• Transactions of Materials Processing
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• v.26 no.3
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• pp.174-180
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• 2017

In this study, a new spot welding with electric resistance heated dies is suggested for the spot welding of non-ferrous metal plates for drawing and concurrent spot welding. This welding method involves two heating processes such as heating by conduction of electric resistance heated dies and heating by resistance between contacted surfaces of two plates by welding current induced to copper dies for the fusion of contacted metal. This welding process has welding variables such as current induced in heated and copper dies, the inner diameters of heated dies, and edge shape of the copper dies. Experimental conditions for each current should be established to get successful welding strength. The welding strength could reach to the desired value in industrial fields under the following conditions of contact diameters of heated dies in this case of overlapped aluminum5052 plates with 0.3-mm thickness: inner and outer diameters of 5.0 and 16mm, respectively; diameter of copper dies, 5.0mm; heating current, 6.8kA in heated steel dies; welding current, 8.6 kA in copper dies.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.325-330
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• 2010

Many surface protection methods have been developed to apply for constructional steels used under severe corrosive environment. Thermal spray coating has been known to be an attractive technique due to its relatively high coating speed. Furthermore high corrosion resistance of coated film with thermal spray is required to expand its application. Four types of coated films(DFT:300 um) such as pure zinc, pure aluminum and two Al-Zn alloy (Al:Zn=85:15 and Al:Zn=95:5) onto the carbon steel (SS401) were prepared with arc spray, and the corrosion behavior of their samples were evaluated by electrochemical method in this study. Pure aluminum sample showed high corrosion resistance behavior exposed to sea water solution and pure zinc and alloy (Al:Zn=95:5) samples followed pure aluminum sample. The other alloy(Al:Zn=85:15) so called galvalume coated onto the carbon steel ranks the 4th corrosion resistance in this study. The results of porosity ratio of those samples by observation are well matched with the electrochemical data.

• Journal of Welding and Joining
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• v.22 no.4
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• pp.43-49
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• 2004

Conventional method for electrode force application in resistance spot welding(RSW) processes is to use pneumatic cylinder. However, due to its inherent problems in pneumatic power system such as compressibility of air and poor transient response characteristics, new electrode force system with servo control are recently introduced in RSW machine. This machine is called “servogun”. The purpose of this study is to evaluate performance of servogun in case of spot welding of aluminum alloy. Aluminum alloy(A5052) sheets are spot welded using pneumatic gun and servogun. Both results are compared by means of macro cross-section etching test and tensile shear strength test. Numerous previous research have reported nugget with many voids and cracks are not uncommon defects in spot welds with aluminum alloy. The experimental results show similar defects in case of pneumatic gun. In contrast, use of servogun considerably reduced generation of voids and cracks. In case of step-wise increased forging force at the end of welding cycle with servogun, crack-free and void-free nuggets have been observed. The performance of servogun has been also verified by series of tensile shear test. Higher strength values have been achieved with servogun in comparison to that of pneumatic gun.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.14-21
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• 2003

This study deals with the influence of ceramic coating on characteristics of friction and abrasion of aluminum allot(7075 T6) used in mechanical casting. In this research, frictional wear characteristic of ceramic coating materials such as $A1_2O_3$, $Si_3N_4$, SiC was investigated using aluminum alloy(7075 T6) and stainless 403 cast iron under room temperature and normal air pressure. The coating layer was observed using SEM. The conclusions are as follows: 1) Friction coefficients of $A1_2O_3$, SiC and $Si_3N_4$ are obtained 0.63 0.56 and 0.54 respectively. 2) Abrasion resistance of stainless 403 cast iron with $Si_3N_4$ is the best among the ceramic coating materials. 3) Abrasion mechanism of aluminum alloy(7075 T6) coaled with ceramic material and stainless 403 cast iron is caused by brittle fracture. 4) Coating the ceramic material on the aluminum alloy(7075 T6) can effectively increase the antiwear, impact properties, and corrosion resistance.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.120-126
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• 2010

It was known that the excellent wear resistance of hyper eutectic aluminum alloy is based on the primary Si particles which are distributed in the base metal. When the primary Si volume fraction increases, the smaller size have excellent wear resistance characteristics. However, this trend always does not match. There is no investigation result based on the materials and methods for real using parts. In this study, using the automotive parts manufacturer currently in use hyper eutectic Al alloy tensile test specimen type sample was fabricated by 350Ton high pressure die-casting machine. Then, fluidity, tensile, impact and wear resistance properties were evaluated. If the casting quality, primary Si size, fraction and distribution are similar, mechanical properties and wear resistance are equivalent.

