exposed Up to 25 000 Hours at 200 to 400 F 370 to 480 K written by Dick M. Royster and published by . This book was released on 1969 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Technical Report written by and published by . This book was released on 1959 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Creep of Aluminum lithium Alloy written by Robert P. Marshall and published by . This book was released on 1961 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Note National Advisory Committee for Aeronautics written by United States. National Advisory Committee for Aeronautics and published by . This book was released on 1958 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A New Theoretical Interpretation of the High Temperature Deformation of Solid Solution Alloys Based on the Steady State and Transient Creep Properties of Aluminum 5 5 at percent Magnesium written by Michael John Mills and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
