Download or read book Fatigue Life Analysis of 6061 T6 and 7075 T6 Aluminum Alloys After Retrogression Head Treatment and Thermomechanical Treatment written by Xaver Neumeyer and published by . This book was released on 2006 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experiments and Modeling of the Effect of Heat Exposure on Fatigue of 6061 and 7075 Aluminum Alloys written by Andrew T. Brammer and published by . This book was released on 2013 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: Strain-controlled fatigue tests were performed on 6061-T6 and 7075-T651 aluminum alloys as well as additional specimens of the same materials after exposure to a temperature of 538oC for 1 hour and cooling to room temperature. The fatigue behavior of all four materials was characterized using traditional strain-life analysis. The fatigue data was found to show no appreciable effect of the heat exposure in low cycle fatigue, and a decrease in fatigue life in high cycle fatigue in both 6061 and 7075. In addition, scanning electron microscopy was employed to determine that crack initiation occurred at Fe-rich particles and subsequence analysis was used to measure crack growth rates. The fatigue cracks were found to initiate at cracked intermetallic particles in the peak-aged alloys and at de-bonded particles in the heat exposed alloys. Using standard metallographic techniques, microstructural characterization including grain size, intermetallic particle size, and nearest neighbor distance were quantified. As such, this characterization data was implemented into a microstructure-sensitive fatigue model resulting in a unique set of modeling parameters to capture the experimental results of both the peak-aged and thermally-affected 6061 aluminum alloy and 7075 aluminum alloy data.

Download or read book Room Temperature Tensile Properties of Large 7075 T6 and 7075 T73 Aluminum alloy Forgings written by D. P. Moon and published by . This book was released on 1970 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Room-temperature tensile properties were determined for large 7075-T6 and 7075-T73 aluminum-alloy forgings. Forging sizes ranged from about 1.5 to 15 inches (short-transverse direction) for production forgings and up to 20 inches for step forgings. Heat-treated thickness was 0.75 to 1.000 inch for the T6 temper but ranged up to 10 inches for the T73 temper. Regression coefficients and standard d deviations are presented for three properties (TUS, TYS, and elongation) in each of three test directions. In addition, average values and two statistical minima are tabulated for each property and test direction at each of several discrete sizes, and a comparison is made with the corresponding requirements of Specification MIL-A-22771C(ASG). (Author).

Download or read book A Study of Fatigue and Fracture in 7075 T6 Aluminum Alloy in Vacuum and Air Environments written by Charles Michael Hudson and published by . This book was released on 1973 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Axial load fatigue life, fatigue-crack propagation, and fracture toughness experiments were conducted on sheet specimens made of 7075-T6 aluminum alloy. These experiments were conducted at pressures ranging from atmospheric to 5 x 10 to the minus 8th torr. Analysis of the results from the fatigue life experiments indicated that for a given stress level, lower air pressures produced longer fatigue lives. At a pressure of 5 x 10 to the minus 8th torr fatigue lives were 15 or more times as long as at atmospheric pressure. Analysis of the results from the fatigue crack propagation experiments indicated that for small stress intensity factor ranges the fatigue crack propagation rates were up to twice as high at atmospheric pressure as in vacuum. The fracture toughness of 7075-T6 was unaffected by the vacuum environment. Fractographic examination showed that specimens tested in both vacuum and air developed fatigue striations. Considerably more striations developed on specimens tested at atmospheric pressure, however.

Download or read book Fracture Mechanics and Acoustic Emission Response of Retrogression Reaged 7075 T6 Aluminum Alloy written by K. I. McRae and published by . This book was released on 1982 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stress corrosion cracking of high strength, structural aluminum alloys, such as 7075 in the T6 temper, is a commonly encountered problem. Recently, an alternative heat treatment, known as retrogression and reaging, has been proposed. It is purported that this heat treatment imparts a stress corrosion cracking resistance for 7075-T6 equal to that of the T73 temper, with only a negligible decrease in yield strength. In order to fully characterize this heat treatment, the plane strain fracture toughness, KIc, and the resistance to fatigue crack growth were compared to those of the same alloy in the normal T6 condition. Small increases in each of these mechanical properties were detected. The acoustic emission (AE) response to crack growth during testing was also investigated. It was determined that the number of AE signals is proportional to the crack length or total crack area. This response is consistent with proposed mechanisms for acoustic emission in this material. It is further noted that no significant difference exists in the AE response of 7075-T6 in the normal and retrogression-reaged conditions. (Author).

