The Relationship of High Strength Aluminum Alloy Corrosion Behavior and Corrosion Environment

2014 ◽  
Vol 904 ◽  
pp. 86-89
Author(s):  
Song Zhou ◽  
Li Hui ◽  
Liang Xu ◽  
Yu Tong Guo ◽  
Shao Hua Ma
Keyword(s):  
Aluminum Alloy ◽  
High Strength ◽  
Corrosion Damage ◽  
Fuel Tank ◽  
Nacl Solution ◽  
Surface Corrosion ◽  
Corrosion Pit ◽  
Corrosion Pits ◽  
Relationship Of ◽  
The Relationship

The aim of this article is to research the characteristics of corrosion pit on 2xxx aluminum alloys in different environments (3.5wt% NaCl solution, water in fuel tank and wet air). Measure the area of corrosion pit, the depth of corrosion pit in different environments. The results show that in 3.5wt% NaCl solution: the initiation of surface corrosion pits mainly occur in 24h, with time increasing ,the depth of corrosion pit rises indistinctively; in water in fuel tank : during 24h-120h, with the extension of corrosion time, the maximum depth of corrosion pits changed a little, the maximum corrosion area became a little smaller than that in 3.5wt% NaCl solution; in wet air: the corrosion damage was smaller than that in 3.5wt% NaCl solution and water in fuel tank, the depth of the corrosion pit was about 20μm, the biggest size of corrosion pit area was about 0.5 x104μm2.

Corrosion Damage Residual Strength Research of Shot Peening Aluminum Alloy

2011 ◽  
Vol 121-126 ◽  
pp. 2587-2591
Author(s):  
Sheng Li Lv ◽  
You Cui ◽  
Wei Zhang ◽  
Xiao Yan Tong
Keyword(s):  
Aluminum Alloy ◽  
Surface Treatment ◽  
Residual Strength ◽  
Shot Peening ◽  
Corrosion Damage ◽  
Solid Model ◽  
Element Analysis ◽  
Engineering Technique ◽  
Relationship Of ◽  
The Relationship

The pre-corrosion damage tests of LC4 aluminum alloy with the shot peening surface treatment and un-shot peening surface treatment are performed under different time levels. The residual strength has been studied by test after corrosion damage. An analysis procedure is developed using 3D reconstruction solid model and finite element analysis to predict residual strength, The relationship of static intensity and the corrosion damage are founded. An effective engineering technique for predicting residual strength of corroded structure is established on the base of this studying work.

Modeling the Influence of Microstructure on Stress Distributions and Concentrations in Pitting Corrosion

2018 ◽  
Author(s):  
Patrick Brewick ◽  
Andrew Geltmacher ◽  
Siddiq M. Qidwai
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Mechanical Load ◽  
High Strength ◽  
Geometrical Shape ◽  
Stress Distributions ◽  
Concentration Factors ◽  
Corrosion Pit ◽  
Stress Concentration Factors ◽  
Corrosion Pits

Despite the many advances made in material science, stainless steel and aluminum remain the structural materials best-suited for the naval fleet. While these metallic materials offer many benefits, such as high strength and good toughness, their persistent exposure to the maritime environment inevitably leads to issues with corrosion. Among the various manifestations of corrosion, pitting corrosion is of particular concern because the transition of corrosion pits to stress-corrosion cracks can lead to catastrophic failures. Traditional pitting corrosion analyses treat the pit shape as a semi-circle or ellipse and typically assume a growth pattern that maintains the original geometrical shape. However, when the underlying microstructure is incorporated into the model, pit growth is related to the grains surrounding the pit perimeter and the growth rate is proportional to crystallographic orientation. Since each grain has a potentially different orientation, pit growth happens at non-uniform rates leading to irregular geometries, i.e., non-circular and non-elliptical. These irregular pit geometries can further lead to higher stresses. This work presents a detailed look at corrosion pit growth coupled with mechanical load through a numerical model of a two-dimensional stable corrosion pit. Real microstructural information from a sample of 316 stainless steel is incorporated into the model to analyze microstructural effects on pit growth. Through this work, stress distributions and stress concentration factors are examined for a variety of pit geometries, including comparisons of their range of values to a typical, semi-circular pit. The consequences of these stress distributions and concentration factors are discussed.

