Mechanical and Electrochemical Coupled Pitting Behavior of 2219 Aluminum Alloy: A Theoretical and Experimental Study

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Yuanyang Miao ◽  
Shengli Lv ◽  
T. S. Srivatsan ◽  
Xiaosheng Gao
Keyword(s):  
Aluminum Alloy ◽  
Damage Mechanics ◽  
Mechanical Load ◽  
Theoretical Estimate ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Accelerated Corrosion ◽  
Alloy Chemistry ◽  
Accelerated Corrosion Tests ◽  
Corrosion Pits

Abstract This study attempts to provide a theoretical estimate coupled with an analysis of the measured data to predict pitting damage of an aluminum alloy 2219 under the conjoint influence of mechanical load and corrosive environment. In accordance with the basic principle of crater growth coupled with the synergistic influences of mechanical and chemical effects, the law governing the presence and growth of corrosion pits was studied. Based on the concept of microscopic damage mechanics, porosity as a damage variable was introduced and the resulting model for estimating the reduction in elastic modulus of the material that has experienced observable damage due to pitting was established. Accelerated corrosion tests and uniaxial tensile tests are carried out, and a research-grade microscope coupled with a laser range finder was used to study the formation, presence, and growth of the pits with time. It was found that the corrosion pit in the chosen aluminum alloy can be simulated as a semi-ellipsoid, and the relationship between the depth of the pit and applied stress is an exponential function. This enabled in establishing the influence of alloy chemistry on nature, extent, and severity of damage due to pitting. The macroscopic morphology of the damaged specimens after corrosion was carefully observed and analyzed. The influence of time of exposure to the environment and applied load on damage due to pitting was verified. A comparison between the calculated results and experimental data reveals an overall correctness of the method developed and discussed in this paper.

scholarly journals Determination of Forming Limits Based on Finite Element Simulations

2021 ◽  
Author(s):  
Fuhui Shen ◽  
Kai Chen ◽  
Junhe Lian ◽  
Sebastian Münstermann
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Tensile Tests ◽  
Finite Element Simulations ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Anisotropic Plasticity ◽  
Forming Limits ◽  
Dog Bone ◽  
Spatio Temporal

Two categories of experiments have been performed to obtain the experimental forming limits of a ferritic stainless steel from uniaxial to equibiaxial tension, including Nakajima tests and tensile tests of flat specimens with different geometries of the central hole as well as the notched dog bone. The plasticity behavior of the investigated material is described using an evolving non-associated anisotropic plasticity model, which is calibrated based on experimental results of uniaxial tensile tests along different loading directions. A damage mechanics model is calibrated and validated based on the global force and displacement response of tensile tests. Finite element simulations of the Nakajima tests and the tensile tests of various geometries have been performed using the anisotropic material model. A novel spatio-temporal method is developed to evaluate the forming limits under different stress states by quantitatively characterizing the plastic strain distribution on the specimen surface. The forming limits have been independently determined from finite element simulation results of tensile specimens and Nakajima specimens using the spatio-temporal evaluation method. The forming limits obtained from numerical simulations of these two types of experiments are in good agreement with experimental results.

scholarly journals Anisotropic Deformation Behavior of Al2024T351 Aluminum Alloy

2013 ◽  
Vol 10 (1) ◽  
pp. 80 ◽  
Author(s):  
R Khan
Keyword(s):  
Aluminum Alloy ◽  
Yield Strength ◽  
Deformation Behavior ◽  
Yield Criterion ◽  
Tensile Tests ◽  
Rolled Plate ◽  
Uniaxial Tensile ◽  
Element Analysis ◽  
Yield Criteria ◽  
Von Mises

 The objective of this work was to investigate the effects of material anisotropy on the yielding and hardening behavior of 2024T351 aluminum alloy using isotropic and anisotropic yield criteria. Anisotropy may be induced in a material during the manufacturing through processes like rolling or forging. This induced anisotropy gives rise to the concept of orientation-dependent material properties such as yield strength, ductility, strain hardening, fracture strength, or fatigue resistance. Inclusion of the effects of anisotropy is essential in correctly predicting the deformation behavior of a material. In this study, uniaxial tensile tests were first performed in all three rolling directions, L , T  and S , for smooth bar specimens made from hot rolled plate of Al2024 alloy. The experimental results showed that the L - and T -directions yielded higher yield strengths and a greater percentage of elongation before fracture than the S -direction. Subsequently, finite element analysis of tensile specimens was performed using isotropic (von Mises) and anisotropic (Hill) yield criteria to predict the onset of yielding and hardening behaviors during the course of deformation. Hill's criterion perfectly fitted with the test data in the S -direction, but slightly underestimated the yield strength in L -direction. The results indicated that the Hill yield criterion is the most suitable one to predict the onset of yielding and hardening behaviors for 2024T351 aluminum alloy in all directions. 

