• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.451-459
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• 2011

Austenitic stainless steels of 300 series are widely used as the structural material due to excellent their cryogenic mechanical properties at cryogenic temperature. There are 316 steel which molybdenum is added to improve the austenitic stability, 316L which carbon contents is reduced to decrease the grain boundary precipitation during welding process, and 316LN which nitrogen is added to improve the austenitic stability and the mechanical strength. But material researches for the welding conditions and mechanical properties at the cryogenic temperature were insufficient so far. In this paper, the characteristics of mechanical properties considering the effect of welding conditions and cryogenic temperature are studied.

• Corrosion Science and Technology
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• v.18 no.1
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• pp.1-7
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• 2019

To find proper lathe machining parameters for SA182 Grade 304 stainless steel (SS), six kinds of samples with different machining surface states were prepared using a lathe. Surface morphologies and microstructures of near surface deformed layers on different samples were analysed. Surface morphologies and chemical composition of oxide films formed on different samples in simulated primary water with $100{\mu}g/L\;O_2$ at $310^{\circ}C$ were characterized. Results showed that surface roughness was mainly affected by lathe feed. Surface machining caused grain refinement at the top layer. A severely deformed layer with different thicknesses formed on all samples. In addition to high defect density caused by surface deformation, phase transformation, residual stress, and strain also affected the oxidation behaviour of SA182 Grade 304 SS in the test solution. Machining parameters used for # 4 (feed, 0.15 mm/r; back engagement, 2 mm; cutting speed, 114.86 m/min) and # 6 (feed,0.20 mm/r; back engagement, 1 mm; cutting speed, 73.01 m/min) samples were found to be proper for lathe machining of SA182 Grade 304 SS.

• Journal of Powder Materials
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• v.24 no.2
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• pp.128-132
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• 2017

Harmonic structure materials are materials with a core-shell structure having a shell with a small grain size and a core with a relatively large grain size. They are in the spotlight because their mechanical properties reportedly feature strength similar to that of a sintered powder with a fine grain size and elongation similar to that of a sintered powder with a coarse grain size at the same time. In this study, the tensile properties, microstructure, and stretch-flangeability of harmonic structure SUS304L made using powder metallurgy are investigated to check its suitability for automotive applications. The harmonic powders are made by mechanical milling and sintered using a spark plasma sintering method at 1173 K and a pressure of 50 MPa in a cylindrical die. The sintered powders of SUS304L having harmonic structure (harmonic SUS304L) exhibit excellent tensile properties compared with sintered powders of SUS304L having homogeneous microstructure. In addition, the harmonic SUS304L has excellent stretch-flangeability compared with commercial advanced high-strength steels (AHSSs) at a similar strength grade. Thus, the harmonic SUS304L is more suitable for automotive applications than conventional AHSSs because it exhibits both excellent tensile properties and stretch-flangeability.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.129-130
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• 2004

The stainless steel sheet which is one of primary barrier components for membrane on LNG ship is ordinarily welded by either TIG or PAW. The weld shapes of acceptant tolerance for membrane construction are scripted by G.T.T.(Gaztransport ＆ Technigaz)‘s rules such as penetration depth, weld throat and weld length etc. This paper presents relationship between weld metal shear strength and weld penetration formed with plasma arc welding. The results show penetration depth is not decisive factor on shear strength, but weld throat and length.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.215-215
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• 2015

Ag-Cu 공정 합금을 이용한 스테인리스 강의 brazing 거동에 미치는 산소의 영향을 조사하고 최적 brazing 조건을 도출하기 위하여 304L 스테인리스 강에 대한 다양한 산소농도의 Ag-Cu 공정 합금의 젖음성을 실험적으로 측정하였다. 0.02~0.07wt%의 범위에 해당하는 산소를 함유하였을 때 양호한 젖음 특성을 나타내었고, sandwich brazing 테스트를 통하여 유사한 조건에서 건전한 접합면을 얻을 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1317-1323
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• 2010

In this study, the weld residual stress distribution at a dissimilar-metal welded plate of low alloy carbon steel and stainless steel, which are widely used in nuclear power plants, was characterized. A plate mock-up with butt welding was fabricated using SA 508 low alloy steel and Type 304 stainless steel plates and the residual stresses were measured by the X-ray diffraction method after electrolytic polishing of the plate specimen. Finite element analysis was carried out in order to simulate the butt welding of dissimilar metal plate, and the calculated weld residual stress distribution was compared with that obtained from the measured data. The characteristics of the three-dimensional residual stress distribution in a butt weld of dissimilar metal plates were investigated by comparing the measured and calculated residual stress data.