Download or read book Effect of Stress Ratio on Fatigue crack Growth in 7075 T6 and 2024 T3 Aluminum alloy Specimens written by C. M. Hudson and published by . This book was released on 1969 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stress ratio effects on fatigue crack growth in sheet aluminum alloys.

Download or read book Tear Resistance and Stress Relaxation Behavior of High strength AA7075 T6 Aluminum Alloy Sheet at Warm Temperatures Near 200 C written by Daniel Edward Nikolai and published by . This book was released on 2020 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of lightweight metals is of great interest to the automotive industry for improving vehicle efficiency. The automotive industry is particularly interested in lightweight metals with high strength-to-density ratios that can perform well in crash scenarios. To this end, high-strength aluminum alloys are investigated for body-in-white applications. Currently, 6xxx series aluminum alloys are the most commonly used aluminum materials for the body-in-white. AA7075-T6 offers comparable density to and significantly higher strength than the 6xxx series aluminum alloys. However, AA7075-T6 demonstrates low ductility and formability at room temperature, which are barriers to producing and mechanically fastening components for the body-in-white. Prior investigations by Rader et. al. demonstrated that the ductility of AA7075-T6 sheet is approximately doubled at warm temperatures near 200 °C, allowing it to be stamped to complex geometries. However, joining of AA7075-T6 sheet remains a significant challenge. The present study investigates the material behaviors necessary to determine the potential for joining of AA7075-T6 sheet at warm temperatures by self-piercing riveting. Self-piercing riveting is commonly used with the lower strength 6xxx series aluminum alloys in the automotive industry. Tear-resistance and stress-relaxation experiments are conducted to evaluate the potential for successfully implementing of self-pierce riveting in AA7075-T6 sheet at warm temperatures. Tear energy measurements at warm temperatures appropriate for retrogression heat treatments in AA7075-T6 are compared to measurements at room temperature. A four-fold increase in the tear energy of AA7075-T6 at warm temperatures suggests a high possibility for success with self-piercing riveting at these temperatures. Rapid stress relaxation of up to 45% of the flow stress produced during deformation at warm temperatures indicates a potentially significant reduction in residual stresses after deformation, which should reduce spring-back after forming and reduce the chance of delayed cracking in AA7075-T6 sheet after the application of a self-piercing rivet. These experimental results support the potential to successfully apply a self-piercing rivet to AA7075-T6 sheet at a warm temperature while simultaneously retrogressing the material. Because a subsequent reaging heat treatment is known to restore full strength following a retrogression heat treatment, the retrogression riveting and reaging process is proposed as a method to successfully join AA7075-T6 sheet material while retaining the full strength of the T6 condition

Download or read book Properties of a Retrogressed and Re Aged 7075 Aluminum Alloy written by E. S. Tankins and published by . This book was released on 1984 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: Retrogression and Re-aging (RRA) is a new thermal process introduced for the purpose of enhancing corrosion resistance of 7075-T651 aluminum alloy while maintaining its T6 strength. In this study a 7075 material so treated was investigated for its mechanical and corrosion resistant properties. Results indicated that the RRA treated 7075 was significantly better than the T6 temper in resistance to stress corrosion cracking and exfoliation corrosion. The loss in strength from RRA treatment was minimal. Electron microscopy of the fractured surface showed a distinct difference in the fracture mode when compared to the T6 temper condition. Tests results indicated that the RRA heat treatment resulted in fatigue and fracture toughness properties superior to the 7075-T651. Keywords: SEM fractography, Differential scanning colorimetry, Hardness, Conductivity, Fracture toughness, Fatigue, and Crack propagation.