Investigation of the joinability of the high-strength aluminum alloy AA7075 in shear-clinching processes

2021 ◽  
pp. 146442072110679
Author(s):  
S Wiesenmayer ◽  
M Merklein
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
High Strength ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
High Strength Aluminum Alloy ◽  
Heat Treated ◽  
Strength Alloy ◽  
Heating Up

Shear-clinching has proven to be a suitable technology for joining of high-strength materials. However, the mechanical properties of the upper joining partner are limited due to the high strains, which occur during the process. Therefore, shear-clinching of the high-strength aluminum alloy AA7075 in the T6 temper is not possible. Yet, the mechanical properties of hardenable alloys of the 7000 series can be influenced by a heat treatment. Thus, within the scope of this work, the joinability of the high-strength alloy AA7075 in shear-clinching processes in dependance of its temper is investigated. The as fabricated state F, the artificially aged T6 temper, a paint baked state and the naturally aged T4 temper are compared to the fully solution annealed W temper as well as to a retrogression heat-treated state. For retrogression heat treatment, a laser is used as heat source, heating up the alloy for a short term in order to only partially dissolve precipitations. The resulting mechanical properties are determined with uniaxial tensile tests. Moreover, the influence of the mechanical properties of AA7075 on the shear-clinching process, the joint formation and the resulting joint strength is analyzed.

Remaining Life Evaluation and Maintenance of Service-Exposed HP-Nb Reformer Tubes

2006 ◽  
Vol 324-325 ◽  
pp. 407-410
Author(s):  
Yong Jiang ◽  
Jian Ming Gong ◽  
Shan Tung Tu
Keyword(s):  
Damage Mechanics ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Remaining Life ◽  
Service Temperature ◽  
Metallographic Examination ◽  
Life Evaluation ◽  
Reformer Tubes ◽  
Different Parts ◽  
Reformer Tube

This paper is aimed at investigating the damage and remaining life of a whole HP-Nb hydrogen reformer tube serviced for 12 years. The damage and remaining life evaluation of different parts of the tube were made using metallographic examination, ambient and high temperature uniaxial tensile tests, creep rupture tests and damage mechanics analysis. The results showed that different parts of the tube have the different damage and remaining life due to different service temperature, higher the service temperature, severer the damage and shorter the remaining life. Based on these research results, a case of local maintenance of the reformer tube was introduced.

Effects of Temperature and Strain Rate on Commercial Aluminum Alloy AA5083

2014 ◽  
Vol 660 ◽  
pp. 332-336 ◽  
Author(s):  
Mohd Khir Mohd Nor ◽  
Ibrahim Mohamad Suhaimi
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Deformation Behaviour ◽  
Model Development ◽  
Tensile Tests ◽  
Gauge Length ◽  
Uniaxial Tensile ◽  
Important Conclusion ◽  
Commercial Aluminum Alloy

Superplastic forming, SPF is a special metalworking process that allows sheets of metal alloys such as aluminum to be stretched to lengths over ten times. Nowdays, only a few aluminium alloys can meet the specific requirement of SPF manufacturing process and not much data available to represent their mechanical behaviour. In order to deal with this issue, this research project is conducted to investigate the characteristics of commercial aluminum alloy, AA5083 when tested at different strain rates and temperatures. These parameters play a crucial roles in the design and manufacturing processes of military, automotive and aerospace structures. Equally, the effects must be considered in the constitutive model development to accurately capture the deformation behaviour of such materials. The specimens were prepared according to 12.5mm gauge length standard. The Uniaxial Tensile Tests were carried out at various strain rate from 4.167 x10-1s-1to 4.167 x10-5s-1over a wide temperature range from ambient to 95°C. The experimental data shows that increasing strain rate increases flow stress, while increasing temperature decrease flow stress. This is leads to important conclusion that material AA5083 exhibits strain rate and temperature sensitivite, and suit with the SPF operating condition.

scholarly journals Corrosion behavior of galvanic couple between aluminum alloy and carbon steel with accelerated corrosion tests