• Resources Recycling
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• v.17 no.2
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• pp.36-45
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• 2008

Pickling of oxidized 304 stainless steel has been investigated using rotating disk electrode in waste acid solutions generated from the etching process of silicon wafer in order to recycle them. The waste acid solution contained acetic, nitric, hydrofluoric acids, and silicon of $19.6g/L^{-1}$. Electrochemical behavior during the pickling was distinctively different between the original and silicon-removed acid solutions. Open circuit potential was continuously changed in the original solution, while it was discontinuously changed and fluctuated in the silicon-removed solution. Fast and abrupt removal of surface oxide layer with severe pitting was observed in the silicon-removed solution. It was found that solution temperature had the most influential effect on glossiness. Surface glossiness after pickling was decreased with solution temperature. At the same condition, the glossiness was higher in the original solution than in the silicon-removed solution.

• Korean Journal of Metals and Materials
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• v.48 no.10
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• pp.893-900
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• 2010

In the present work, the impact loads and their effects on the surface damage under the simultaneous cavitation bubble and solid particle collapses in the sea water have been quantitatively investigated for the austenitic 304 stainless steel by using a vibratory cavitation test device. To do this, angular $SiO_2$ solid particles with an average size of $150{\mu}m$ were dispersed into the test liquid, and the measured impact amplitudes were converted into the impact loads by a steel ball drop test. The maximum impact load was determined to be 28.2 N in the absence of solid particles, but increased to 33.7 N in the presence of solid particles. In addition, the critical impact loads, $L_{crit}$, required to generate pits with sizes greater than $3{\mu}m$ were measured to be 19.6 N and 16.6 N, respectively, for the cavitation bubble collapse and solid particle collapse. As a result of the cavitation erosion test, the incubation time and erosion rate were 1.2 times lower and 1.5 times higher, respectively, by a solid particle collapse compared to those only by the cavitation bubble collapse, indicating a drastic decrease in a resistance to cavitation erosion by the solid particle collapse.

• Corrosion Science and Technology
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• v.20 no.2
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• pp.85-93
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• 2021

The corrosion damage of materials in marine environment mainly occurs by Cl^- ions due to the breakdown of passive films. Additionally, various characteristics in seawater such as salinity, temperature, immersion time, flow rate, and biological activity also affect corrosion characteristics. In this study, the corrosion characteristics of stainless steels (STS 304 and STS 316L) and anodized aluminum alloys (AA 3003 and AA 6063) were evaluated with seawater temperature parameters. A potentiodynamic polarization experiment was conducted in a potential range of -0.25 V to 2.0 V at open circuit potential (OCP). Corrosion current density and corrosion potential were obtained through the Tafel extrapolation method to analyze changes in corrosion rate due to temperature. Corrosion behavior was evaluated by measuring weight loss before/after the experiment and also observing surface morphology through a scanning electronic microscope (SEM) and 3D microscopy. Weight loss, maximum damage depth and pitting damage increased as seawater temperature increased, and furthermore, the tendency of higher corrosion current density with an increase of temperature attributed to an increase in corrosion rate. There was lower pitting damage and lower corrosion current density for anodized aluminum alloys than for stainless steels as the temperature increased.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.4
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• pp.197-204
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• 2003

Honeycomb structure has been fabricated by brazing method using 0.1 wt%C and 1.0wt%C carbon steel core and STS304 stainless steel face sheet. Core shear strength ratio in W and L directions was 1:1.03 in 7 mm cell size, whereas 1:1.45 in 4 mm cell size. Flexural strength on face sheet was 166.4 MPa (0.1 wt%C, W direction), 171.1 MPa (0.1 wt%C, L direction), and 120.2 MPa (1.0 wt%C, W direction) in 7 mm cell size. And in 4mm cell size specimen, it was 169.2 MPa (0.1 wt%C, W direction), 224.2 MPa (0.1 wt%C, L direction). This means that flexural strength of 0.1 wt%C core material was higher than that of 1.0wt%C core material, which was contrary to expectation. SEM and EDS analysis represented that grain boundary diffusion had occurred in0.1 wt%C core, but no grain boundary diffusion in 1.0 wt%C core. And corrugated surface of 0.1 wt%C core was flat, whereas that of 1.0 wt%C core was not flat. As a result, contact area between two 1.0 wt%C cores was much less than that of 0.1 wt% cores, It is thought to be main reason for lower flexural strength of 1.0 wt%C core.