Download or read book Variable amplitude Fatigue Tests with Particular Attention to the Effects of High and Low Loads written by Eugene C. Naumann and published by . This book was released on 1962 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fatigue Life Fatigue Crack Propagation and Fracture Toughness Study of 7075 Aluminum Alloy Subjected to Thermomechanical Processing written by Moon Hee Lee and published by . This book was released on 1984 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to its high strength/weight ratio, 7075 aluminum alloy has been widely used as an aerospace material. However, it has relatively low fatigue strength and low fracture toughness in the T6 condition. Thermomechanical processing, including pre-cyclic loading and stretching at high and ambient temperatures, has been investigated with the aim of improving these properties. Fatigue life tests show that all four thermomechanical processes investigated increase the fatigue life at low stress levels, but cause a reduction at high stress levels. The effect of the precipitate free zone (PFZ) width on the fatigue crack propagation rate and fracture toughness has also been investigated. The fatigue crack propagation rate of the alloy with a wide PFZ was found to be approximately the same as that of the alloy with a narrow PFZ under similar conditions of cyclic loading. The alloy with the wide PFZ demonstrated a greater value of fracture toughness than that shown by the alloy with the narrow PFZ. These experimental results have been analyzed taking recently proposed theoretical models into account. Transmission electron microscopy showed that a large number of dislocations were generated within the soft PFZ areas as a result of the cyclic pre-loading. This is believed to contribute to the increase in fatigue life at low applied stress levels. Scanning electron microscopy has shown an intergranular fracture mode for the alloy with the narrow PFZ and a dimple rupture mode for the alloy with the wide PFZ.

Download or read book Effect of Service Usage on Tensile Fatigue and Fracture Properties of 7075 T6 and 7178 T6 Aluminum Alloys written by Richard A. Everett and published by . This book was released on 1975 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fatigue Behavior of 2014 T6 7075 T6 and 7079 T6 Aluminum Alloy Regular Hand Forgings written by D. A. Paul and published by . This book was released on 1960 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On Stress Interaction in Fatigue and Cumulative Damage Rule written by Alfred M. Freudenthal and published by . This book was released on 1960 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Changing Stress Amplitude on the Rate of Fatigue crack Propagation in Two Aluminum Alloys written by C. M. Hudson and published by . This book was released on 1961 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of fatigue tests with specimens subjected to constant amplitude and two-step axial loads were conducted on 12-inch-wide sheet specimens of 2024-T3 and 7075-T6 aluminum alloy to study the effects of a change in stress level on fatigue-crack propagation. Comparison of the results of the tests in which the specimens were tested at first a high and then a low stress level with those of the constant-stress-amplitude tests indicated that crack propagation was generally delayed after the transition to the lower stress level. In the tests in which the specimens were tested at first a low and then a high stress level, crack propagation continued at the expected rate after the change in stress levels.

Download or read book Aluminum 7075 T6 Fatigue Data Generation and Probabilistic Life Prediction Formulation written by John G. Kemna and published by . This book was released on 1998-09-01 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: The life extension of aging fleet aircraft requires an assessment of the safe-life remaining after refurbishment. Risk can be estimated by conventional deterministic fatigue analysis coupled with a subjective factor of safety. Alternatively, risk can be quantitatively and objectively predicted by probabilistic analysis. In this investigation, a general probabilistic life formulation is specialized for constant amplitude, fully reversed fatigue loading utilizing conventional breakdown laws applied to the general probability damage function. Experimental data was collected both as a bench mark data base, as well as an example of the implementation of probabilistic fatigue life prediction. Fully reversed, sinusoidal fatigue testing under load control was carried Out at load levels giving high cycle fatigue lives from 1 x 104 to 5 x 106 cycles. The number of replications at each stress level is greater than currently available in the literature, thereby increasing the confidence of predictions in the long-life domain, as well as extending the statistical basis for probabilistic inference. The load level data sets are interpreted by the probabilistic damage function for life location as well as life shape parameters using maximum likelihood analysis. Homologous life ranking and the minimum entropy hypothesis are investigated as well.

Download or read book Fatigue Crack Propagation in 2024 T3 and 7075 T6 Aluminum Alloys at High Stresses written by Robert G. Dubensky and published by . This book was released on 1971 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Influence of Programing Techniques and of Varying Limit Load Factors on Maneuver Load Fatigue Test Results written by Patrick L. Corbin and published by . This book was released on 1966 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Variable-amplitude axial-load fatigue tests were conducted on 7075-T6 aluminum-alloy edge-notched specimens having a theoretical elastic stress concentration factor of 4. The load programs were designed to approximate maneuver load spectra. Fatigue life was found to be shorter for random form tests than for block form tests having the same load spectrum. The greatest change in life occurred when the test program contained negative loads. Life for variable-amplitude tests was found to increase as much as 60 percent above the original test life after preloading with a program having a higher limit load factor. The summations of cycle ratios were approximately 2 for tests without negative loads but were approximately 1 for tests with negative loads.