scholarly journals Effects of Actual Marine Atmospheric Pre-Corrosion and Pre-Fatigue on the Fatigue Property of 7085 Aluminum Alloy

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 81
Author(s):  
Laixin Shi ◽  
Lin Xiang ◽  
Jianquan Tao ◽  
Jun Liu ◽  
Qiang Chen ◽  
...  

Effects of actual marine atmospheric precorrosion and prefatigue on the fatigue property of 7085-T7452 aluminum alloy were investigated by using the methods of marine atmospheric outdoor exposure tests and constant amplitude axial fatigue tests. Marine atmospheric corrosion morphologies, fatigue life, and fatigue fractography were analyzed. After three months of outdoor exposure, both pitting corrosion and intergranular corrosion (IGC) occurred, while the latter was the dominant marine atmospheric corrosion mode. Marine atmospheric precorrosion could result in a dramatical decrease in the fatigue life of the as-received 7085-T7452 aluminum alloy, while selective prefatigue can improve the total fatigue life of the precorroded specimen. The mechanism of the actual marine atmospheric corrosion and its effects on the fatigue life of the 7085-T7452 aluminum alloy were also discussed.

1981 ◽  
Vol 103 (3) ◽  
pp. 223-228 ◽  
Author(s):  
A. Kantimathi ◽  
J. A. Alic

Fretting fatigue tests have been conducted on 7075-T7351 aluminum alloy coupons with fretting pads of the same material. Three different stress ratios were used, the otherwise constant amplitude axial loads being interrupted every 1000 cycles by either tensile overloads to 400 MPa or compressive underloads to −200 MPa. Tensile overloads greatly prolonged fatigue life for low stresses where the overload ratios were 1.6 and above; compressive underloads had comparatively little effect. The results are discussed in terms of crack growth retardation phenomena.


2018 ◽  
Vol 53 (8) ◽  
pp. 676-686
Author(s):  
Nikolaos D Alexopoulos ◽  
Evangelos Migklis ◽  
Dimitrios Myriounis

Fatigue mechanical behavior of wrought aluminum alloy (Al-Mg-Si) 6156 at T4 temper is experimentally investigated. Constant-amplitude fatigue tests, at fixed stress ratio R = 0.1, were carried out, and the respective stress–life diagram was constructed and compared against the competitive 6xxx aluminum alloys, for example, 6082 and 6061. Fatigue endurance limit of AA6156 was found to be approximately 155 ± 5 MPa, that is, almost 30% below yield stress Rp of the material. AA6156 presents almost 50% higher fatigue life in the high-cycle fatigue area and approximately 20% higher fatigue endurance limit, when compared with other 6xxx series aluminum alloys. Significant work hardening was induced due to fatigue and was experimentally validated by the measurements of residual stiffness of fatigue loops as well as of absorbed energy per fatigue loop. Work-hardening exponent was essentially decreased by almost 25% from the first fatigue cycles and up to 10% of fatigue life. Fracture surfaces of specimens loaded at applied stresses close to fatigue endurance limit exhibited signs of coarse voids due to the formed precipitates at the matrix. The fracture mechanism was a mixture of transgranunal and intergranular fracture for the fatigue specimens tested at higher applied fatigue loadings.


2019 ◽  
Vol 300 ◽  
pp. 09003
Author(s):  
Benaïssa Malek ◽  
Catherine Mabru ◽  
Michel Chaussumier

The purpose of the present research project is to study multiaxial fatigue behavior of 2618 alloy. The influence of mean stress on the fatigue behavior under tension and torsion is particularly investigated. Fatigue tests under combined tensile-torsion, in or out of phase, as well as combined tensile-torsion-internal pressure tests have also been conducted. Multiaxial fatigue results are analyzed according to Fatemi-Socie criterion to predict the fatigue life.


2010 ◽  
Vol 118-120 ◽  
pp. 221-225 ◽  
Author(s):  
Cheng Long Xu ◽  
Sheng Li Lv ◽  
Zhen Guo Wang ◽  
Wei Zhang

The purpose of this work was to predict the fatigue life of pre-corroded LC4 aluminum alloy by applying artificial neural network (ANN). Specimens were exposed to the same corrosive environment for 24h, 48h, and 72h. Fatigue tests were conducted under different stress levels. The existing experimental data sets were used for training and testing the construction of proposed network. A suitable network architecture (2-15-1) was proposed with good performance in this study. For evaluating the method efficiency, the experimental results have been compared to values predicted by ANN. The maximum absolute relative error for predicted values does not exceed 5%. Therefore it can be concluded that using neural networks to predict the fatigue life of LC4 is feasible and reliable.


1985 ◽  
Vol 107 (3) ◽  
pp. 214-220 ◽  
Author(s):  
T. Shimokawa ◽  
Y. Hamaguchi

The objective of this study is to identify the most closely related variable to the distribution of fatigue life in unnotched and three kinds of notched 2024-T4 aluminum alloy specimens. Carefully designed fatigue tests under a constant temperature and humidity condition provided fatigue life distributions over a wide range of stress amplitude. This study used about 1000 specimens. On the basis of the test results, the dependence of the scatter in fatigue life on notch configuration, the period to crack initiation, the level of stress amplitude, the median fatigue life, and the slope of the median S-N curve is investigated, and the relationship between the distributional form of fatigue life and the shape of the median S-N curve is discussed. It is concluded that the slope and shape of the median S-N curve in the vicinity of the test stress level are closely related to the scatter and distributional form of fatigue life respectively. This is common to the unnotched and three kinds of notched specimens. A variability hypothesis to correlate the median S-N curve with fatigue life distributions is examined.


