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Abstract Stress-relaxation ageing behaviour of peak-aged aluminium alloy 6082 (AA6082-T6) has been experimentally investigated with initial loading in both elastic and plastic regions in this study. The stress-relaxation ageing tests with various initial strain levels were carried out at 160 °C for up to 12 h and room temperature tensile tests were performed subsequently. Selected samples have been examined using transmission electron microscopy (TEM) to study microstructural evolution during the process. The results show that the total stress relaxed after 12 h test increases significantly with increasing initial strain levels. The initial strain levels contribute little effect on yield strength evolution during stress-relaxation ageing, as softening from the coarsening of β ′ ′ precipitates is balanced by hardening from dislocations. Stress-relaxation mechanisms of the material have been analysed on the basis of creep stress exponent. In the elastic region, a creep stress exponent of 3 with a threshold stress of 70.1 MPa has been obtained, indicating a dislocation glide controlled creep mechanism; while in the plastic region, a decreasing threshold stress with increasing initial strain levels has been proposed to achieve a positive creep stress exponent. Highlights • Stress-relaxation ageing behaviour of AA6082 in the plastic region have been investigated for the first time. • Coarsening of β ′ ′ precipitates is significantly accelerated when initially loaded in the plastic region. • Dislocation glide is the main stress-relaxation mechanism when the material is initially loaded in the elastic region. • A decreasing threshold stress with increasing initial strain is proposed for stress-relaxation ageing in the plastic region. [ABSTRACT FROM AUTHOR]

6082 is a relatively new alloy that currently provides the best combination of properties in 6xxx series alloys. A series of tests was conducted on the stability of heat-treated aluminium alloy 6082-T6 circular tube columns to check the reliability of buckling strength predictions of 6082-T6 alloy circular tube columns using current design rules. First, nine stub columns were tested to obtain stress–strain curves and three parameters of the Ramberg–Osgood expression ( E , σ 0.2 and n ). The experimental stress–strain curves were in good agreement with the Ramberg–Osgood expression, and the mean value of σ 0.2 / n obtained from the tests was close to the Steinhardt assumption. Second, prior to column tests, the initial out-of-straightness of 15 circular tubes was accurately measured. Third, these 15 tubes, with five nominal slenderness ratios varying from 20.4 to 69.6, were tested between two pinned ends under axial compression to obtain failing modes and buckling strengths. Finally, the experimental buckling strengths were compared with the buckling strengths predicted by several current aluminium structure design codes, including the American Aluminium Design Manual (AA), Australian/New Zealand Standard 1664 (AS/NZS), and Eurocode 9 (EC9), as well as the general column curve formulation proposed by Rasmussen and Rondal [13] . These comparisons shows that the AA predictions are too conservative at small slenderness ratios, the AS/NZS predictions are unsafe at large slenderness ratios, the EC9 predictions are conservative, and the Rasmussen–Rondal formulation provides the closest and generally conservative strength predictions. [ABSTRACT FROM AUTHOR]

This paper presents a column curve formula capable of producing accurate strengths for extruded members of 6082-T6 aluminium-alloys failing by flexural buckling under axial compression. The formula uses the Perry-type curve. The material properties are expressed in terms of the Ramberg–Osgood parameters ( E , f 0.2 , and n ), obtained from tensile coupon tests of the finished product. 30 specimens of 6082-T6 aluminium alloy, including 15 H-section and 15 rectangular hollow-sections were tested under axial load using a pin-ended condition. Numerical models were then developed using the FE software ANSYS, and were verified against the experimental results. The coefficient of stability was determined and compared with the coefficients of stability from different codes such as American standard (American specification for aluminium structures), Eurocode 9 (European code for design of aluminium structures), GB50017-2003 (Chinese Code for design of steel structures) and GB50429-2007 (Chinese Code for the design of Aluminium Structures). The experiment column curve was then derived and compared with the curves of columns of different codes. Lastly a comparison between the present test results and the results of Rasmussen and Rondal (2000) [1] is presented. [ABSTRACT FROM AUTHOR]

Abstract: The evolution of microstructure and texture in Al6082 precipitation-hardened alloy during equal-channel angular pressing (ECAP) was studied. It was found that although the dislocation density and the subgrain size saturated after 1 pass, the size of grains bounded by high angle boundaries reached its minimum value only after 4 passes. Furthermore, the grain orientation distribution changes between 4 and 8 passes, indicating the development of grain boundary structure even after the saturation of the parameters of the microstructure. As a result of this evolution, the initial texture of the commercial alloy was diminished after 8 passes and the grain orientation distribution became to be close to random case. [Copyright &y& Elsevier]

The solution heat treatment (SHT) process resolving hardening precipitates in high strength aluminium alloys is a critical step for high-efficient forming processes, such as Hot Form Quench (HFQ®). SHT largely determines the overall cycle time of a forming process. However, effects of heating process parameters, such as the heating rate and soaking time, on the microstructure and the associated mechanical properties of aluminium alloy 6082, one of the most commonly used aluminium alloys, for HFQ applications, have not been systematically investigated. The aim of this study is to explore and understand the relationships among heat treatment conditions, grain microstructure and associated mechanical properties for AA6082. A series of uniaxial tensile tests conducted under various SHT conditions revealed significant variations on mechanical behaviour characterised by stress-strain curves. To correlate these stress-strain relationship with underlying microstructure, the grain and orientation distribution of each heat-treated sample were characterised by the electron backscatter diffraction (EBSD) technique. Due to the presence of a large number of microscopic variables, such as grain size, morphology, texture, grain boundary and etc., the crystal plasticity finite element (CPFE) modelling was employed to identify the key microscopic factors which determine the differences in the observed strength and ductility for all samples. A new CPFE model integrated with local strain criterion was proposed and validated to correlate the ductility and the strength with the material microstructure. This rigorous investigation provides more insights on how microstructure (grain size and texture) affects the mechanical behaviour for AA6082, which enables to enlarge the capability of HFQ for industrial applications. • Grain size effect is unlikely a dominated factor to affect mechanical properties of AA6082 (T6) in the HFQ process. • During the solution heat treatment, recrystallisation resulted texture is found using EBSD. • The changes of the strength and ductility due to texture formation can be captured by CPFE. • Effects of heating process parameter on grain structure and texture are able to be quantified. [ABSTRACT FROM AUTHOR]

Vibro-abrasive processing is the basic method for the mass finishing of parts and components in various industries. Continuous progress in the development of processing media and machine design solutions means that every research effort into vibro-abrasive processing broadens the scope of knowledge in the selection of media, parameters, and applications in various industry fields. In this paper, an attempt is made to parametrize the vibratory grinding process, which is one of the three stages of high gloss finishing. Samples of the 6082 aluminium alloy intended for use in loaded machine parts and forged car wheel rims were subject to a research analysis. The samples were processed in a rotary vibrator equipped with a sample fixing system, using resin media and auxiliary com-pounds. On the basis of the analysis, the processing capacities were determined for the selected conditions and abrasive media. The influence of time and applied processing media on the change in samples' roughness was determined. The effects of processing were examined with the use of laser devices measuring surface roughness in the areas of 3D and 2D analysis. The analysis of the test results showed that the use of S12TZ type resin media in a 12-hour finishing process of the 6082 aluminium alloy allowed for a 75.5% reduction in surface roughness, which corresponds to approximately 6.3% per hour of processing. [ABSTRACT FROM AUTHOR]