• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03a
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• pp.73-80
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• 1996

Commerical purity aluminium , copper and STS 304 stainless steel sheets are welded by ultrasonic welding. The microstructures, x-ray diffraction profiles of planes , pole figures of the surface of original metal sheets are compared with those of the weld interface. The microstructures show disturbance and dark areas in the weld interface and grain refinement in the vicinity of the interface. The x-ray diffraction intensity of each plane in weld interface decreased in all metal sheets with exception of 9200) in steel sheet. The microstructure and x-ray diffraction intensity is affected by the mixture of deformation, heating and vibratin duringthe ultrasonic welding. Therefore, after the ultrasonic welding, the positions of the peak intensity in the pole figures are changed, the value of the maximum pole intensity is decreased in Al, is increased in copper and stainless steel. Very strong {100} <001> texture, strong {100} <001>,{123}<634> textures in original Al surface are transformed into weak, {100}<001>, {110}<112> and {112}<111> components in weld surface, weak (110) fiber is slightly changed to (110) fiber in copper, (100)and ${\gamma}$ fiber components are transformed into strong ${\gamma}$ fiber component in stainless steel.

• Journal of the Korean institute of surface engineering
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• v.25 no.5
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• pp.235-252
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• 1992

(Ti, Al)N films were deposited on 304 stainless steel sheet by D.C. magnetron sputtering using Al target and Ti plate. The high temperature oxidation of (T, Al)N films with the variation of composition has been investigated. The chemical composition of (Ti, Al)N films with the variation of composition has been investigated. The chemical composition of (Ti, Al)N films was similar to the sputter area ratio of titanium to aluminum target by means of EDS and AES survey. The high temperature oxidation test of (Ti, Al)N showed that (Ti, Al)N has better high temperature resistance than TiN and TiC films. TiC films were cracked at 40$0^{\circ}C$ in air TiN films quickly were oxidised at $600^{\circ}C$, were spalled more than $700^{\circ}C$. But (Ti, Al)N films are relatively stable to$ 900^{\circ}C$. The good resistance to high temperature oxida-tion of (Ti, Al)N films are due to the formation of dense Al2O3 and TiO2 oxide layer. Especially, Al2O3 oxide layer is more important. The results obtained from this study show, it is believe that the (Ti, Al)N film by D.C. magnetron sputtering is promising for the use of high temperature and wear resistance mate-rials.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.3
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• pp.221-232
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• 2017

In this study, bipolar plates in fuel cells are formed using rubber forming process. The effects of important parameters in rubber forming such as hardness and thickness of rubber pad, speed and pressure of punch that compress blank, and physical property of materials on the channel depth were analyzed. In the soft material sheet Al1050, deeper channels are formed than in materials STS304 and Ti-G5. Formed channel depth was increased when hardness of rubber pad was lower, thickness of rubber pad was high, and speed and pressure of punch were high. It was found the deepest channel was achieved when forming process condition was set with punch speed and pressure at 30 mm/s and 55 MPa, respectively using rubber pad having hardness Shore A 20 and thickness 60 mm. The channel depths of bipolar plates formed with Al1050, STS304 and Ti-G5 under the above process condition were 0.453, 0.307, and 0.270 mm, respectively. There were no defects such as wrinkle, distortion, and crack found from formed bipolar plates.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.232-233
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• 2005

Stainless steel has been stably used closed by passivity oxidation films($Cr_2O_3$) is made by neutral atmospheric environment. However, passivity oxidation films of the surface of stainless steel occasionally comes to be destroyed in seawater which is influenced by an environment having halogen ion like $Cl^-$, then, localization corrosion comes to occur. Stainless steel 304 for shaft system material of the small-size FRP fishing boat on seawater environments made an experiment on simulation of sacrifical anode(Al, Zn). Through these experiment and study, following results have been obtained ; According to the field inspection and corrosion simulation, the corrosion on the 2nd class stainless steel shaft(STS 304) in FRP fishing boat has been verified to occur by crevice corrosion and galvanic corrosion etc.. According to the comparison and analysis of Stainless steel 304 shaft materials after simulation leaving unprotected and applying cathodic protection, unprotected shaft specimen of stainless steel 304 was severely corroded, but, protected shaft specimen was not totally corroded. This result is assumed to be made by the facts that anodic reaction, $Fe{\rightarrow}Fe^{2+}$ + $2e^-$, has been restricted by the cathodic protection current of sacrificial anode material.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.3
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• pp.67-72
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• 2015

A study on thermal properties for a single-layer metal and a 2-ply metal (clad metals) was investigated for the application of heat sink. For the single-layer metal, a stainless steel (STS) and an aluminum (Al) were selected. Also, a roll bonded clad metal with STS and Al was chosen for the 2-ply metal. The thermal conductivity of the sample was obtained from the thermal diffusivity measured by the light flash analysis (LFA), specific heat and density. Measured thermal property values were compared with the calculated values using the data from the references. For the single-layer metal, measured values for the thermal diffusivity and thermal conductivity were smaller than calculated values. Differences between measured and calculated values were about 6% and 18% for the STS and Al samples, respectively. For the clad metals, however, a large difference (55%) was observed. Here, a relatively small thermal conductivity measured by LFA was due to the existence of a interface between STS and Al in the clad metal. Such a interface reduces the moving velocity of free electrons and phonons in the clad metal. For the development of a high performance heat-issipation module with the multi-layer structure, the control of interface properties which determine thermal properties was confirmed to be important.

