• Journal of Powder Materials
• /
• v.30 no.3
• /
• pp.203-209
• /
• 2023

Aluminum alloy-based additive manufacturing (AM) has emerged as a popular manufacturing process for the fabrication of complex parts in the automotive and aerospace industries. The addition of an inoculant to aluminum alloy powder has been demonstrated to effectively reduce cracking by promoting the formation of equiaxed grains. However, the optimization of the AM process parameters remains challenging owing to their variability. In this study, the response surface methodology (RSM) was used to predict the crack density of AM-processed Al alloy samples. RSM was performed by setting the process parameters and equiaxed grain ratio, which influence crack propagation, as independent variables and designating crack density as a response variable. The RSM-based quadratic polynomial models for crack-density prediction were found to be highly accurate. The relationship among the process parameters, crack density, and equiaxed grain fraction was also investigated using RSM. The findings of this study highlight the efficacy of RSM as a reliable approach for optimizing the properties of AM-processed parts with limited experimental data. These results can contribute to the development of robust AM processing strategies for the fabrication of high-quality Al alloy components for various applications.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.7
• /
• pp.1076-1086
• /
• 2003

The effect of a rubber mould on densification behavior of aluminum alloy powder was investigated under cold isostatic compaction. A thickness of rubber mould and friction effect between die wall and rubber mould were also studied. The hyperelastic constitutive equation based on the Ogden strain energy potential was employed to analyze deformation of rubber. The elastoplastic constitutive equation of Shima and Oyane and that of Lee on densification were implemented into a finite element program (ABAQUS) to simulate densification of metal powder for cold isostatic pressing and rubber isostatic pressing. Finite element results were compared with experimental data for densification and deformation of aluminum alloy powder under isostatic compaction.

• Transactions of Materials Processing
• /
• v.4 no.3
• /
• pp.222-232
• /
• 1995

The planar anisotripic FEM analysis for predicting earing profiles and draw-in amounts in the deep-drawing process is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-based unit vector and normal contact pressure. The consistent full set of governing relations, which is comprising euilbrium and geometric constraint equations, is appropriately linearized. Barlat's strain-rate potential is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and potential parameters. The linear triangular membrane elements are used for depicting the formed sheet. In the numerical simulations of deep drawing processes of a flat-top cylindrical cup for 2090-T3 aluminum alloy sheet show good agreement with experiments, although some discrepancies were observed in the directional trend of cup height and thickness strains.

• Transactions of Materials Processing
• /
• v.18 no.6
• /
• pp.494-499
• /
• 2009

The time-dependent constitutive law was utilized based on viscoelastic-plasticity to predict the time-dependent spring-back behavior of aluminum alloy 6022-T4 sheets. Besides nonlinear viscoelasticity, non-quadratic anisotropic yield function, Yld2000-2d, was used to account for the anisotropic yield behavior, while the combined isotropic-kinematic hardening law was used to represent the Bauschinger effect and transient hardening. For verification purposes, finite element simulations were performed for the draw-bending and the results were compared with experimental results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.05a
• /
• pp.330-333
• /
• 2009

The time-dependent constitutive law was developed based on viscoelastic-plasticity to describe the time-dependent spring-back behavior of aluminum alloy 6022-T4 sheets. Besides nonlinear viscoelasticity, non-quadratic anisotropic yield function, Yld2000-2d, was used to account for the anisotropic yield behavior, while the combined isotropic-kinematic hardening law was used to represent the Bauschinger effect and transient hardening. For verification purposes, finite element simulations were performed for the draw-bending and the results were compared with experimental results.

• Structural Engineering and Mechanics
• /
• v.59 no.5
• /
• pp.885-899
• /
• 2016

The energy-based approach to predict the fatigue crack growth behavior under constant and variable amplitude loading (VAL) of the aluminum alloy 2024 T351 has been investigated and detailed analyses discussed. Firstly, the plastic strain energy was determined per cycle for different block load tests. The relationship between the crack advance and hysteretic energy dissipated per block can be represented by a power law. Then, an analytical model to estimate the lifetime for each spectrum is proposed. The results obtained are compared with the experimentally measured results and the models proposed by Klingbeil's model and Tracey's model. The evolution of the hysteretic energy dissipated per block is shown similar with that observed under constant amplitude loading.

• Transactions of Materials Processing
• /
• v.33 no.1
• /
• pp.12-17
• /
• 2024

Aluminum-zinc-magnesium alloy is a well-known alloy that is both strong and lightweight. Precipitation strengthening plays a significant role in the strength mechanism of this alloy, with nano-sized η-based precipitates being the representative precipitates. However, the growth of η precipitates can lead to a decrease in strength, necessitating research into ways to control their growth. In this study, we observed the atomic-level behavior of η₂ precipitates and discovered that the precipitates grew through a combination with magnesium after a zinc segregation layer was formed around them.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.829-830
• /
• 2006

Recent research at Harbin Institute of Technology on the synthesis of nanocrystalline and untrafine grained materials by mechanical alloying/milling is reviewed. Examples of the materials include aluminum alloy, copper alloy, magnesium-based hydrogen storage material, and $Nd_2Fe_{14}B/{\alpha}-Fe$ magnetic nanocomposite. Details of the processes of mechanical alloying and consolidation of the mechanically alloyed nanocrystalline powder materials are presented. The microstructure characteristics and properties of the synthesized materials are addressed.

• Journal of Korea Foundry Society
• /
• v.33 no.1
• /
• pp.8-12
• /
• 2013

Although aluminum-silicon based commercial casting alloys have been used in applications that demand high electrical or thermal conductivity, new aluminum casting alloys that possess higher conductivities are currently required for advanced applications. Therefore, there is much research into the development of new high conductivity aluminum casting alloys that contain lower amounts of or no silicon. In this research, the properties and casting characteristics of Al-Zn-Fe-Si alloys with various Fe and Si contents were investigated. Two types of AlFeSi phases were formed depending on the Fe and Si contents. As the silicon content increased, the tensile strength of the Al-Zn-Fe-Si alloy increased slightly, while the electrical conductivity decreased slightly. It was also observed that both the fluidity and hot cracking susceptibility of the investigated alloys were closely related to the formation of the AlFeSi phases.

• Corrosion Science and Technology
• /
• v.15 no.4
• /
• pp.189-197
• /
• 2016

It is a common practice to conduct periodic washes at designated intervals in order to prevent the atmospheric corrosion of aircraft. The wash interval depends on the atmospheric conditions, but the wash intervals set by the U.S. Air Force were widely adopted in Korea without detailed knowledge of the background data. Therefore, it is necessary to determine our own wash intervals representing the atmospheric and geographical conditions in Korea. This study analyzed previous wash interval algorithms and atmospheric data in Korea. New wash intervals are then proposed based on the corrosion rate equation in ISO-9223:2012. Atmospheric corrosion testing was conducted using 7075 and 1050 aluminum alloy specimens to verify the accuracy of the corrosion rate equation in ISO-9223:2012. Test results showed a reasonable agreement with the corrosion rates predicted by the equation.