Damage and stress state influence on the Bauschinger effect in aluminum alloys

The Bauschinger effect is one of the fundamental properties of most metal alloys exposed to plastic deformation under non-monotonic loading. Development of the methods for quantifying this effect is one the important issues of the theory of plasticity. Calculation of the parameter characterizing the aforementioned effect is required for determination of the stress state in plastically deformable blanks upon pressure metal treatment. The value of the parameter (determined in standard tensile tests followed by subsequent compression of samples) is defined by the ratio of the conditional yield strength of the sample under compression to the value of the preliminary tensile stress. A series of cylindrical samples (~10 pcs.) is usually taken for tensile-compression tests. According to the traditional procedure, long-size standard specimens are pre-stretched to various degrees of plastic deformation. After that short specimens are cut out from those specimens for compression tests to determine the conditional compressive yield strength with a tolerance of 0.2% for plastic deformation. Such a procedure is rather time consuming and expensive. We propose and develop a new single-model method for estimating the Bauschinger effect which consists in testing of a single long-size specimen for tension followed by compression of the specimen in a special device providing deformation of a previously stretched specimen without flexure under conditions of a linear stress state. The device was designed, manufactured and underwent the appropriate tests. The device contains supporting elements in the form of conical-shaped sectors that prevent flexure of a long cylindrical specimen upon compression, a ratio of the working part length to diameter ranges from 5 to 10. The results of experimental determination of the parameter β characterizing the indicated effect are presented. The results of comparing the values of the parameter β determined by the developed and traditional methods revealed the possibility of determining the parameter β using the proposed method. To reduce the complexity of performing tests related to determination of the parameter β we approximated it in the form of an exponent as a function of the magnitude of plastic deformation and determine the only one value of β0 under plastic deformations exceeding 0.05. In this regard, β0 can be considered a new characteristic of the material. The calculated data are in good agreement with the experimental results. The values of β0 are determined for a number of studied steel grades.

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Stress-state dependence of cavitation and flow behavior in superplastic aluminum alloys

Metallurgical and Materials Transactions A ◽

10.1007/s11661-003-0005-4 ◽

2003 ◽

Vol 34 (11) ◽

pp. 2449-2463 ◽

Cited By ~ 19

Author(s):

D. H. Bae ◽

A. K. Ghosh ◽

J. R. Bradley

Keyword(s):

Stress State ◽

Aluminum Alloys ◽

Flow Behavior ◽

State Dependence ◽

Stress State Dependence

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Bauschinger Effect Prediction in Thick-Walled Autofrettaged Cylindrical Pressure Vessels

Journal of Pressure Vessel Technology ◽

10.1115/1.4036426 ◽

2017 ◽

Vol 139 (4) ◽

Cited By ~ 2

Author(s):

V. Bastun ◽

I. Podil'chuk

Keyword(s):

Stress State ◽

Strain Hardening ◽

Bauschinger Effect ◽

Complex Loading ◽

Longitudinal Axis ◽

Complex Stress ◽

Pressure Vessels ◽

Complex Stress State ◽

Induced Anisotropy

The paper addresses the Bauschinger effect under complex stress state in materials with deformation-induced anisotropy whose strain hardening is described by the isotropic–kinematic (translational) type hardening hypothesis. The Bauschinger effect is analyzed using the model based on the yield surface conception and graphical–analytical method of construction of constitutive equations under complex loading. As an example, cylindrical pressure vessels with closed and open ends subjected to autofrettage are considered. The tension–compression Bauschinger effect in the axial and hoop directions as well as the Bauschinger effect under reversed torsion with respect to the longitudinal axis is determined. The role of such factors as the level of prestraining under autofrettage, relation between isotropic and kinematic components of the strain hardening, and chemical composition of the material is analyzed. The results obtained are presented in the form of plots.

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On the Applicability of Acoustoelasticity for Residual Stress Determination

Journal of Applied Mechanics ◽

10.1115/1.3157735 ◽

1981 ◽

Vol 48 (4) ◽

pp. 791-795 ◽

Cited By ~ 21

Author(s):

G. C. Johnson

Keyword(s):

Residual Stress ◽

Plastic Deformation ◽

Stress State ◽

Aluminum Alloys ◽

Nondestructive Evaluation ◽

Theoretical Development ◽

Stress Determination ◽

Acoustic Response ◽

Residual Stress Determination ◽

Residual Stress State

Acoustoelasticity has recently been used for the nondestructive evaluation of residual stresses. In making such measurements the assumption has been made that the plastic flow leading to the residual stress state did not change the acoustic response of the material. This paper examines the extent to which that assumption holds for three aluminum alloys. The acoustoelastic theory is summarized and results are presented for tests of specimens under uniaxial tension which are subjected to plastic deformation followed by complete unloading. It is shown that the assumption made does not hold for all materials and that further theoretical development is required for general quantitative residual stress determination.

