Download or read book A Study of Constituent Dispersoid and Hardening Particles in the Fracture of 7075 Aluminum Alloys written by Joseph S. Santner and published by . This book was released on 1977 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ten different alloys based on the 7075 composition are used to study the effect of purity level, dispersoid type, and heat treatment on 7075's fracture toughness. Five different purity levels ranging from 0.30 w/o to 0.30 w/o Fe+Si and two different dispersoid types were investigated. Each alloy was given two different heat treatments with both the longitudinal and the long-transverse directions tested. The notched round tensile test was modified to give the 'plastic energy per unit area'. This parameter used for ranking fracture toughness gave the same results as the total energy per unit area measured on precracked Charpy specimens. Moreover, the fracture toughness ranking for these ten alloys was the same in the longitudinal and long-transverse directions. This suggests the elongated distribution of constituent particles in the rolling direction does not change the failure mechanism. Fractographic evidence showed a clear difference in the fracture topography between the ten alloys. An analysis of variance demonstrated that heat treatment was the most significant variable investigated that affects fracture toughness. This result supports a two-stage ductile fracture failure mechanism which suggests that the dispersoid and hardening particles are primarily responsible for the fracture toughness of the higher purity aluminum alloys used by the aerospace industry today. (Author).

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1977 with total page 1110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1978 with total page 1510 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aluminum Alloys Contemporary Research and Applications written by A. K. Vasudevan and published by Elsevier. This book was released on 2012-12-02 with total page 727 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the structure and properties of the current and potential aluminum alloys in terms of their structure (and structural transformations by new processing methods) and the relationship between structure and mechanical and other properties. The alternative materials that challenge aluminum are considered as well, since the challenge of new competitive materials is a strong influence on innovation. The book bridges the gap between current scientific understanding and engineering practice. It is an up-to-date reference that will be of use to researchers and advanced students in metallurgy and materials engineering.

Download or read book The Delayed Fracture of Aluminum Alloys End of Year Report written by Joseph R. Pickens and published by . This book was released on 1982 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanisms of failure of high-strength aluminum alloys in saline environments was investigated. It was found that the mechanism of stress corrosion cracking (SCC) in a commercial Al-Mg alloy, 5083, is dominated by hydrogen embrittlement (HE). The dominant contribution of HE was discerned by comparing SCC susceptibility under Modes I and III loading. The influence of the surface oxide film on the SCC susceptibility of 7075 and 7175 alloys was also examined. It was found that unlike certain high purity alloys, the susceptibility of these commercial alloys is not significantly influenced by the composition of the oxide. In these 7xxx alloys, the insoluble constituent particles provide sites for SCC initiation. The greater susceptibility of 7075, compared with its higher purity version, 7175, is in part a result of its lower value fraction of the constituent particles. (Author).

Download or read book The Microstructure and Plane Strain Fracture Toughness of High Strength Aluminum Alloys written by Peter John Guest and published by . This book was released on 1967 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Particle Cracking Damage Evolution in 7075 Wrought Aluminum Alloy Under Monotonic and Cyclic Loading Conditions written by James Joel Harris and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 7xxx series Al-Zn-Mg-Cu-base wrought Al-alloy products are widely used for aerospace structural applications where monotonic and cyclic mechanical properties are of prime concern. Microstructure of these commercial alloys usually contains brittle coarse constituent particles or inclusions of Fe-rich intermetallic compounds and Mg2Si, typically in the size range of 1 to 50 micron. Plastic deformation and fracture of 7xxx series alloys (as well as of numerous other wrought Al-alloys) is associated with gradual microstructural damage accumulation that involves cracking of the coarse constituent particles, growth of voids around the cracked particles, and the void coalescence. To understand and model the microstructural damage evolution processes such particle cracking, quantitative microstructural data associated with the damage nucleation are required under monotonic as well as cyclic loading conditions. In the past quantitative characterization of particle cracking damage in these alloys has been problematic. However, with recent advances in digital image analysis and stereology based techniques, it is now possible to quantitatively characterize the damage nucleation in hot-rolled 7075(T6) Al-alloy (a typical alloy of 7xxx series) due to cracking of the Fe-rich coarse constituent particles. The objectives of this work are: *Quantitative characterization of the cracking of Fe-rich constituent particles as a function of strain under quasi-static loading. This involves measurements of number density of cracked particles, volume fraction of the cracked particles, their size, shape, and orientation distribution, as well as nearest neighbor distribution and two-point correlation functions to quantify spatial dispersion of the cracked particles in a series of interrupted uniaxial tensile test specimens at different strain levels. *Quantitative characterization of the cracking of Fe-rich constituent particles under cyclic loading to study the differences between the particle cracking damage due to monotonic and cyclic loading.

