• Proceedings of the KWS Conference
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• 대한용접접합학회 2000년도 특별강연 및 추계학술발표대회 개요집
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• pp.50-53
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• 2000

• Proceedings of the KWS Conference
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• 대한용접접합학회 2000년도 특별강연 및 추계학술발표대회 개요집
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• pp.324-326
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• 2000

• Journal of Welding and Joining
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• 제23권2호
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• pp.6-9
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• 2005

• Proceedings of the KWS Conference
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• 대한용접접합학회 2001년도 추계학술발표대회 개요집
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• pp.37-40
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• 2001

• Journal of Surface Science and Engineering
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• 제42권1호
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• pp.13-20
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• 2009

Friction stir welding(FSW) was developed as a new solid state welding technique by The Welding Institute (TWI). On the basis of FSW, a new processing technique, friction stir processing (FSP), has recently been developed. FSP has been applied to cast aluminum alloy to modify the microstructure to enhance mechanical characteristic. FSP is a new solid state processing technique for microstructural modification in metallic materials. FSP has been applied to aluminum alloy to modify the microstructure to enhance mechanical characteristic. In this study, we investigated optimum condition friction stir processing with the evaluation of mechanical characteristic for 5456-H116 Al alloy. The mechanical characteristics of base metal similar with in 15 mm/min, 250 RPM with full screw probe. This condition is concluded that optimum friction stir processing condition. The result of this investigation will be able to application for repair of welding part for aluminum ship.

• Transactions of the Korean Society of Machine Tool Engineers
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• 제16권6호
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• pp.29-36
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• 2007

The present study examined the mechanical properties of the friction welding of Ni-Cr-Mo to SM45C. Friction welding was conducted at welding conditions of 2,000 rpm, friction pressure of 100MPa, friction time of 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 seconds, upset pressure of 150MPa, and upset time of 3.0 seconds. When the friction time was 1.6 seconds, the maximum tensile strength of the friction weld happened to be 1,020MPa, which is 120% of the base material's tensile strength(850MPa). At the same condition, the maximum shear strength was 438MPa, which is equivalent to 103% of the base material's shear strength(425MPa). At the same condition, the maximum vickers hardness was Hv490 at Ni-Cr-Mo nearby weld interface, which is higher Hv40 than condition of the friction time 0.8 seconds, and the maximum vickers hardness was Hv305 from weld interface of SM45C, which is higher Hv12 than condition of the friction time 0.8 seconds. The results of microstructure analysis show that the structures of two base materials have fined and rearranged along a column due to heating and axial force during friction, which has affected in raising hardness and tensile strength.

• Journal of Welding and Joining
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• 제33권2호
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• pp.23-31
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• 2015

Stainless steel is used in automobile muffler and exhaust systems. However, in comparison with other steels it has a high thermal expansion rate and low thermal conductivity, and undergoes excessive thermal deformation after welding. To address this problem, we evaluated the use of arc brazing in place of welding for the processing of an exhaust system, and investigated the parameters that affect the joint characteristics. Muffler parts STS439 and hot-dipped Al coated steel were used as test specimens, and CuAl brazing wire was used as the filler metal for the cold metal transfer (CMT) welding machine, which is a low heat input arc welder. In addition, a Box-Behnken design of experiment was used, which is a response surface methodology. The main process parameters (current, speed, and torch angle) were used to determine the appropriate welding quality and the mechanical properties of the brazing part was evaluated at the optimal welding condition. The optimal processing condition for arc brazing was 135A current, 51cm/min speed and $74^{\circ}$ torch angle. The process was applied to an actual exhaust system muffler and the prototype was validated by thermal fatigue, thermal shock, and endurance limit tests.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제25권11호
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• pp.1813-1819
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• 2001

Partial penetration welding Joint defines that groove welds without steel backing, welded from on side, and groove weeds welded from both sides but without back gouging, that is. it has an unwelded portion at the root of the weld. In this study we analysed fur residual stress and displacement distribution on partial penetration welding condition of thick plate metal. For 25.4mm thick plate, theoretical residual stress and displacement analysis by finite element method using ABAQUS was carried out and compared with the experimental result using hole-drilling method. In results of the condition of partial penetration, it appeared that longitudinal stress at welding area was a little difference and transverse stress did not have any effect by partial penetration multi-pass welding. From a point of welding distortion in partial penetration multi-pass welding, it seemed to be better to control root face smaller than 6.35mm.

• Journal of Power System Engineering
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• 제15권2호
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• pp.61-68
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• 2011

This paper investigates the tensile properties of the friction stir welded joints of Al 7075-T651 aluminum plate according to the welding conditions. A 7075-T651 aluminum alloy plate with a thickness of 6.0 mm was used in this investigation. For the friction stir welding (FSW) process, a tool with shoulder diameter of 20 mm and probe diameter of 9 mm was used. The rotation speed and traverse speed conditions were changed in this study, the other welding conditions are constant. The welding direction was aligned with the material rolling direction, and dimension of the FSW plate were $250{\times}100{\times}6\;mm$. As far as this work is concerned, the optimal FSW conditions are determined as the rotation speed, 600 rpm and traverse speed 0.8 mm/sec or the rotation speed, 800 rpm and traverse speed 0.5 mm/sec.

• Journal of Welding and Joining
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• 제26권1호
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• pp.63-68
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• 2008

This paper has aimed to prevent excessive heat input by controlling arc distribution and heat input capacity with pulse GTAW in order to improve weld quality in 0.08mm pressure gauge diaphragm and flange welding parts. A design of experiment was designed using Box-Behnken method to optimize a welding process. The pulse GTAW parameters such as pulse current, base current, pulse duty, frequency and welding speed were set to input variables while hydraulic pressure that represents welding characteristics in diaphragm and flange joint were set to output variables. Based on the test result, a second regression equation was obtained between input and output variables and turned out significant. Besides, an influence of parameters has been confirmed through response surface analysis using the second-order regression equation and optimum welding condition was obtained through a grid-search method. The optimum welding condition was set to pulse current 84.4(A), base current 29.6(A), pulse duty 58.8(%), frequency 10(%), and welding speed 596(mm/min). Then, decent bead shape was acquired with no excessive heat input under the $2.3kgf/cm^2$ of hydrostatic pressure.