Microstructure, Slip Distribution, and Strain Hardening in Aluminum Alloys

2009 ◽  
pp. 35-35-25 ◽  
Author(s):  
RE Sanders
Keyword(s):  
Aluminum Alloys ◽  
Strain Hardening ◽  
Slip Distribution

Sensitivity Analysis of the Material Flow Stress in Machining

Manufacturing ◽  
2003 ◽  
Author(s):  
Ning Fang
Keyword(s):  
Sensitivity Analysis ◽  
Flow Stress ◽  
Aluminum Alloys ◽  
Strain Rate ◽  
Strain Hardening ◽  
Material Flow ◽  
Chemical Compositions ◽  
Wide Range ◽  
Strain Rate Hardening ◽  
Factor Governing

Among the effects of strain hardening, strain-rate hardening, and temperature softening, it has long been argued about which effect is predominant in governing the material flow stress in machining. This paper compares four material constitutive models commonly employed, including Johnson-Cook’s model, Oxley’s model, Zerilli-Armstrong’s model, and Maekawa et al.’s model. A new quantitative sensitivity analysis of the material flow stress is performed based on Johnson-Cook’s model covering a wide range of engineering materials, including plain carbon steels with different carbon contents, alloyed steels, aluminum alloys with different chemical compositions and heat treatment conditions, copper and copper alloys, iron, nickel, tungsten alloys, etc. It is demonstrated that the first predominant factor governing the material flow stress is either strain hardening or thermal softening, depending on the specific work material employed and the varying range of temperatures. Strain-rate hardening is the least important factor governing the material flow stress, especially when machining aluminum alloys.

Restoration of the fatigue limit of structural elements made of aluminum alloys by surface strain-hardening

1989 ◽  
Vol 21 (8) ◽  
pp. 981-985
Author(s):  
M. N. Stepnov ◽  
S. P. Evstratova ◽  
V. V. Logvinenko ◽  
V. V. Mozalev
Keyword(s):  
Aluminum Alloys ◽  
Strain Hardening ◽  
Fatigue Limit ◽  
Surface Strain ◽  
Structural Elements

Strain-Rate Sensitivity of Aluminum Alloys AA1200 and AA3103

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
O.-G. Lademo ◽  
O. Engler ◽  
J. Aegerter ◽  
T. Berstad ◽  
A. Benallal ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Constitutive Model ◽  
Strain Rate ◽  
Strain Hardening ◽  
Rate Sensitivity ◽  
Structural Parameter ◽  
Model Parameters ◽  
Good Representation ◽  
Nominal Strain Rate ◽  
Instantaneous Rate

Tensile tests are carried out for the aluminum alloys AA1200 and AA3103 at various strain-rates in the range from 10−4 s−1 to 1 s−1. Tests with constant nominal strain-rate and strain-rate jump tests are conducted, and the instantaneous rate sensitivity and the rate sensitivity of strain hardening are investigated. For both materials, the instantaneous rate sensitivity is found to be rather independent of strain, while the rate sensitivity of the strain hardening is important and the saturation stress increases with increasing strain-rate. A phenomenological constitutive model is described that comprises a kinetic equation governing the instantaneous rate sensitivity of the flow stress and a structural parameter that determines the mechanical state of the material. The evolution of the structure parameter is assumed to depend on strain-rate. The model parameters are determined for the two materials using the available experimental information. It is found that the constitutive model provides a good representation of the experimental results.

Intermediate Heat Treatment – A New Proceeding for Aluminum Alloys Using Forming Limit Diagrams

2011 ◽  
Vol 473 ◽  
pp. 428-435 ◽  
Author(s):  
Kathleen Siefert ◽  
Marion Merklein ◽  
Almut Töpperwien ◽  
Winfried Nester ◽  
Martin Grünbaum
Keyword(s):  
Heat Treatment ◽  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Strain Hardening ◽  
Room Temperature ◽  
Forming Limit ◽  
Cold Forming ◽  
Intermediate Heat Treatment ◽  
Heat Treated ◽  
Strain Paths

This paper presents a new procedure for a heat treatment embedded between two cold forming steps. A first cold forming step induces a defined strain hardening in the material. The following step is the heat treatment which takes place in a furnace at various temperatures and for certain durations. The application of such an intermediate heat treatment reduces the strain hardening of the material and enhances the elongation. This allows a higher degree of deformation in the second cold forming operation. The achievable properties of the aluminum alloy AlMg4.5Mn (AA5182) were discussed in detail. Further investigations using Nakajima test setup revealed an increased formability of the material. First the Nakajima samples were pre-strained along different linear strain paths to a predefined strain value. Afterwards the samples were heat treated without allowing the aluminum alloy to recrystallize. After cooling down the samples to room temperature, the tests are continued until the material’s fracture. As a result heat treatment dependent forming limit curves (FLC) are obtained. In comparison with a measured FLC at room temperature the support of the intermediate heat treatment on enhanced formability were shown. Furthermore the method is not restricted to AA5182 aluminum alloys.

Dynamic Plastic Buckling of Cylindrical Shells in Sustained Axial Compressive Flow

1968 ◽  
Vol 35 (1) ◽  
pp. 80-86 ◽  
Author(s):  
A. L. Florence ◽  
J. N. Goodier
Keyword(s):  
Aluminum Alloys ◽  
Strain Hardening ◽  
Satisfactory Agreement ◽  
Cylindrical Shells ◽  
Flow Tube ◽  
Plastic Buckling ◽  
Compressive Flow ◽  
Hardening Modulus ◽  
Impact Experiments ◽  
Dynamic Plastic Buckling

A theory is postulated to explain the dynamic plastic buckling of cylindrical shells in sustained axial compressive flow. Tube impact experiments are described in which uniform axisymmetric waves were produced. Predicted and experimental wavelengths are in satisfactory agreement. According to the theory presented, wavelengths do not depend strongly on strain-hardening modulus and, based on results for two aluminum alloys, neither do experimental wavelengths. This result is shown to apply also to slow plastic buckling.

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