Download or read book Microstructural Effect on Fatigue of 7075 Aluminum Alloy written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study was conducted to characterize the fatigue behavior of underaged and overaged 7075 aluminum alloy in vacuum of 4xl0(exp -8) torr. An emphasis was placed on clarifying the effects of different microstructures, arising from the underaging and overaging treatments, on the threshold fatigue crack growth (FCG). The FCG was measured under constant amplitude loading of stress ratios, ranging from 0.1 to 0.85, in vacuum of 4xl0(exp -8) torr. The result was analyzed in terms of threshold stress intensity range for FCG and maximum stress intensity. It was found that the underaging resulted in lower electrical conductivity, higher hardness, and greater resistance to threshold FCG than the overaging. This is attributable to the difference in microstructure.

Download or read book Effect of Microstructure on Pit to Crack Transition of 7075 T6 Aluminum Alloy written by Kimberli Jones and published by . This book was released on 2006 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this research was to gain an increased understanding of how microstructure influences pit growth, pit-to-crack transition, and critical crack propagation to fracture. Two thicknesses of 7075-T6 aluminum alloy were etched and subjected to corrosion fatigue in a 3.5 % sodium chloride environment. 7075-T6 aluminum alloy is of particular interest to the aging aircraft community, as this alloy has been used extensively on wing and fuselage structures for both military and commercial aircraft in the past. Testing was interrupted at various intervals to obtain information on pit generation, growth, and potential cracking. Results indicated that microstructure has a significant influence on pit-to-crack transition and fatigue crack propagation. Short cracks (

Download or read book Review of the Effects of Microstructure on Fatigue in Aluminum Alloys written by Jack Telesman and published by . This book was released on 1984 with total page 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 Effect of Microstructure on the Yield Strength and Stress Corrosion Resistance of 7075 Aluminium Alloy written by M. Hua and published by . This book was released on 1990 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Microstructure and Environment on Stress Corrosion of 7075 Aluminum Alloy written by G. Geschwind and published by . This book was released on 1973 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Grain boundary microstructure as well as the pH in a chloride ion solution environment was found to be significant to stress corrosion attack in 7075 aluminum alloys. The influence of these factors on both the initiation and propagation of cracking and the mode of attack in these alloys are described. Microstructural modifications to attain desirable stress corrosion resistance are suggested.

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 Effect of Microstructure on Pit to crack Transition of 7075 T6 Aluminum Alloy written by Kimberli Jones and published by . This book was released on 2004 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Microstructure on Fatigue Crack Growth of 7XXX Aluminum Alloys Under Constant Amplitude and Spectrum Loading written by T. H Sanders (Jr) and published by . This book was released on 1978 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation was made to identify microstructural features which control the fatigue crack growth characteristics of 7XXX aluminum alloys. Constant amplitude and simple overload tests were conducted in humid air on controlled microstructural variations of alloys 7075 and 7050. Results indicated that relative influence of different microstructural features and ranking of the alloys based on fatigue crack propagation resistance depend on loading conditions.

Download or read book Corrosion and Corrosion fatigue Behavior of 7075 Aluminum Alloys Studied by in Situ X ray Tomography written by Tyler Stannard and published by . This book was released on 2017 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: 7XXX aluminum alloys have high strength to weight ratio and low cost. They are used in many critical structural applications including automotive and aerospace components. These applications frequently subject the alloys to static and cyclic loading in service. Additionally, the alloys are often subjected to aggressive corrosive environments such as saltwater spray. These chemical and mechanical exposures have been known to cause premature failure in critical applications. Hence, the microstructural behavior of the alloys under combined chemical attack and mechanical loading must be characterized further. Most studies to date have analyzed the microstructure of the 7XXX alloys using two dimensional (2D) techniques. While 2D studies yield valuable insights about the properties of the alloys, they do not provide sufficiently accurate results because the microstructure is three dimensional and hence its response to external stimuli is also three dimensional (3D). Relevant features of the alloys include the grains, subgrains, intermetallic inclusion particles, and intermetallic precipitate particles. The effects of microstructural features on corrosion pitting and corrosion fatigue of aluminum alloys has primarily been studied using 2D techniques such as scanning electron microscopy (SEM) surface analysis along with post-mortem SEM fracture surface analysis to estimate the corrosion pit size and fatigue crack initiation site. These studies often limited the corrosion-fatigue testing to samples in air or specialized solutions, because samples tested in NaCl solution typically have fracture surfaces covered in corrosion product. Recent technological advancements allow observation of the microstructure, corrosion and crack behavior of aluminum alloys in solution in three dimensions over time (4D). In situ synchrotron X-Ray microtomography was used to analyze the corrosion and cracking behavior of the alloy in four dimensions to elucidate crack initiation at corrosion pits for samples of multiple aging conditions and impurity concentrations. Additionally, chemical reactions between the 3.5 wt% NaCl solution and the crack surfaces were quantified by observing the evolution of hydrogen bubbles from the crack. The effects of the impurity particles and age-hardening particles on the corrosion and fatigue properties were examined in 4D.

