• Laser Solutions
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• v.14 no.3
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• pp.12-16
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• 2011

In automotive industry, because of the consideration of fuel economy, lightweight alloys have been adopted and are expected to be extensively used in the future. Magnesium alloys are among the promising materials, due to their lightweight and good mechanical properties. This study is related to the laser weldability of AZ31B magnesium alloy, an all-purpose wrought alloy with good strength and ductility. A 4kW Nd:YAG laser was used to join AZ31B sheet, and the effects of welding parameter on the quality of lap-welded joints were investigated. As a result of this study, the optimal condition was obtained, and the effect of gap distance was also revealed on the porosity control.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.298-300
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• 2006

• Journal of Welding and Joining
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• v.29 no.3
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• pp.82-88
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• 2011

With a tendency for the application of thin magnesium alloy plates in portable electronic equipment such as cell phone and notebook PC, there is a requirement to develop a welding technology for the lap welding of these thin magnesium alloy. This paper presents the single pulsed laser welding of AZ31B magnesium alloy. The effects of fiber types and parameters such as peak power and pulse width on laser weldability were investigated. The results show that weld defects, especially solidification crack, were always generated in the weld. These defects couldn't be controlled by the simple square pulse, but could be improved through the application of variable pulse. It is because that variable pulse has effect of solidification delay by dropping peak power gradually.

• Journal of Welding and Joining
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• v.24 no.3
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• pp.22-26
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• 2006

It is necessary to investigate the welding performance and fracture resistance of welding part in structure. This study presented a most suitable condition of welding process for butt and lap joints by $CO_2$ arc welding which is widely used in the vehicle structure. Also it was conducted to tensile and fatigue test under various welding conditions. For butt and lap joints, the best conditions of welding voltage and current were 30V and 320A, respectively, in 3.2 and 4.5 mm thick steel plate. Under this condition it could be taken the highest tensile strength and fatigue strength, and a good bead appearance.

• Journal of Welding and Joining
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• v.26 no.5
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• pp.49-59
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• 2008

Hastelloy C-276, corrosion resistant alloy at high temperature, is used in chemical plant and power generation industry. In this study, process parameter of laser welding for welding property in Hastelloy C-276 using a continuous wave Nd:YAG laser was studied. As the result of experiment, laser welding did not show segregation or crack at heat affected zone compared to conventional GTWA welding. The melting zone showed cell dendritic structure along with welding line. In addition, planer front solidification is occurred from welding structure, and it was progressed to cellular solidification. Optimal process parameter for butt welding was 1.2kW and 2.0 m/min for laser power and welding speed, respectively. While heat input, output density, tensile stress, and longitudinal strain was $441.98{\times}103$ J/cm2, $29.553{\times}103$ W/cm2, 768 MPa, and 0.689, respectively. Lap welding of the same material showed greater discrepancy in tensile property during 1 line and 2 line welding. For 1 line welding, tensile stress was about 320 MPa, and 2 line showed slightly larger tensile stress. However, strain was decreased by 20%. From this result, lap welding of the same material, Hastelloy C-276, with 2 line welding is considered to be more effective process than 1 line welding with consideration of mechanical property.

• Journal of the Korean institute of surface engineering
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• v.42 no.6
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• pp.294-300
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• 2009

The Friction Stir Welding (FSW) has mainly been used for making butt joints in Al alloys. The development of Friction Stir Lap Welding (FSLW) would expand the number of applications. In this study, for effective application on thin aluminum alloy lap joint, non-heat treatment A5052 alloys were joined by FSLW with the length of probe 2.3 mm and 3.0 mm. Investigating the characteristics of joint area showed the results were as below ; When the length of probe was 2.3 mm, good joint area was formed at all welding condition except for 600 rpm-700 mm/min. In the case of 3.0 mm probe length, there was formed good joint area without defects at 1500 rpm-100 mm/min. The width of joint area, position and size of defects were very important factors for FSLW, due to heat input and stirring intensity.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.101-107
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• 2003

Since stainless steel sheets have good mechanical properties, weldability, appearance and corrosion resistance, they are commonly used as one of the structural materials of the railroad cars or the commercial vehicles which are manufactured by the spat welding. Among the many kinds of spot welded lap joints, it can be found that multi-lap joints are employed in their body structure. But, fatigue strength of these joints is lower than that of base metal due to high stress concentration at the nugget edge of spot weld and is considerably influenced by welding conditions as well as the mechanical and geometrical factors. Thus, it is necessary to establish a reasonable and systematic design criterion for the long life design of the spot-welded body structures. In this paper, the stress distribution and deformation around the spot-welded multi-lap joints subjected to tensile shear load was numerically analyzed. Also, the $\Delta$P-Nf curve was obtained by fatigue tests. Using these results, $\Delta$P-Nf curves were rearranged in to the ${\Delta}{\sigma}$-Nf relation with the maximum stress at nugget edge of spot weld.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.6
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• pp.728-735
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• 2003

This paper shows the possibility of performing Lap joint using the friction stir welding with $2mm^t$ aluminum alloy plate and the determination of tool-dimensions for FSW in milling machine. This research also is reported on obtaining the tensile-shear strength, 91.3 (MPa) and the energy absorption, 26.3 (J) for Lap jointed specimen. The optimal tool-dimensions and method for Lap joint using FSW is as follows; each diameter of shoulder and pin is $9\phi(mm) and 3\phi(mm)$, the length of pin is 3.6(mm), Pressing the shoulder of tool into original base metal is not reasonable.

• Journal of Welding and Joining
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• v.32 no.6
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• pp.56-63
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• 2014

To develop and understand dissimilar metals joining of Stainless steel and Copper, ultra-high speed laser lap welding was studied using single mode fiber laser in this study. SUS304 and Cu have large differences in materials properties, and Cu and Fe have no intermetallic compounds by typical binary phase of Cu and Fe system. In this study, ultra-high speed lap welds of SUS304 and Cu dissimilar metals using single-mode fiber laser was generated, and weldability of the weld fusion zone was evaluated using a tensile shear test. To understand the phenomenon of tensile shear load, weld fusion zone of interface weld area and fracture parts after tensile shear test were observed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis system. And it was confirmed that Cu was easily melting and penetrating in the grain boundaries of SUS304 because of low melting temperature. And high thermal conductivity of copper occurred dissipate heat energy rapidly. These properties cause the solidification cracking in weld zone.

• Journal of Powder Materials
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• v.20 no.4
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• pp.302-307
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• 2013

A5J32-T4 and A5052-H32 dissimilar aluminum alloy plates with thickness of 1.6 and 1.5 mm were welded by friction stir lap welding (FSLW). The FSLW were studied using different probe length tool and various welding conditions which is rotation speed of 1000, 1500 rpm and welding speed of 100 to 600 mm/min and material arrangement, respectively. The effects of plunge depth of tool and welding conditions on tensile properties and weld nugget formation. The results showed that three type nugget shapes such as hooking, void, sound have been observed with revolutionary pitch. This plunge depth and material arrangement were found to effect on the void and hooking formation, which in turn significantly influenced the mechanical properties. The maximum joint efficiency of the FSLWed plates was about 90% compared to base metal, A5052-H32 when the A5052-H32 was positioned upper plate and plunge depth was positioned at near interface between upper and lower plates.