2021 ◽  
Vol 71 (2) ◽  
pp. 102-111
Author(s):  
Yoshiyuki Oya ◽  
Shohei Iwao ◽  
Daisuke Nagasawa ◽  
Kazuhiko Minami ◽  
Kazuhiro Kobori ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Carbon Steel ◽  
Corrosion Behavior ◽  
Accelerated Corrosion ◽  
Corrosion Tests ◽  
Galvanic Couple ◽  
Accelerated Corrosion Tests

Anisotropic Behavior in Plasticity and Ductile Fracture of an Aluminum Alloy

2015 ◽  
Vol 651-653 ◽  
pp. 163-168 ◽  
Author(s):  
Yan Shan Lou ◽  
Jeong Whan Yoon
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Ductile Fracture ◽  
Stress Triaxiality ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Anisotropic Plasticity ◽  
Dog Bone ◽  
Associate Flow Rule ◽  
Anisotropic Plastic

Anisotropic mechanical behavior is investigated for an aluminum alloy of 6K21-IH T4 both in plastic deformation and ductile fracture. Anisotropic plastic deformation is characterized by uniaxial tensile tests of dog-bone specimens, while anisotropy in ductile fracture is illustrated with specimens with a central hole, notched specimens and shear specimens. All these specimens are cut off at every 15º from the rolling direction. The r-values and uniaxial tensile yield stresses are measured from the tensile tests of dog-bone specimens. Then the anisotropic plasticity is modeled by a newly proposed J2-J3 criterion under non-associate flow rule (non-AFR). The testing processes of specimens for ductile fracture analysis are simulated to extract the maximum plastic strain at fracture strokes as well as the evolution of the stress triaxiality and the Lode parameter in different testing directions. The measured fracture behavior is described by a shear-controlled ductile fracture criterion proposed by Lou et al. (2014. Modeling of shear ductile fracture considering a changeable cut-off value for stress triaxiality. Int. J. Plasticity 54, 56-80) for different loading directions. It is demonstrated that the anisotropic plastic deformation is described by the J2-J3 criterion with high accuracy in various loading conditions including shear, uniaxial tension and plane strain tension. Moreover, the anisotropy in ductile fracture is not negligible and cannot be modeled by isotropic ductile fracture criteria. Thus, an anisotropic model must be proposed to accurately illustrate the directionality in ductile fracture.

Research on Superplasticity of Supplied 5A06 Aluminium Alloy Sheet

2016 ◽  
Vol 838-839 ◽  
pp. 127-131
Author(s):  
Bao Peng Bi ◽  
Yong Wang
Keyword(s):  
Aluminum Alloy ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Strain Rate Range ◽  
Alloy Sheet ◽  
Uniaxial Tensile ◽  
5A06 Aluminum Alloy ◽  
Bulging Test

Superplasticity of supplied 5A06 aluminum alloy is reviewed in this paper. Supplied 5A06 aluminum alloy is researched on superplasticity by the methods of same strain rate high temperature uniaxial tensile tests at temperature range375°C-500°Cand strain rate range 2.5×10-4s-1~1.0×10-2s-1. Microstructure and fracture of tensile samples are analyzed and discussed, deduce that grain boundary sliding (GBS) is the predominant deformation mechanism. Superplastic formability of the alloy is evaluated by gas bulging test at elevated temperatures. Gas bulging test demonstrates the deformation process parameters for the best superplastic formability is 400°Cand 0.005s-1 ,suggesting good application prospect for this aluminum alloy.

scholarly journals Investigation on Fracture of a 6014-T4 Aluminum Alloy Sheet in the Flanging and Hemming Process Based on Numerical and Experimental Methods

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 81
Author(s):  
Zhengwei Gu ◽  
Gang Wang ◽  
Ge Yu
Keyword(s):  
Aluminum Alloy ◽  
Uniform Elongation ◽  
Natural Aging ◽  
Strain Ratio ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Uniaxial Tensile ◽  
Strain Hardening Exponent ◽  
Plastic Strain Ratio ◽  
Aging Period

The fracture of a flat-surface straight-edge hemmed component of aluminum alloy sheets was investigated in this study. The specimen was made of 1 mm thick 6014-T4. Natural aging characteristics of 6014-T4 were studied via uniaxial tensile tests. The results show that the yield stress and ultimate tensile strength increased while the uniform elongation, strain hardening exponent, and plastic strain ratio decreased during the natural aging period, which worsened the formability. The sheet was biaxially stretched to obtain a pre-strain before the flanging and hemming operation. The influence of the flanging radius on the fracture was evaluated using experimental and numerical methods, and the optimum values were obtained. The comparison between the roller hemming and die hemming process proved that the former tends to produce better formability.

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