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1977 with total page 1530 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Micromechanisms of Crack Extension in Alloys written by John A. Blind and published by . This book was released on 1982 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work describes an investigation of the effect of manganese-bearing dispersoid particles on the fracture characteristics of peak aged Al-Mg-Si alloys. Current elastic and elastic-plastic fracture toughness parameters are reviewed. The applicability of these parameters as criteria for the onset of crack extension and their variation with alloy microstructure are examined based on experimental results for a series of alloys containing differing volume fractions of disperoid. High purity alloys were used to isolate the effect of dispersoids from that of coarse constituent particles. Also, for comparison, one alloy of commercial purity containing both disperoids and coarse iron-bearing inclusions was studied. The ductile fracture toughness, JIc, and the resistance to instability as measured by the tearing modulus, T, were found to increase with disperoid content. The values of these parameters were lower in the commercial purity alloy than for the equivalent high purity alloy. The effect of an increasingly triaxial state on fracture strain was measured using a series of notched tensile specimens. The alloy ductility was found to increase with disperoid content and to decrease with increased stress triaxiality. Crack tip plastic zone sizes on the midplane of compact tension specimens were measured using the SEM electron channelling pattern technique. Zone size was found to correlate with the square of the applied stress intensity factor. The constant of proportionality decreased with increasing disperoid content. The calculated work per unit area of new crack surface was found to correspond to the ductile fracture toughness measured for each alloy.

Download or read book Report of the research group for study on the deformation and fracture of high strength aluminum alloys with special reference to high temperature written by Research Group for Study on the Deformation and Fracture of High Strength Aluminum Alloys with Special Reference to High Temperature and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microstructural Characterization and Corrosion Behavior of Al 7075 Alloys Using X ray Synchrotron Tomography written by Sudhanshu Shekhar Singh and published by . This book was released on 2015 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Al 7075 alloys are used in a variety of structural applications, such as aircraft wings, automotive components, fuselage, spacecraft, missiles, etc. The mechanical and corrosion behavior of these alloys are dependent on their microstructure and the environment. Therefore, a comprehensive study on microstructural characterization and stress-environment interaction is necessary. Traditionally, 2D techniques have been used to characterize microstructure, which are inaccurate and inadequate since the research has shown that the results obtained in the bulk are different from those obtained on the surface. There now exist several techniques in 3D, which can be used to characterize the microstructure. Al 7075 alloys contain second phase particles which can be classified as Fe-bearing inclusions, Si-bearing inclusions and precipitates. The variation in mechanical and corrosion properties of aluminum alloys has been attributed to the size, shape, distribution, corrosion properties and mechanical behavior of these precipitates and constituent particles. Therefore, in order to understand the performance of Al 7075 alloys, it is critical to investigate the size and distribution of inclusions and precipitates in the alloys along with their mechanical properties, such as Young's modulus, hardness and stress-strain behavior. X-ray tomography and FIB tomography were used to visualize and quantify the microstructure of constituent particles (inclusions) and precipitates, respectively. Microscale mechanical characterization techniques, such as nanoindentation and micropillar compression, were used to obtain mechanical properties of inclusions. Over the years, studies have used surface measurements to understand corrosion behavior of materials. More recently, in situ mechanical testing has become more attractive and advantageous, as it enables visualization and quantification of microstructural changes as a function of time (4D). In this study, in situ X-ray synchrotron tomography was used to study the SCC behavior of Al 7075 alloys in moisture and deionized water. Furthermore, experiments were performed in EXCO solution to study the effect of applied stress on exfoliation behavior in 3D. Contrary to 2D measurements made at the surface which suggest non-uniform crack growth rates, three dimensional measurements of the crack length led to a much more accurate measurement of crack growth rates.