• International Journal of Automotive Technology
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• v.7 no.5
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• pp.565-570
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• 2006

The development of a light-weight vehicle is in great demand for enhancement of fule efficiency and dynamic performance. The vehicle weight can be reduced effectively by using lightweight materials such as aluminum and magnesium. However, if such materials are used in vehicles, there are often instances when different materials such as aluminum and steel need to be joined to each other. The conventional joining method, namely resistance spot welding, cannot be used in joining different materials. Self-piercing rivet(SPR) and adhesive bonding, however, are good alternatives to resistance spot welding. This paper is concerned with the crushing test of double hat-shaped member made by resistance spot welding, SPR and adhesive bonding. Various parameters of crashworthiness are analyzed and evaluated. Based on these results, the applicability of SPR and adhesive bonding are proposed as an alternative to resistance spot welding.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.161-163
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• 1997

Heatcycle testing for aluminum connector is very important. But because of connecting or disconnecting the test circuit, measuring resistance is difficult. Also the previous measuring resistance instrument is analog type. So measuring method is difficult. And four measuring points for one test circuit cause difficulty in automation. In this paper we developed the automatic system for measuring resistance. Automation will allow more information to be gathered, which will lead to the connector aging process being better understood and controlled.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.166-173
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• 1996

There are kinds of materials for protective heat shield, i.e.Zn-coated steel, AI-coated steel and aluminum alloy sheets. This study compare formability, corrosion resistance, heat protectability, weight, and cost of these materials for heat protective shield. Generally aluminum alloy sheets are less formable than steel sheets, but A1100 alloy sheet shows almost same press quality of steel parts, using the press dies which producing steel parts. The heat shields using aluminum alloy sheet and steel sheet show almost same heat protectibility. It is the conclusion that Zn-coated merit, and AI-coated steel sheet and aluminum alloy sheet can be used to protect functional corrosion in severely corrosive market area. The material cost of AI-coated steel sheet and aluminum alloy sheet for a mid-size car is almost same, so aluminum alloy sheet is more recommendable in the point of weight reduction of vehicle.

• Journal of the Korean institute of surface engineering
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• v.57 no.3
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• pp.201-207
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• 2024

This study compared the chemical resistance properties according to various sealing treatment methods for the anode film formed during the anodization process of Al6061 alloy. Al6061 aluminum was used in four different sealing treatment methods: boiling water sealing, lithium sealing, nickel sealing, and pressurized sealing, and each sample was evaluated for corrosion resistance through a 5% HCl bubble test and the microstructure was observed through a scanning electron microscope(SEM). According to the results, corrosion resistance increased as time and temperature increased in all sealing treatment methods. Relatively, corrosion resistance was high in the order of boiling water sealing, lithium sealing, nickel sealing, and pressure sealing, and the best corrosion resistance was found in pressure sealing. These research results can be helpful in selecting a process necessary to improve the efficiency and performance of anodizing process in the industrial field using aluminum alloys.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.149-149
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• 2017

Aluminum alloys have poor corrosion resistance compared to the pure aluminum due to the additive elements. Thus, anodizing technology artificially generating thick oxide films are widely applied nowadays in order to improve corrosion resistance. Anodizing is one of the surface modification techniques, which is commercially applicable to a large surface at a low price. However, most studies up to now have focused on its commercialization with hardly any research on the assessment and improvement of the physical characteristics of the anodized films. Therefore, this study aims to select the optimum temperature of sulfuric electrolyte to perform excellent corrosion resistance in the harsh marine environment through electrochemical experiment in the seawater upon generating porous films by variating the temperatures of sulfuric electrolyte. To fabricate uniform porous film of 5083 aluminum alloy, we conducted electro-polishing under the 25 V at $5^{\circ}C$ condition for three minutes using mixed solution of ethanol (95 %) and perchloric (70 %) acid with volume ratio of 4:1. Afterward, the first step surface modification was performed using sulfuric acid as an electrolyte where the electrolyte concentration was maintained at 10 vol.% by using a jacketed beaker. For anode, 5083 aluminum alloy with thickness of 5 mm and size of $2cm{\times}2cm$ was used, while platinum electrode was used for cathode. The distance between the two was maintained at 3 cm. Anodic polarization test was performed at scan rate of 2 mV/s up to +3.0 V vs open circuit potential in natural seawater. Surface morphology was compared using 3D analysis microscope to observe the damage behavior. As a result, the case of surface modification showed a significantly lower corrosion current density than that without modification, indicating excellent corrosion resistance.