Effect of Split-Sleeve Cold Expansion on the Fatigue Life of 7050-T7451 Aluminum Alloy

2014 ◽  
Vol 1082 ◽  
pp. 403-407 ◽  
Author(s):  
Hong Huang ◽  
Qing Yun Zhao ◽  
Feng Lei Liu
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Transgranular Fracture ◽  
Alloy Plate ◽  
Cold Expansion ◽  
Compressive Stresses ◽  
Aluminum Alloy Plate ◽  
Relationship Of ◽  
The Relationship

Split-sleeve cold expansion processing was employed on the 7050-T7451 aluminum alloy plate. Fatigue lives were compared according different expansion, then the relationship of fatigue life and expansion was analyzed. Residual stresses were measured with different expansion, and the fatigue fractograph was analyzed by SEM. The results show that the split-sleeve cold expansion can obtain longer life compared with the non-strengthen hole. When over the optimum expansion, fatigue life began to decrease. The maximum fatigue life increased to 2.92 times with 4.1% expansion. The maximum values of radial residual stresses grew with expansion. The depths of residual compressive stresses were more than 6mm with 2.6% and 4.1% expansion. The fatigue fractograph shows mixed transgranular fracture.

Fatigue Crack Growth of LC9 Aluminum Alloy under Flying Loading with Corrosion Damage

2014 ◽  
Vol 488-489 ◽  
pp. 66-69
Author(s):  
Xu Dong Li ◽  
Zeng Jie Cai ◽  
Zhi Tao Mu
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Cracks ◽  
Corrosion Damage ◽  
Growth Behavior ◽  
Transport Aircraft ◽  
Suitable Parameter ◽  
Corrosion Pits

This paper investigates the growth behavior of fatigue cracks initiated at corrosion pits in laboratory coupons of LC9 aluminum alloy subjected to a transport aircraft loading spectrum. Corrosion pits were introduced by exposing the coupons to EXCO solution for a variety of periods to produce corrosion damage varying from mild to severe. In general, the presence of corrosion damage reduced the fatigue lives of components to a severe extent. It was found that the depth of the corrosion pit was a suitable parameter for characterizing the corrosion damage and for predicting the fatigue life of the coupons using commercial fatigue crack growth software

scholarly journals Research on Corrosion Damage Evolution of Aluminum Alloy for Aviation

2020 ◽  
Vol 10 (20) ◽  
pp. 7184
Author(s):  
Zhigang Gao ◽  
Yuting He ◽  
Sheng Zhang ◽  
Tianyu Zhang ◽  
Fei Yang
Keyword(s):  
Aluminum Alloy ◽  
Corrosion Rate ◽  
Early Stage ◽  
Three Dimensional ◽  
Gumbel Distribution ◽  
Corrosion Damage ◽  
Environmental Data ◽  
Evolution Law ◽  
Immersion Corrosion ◽  
Corrosion Pits

Based on the real annual average value of atmospheric environmental data in the Wanning area of Hainan Province in China by selecting 7075 ultra-high-strength aluminum alloy specimens for aviation, a new corrosion solution was designed and the traditional alternate immersion corrosion method of using the alternate immersion corrosion test box was improved to simulate the environment of the internal structure of the aircraft. On this basis, two kinds of corrosion damage parameters, the depth of corrosion pits and corrosion rate, were quickly and accurately obtained by the three-dimensional profile of the specimen and binarization images’ method. The optimal linear regression equation combination of pitting depth and corrosion rate was established, and the dynamic evolution equation of the depth of corrosion pits and corrosion rate was obtained. The results showed that: The depth of corrosion pits in the early stage of corrosion (8 h and 24 h) obeyed the Gumbel distribution and Weibull distribution, respectively, and the later stage (48 h, 72 h, 96 h, and 120 h) conformed to the normal distribution; the depth of corrosion pits’ evolution law was in the form of double straight lines and the corrosion rate evolution law was in the power function form (y = a × xb); and the depth of corrosion pits changed rapidly in the early stage and gradually slowed down in the later stage, while the corrosion rate was just the opposite.

