• Proceedings of the KWS Conference
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• 2009.11a
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• pp.202-204
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• 2009

Erosion is a common failure mode of materials frequently encountered in plant and power industry. Although the erosion resistance of Fe-base alloy has been inferior to the other expensive materials, it is expected that the strain-induced martensitic transformation can impart high erosion resistance to Fe-base alloy. The key technology to develop Fe-base metal cored welding wire for erosion resistant overlay welding may include the strain-induced metallurgy for hardening rate control and the welding flux metallurgy for dilution control. Sophisticated studies showed that the strain-induced martensitic transformation behavior was related to the critical strain energy which was dependent on the alloy composition. Dilution and bead shape of overlay weld were proved to be affected by metal transfer mode during gas tungsten arc welding and elements in welding fluxes. It was considered that the highly erosion resistant Fe-base overlay weld could be achieved by precise control of alloy composition to have proper level of critical strain energy for energy absorption and welding flux formulation to have small amount of deoxidizing metallic elements for dilution.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1322-1327
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• 2007

Many automotive companies have tried to apply the aluminum alloy sheet to car body because reducing the car weight can improve the fuel efficiency of vehicle. In order to do that, sheet materials require of weldablity, formability, productivity and so on. Aluminum alloy was not easy to join these metals due to its material properties. Thus, the laser is good heat source for aluminum alloy welding because of its high heat intensity. However, the welding quality was not good by porosity, underfill, and magnesium loss in welded metal for AA5182 aluminum alloy. In this study, Nd:YAG laser welding of AA 5182 with filler wire AA 5356 was carried out to overcome this problem. The weldability of AA5182 laser welding with AA5356 filler wire was investigated in terms of tensile strength and Erichsen ratio. For full penetration, mechanical properties were improved by filler wire. In order to optimize the process parameters, model to estimate tensile strength by artificial neural network was developed and fitness function was defined in consideration of weldability and productivity. Genetic algorithm was used to search the optimal point of laser power, welding speed, and wire feed rate.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.792-795
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• 1996

In TIG welding of pipe, back bead size monitoring is important for weld quality assurance. Many researches have been performed on estimation of the back bead size by heat conduction analysis. However numerical conduction model based on many uncertain thermal parameters causes remarkable errors and thermomechanical phenomena in molten pool can not be considered. In this paper, filler wire feeding force in addition to weld current, wire feedrate, torch travel speed and orbital position angle is monitored to estimate back bead size in orbital TIG welding. Monitored welding process variables are fed into an artificial neural network estimator which has been trained with the monitored process variables (input patterns) and actual back bead size (output patterns). Experimental verification of the proposed estimation method was performed. The predicted results are in a good agreement with the actual back bead shape. The results are quite promising in that estimation of invisible back bead shape can be achieved by analyzing the welding parameters without any conventional NDT of welds.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.187-192
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• 2002

Applicability of laser micro welding process to the fabrication of medical devices was investigated. Austenitic stainless steel wire (SUS304) was spot melted and crosswise welded, which is one of the most possible welding process for the fabrication of medical devices, by using a Nd-YAG laser. Effects of welding parameters on the microstructure, tensile strength and corrosion resistance were discussed. In the spot melting, melted metal width decreased with decreasing the input energy and pulse duration. Controlling the laser wave to reduce laser noise which occurred in the early stage of laser irradiation made reasonable welding condition wider in the welding condition of small pulse duration such as 2ms. The microstructure of the melted metal was a cellular dendrite structure and the cell size of the weld metal was about 0.5~3.5 ${\mu}{\textrm}{m}$. Tensile strength increased with the decrease of the melted metal width and reached to a maximum about 660MPa, which is comparable with that for the tempered base metal. Even by immersion test at 318K for 3600ks in quasi biological environment (0.9% NaCl), microstructure of the melted metal and tensile strength hardly changed from those for as melted material. In the crosswise welding, joints morphologies were classified into 3 types by the melting state of lower wire. Fracture load increased with input energy and melted area of lower wire, and reached to a maximum about 80N. However, when input energy was further increased and lower wire was fully melted, fracture load decreased due to the burn out of weld metal.