• Korean Journal of Materials Research
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• v.3 no.3
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• pp.282-291
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• 1993

Joining ${Al}_{2}{O}_{3}$ and STS 304 stainless steel by active metal brazing method with using CuI Owt % Ti and Cu -7 .5wt % Zr insert metal, their interfaces were analyzed and strength of the joint brazed with Cu-7.5wt % Zr insert metal also investigated with shear strength testing method. In brazing with Cu-lOwt% Ti insert metal, the single reaction layer was formed by the reaction with Ti and ${Al}_{2}{O}_{3}$ at the interface between ${Al}_{2}{O}_{3}$ and insert metal, but the double reaction layer was found in brazing with Cu-7.5wt % Zr insert metal because of the difference of their wettability on the surface of ${Al}_{2}{O}_{3}$. Fracture shear strength about 86MPa was obtained from ${Al}_{2}{O}_{3}$/Cu-7.5wt% Zr/STS 304 stainless steel joint and reasonable strength of the joints is attributed to the formation of double reaction layer at the interface.

• Transactions of Materials Processing
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• v.20 no.3
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• pp.257-264
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• 2011

Multilayer(clad) sheets, composed of two or more materials with different properties, are fabricated using the roll-bonding process. A good formability is an essential property for a multilayered sheet in order to manufacture parts by plastic deformation. In this study, the influences of temperature and strain rate on the plastic properties of stainless steel-aluminum-magnesium multilayered(STS-Al-Mg) sheets were investigated. Tensile tests were performed at various temperatures and strain rates on the multilayered sheet and on each separate layer. Fracture of the multilayered sheet was observed to be temperature-dependent. At the base temperature of $200^{\circ}C$, all materials fractured simultaneously. At lower temperatures, the Mg alloy sheet fractured earlier than the other materials. Conversely, the other materials fractured earlier than the Mg alloy sheet at higher temperatures. The uniform and total elongations of the multilayered sheet were observed to be higher than that of each material at a temperature of $250^{\circ}C$. Larger uniform elongations were obtained for higher strain rates at constant temperature. The same trend was observed for the Mg alloy sheet, which exhibited the lowest elongation among the three materials. The tensile strengths and elongations of the single layer sheets were compared to those of the multilayer material. The strength of the multilayered sheet was successfully calculated by the rule of mixture from the values of each single layer. However, no simple correlation between the elongation of each layer and that of the multilayer was obtained.

• Journal of Korea Ship Safrty Technology Authority
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• s.21
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• pp.66-77
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• 2006

Stainless steel has been stably used closed by passivity oxidation films(Cr₂O₃) is made by neutral atmospheric environment. However, passivity oxidaton films of the surface of stainless steel occasionally comes to be destroyed in seawater which is influenced by an environment having galogen ion like Cl‾, then, localization corrosion comes to occur Stainless steel 304 for shaft system material of the small-size FRP fishing boat on seawater environments made an experiment on simulation of sacrifical anode(Al, Zn). Through these experiment and study, following results have been obtained ; According to the field inspection and corrosion simulation, the corrosion on the 2nd class stainless steel shaft(STS304) in FRP fishing boat has been verified to occur by crevice corrosion and galvanic corrosion etc., According to the comparison and analysis of Stainless steel 304 was severely corroded, but, protected shaft specimen was not totallay corroded. This result is assumed to be made by the facts that anodic reaction, Fe → fe²+＋ 2e¯, has been restricted by the cathodic protection current of sacrificial anode material.

• Corrosion Science and Technology
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• v.20 no.2
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• pp.52-61
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• 2021

This study using experimental design and linear regression technique was implemented in order to predict the pitting potential of stainless steel in marine environments, with the target materials being AL-6XN and STS 316L. The various variables (inputs) which affect stainless steel's pitting potential included the pitting resistance equivalent number (PRNE), temperature, pH, Cl^- concentration, sulfate levels, and nitrate levels. Among them, significant factors affecting pitting potential were chosen through an experimental design method (screening design, full factor design, analysis of variance). The potentiodynamic polarization test was performed based on the experimental design, including significant factor levels. From these testing methods, a total 32 polarization curves were obtained, which were used as training data for the linear regression model. As a result of the model's validation, it showed an acceptable prediction performance, which was statistically significant within the 95% confidence level. The linear regression model based on the full factorial design and ANOVA also showed a high confidence level in the prediction of pitting potential. This study confirmed the possibility to predict the pitting potential of stainless steel according to various variables used with experimental linear regression design.

• Journal of Technologic Dentistry
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• v.23 no.1
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• pp.21-30
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• 2001

For biomedical applications. Ti-X%Zr-Y%Pd(X: $10{\sim}20$, Y:0.2 or 0.4) based alloys not containing harmful Al and V were newly designed, and polarization curves for their alloys were measured at $37^{\circ}C$ in 5% HCl solution in order to understand effects of Zr on the corrosion. From the results of anodic polarization behavior, it was found that the corrosion resistance increased with increasing Zr content. The results show their potential to develope Ti-based alloys for biomedical materials. The Ti-20%Zr-0.2%Pd alloy shows excellent corrosion resistance and was superior to those of the Ti. Ti-6%Al-4%V ELI alloy, Co-30%Cr-6%Mo alloy and STS 316L stainless steel.