2012 ◽  
Vol 06 ◽  
pp. 336-342 ◽  
Author(s):  
MD. SHAFIUL FERDOUS ◽  
CHOBIN MAKABE ◽  
TATSUJIRO MIYAZAKI ◽  
NOBUSUKE HATTORI

A method of improving the fatigue life and crack growth behavior of a center holed specimen was investigated. Local plastic deformation was applied around the hole by indentation to achieve the purpose. A series of fatigue tests was conducted on aluminum-alloy 2024-T3. Push-pull tests were performed under a stress ratio of R= -1 and a frequency of 10Hz. The observations of the crack initiation and growth were performed with a microscope, and hardness around the hole was measured by Vickers hardness testing machine. In the present study, the longest fatigue life was observed in the case of an indentation specimen with the highest load. The indentation was performed on both sides of the hole edges. The crack growth rate was decreased by indentation or expansion of the material around the hole. From the experimental results, it is found that the fatigue life and crack growth behavior of a holed or notched specimen can be improved by a simple technical method that is related to the local plastic working.


2016 ◽  
Vol 713 ◽  
pp. 334-337
Author(s):  
Tian Qing Liu ◽  
Xin Hong Shi ◽  
Jian Yu Zhang

Fatigue tests have been carried out to investigate the effects of mean-stress and phase-difference on the tension-torsion fatigue failure of 2A12-T4 aluminum alloy. The results show that for fully reversed tension-torsion loading, the fatigue life increases with the increase of phase angle, but the fatigue life decreases with the increase of phase angle, when mean-stress exists, both for shear mean-stress and normal mean-stress. Fracture appearance shows that the crack initiation is on the direction of maximum shear stress amplitude plane. Critical plane criteria based on the linear combination of the maximum shear stress amplitude and maximum normal stress are studied and further discussion on the drawbacks of this kind of criteria are performed.


2013 ◽  
Vol 211 ◽  
pp. 83-88
Author(s):  
Marek Cieśla

Usefulness of the magnesium alloys for construction of structural components is determined, apart from their low density, by a number of favourable mechanical properties and in the case of their use for components of transport means additionally by good fatigue strength. In this study, 12 mm diameter extruded rods of AZ31 and AZ61 magnesium alloys were used as test material. After extrusion the rods were annealed at a temperature of 400°C, with a 60 min soaking period and subsequent cooling in air. Cylindrical specimens with a diameter of d0 = 8 mm were made for the fatigue test under high-cycle rotary bending conditions with the cycle asymmetry coefficient R = -1. The tests were carried out for a limited fatigue strength range. Examination of microstructure of tested alloys and fatigue fractography were also performed. During the high-cycle fatigue tests it was found that the AZ61 alloy has a longer fatigue life. Based on the obtained results, fatigue life characteristics of the tested materials were drawn up.


2016 ◽  
Vol 853 ◽  
pp. 77-82
Author(s):  
Xu Chen ◽  
Rui Si Xing ◽  
Xiao Peng Liu

Aluminium alloys are widely used in the fields of automobile, machinery and naval construction. To investigate the effect of non-proportional loadings and corrosive environment on the fatigue resistance of 6061-T6 aluminum alloy, a set of uniaxial and multiaxial low cycle fatigue tests were carried out. Firstly, the results of uniaxial tests showed that the alloy exhibited cyclic hardening then cyclic softening. With the increase of stress amplitude the cyclic softening became pronounced. The increasing of plastic deformation was basically cyclically stable with small plastic strain amplitude accumulation when the stress amplitude was lower than 200MPa ,while it was increasing rapidly when the stress amplitude was higher than 220MPa. Secondly, it was observed that non-proportional cycle additional hardening of 6061-T6 aluminum alloy was little. While the fatigue life was badly affected by the loading paths. Thirdly ,the fatigue corrosion interactions were also talked about in details by performing the tests under the same loading conditions with corrosive environment. The experiment proved that the seawater corrosion has huge impact on fatigue life under pH 3. Finally, a multi-axial fatigue life prediction model was used to predict the fatigue life with or without the corrosive environment which showed a good agreement with experimental data.


Materials ◽  
2005 ◽  
Author(s):  
M. A. Wahab ◽  
J. H. Park ◽  
S. S. Pang

Corrosion-Prevention-Compounds (CPC) are commonly used to prevent corrosion in the aircraft industry. The presence of corrosive environment on aircraft structures has detrimental effects on the aircraft components which reduces the fatigue life and may also accelerate the crack growth rate in the structures. This is an experimental study on 2024-T3 aluminum alloy to investigate the effect of fatigue crack growth (life from threshold crack growth to final failure) using CPC on fatigue life. The corrosion fatigue with the presence of water-vapor reduces the total fatigue life. The fatigue life with the CPC treatment is shown to increase the fatigue life due to the protection from the corrosive environment containing water-vapor. Test results are obtained for various stress ratios and frequencies with and without the CPC treatment under constant amplitude fatigue loading in water vapor. The second aspect of this work is to investigate the effect of periodic overloads and the limitation in their spacing cycles on the fatigue life under constant amplitude fatigue loading. The results confirm the earlier work that the fatigue life increases due to the periodic overloads in 2024-T3 aluminum alloy. The interactions between overloads that are controlled by the spacing cycles between overloads are also examined. From scanning electron microscopic work the transition from the ductile to brittle mode is observed clearly in this experimental work.


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