Finite Element Analysis of Aluminum Alloy Pitting Stress Concentration

2012 ◽  
Vol 538-541 ◽  
pp. 1664-1669
Author(s):  
Li Hui ◽  
Ying Ying Zhang ◽  
Liang Xu ◽  
Song Zhou ◽  
Yan Wang
Keyword(s):  
Finite Element ◽  
Aluminum Alloy ◽  
Stress Concentration ◽  
Fatigue Crack Initiation ◽  
Measurement Data ◽  
Local Stress ◽  
Element Analysis ◽  
Corrosion Pit ◽  
Corrosion Pits ◽  
Corrosion Time

Based on measurement data and the specific morphology of corrosion pit, three-dimensional finite element model of the corrosion damage specimen is established. Then the local stress condition of corrosion pits is given making use of finite element method, the results of stress concentration due to corrosion pits are also obtained, we can compare the stress concentration arised from the corrosion pit on aluminum alloy specimens in different corrosion time. Results show that the corrosion pits produce stress concentration and become the source of fatigue crack initiation and propagation. With the increasing of corrosion time, the pits get deeper and deeper, and the stress concentration gets more serious near the pits.

Correlation between Fracture Toughness and Quantitative Characterization of Microstructure in 7055 Aluminium Alloy

2016 ◽  
Vol 877 ◽  
pp. 416-420
Author(s):  
Hong Wei Yan ◽  
Xi Wu Li ◽  
Bai Qing Xiong ◽  
Yong An Zhang ◽  
Zhi Hui Li ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Aluminum Alloy ◽  
High Strength ◽  
Optical Metallography ◽  
Quantitative Characterization ◽  
High Strength Aluminum Alloy ◽  
Quantitative Characteristics ◽  
The Relationship ◽  
Electron Back Scattered Diffraction

Microstructure of high strength aluminum alloy have determinant effect on the properties, thus an effort has been made to investigation the relationship between fracture toughness and quantitative characteristics of microstructure in high strength aluminum alloy. Fracture toughness was tested for aluminum alloy specimens with various microstructure. The corresponding microstructure was observed by optical metallography and electron back-scattered diffraction, and quantitative characterization was conducted by further analysis of result obtained. Correlation between fracture toughness and parameters included grain size, percentage of recrystallization, substructure content and area fraction of residual phases was investigated. It was shown that percentage of recrystallization was a crucial factor for the fracture toughness, and correlations were established with proper and reasonable correction.

The corrosion behavior of chromated AA2024 aluminum alloy in 3.5% NaCl solution

2019 ◽  
Vol 66 (6) ◽  
pp. 879-887 ◽  
Author(s):  
Yong Zhou ◽  
Pei Zhang ◽  
Jinping Xiong ◽  
Fuan Yan
Keyword(s):  
Aluminum Alloy ◽  
Grain Boundary ◽  
Corrosion Behavior ◽  
Electrochemical Measurement ◽  
Nacl Solution ◽  
Content Type ◽  
Chromate Conversion Coating ◽  
Chromate Coating ◽  
Corrosion Mechanisms ◽  
Corrosion Pits

