• Journal of the Korean institute of surface engineering
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• v.50 no.5
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• pp.421-426
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• 2017

Herein, we investigated surface morphological characteristics of anodic films on Al6061 alloy prepared by unipolar pulsed Micro-arc oxidation (MAO) in a mixed solution of $Na_2SiO_3$ + KOH. The number and size of pores as well as craters on anodic alumina surface were studied as a function of different voltages, duty cycles and applied anodic current densities. The morphological characteristics of all samples were investigated by scanning electron microscopy, conforming that the most uniform surface morphology of MAO films on Al1050 alloy was obtained at high applied current density with low duty cycle.

• Journal of the Semiconductor & Display Technology
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• v.14 no.2
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• pp.47-52
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• 2015

In this paper, the performance of uncoated- and Titanium nitride aluminium TiAlN-PVD coated- carbide twist drills were investigated when drilling aluminium alloy, Al 6061. This research focuses on the optimization of drilling parameters using the Taguchi technique to obtain minimum surface roughness and thrust force. A number of drilling experiments were conducted using the L9 orthogonal array on a CNC vertical machining center. The experiments were performed on Al 6061 material l blocks using uncoated and coated HSS twist drills under dry cutting conditions. Analysis of variance(ANOVA) was employed to determine the most significant control factors. The main objective is to find the important factors and combination of factors influence the machining process to achieve low surface roughness and low cutting thrust force. From the analysis of the Taguchi method indicates that among the all-significant parameters, feed rate are more significant influence on surface roughness and cutting thrust than spindle speed.

• Corrosion Science and Technology
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• v.21 no.5
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• pp.348-359
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• 2022

Interest in electric vehicle is on the rise due to global eco-friendly policies. To improve the efficiency of electric vehicles, it is essential to reduce weights of components. Since electric vehicles have various electronic equipment, the research on stray current corrosion is required. In this research, a galvanostatic corrosion experiment was performed on 6061-T6 Al alloy for electric vehicle battery housing using chloride concentration and applied current density as variables in a solution simulating an acid rain environment. As a result of the experiment, when chloride concentration and applied current density were increased, corrosion damage became larger. In particular, pitting damage was dominant at an applied current density of 0.1 mA/cm². Pitting damage over the entire surface was found at a current density of 1.0 mA/cm². In conclusion, chloride concentration had a relatively large effect on localized corrosion. The applied current density had a great effect on uniform corrosion. However, in the case of applied current density, localized corrosion was also greatly affected by interaction with chloride.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1787-1794
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• 2002

TiNi alloy fiber was used to solve the problem of the tensile residual stress as the reinforced material. TiNi alloy fiber improves the tensile strength of composite by occurring compressive residual stress in the matrix using shape memory effect. In order to generate compressive residual stress in TiNi/Al6061 shape memory alloy(SMA) composite, 1, 3 and 5% pre-strains were applied to the composite in advance. It was also evaluated the effect of compressive residual stress corresponding to the pre-strain variation and the volume fraction of TiNi alloy. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain in TiNi/Al6061 SMA composite. The results of the microscopic damage evaluation of TiNi/Al6061 SMA composite under various pre-strain using AE technique can be divided into three stage corresponding to the AE signals. AE counts and events were useful parameters to evaluate the fracture mechanism according to the variation of pre-strain. In addition, two dimensional AE source location technique was applied for monitoring the crack initiation and propagation in composite.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.2
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• pp.99-107
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• 2009

This study produced a design curve and fatigue limit for a variation in volume ratio and reduction ratio of TiNi/Al composites. In many cases, stress-life curve does not indicate fatigue limit, so it was presented by probabilistic-stress-life curve. Goodman diagram was used to analyze the fatigue strength of materials with a finite life determined by repeated load and the fatigue strength of endurance limit with an infinite life. The fatigue experiment was conducted using the scenk-type plane bending specimen in same shape. The result of the fatigue test, which had been conducted under consistent stress amplitude, was examined. (i) The optimal condition for TiNi/Al in accordance with hot pressing (ii) Impacts of fatigue limit caused by a variation in reduction ratio and volume ratio of TiNi/Al composites (iii) Probability distribution for fatigue limit of TiNi/Al2024 and TiNi/Al6061.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.154-158
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• 2002

The mechanical properties of Al 6061 excluded bar were deformed in high temperature with the variable deformation conditions and characterized by the tensile test. Three types of different strain rate were experimentally performed by using hydraulic press, crank press and hammer and two types of the nominal strain 0.5 and 0.8 were achieved. To decide optimum forging process, the relationship among the strain rate, strain and mechanical properties was explained by analyzing the microstructures of the forged and heat heated parts. The strength was deeply related with the strain rate due to the dynamic recrystallization (DRX) in hot forging, and the best forging condition was presented in Al 6061 alloy.

• International Journal of Korean Welding Society
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• v.2 no.2
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• pp.42-46
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• 2002

The solidification cracking susceptibilities of Al-Mg-Si alloy laser welds were assessed using the self-restraint tapered specimen crack test. The cracking susceptibility of 6061 and 6082 Al-Mg-Si alloy laser welds was substantially reduced when the filler wire containing high Si such as Al-12 wt.% Si (4047A) was used. The amount of eutectic was observed to affect the solidification cracking of Al-Mg-Si alloy laser welds. Abundant eutectic seems to heal the cracking and reduces the cracking susceptibility, while an initial increase in eutectic liquid leads to the increased cracking tendency.

• Transactions of Materials Processing
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• v.8 no.6
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• pp.576-582
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• 1999

The high temperature behavior of Al 6061 alloy was characterized by the hot torsion test in the temperature ranges of 400∼550℃ and the strain rate ranges of 0.05∼5/sec. To decide optimum deformation condition, three types of deformation maps were individually made from the critical strain (εc). deformation resistance(σp) and deformation efficiency (η). The critical strain(εc) for dynamic recrystallization (DRX) which was decided from the inflection point of strain hardening rate(θ) - effective stress (σ) curve was about 0.65 times of peak strain (εp). The relationship among deformation resistance (peak stress, σp), strain rate (ε), and temperature (T) could be expressed by ε=2.9×1013[sinh(0.0256σp]7.3exp (-216,000/RT). The deformation efficiency (η)which was calculated on the basis of the dynamic materials model (DMM) showed high values at the condition of 500∼550℃, 5/sec for 100% strain. The results from three deformation maps were compared with microstructures. The best condition of plastic deformation could be determined as 500℃ and 5/sec.

• Journal of the Korean institute of surface engineering
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• v.47 no.6
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• pp.282-286
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• 2014

Wear characteristic of the nitrided SKD61 which is a typical mold material using for the extrusion of Al6061 alloy was investigated. The surface of SKD61 was nitrided by salt bath and plasma processes. The thickness of surface nitride layer was about $8.9{\mu}m{\sim}21.3{\mu}m$. Reciprocating friction wear test conducted using pin on disk type indicated the plasma treatment followed salt bath has a lower friction coefficient and a smaller adhesive wear with Al6061 alloy. That was identified by the $Fe_4N$ which has a better wear resistance than FeN mainly formed by plasma nitriding.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.11a
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• pp.20-20
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• 2001