Download or read book Effect of Stress Ratio on Fatigue Crack Growth and Mode of Fracture in 2024 T4 and 7075 T6 Aluminum Alloys in the Low cycle Range written by D. Y. Wang and published by . This book was released on 1966 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigation was conducted at minimum-to-maximum stress ratios R of -2.5, -2.0, -1.5, -1.0, 0.0 and 0.6. It was observed that the fracture mechanism of low-cycle fatigue involves Stage II fatigue crack growth which is characterized by the development of ductile striations and two essential types of secondary fracture surfaces. It is shown that ductile fatigue crack growth, which involves two types of ductile striations, is governed by the local irreversible plastic deformation at the crack tip in both alloys. The most important mode of secondary crack growth in 2024-T4 aluminum is the brittle fracture or decohension of the constituent particles ahead of the crack tip and the subsequent growth of the interior cracks toward the main crack. The size of the plastic zone at the crack tip appears to determine the degree of influence of this mode of fracture on overall crack growth rate. In 7075-T6, the dominant mode of secondary crack growth is the quasi-cleavage fracture of the matrix. The frequency of occurrence of these two modes of secondary crack growth increases with the stress ratio, i.e., with increasing mean stress. The change in the modes of crack growth as we change from low to high mean stress contributes to the relative differences in fatigue strength of the two materials at various stress ratios.

Download or read book Fracture Behavior Evaluation of High Strength 7050 and 7075 Aluminum Alloys Using V Notched Specimen written by Parvin Abachi and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The fracture behaviors of high-strength 7050 and 7075 aluminum alloys (AA7050 and AA7075) were investigated using small size, V-notched tear specimens. In accordance with ASTM B871-01 standard test method, the thickness and notch angle were selected as 6.35 mm and 60°, respectively. All tear specimens (also called Kahn specimens) were machined in L-T orientation and the mechanical tests were conducted at RT. To evaluate crack propagation route during failure process, interrupted tear tests were also conducted on AA7075. The subsized cylindrical tension test specimens were machined in L direction of the bulk materials to study the elastic-plastic behavior of the alloys in accordance with ASTM B 557M-98 standard test method. The microstructures of T73651 and T6 heat-treated alloys were examined using optical microscopy and SEM. The precipitate characterization of heat-treated specimens was performed using Clemex image analysis software. The rupture mechanisms were also studied by examination of specimen fracture surfaces using SEM. According to the results, the amount, size and distribution of intermetallic particles have been identified as the important factors on failure of the examined alloys. Both examined alloys show the same damage initiation mechanism; however, the failure mechanism is different to some extent. Depending on the stress condition, two major failure micromechanisms, id est, "internal necking mechanism" and "void sheet mechanism," are prevailing for both alloys. The results of mechanical tests and determination of tear strength to 0.2% tensile yield strength ratio made it possible to evaluate specimens' notch toughness. The comparison of specimens' resistance to stable crack propagation and subsequent fracture in the presence of crack-like stress concentrator was provided using tear test data.

Download or read book Notched Fatigue Behavior to 7075 Base Aluminum Alloys written by Joseph S. Santner and published by . This book was released on 1978 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ten different alloys based on the 7075 composition were utilized to study the effects of purity level (w/o Fe+Si) and dispersoid type on the notched fatigue behavior in two different environments. These same alloys were used in other AFML investigations to determine how the various precipitates found in commercial 7000 series aluminum alloys control the mechanical properties. Purity significantly affects the notched (Kt=3) fatigue life only in an inert test environment at the lowest load tested. Purity did not significantly affect the notched fatigue life when tests were conducted in an aggressive test environment. While the dispersoid type did change the macroscopic fracture appearance of the test specimen, this produced a small change in the notched fatigue life which was not significant at the one percent alpha level. By far, the test environment was more important than the metallurgical variables considered. This is somewhat surprising since the duraction of the tests were at most two days, allowing little time for corrosion. It appears that specifying stricter alloy purity levels or different dispersoid types will not improve the notched fatigue life of wrought 7000 series aluminum alloys. (Author).

Download or read book Advances in the Metallurgy of Aluminum Alloys written by Murat Tiryakioglu and published by ASM International(OH). This book was released on 2001 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the James T. Staley Honorary Symposium on Aluminum Alloys, 5-7 November 2001, Indianapolis, Indiana. This volume provides an update on the background and recent developments in aluminum metallurgy related to alloy and temper development, structure-property relationships, structure evolution, fatigue and fracture, and heat treatment. It includes papers prepared by international experts from industry and academia. Contents include: Overview of contributions of Dr. James T. Staley to aluminum metallurgy; Microstructure-property relationships; Fatigue and fracture; Quenching and quench factor analysis; Precipitation strengthening; Structure evolution; Alloy and temper development.