Deformation Characteristics of 6066 and 6069 Aluminum Alloys at Elevated Temperatures

2016 ◽  
Vol 838-839 ◽  
pp. 267-271 ◽  
Author(s):  
Shohei Koizumi ◽  
Junya Kobayashi ◽  
Goroh Itoh

Currently liners of high-pressure hydrogen storage container for fuel cell vehicles are manufactured from the 6061 aluminum alloy pipes through spinning at elevated temperatures. Since the surroundings of the containers are reinforced with a large amount of high-cost CFRP, the use of 6066 or 6069 aluminum alloy with higher strength than 6061 is demanded to lower the cost of the container. However, the formability of these aluminum alloys at elevated temperatures has not been elucidated yet. In this study, tensile deformation characteristics of 6066 and 6069 aluminum alloys at temperatures ranging from 25 to 550°C were investigated. The total elongation of 6066 aluminum alloy was higher than that of 6069 aluminum alloy at 450°C. This may be caused by the lower volume fraction of constituent particles. The flow stresses of the two alloys were almost the same, and were decreased with increasing testing temperature. The increase in elongation and decrease in strength observed in the two alloys were attributable to dynamic recovery.

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
B. Ravi Kumar ◽  
Vishal Singh ◽  
Tarun Nanda ◽  
Manashi Adhikary ◽  
Nimai Halder ◽  
...  

The authors simulated the industrially used continuous annealing conditions to process dual phase (DP) steels by using a custom designed annealing simulator. Sixty-seven percentage of cold rolled steel sheets was subjected to different processing routes, including the conventional continuous annealing line (CAL), intercritical annealing (ICA), and thermal cycling (TC), to investigate the effect of change in volume fraction, shape, and spatial distribution of martensite on tensile deformation characteristics of DP steels. Annealing parameters were derived using commercial software, including thermo-calc, jmat-pro, and dictra. Through selection of appropriate process parameters, the authors found out possibilities of significantly altering the volume fraction, morphology, and grain size distribution of martensite phase. These constituent variations showed a strong influence on tensile properties of DP steels. It was observed that TC route modified the martensite morphology from the typical lath type to in-grain globular/oblong type and significantly reduced the martensite grain size. This route improved the strength–ductility combination from 590 MPa–33% (obtained through CAL route) to 660 MPa–30%. Finally, the underlying mechanisms of crack initiation/void formation, etc., in different DP microstructures were discussed.


2021 ◽  
Author(s):  
Leszek A. Dobrzański

This chapter introduces advanced aluminum alloy matrix composites and their manufacturing processes. In the beginning, the state of the art is characterized and the general characteristics of aluminum and its practical applications are presented, starting with the history of aluminum. The current approximate distribution of bauxite resources in the world and the production of bauxite and alumina in the leading countries of the world, as well as the production of primary and secondary aluminum and the range of aluminum end products, are presented. Aluminum alloys intended for plastic deformation and castings, and composite materials in general and with a matrix of aluminum alloys in particular, have been characterized in general. Against this background, a detailed review of the results of the Author’s own research included in numerous projects and own publications on advanced composite materials, their production technology, their structure, and properties were done. The range of aluminum alloy matrices of composite materials was adequately characterized, which include AlSi12, AlSi7Mg0.3, AlMg1SiCu, AlMg3, AlMg5, and AlMg9, respectively. Composite materials tested in terms of manufacturing technology include three groups. The first group includes gas pressure infiltration with liquid aluminum alloys of suitably formed porous preforms. Porous frameworks as a reinforcement for pressure-infiltrated composite materials with a matrix of aluminum alloys are produced by three methods. Al2O3 powder with the addition of 30–50% carbon fibers is uniaxially pressed, sintered, and heated to thermally degrade the carbon fibers and create the required pore sizes. In the second case, the ceramic porous skeleton is produced with the use of halloysite nanotubes HNTs by mechanical milling, press consolidation, and sintering. A third method is SLS selective laser sintering using titanium powders. Another group of manufacturing technologies is the mechanical synthesis of the mixture of AlMg1SiCu aluminum alloy powder and respectively, halloysite nanotubes HNTs in a volume fraction from 5 to 15% or multi-wall carbon nanotubes MWCNTs in a volume fraction from 0.5 to 5%, and subsequent consolidation involving plastic deformation. The third group of analyzed materials concerns composite surface layers on substrates of aluminum alloys produced by laser feathering of WC/W2C or SiC carbides. The structure and properties of the mentioned composite materials with aluminum alloys matrices are described in detail. The chapter summary provides final remarks on the importance of advanced aluminum alloy composite materials in industrial development. The importance of particular groups of engineering materials in the history and the development of the methodology for the selection of engineering materials, including the current stage of Materials 4.0, was emphasized. The importance of material design in engineering design is emphasized. Concepts of the development of societies were presented: Society 5.0 and Industry 4.0. The own concept of a holistic model of the extended Industry 4.0 was presented, taking into account advanced engineering materials and technological processes. Particular attention was paid to the importance of advanced composite materials with an aluminum alloy matrix in the context of the current stage of Industry 4.0 of the industrial revolution. Growth in the production of aluminum, its alloys, and composites with its matrix was compared with that of steel. Despite the 30 times less production, aluminum is important due to its lower density. The challenges posed by the development in the Industry 4.0 stage, including the expectations of the automotive and aviation industry, force constant progress in the development of new materials with the participation of aluminum, including the composite materials with an aluminum alloy matrix presented in this chapter.


2020 ◽  
Author(s):  
Jianping Lin ◽  
Xingyu Bao ◽  
Yong Hou ◽  
Junying Min ◽  
Xinlei Qu ◽  
...  