• Transactions of Materials Processing
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• v.24 no.5
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• pp.317-322
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• 2015

A process for the concurrent welding and extruding of pipe was designed for continuous production of fin tubes. Unlike a conventional pipe extrusion, the new process is able to extrude a pipe continuously without limit of length by using spring type wire material. The current paper provides the basic research for welding during the extrusion using a spring type wire material. The object of the current study is to investigate the possibility that the spring type wire material could be extrude into a welded pipe. The appropriate extrusion ratio was selected through investigation of loads using computer simulations. As a result, experiments showed that pipe could be welded and simultaneously extruded with spring type wire material of aluminum. The tensile strength of the welded and extruded aluminum pipe can reach 80% of tensile strength of original aluminum feedstock.

• Laser Solutions
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• v.11 no.3
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• pp.16-20
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• 2008

The lap Joint welding of 6K21 aluminum sheets by Nd:YAG laser were performed with an aluminum 5183 filler wire or without a filler wire. The porosity of laser welding beads were observed through an optical microscope and X-ray photography with various levels of welding speed and gap size. The porosity was observed in the gap between upper and lower sheet near a heat affected zone when autogenous welding. Decrease of welding speed and use of AA5183 filler wire reduced porosity significantly.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2006.06a
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• pp.108-111
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• 2006

Recently, mobile information devices, such as cellular phone, PDA(Personal Digital Assistant, PDA) are getting smaller and thinner. Accordingly, ultra precision welding technology is required to manufacture the high performance system for use in the telecommunication industry. In this study, we propose the laser micro welding process. Using ytterbium fiber laser, a wide range of experiments have been carried out for the gold wire-to-gold thin film welding.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.4
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• pp.770-783
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• 2015

Lately, high production rate welding processes for Al alloys, which are used as LNG FPSO cargo containment system material, have been developed to overcome the limit of installation and high rework rates. In particular, plasma-metal inert gas (MIG) hybrid (PMH) welding can be used to obtain a higher deposition rate and lower porosity, while facilitating a cleaning effect by preheating and post heating the wire and the base metal. However, an asymmetric undercut and a black-colored deposit are created on the surface of PMH weld in Al alloys. For controlling the surface defect formation, the wire feeding speed and nozzle diameter in the PMH weld was investigated through arc phenomena with high-speed imaging and metallurgical analysis.

• Journal of Technologic Dentistry
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• v.36 no.4
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• pp.239-246
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• 2014

Purpose: The purpose of this study was to compare the tensile strength and mechanical properties of orthodontic wire joints made by gas soldering and laser welding, with and without filling material, to identify the effectiveness and potential clinical application of laser welded orthodontic wires. Methods: Three joint configurations of orthodontic wire were used: diameter 0.9 to 0.9 mm wire, diameter 0.9 to 0.5 wire and diameter 0.9 mm wire to band. The joints were made using three different methods: gas soldering, laser welding with and without filling material. For each kind of joint configuration or connecting method 7 specimens were carefully produced. The tensile strengths were measured with a universal testing machine (Zwick/Roell, Instron, USA). The hardness measurements were carried out with a hardness tester(Future-Tech Co. Tokyo, Japan). Data were analyzed by AVOVA(p= .05) and Turkey HD test(p= .05). Results: In all cases, gas soldering joints were ruptured on a low level on tensile bonding strength. Significant differences between laser welding and gas soldering(p< .05) were found in each joint configuration. The highest tensile strength means were observed for laser welding, with filling material, of 0.9 to 0.9 mm wire joint. Conclusion: In conclusion, the elastic modulus and tensile strength means of laser soldering with filling material were the highest, and the tensile strength means of laser soldering were higher than those of gas soldering.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.4
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• pp.41-47
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• 2000

In this study, the purpose finds out the best welding conditions for bonding of electric wire by ultrasonic welding. The material was plastic-insulating low-voltage-cabels for automobiles. The experiment varied the values of welding time and welding pressure and fixed the values of amplitude and energy. With the facts, the best condition for ultrasonic welding to achieve bonding exactly is gained according to the size of the cross-sectional area of the cable, and the adhesive intensity is greatly influenced by the variables of welding time and welding pressure. Also when the welding time and welding time and welding pressure increase as the cross-sectional areas of the cable increase the welding result in gained exactly.