Purpose A chromate conversion coating was prepared on the surface of bare AA2024 aluminum alloy by direct immersion in the chromating treatment bath, and the corrosion behavior of chromated AA2024 aluminum alloy in 3.5 per cent NaCl solution was studied by electrochemical measurement and microstructural observation. Design/methodology/approach According to the polarization curve test and the scanning electron microscope observation, the corrosion evolution of chromated AA2024 in 3.5 per cent NaCl solution was divided into the following three stages: coating failure, pitting corrosion and intergranular corrosion (IGC). Findings In the first stage, the chromate coating degraded gradually due to the combined action of chloride anions and water molecules, resulting in the complete exposure of AA2024 substrate to 3.5 per cent NaCl solution. Subsequently, in the second stage, chloride anions adsorbed at the sites of θ phase (Al2Cu) and S phase (Al2CuMg) on the AA2024 surface preferentially, and some corrosion pits initiated at the above two sites and propagated towards the deep of crystal grains. However, the propagation of a pit terminated when the pit front arrived at the adjacent grain boundary, where the initiation of IGC occurred. Originality/value Finally, in the third stage, the corrosion proceeded along the continuous grain boundary net and penetrated the internal of AA2024 substrate, resulting in the propagation of IGC. The related corrosion mechanisms for the bare and the chromated AA2024 were also discussed.

ERECTILE DYSFUNCTION AS A PREDICTOR AND A COMPANION OF CARDIOVASCULAR DISEASE

2021 ◽  
pp. 178-182
Author(s):  
Анна Сергеевна Смольянникова ◽  
Ирина Сергеевна Добрынина ◽  
Анна Александровна Зуйкова ◽  
Елена Анатольевна Ханина ◽  
Марина Николаевна Муравицкая
Keyword(s):  
Blood Pressure ◽  
Erectile Dysfunction ◽  
Cardiovascular Diseases ◽  
High Strength ◽  
Vascular Lesions ◽  
Control Group ◽  
Endocrine Disorders ◽  
Cardiovascular Pathology ◽  
Relationship Of ◽  
The Relationship

Эректильная дисфункция - патология, связанная не только с наличием у больного урологических, психических или эндокринных нарушений. Нарушению эректильной функции способствуют многочисленные факторы, в том числе кардиоваскулярные заболевания, к которым в частности относится атеросклеротическое поражение сосудов на фоне дислипидемии. Эректильная дисфункция часто является первым симптомом системного атеросклероза. Целью исследования является изучение связи эректильной дисфункции и уровня тестостерона крови с дислипидемией и частными проявлениями сердечно-сосудистой патологии для своевременного выявления и начала лечения латентных форм кардиоваскулярных заболеваний. Была проведена оценка соответствующих показателей у выделенных групп исследуемых: основная группа - больные, обратившиеся за помощью по поводу эректильной дисфункции, контрольная группа - относительно здоровые исследуемые, не предъявляющие жалоб на эректильную функцию. В результате оценки полученных данных между количеством баллов, набранных по тесту-опроснику МИЭФ-5, уровнем тестостерона и показателями сАД, дАД, SCORE, общего холестерина и коэффициентом атерогенности выявлены связи умеренной и высокой силы. Пациенты, обратившиеся за амбулаторной помощью по поводу эректильной дисфункции, имели высокие показатели коэффициента атерогенности, что свидетельствует о высокой вероятности атеросклеротического поражения сосудов и в дальнейшем развития сердечно-сосудистой патологии Erectile dysfunction is a pathology associated not only with the presence of urological, mental or endocrine disorders in the patient. Numerous factors contribute to the development of erectile dysfunction, including cardiovascular diseases, which in particular include atherosclerotic vascular damage on the background of dyslipidemia. Erectile dysfunction caused by arteriosclerosis of the penile arteries is often the first symptom of systemic arteriosclerosis. The aim of this research is to study the relationship of erectile dysfunction and blood testosterone levels with dyslipidemia and particular manifestations of cardiovascular pathology for the timely detection and initiation of treatment of latent forms of cardiovascular diseases. To do this, the corresponding indicators were evaluated in the selected groups of subjects: the main group - patients who sought help for erectile dysfunction, the control group-relatively healthy subjects who did not complain about their erectile function. As a result of evaluating the data obtained between the number of points scored according to the MIEF-5 test-questionnaire, the level of testosterone and indicators of systolic blood pressure, diastolic blood pressure, SCORE, total cholesterol and the coefficient of atherogenicity, moderate and high strength relationships were revealed. Patients seeking outpatient care for erectile dysfunction had high rates of atherogenic coefficient, which indicates a high probability of atherosclerotic vascular lesions and further development of cardiovascular pathology

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