Download or read book Effect of Microstructure on Fatigue Crack Growth of 7XXX Aluminum Alloys Under Constant Amplitude and Spectrum Loading written by Aluminum Company of America and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Microstructural Features on Corrosion of Fatigue of High Strength Aluminum Alloys written by E. A. Starke and published by . This book was released on 1978 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Microstructure on 7XXX Aluminum Alloy Fatigue Crack Growth Behavior Down to Near Threshold Rates written by and published by . This book was released on 1981 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation was undertaken to clarify the role of microstructure on steady state (constant load amplitude) and transient (single periodic overload) fatigue crack growth behavior in 7XXX aluminum alloys at low stress intensity factor ranges (delta K). These results were consolidated with data in the literature to obtain an understanding of microstructural effects on crack growth response over a broad delta K range. Constant load amplitude data show that there are significant differences in near-threshold FCG resistance among 7XXX alloys. Overaging to a T7 temper reduces low delta K FCG resistance greatly, whereas intermediate and high delta K FCG resistance is increased by overaging. In the presence of moisture at intermediate delta K levels, increasing Cu content from 1.0 to 2.3% increases crack growth resistance. However, there is no consistent effect of Cu content on near-threshold fatigue performance. Similarly, no clear influence of dispersoid type (Cr vs. Zr) on low delta K FCG resistance was detected. Increasing alloy purity (lowering Fe, Si content) enhances crack growth resistance at high delta K, but has no effect at near-threshold stress intensities. The importance of near-threshold FCG performance to alloy design and materials selection for fatigue resistance is discussed. Potential tradeoffs between design philosophies which emphasize damage tolerance characteristics vs. those which focus on improved life cycle economics are examined.

Download or read book A Fracture Mechanics Study of Corrosion Fatigue written by R. A. M. Chandra Prasad and published by . This book was released on 2022-09-26 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Majority of industrial components fail due to the conjoint actions of fatigue and corrosion. All fatigue failures including one in air can be categorized as corrosion fatigue. Absolute fatigue can take place only in vacuum or inert environment. The effect of corrosion on fatigue has been extensively studied by determining the stress vs. number of cycles (S-N) curve. S-N curve depicts the final fracture, it does not separate the crack initiation and crack propagation. The defect tolerant design based on fracture mechanics concepts assumes that some forms of defects are already present in the materials and a considerable life in spent in crack propagation before the final fracture. Measure of resistance of a material to crack growth (fracture toughness) then becomes extremely important. It is now possible to describe material property of fracture toughness in terms of applied intensity of stress near the crack tip (K). Fracture mechanics based on elastic material behavior (absence of significant yielding) , referred to as the linear elastic fracture mechanics (LEFM) is well suited to materials which have limited ductility. The stress intensity factor (K ) is used both for conditions of static loading (Stress Corrosion Cracking) and for the moving cracks during fatigue loading . In this book the results of corrosion fatigue crack growth on 7075 - Alclad alloy are presented. This alloy is widely used in aircraft and automobile industries. Corrosion resistance is obtained by cladding with a more corrosion resistant aluminum alloy. However, the corrosion protection system may undergo rupture especially during crack growth in the underlying metal. Environment will then play a dominant role in the crack growth process. The design of reliable aircraft structures requires provision that cracks do not propagate under cyclic loading to reach a critical size resulting in fracture. The understanding of crack propagation under the conjoint action of corrosion and fatigue is thus of great technological and economic significance. Conflicting observations have been reported in literature regarding the influence of microstructure and environmental variables on the corrosion crack propagation rates.

Download or read book Effects of Microstructure on Fatigue Crack Growth of High Strength Aluminum Alloys written by W. G. Truckner and published by . This book was released on 1976 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effects of microstructure and composition on resistance to fatigue crack growth were determined using constant amplitude loading conditions in low and high humidity air at test frequencies of 2 and 20 Hz. Strengthening precipitate had the largest effect at delta K above about 4 KSI sq. root of (in.), while solute composition had the largest effect at delta K below about 3 KSI sq. root of (in.). Large intermetallic particles affected growth at high and intermediate levels of delta K. (Author).

Download or read book Effect of Microstructure on Short Fatigue Crack Initiation and Growth in Aluminium Alloys written by David Andrew Downham and published by . This book was released on 1986 with total page 91 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.