Abstract Aluminum alloys have drawn considerable attention in the area of automotive lightweight. High strength aluminum alloys are usually deformed at elevated temperatures due to their poor formability at room temperature. In this work, the yield behavior of 7075 aluminum alloy in T6 temper (AA7075-T6) within the temperature ranging from 25 ℃ to 230 ℃ was investigated. Uniaxial and biaxial tensile tests with the aid of induction heating system were performed to determine the stress vs. strain curves and the yield loci of AA7075-T6 at elevated temperatures, respectively. Von Mises, Hill48 and Yld2000-2d yield criteria were applied to predicting yield loci which were compared with experimentally measured yield loci of the AA7075-T6. Results show that yield stress corresponding to the same equivalent plastic strain decreases with increasing temperature within the investigated temperature range and the shape of yield loci evolves nearly negligibly. The experimental yield locus expands with an increase of equivalent plastic strain at the same temperature and the work hardening rate of AA7075-T6 exhibits obvious stress-state-dependency. The non-quadratic Yld2000-2d yield criterion describes the yield surfaces of AA7075-T6 more accurately than the quadratic von Mises and Hill48 yield criteria, and an exponent of 14 in the Yld2000-2d yield function gives the optimal predictions for the AA7075-T6 at all investigated temperatures.


2016 ◽  
Vol 838-839 ◽  
pp. 272-277 ◽  
Author(s):  
Nobuatsu Tano ◽  
Junya Kobayashi ◽  
Goroh Itoh ◽  
Akira Kurumada ◽  
Shingo Mukae

Tungsten has higher melting point than any other metals. Therefore, tungsten is applied to the electrode for resistance welding. The electrodes for resistance welding of tungsten are mainly used for fusing joining because they have high heat resistance and are hard to be alloyed with work metal pieces. However, the cracks on electrode surface occur during cyclic welding processes. In this study, to reveal the relationship between the elevated temperature deformation characteristics and fracture mechanism of recrystallized and unrecrystallized tungsten, tensile tests were carried out with varying strain rate and testing temperature. At 400°C, the total elongation at a strain rate of 1.4×10-1 s-1 in the recrystallized tungsten decreased more than the total elongation at the other strain rate. At 600°C, total elongation increased by approximately 10%, if the strain rate was increased from 1.4×10-3 s-1 to 1.4×10-1 s-1. Then, the recrystallized tungsten at the strain rate of 1.4×10-1 s-1 had more necking than that of 1.4×10-3 s-1. The may be caused by an environmental embrittlement due to oxygen in the high temperature atmosphere.


Author(s):  
E. A. Kenik ◽  
R. W. Carpenter

Deformation processes in a series of aluminum alloys have been investigated by in situ tensile deformation in the ORNL high voltage electron microscope (HVEM). Both solid-solution-hardened and preoipitation-hardened alloys have been studied in several heat treatments. Interactions of moving dislocations with other dislocations, precipitates, grain boundaries, and other defects were investigated, as were the microstructural processes involved in the ductile failure of such specimens. Specimens of Al-4 wt % Cu and 1100 aluminum alloy were deformed at room temperature in a Gatan tensile deformation stage.


Author(s):  
Mihriban Pekguleryuz ◽  
Erol Ozbakir ◽  
Amir Rezaei Farkoosh

The Diesel engine, introduced by Rudolph Diesel in 1892, achieves a higher combustion ratio and fuel efficiency, has lower CO2 emissions per mile than the gasoline engine and is considered to be one of the most viable environmentally friendly technologies for vehicles. “Clean Diesel” using lower sulfur content fuel has become available since 2006. Currently, the Diesel engine and cylinder head are mostly cast iron to withstand the high compression pressures and temperatures of Diesel operation. Further weight reduction (40%–55%) via aluminum substitution in the Diesel engine would result in substantial fuel economy and increased environmental benefits. Current aluminum alloys cannot meet the requirements of the Diesel engine and a new research topic has emerged in aluminum materials technology to address these requirements. The main issue with aluminum alloys is the low resistance to thermal fatigue that results from the constrained expansion and contraction of the material in the interval regions leading to compressive creep deformation at 300°C during engine heat-up and to tensile deformation around 150°C during engine cooldown. This article discusses the performance requirements and the design principles for aluminum alloys for Diesel engine applications. Efforts on the modification of A356 and A319 alloys via Cu, Mg, Ni, Cr, V, Zr, Ti, and Mn addition are reviewed. Recent studies on Mn/Mo addition are presented and the related principles are introduced in designing high volume fraction, thermally stable, and uniform nanoscale dispersoids using solutes with opposite partitioning coefficients in aluminum.


2014 ◽  
Vol 53 ◽  
pp. 99-105 ◽  
Author(s):  
A. Imandoust ◽  
A. Zarei-Hanzaki ◽  
S. Heshmati-Manesh ◽  
S. Moemeni ◽  
P. Changizian

2012 ◽  
Vol 152-154 ◽  
pp. 358-363 ◽  
Author(s):  
Guo Wei Zhou ◽  
Da Yong Li ◽  
Ying Hong Peng

Uniaxial tensile deformation behavior of 7075-T6 under three different strain rates (0.001, 0.004 and 0.03s-1) and five different temperatures (50, 100, 150, 200 and 250°C) is studied. The total elongation in uniaxial tension increases with increasing temperature in range of 50-200°C and decreases with increasing strain rate. But it drops sharply at 250°C. SEM observations of the fracture surface interpret the change of total elongation and show the fracture tends to transit from brittle mode to ductile mode with increasing temperature. The constitutive model and yield function related with temperature are established based on the experiment results.


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