• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1219-1220
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.495-496
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• 2013

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.234-238
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• 2004

Inconel 625 is useful in variety of industrial applications because of the resistance to attack in various corrosive media at temperatures from $200^{\circ}C$ to aver $1090^{\circ}C$, in combination with good law- and high temperature mechanical strength. Rencently, this material is also used widely in offshore processing piping in order to extend the maintenance term and improve the quality of anti-corrosion. In general, high quality weldments for this material are readily produced by commonly used processes. Not all processes are applicable to this material group, Ni-alloys. Metallurgical characterictics or the unavailability of matching, position or suitable welding processes. Nowadays, the flux cored wire is developed and applied for the better productivity in several welding position including the vertical position. in this study, the weldability and weldment characteristics (mechanical properties) of inconel 625 are considered in FCAW(Flux Core Arc Welding) associated with the several shielding gases($80\%Ar\;+\;20\%CO_2,\;50\%Ar+50CO_2,\;100CO_2$) in viewpoint of welding productivity.

• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.96-100
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• 2004

Inconel 625 is useful in a variety of industrial applications because of the resistance to attack in various corrosive media at temperatures from $200^{\circ}C$ to over $1090^{\circ}C$, in combination with good low and high temperature mechanical strength. Rencently this material has also been widely used in offshore processing piping in order to extend the maintenance term and improve the quality of anti-corrosion. In general, high quality weldings for this material are readily produced by commonly used processes. How, not all processes are applicable to this material group of Ni-alloys. Metallurgical or the unavailability of matching, position or suitable welding processes produce a lower quality. Nowadays, the flux cored wire is developed and applied for increased productivity in several welding positions, including the vertical position. In this study, the weldability and weldment characteristics(mechanical properties) of inconel 625 are considered in FCAW(Flux Core Arc Welding) associated with the several shielding gases$(80\%Ar+20\%CO2,\;50\%Ar+50CO2,\;100CO2)$ in view of welding productivity.

• International Journal of Ocean System Engineering
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• v.2 no.3
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• pp.160-169
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• 2012

Flux Cored Arc Welding (FCAW) is a common practice to join thick plates such as the structural members of large scale offshore structures and very large container ships. The objective of this study was to investigate the mechanical properties and variability of the fatigue crack initiation life in the flux cored arc welded API 2W Gr.50 steel joints typically applied to offshore structures with a focus on the effect of the materials in fatigue crack growth life from the notch root of a compact tension specimen. Offshore structural steel (API 2W Gr.50) plates (60-mm thick) were used to fabricate multi-path flux core arc welded butt welded joints to clearly consider fatigue fractures at the weld zone from the notch. Fatigue tests were performed under a constant amplitude cyclic loading of R = 0.4. The mean fatigue crack initiation life of the HAZ specimen was the highest among the base metal (BM), weld metal (WM), and heat affected zone (HAZ). In addition, the coefficient of variation was the highest in the WMl specimen. The variability of the short fatigue crack growth rates from the notch tips in the WM and HAZ specimens was higher than in BM.

• Journal of Welding and Joining
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• v.28 no.3
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• pp.65-72
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• 2010

Some structural members of large-scale marine vessels such as large-scale offshore structures and very large container ships are assembled by very thick plates of which thickness exceeds 60mm. Also, high-tensile steels have been selected to meet the required structural strength and fatigue strength. Generally, multi-pass welding method such as FCA(Flux-Core Arc) welding has been used to join the thick plates. Considering the welding residual stresses, fatigue strength of the welded joints of thick plates should be assured since the residual stress influences the fatigue strength. This paper presents a numerical procedure to investigate the residual stress of structure joined by multi-pass FCA welding so that it can be incorporated into the fatigue strength assessment considering the effect of welding residual stress. The residual stress distribution is also measured by X-Ray diffraction method. The residual stress obtained by the computational model also has been compared with that of experiment. The results of FEA are in very good agreement with the experimental measurements.

• Journal of Ocean Engineering and Technology
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• v.24 no.2
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• pp.62-66
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• 2010

The goal of this work is to establish the reliability of FCA welded joints for high strength EH36-TMCP ultra thick plate. For this, heat conduction and thermo elasto-plastic analyses have been conducted on a multi-pass, X-groove, butt-joint model to clarify the thermal and mechanical behavior (residual stresses, magnitude of the stresses, and their production and distribution mechanisms) of the weld joint. In addition, the results of the welding residual stress obtained from thermo elasto-plastic analysis was verified and compared with results obtained by XRD analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5933-5938
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• 2014

In this study, the effect of varying the mixture gas during FCA welding was studied for an Atos 60 test piece. To examine the characteristics of welding, the weldability of the material was checked before welding and online monitoring was performed to examine the mechanical properties after welding. The mixture Ar 80% + $CO_2$ 20% at low speed gave very elegant beads with very little spatter. 100% $CO_2$ gave rise to high spatter generation. For Ar 80% + $CO_2$ 20%, the low current region due to the normal short circuits created spatter, which was more than double for 100% $CO_2$. This peak distribution occurred due to the instability of the arc. The tensile test result for Ar 80% + $CO_2$ 20%, Ar 90%+ $CO_2$ 10% and $CO_2$ 100% at 511MPa, 507MPa, and 469MPa showed that the yield strength was improved by 8.1 and 8.9% for 80%+ $CO_2$ 20% and Ar 90%+ $CO_2$ 10%, respectively, compared to 100% $CO_2$. The tensile test result at 622MPa, 609MPa, and 581MPa showed that the yield strength was improved by 7.0% for both the mixture gas compared to 100% $CO_2$.

• Journal of Ocean Engineering and Technology
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• v.26 no.5
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• pp.73-80
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• 2012

It is well known that a considerable amount of scatter is shown in experimental results relating to fatigue crack growth even under identical and constant amplitude cyclic loading conditions. Moreover, flux cored arc welding (FCAW) is a common method used to join thick plates such as the structural members of large scale offshore structures and very large container ships. The objective of this study was to investigate the macro- and microscopic observations of the fatigue crack growth (FCG) behavior of the FCAWed API 2W Gr. 50 steel joints typically applied for offshore structures. In order to clearly understand the randomness of the fatigue crack growth behavior in the materials of three different zones, the weld metal (WM), heat affected zone (HAZ), and base metal (BM), experimental fatigue crack growth tests for each of five specimens were performed on ASTM standard compact tension (CT) specimens under constant amplitude cyclic loading. Special focus was placed on the fatigued fracture surfaces. As a result, a different behavior was observed at the macro-level, depending on the type of material property: BM, HAZ, or WM. The variability in the fatigue crack growth rate for WM was higher than that of BM and HAZ.