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Effect of type of stress state and temperature on the resistance to failure of aluminum alloys

Strength of Materials ◽

10.1007/bf01534030 ◽

1985 ◽

Vol 17 (10) ◽

pp. 1407-1412 ◽

Cited By ~ 1

Author(s):

A. A. Lebedev

Keyword(s):

Stress State ◽

Aluminum Alloys ◽

Type Of Stress State

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Study of Aluminum Alloy 7050 T7451 Isotropic Hardening

Materials Science Forum ◽

10.4028/www.scientific.net/msf.869.526 ◽

2016 ◽

Vol 869 ◽

pp. 526-531

Author(s):

Rodrigo Mendes Lima ◽

Ernesto Massaroppi Jr.

Keyword(s):

Aluminum Alloy ◽

Stress State ◽

Bauschinger Effect ◽

Kinematic Hardening ◽

Isotropic Hardening ◽

Compression Tests ◽

Plastic Deformations ◽

Fem Simulations ◽

Nonlinear Constitutive Model ◽

Cyclic Tension

This paper presents the yielding surface isotropic hardening study of the aluminum alloy 7050 T7451 submitted to monotonic loadings, considering the nonlinear constitutive model proposed by Voce. The stress state imposed characterizes a behavior whose plastic deformations cannot be neglected. The analysis depends on the segregation between the isotropic and the kinematic hardening that composes the material’s behavior during its transient life. Monotonic and cyclic tension-compression tests have been realized in order to allow the Bauschinger Effect understanding. The results have been compared to FEM simulations in order to validate the model.

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Determination of Long-Range Internal Stresses in Cyclically Deformed Copper Single Crystals Using Convergent Beam Electron Diffraction

Crystals ◽

10.3390/cryst10121071 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1071

Author(s):

Roya Ermagan ◽

Maxime Sauzay ◽

Matthew H. Mecklenburg ◽

Michael E. Kassner

Keyword(s):

Plastic Deformation ◽

Stress State ◽

Single Crystals ◽

Bauschinger Effect ◽

Lattice Parameter ◽

Convergent Beam Electron Diffraction ◽

Internal Stresses ◽

Beam Electron ◽

Multiple Slip ◽

Convergent Beam

Understanding long range internal stresses (LRIS) may be crucial for elucidating the basis of the Bauschinger effect, plastic deformation in fatigued metals, and plastic deformation in general. Few studies have evaluated LRIS using convergent beam electron diffraction (CBED) in cyclically deformed single crystals oriented in single slip and there are no such studies carried out on cyclically deformed single crystals in multiple slip. In our earlier and recent study, we assessed the LRIS in a cyclically deformed copper single crystal in multiple slip via measuring the maximum dislocation dipole heights. Nearly equal maximum dipole heights in the high dislocation density walls and low dislocation density channels suggested a uniform stress state across the labyrinth microstructure. Here, we evaluate the LRIS by determining the lattice parameter in the channels and walls of the labyrinth dislocation structure using CBED. Findings of this work show that lattice parameters obtained were almost equal near the walls and within the channels. Thus, a homogenous stress state within the heterogeneous dislocation microstructure is again suggested. Although the changes in the lattice parameter in the channels are minimal (less than 10−4 nm), CBED chi-squared analysis suggests that the difference between the lattice parameter values of the cyclically deformed and unstrained copper are slightly higher in the proximity of the walls in comparison with the channel interior. These values are less than 6.5% of the applied stress. It can be concluded that the dominant characteristics of the Bauschinger effect may need to include the Orowan-Sleeswyk mechanism type of explanation since both the maximum dipole height measurements and the lattice parameter assessment through CBED analysis suggest a homogenous stress state. This work complements our earlier work that determined LRIS based on dipole heights by assessing LRIS through a different methodology, carried out on a cyclically deformed copper single crystal oriented for multiple slip.

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