• Journal of Welding and Joining
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• v.21 no.2
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• pp.57-63
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• 2003

Since new types of vehicles or structures made from thin aluminum alloy are under rapid development and some products are already on the market, welding of aluminium sheet is increasing. MIG(Metal Inert Gas), MIG-Pulse, TIG(Tungsten Inert Gas) welding are the typical Ai welding. MIG welding has the advantage of high speed, but it is difficult to apply to the thin plate, because of bum-through by the high heat input and spatter. MIG-Pulse welding can weld without spatter and burn-through, but when the gap exists at the welding joint, there is quite a possibility of bum-through. TIG welding is difficult to weld at a high speed. AC Pulse welding alternates between DCEP(Direct Current Electrode Positive) and DCEN(Direct Current Electrode Negative). DCEN is higher wire melting rate than DCEP, while lower temperature of droplet than DCEP. In AC Pulse welding, far fixed welding current, wire melting rate increases as the EN ratio increases. For fixed wire feed rate, welding current decreases as the EN ratio increases. Because of these features, the temperature of droplet, the depth of penetration, the width of bead decrease and the reinforcement height increases as EN ratio increases, and these are able to weld at a high speed, lower heat input. It is the purpose of this study that design of AC pulse current waveform for MIG welding of Al sheet and estimation of output characteristic.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.269-274
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• 1999

Aluminum alloy has not only physical characteristic of very high activated high thermal conductivity and high thermal coefficient expansion but also special characteristic of great difference fusibility of hydrogen between liquid and solid phase. Because of these reasons, Aluminum welding is very different. Therefore, only MIG welding method should be applied instead of other welding methods. In this study, in order to select optimal welding conditions, it has been to investigate the effectiveness on the welding current, welding speed, flow rate of gas and welding voltage to occurrence of spatters, external shape of bead, state of penetration and width and hight of bead by using filer metal of A15356(dia. 1.21mm) on the base material of A16061.

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.247-251
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• 2001

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.88-91
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• 2001

New type of vehicles made from thin aluminum alloy are under rapid development and some product are already on the market, but when welding sheet metal joint of aluminum alloy, the main problem are burn-through by the high heat input. The purpose of this study, it is to prevent the burn-through and to shallow penetration that AC pulse welding has diminish the penetration and to lower the droplet temperature at Al sheet metal welding. In this study, we observed the bead appearance and whether it was appeared burn through or not , as the variation of the root gap in the lap and butt-joint welding process.

• 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 Welding and Joining
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• v.29 no.4
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• pp.30-34
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• 2011

• Journal of Ocean Engineering and Technology
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• v.24 no.6
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• pp.92-96
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• 2010

Recently, the application of aluminum alloys has been increasing for lightweight and high quality transport vehicles. Therefore, the proposal has been made to apply high speed hybrid welding methods to the marine grade aluminum alloy (A5052) used for shipbuilding by combining a 3-KW CW Nd : YAG laser and the MIG welding process. In this study, the characteristics of the welding parameters were investigated for a hybrid butt joint. This paper also describes the determination of the heat distribution in a weldment and the welding residual stress using a finite element method. Mechanical experimentation was also used to ascertain the reliability of the weldment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.78-81
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• 2005

The aluminum Subframe for automobile was developed using hybrid process, i.e. extruforming and press forming. To achieve a $30\%$ weight reduction compared with convensional steel subframe keeping satisfactory performance, the design of cross-section of extrusion part was initiated, then forming simulation was performed and the final design was determined. In addition, we tried to estibilish proper aluminum welding conditions for good penetration depth and few pore defact, finally the prototype of aluminum subframe was assembled using MIG welding method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.653-659
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• 2010

Friction stir welding results in low distortion and high joint strength compared with other welding procedures, and is able to join all aluminium alloys that are not considered as virtually weldable with classical liquid state techniques. The comparative study on high cycle fatigue properties between A16005-T6 friction stir welds and MIG weld joints have been performed and fracture mechanisms for the fatigue specimens were investigated. Although mechanical properties are lower than the corresponding base material, FSW joints of A16005-T6 become higher at tensile and fatigue strength in comparison with the traditional fusion weld(MIG). The fracture surfaces of FSW and MIG fatigue specimens cleary show different aspects of the fracture morphology. MIG weldments were characterized by voids and cleavage(brittle fracture) but FSW specimens showed the presence of ductile fracture surface.

• Journal of Welding and Joining
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• v.29 no.1
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• pp.59-64
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• 2011

Al6082-T6 is widely used because of its corrosion resistance and excellent strength. HAZ softening occurs in MIG welding process for this aluminium alloys because this aluminium alloy is heated to higher temperature than its aging temperature during welding. Therefore, low heat input and minimum standard deviation of heat input are required for narrow HAZ width and, for higher strength of welds. In this study, Al6082-T6 was used to examine for HAZ softening with various heat input in aluminium MIG welding. For weldments, micro hardness was measured and tensile test was carried out. Minimum hardness was increased at high speed welding such as 80cm/min and 120cm/min in welding speed comparing with 40cm/min. Also, in case of high speed welding such as 80cm/min and 120cm/min, tensile strength of weldments was increased about 10% comparing with low speed welding(40cm/min).