• Journal of Welding and Joining
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• v.15 no.2
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• pp.64-71
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• 1997

In order to define the effects on shapes of welding joint, during Post Welding Heat Treatment (PWHT), we have carried out numerical analysis on the several test pieces by using computer program which was based on thermal-elasto-plastic-creep theories for the study. And then, welding residual stresses after PWHT were measured same test-pieces to compare with the results of numerical analysis. The main results obtained from this study is as follows: 1) The distribution modes of welding residual stresses are same on the all test pieces after and during PWHT by the both sides (measurement and numerical analysis). 2) The mechanical difference for change the thickness of plate and bevel angle are not appeared. 3) In a mechanical point of view (like material quality test, welding deformation etc.), manimum bevel angle (40$^{\circ}$.) is more suitable than maximum bevel angle (70$^{\circ}$).

• Journal of Welding and Joining
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• v.4 no.2
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• pp.30-39
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• 1986

In manufacturing of pipe walls for boiler units, distortion can result in pipe-web-pipe joints from the nonuniform expansion and contraction of the weld metal and the adjacent base metal during heating and cooling cycle of the welding process. In this study, the stresses and strains during longitudinal welding of the plate-to-pipe joint were investigated. Using the method of successive elastic solution, longitudinal stresses and strains during and after welding were calculated from the information of temperature distributions obtained by Rosenthal's equations. In order to confirm the validity of the numerical results, the temperature and residual stress distributions were measured and compared with the calculated results. In spite of some assumptions, the one-dimensional analytical results of residual stresses were in fairly good agreement with the experimental ones. The residual stresses due to welding of plate-to-pipe joints are tensile near the weld line and compressive in the base metal as in the welding of plates. the amount and distribution of residual stresses were deeply dependent on the heat input ratio of the plate and pipe.

• Journal of Welding and Joining
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• v.28 no.4
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• pp.49-54
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• 2010

Stainless steel sheets are widely used as the structural material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the GMAW (gas metal arc welding). For fatigue design of GMA welded joints such as fillet and plug, ring type joint, it is important to obtain optimum design factor information on GMA welded joints. in this paper, analysis approach for fatigue test using design of experiment are evaluated optimum factor in GMA welded joint type and geometrical parameters of materials. Using these results, that factors applied to fundamental information for fatigue design.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.207-210
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• 2003

The purpose of this work is to find an appropriate welding approach for rotor assembly of a marine turbocharger. The friction welding and laser welding of dissimilar materials, IN713LC and SCM440 were investigated. The quality of the welded joints obtained from two welding processes was evaluated by microstructure observation, micro-hardness and tensile tests. The friction welded joint indicated a good bonding structure in the weld interface. On the other hand, the laser welded joint showed the weld defects and non-welded area in the weld interface.

• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.62-66
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• 2002

The Friction Stir Welding (FSW) is a new joining method that was developed at The Welding Institute (TWI) in England in 1991. It applied heating by the rotational friction and material plastic flow. It was developed as a new joining method to solve the problems of epochally in the welding of Al alloys. In the study, 6000series of Alloy composed of Al-Mg-Si, one of the Al alloys that are utilized for shipbuilding and construction, is selected as a specimen and the numerical is executed against the welded zone of FSW. The material used in this study had the unique properties of strength and anti-corrosion, but since the welded joint of this material is easily softened by the welding heat, FSW is executed and the numerical analysis is carried out around the joint. To examine the mechanical behaviors and properties, F.E.M analysis is executed and the developed thermal-elastic-plastic finite analysis are used.

• Journal of Welding and Joining
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• v.11 no.4
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• pp.44-56
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• 1993

The arc welding processes are substantially nonlinear, in addition to being highly coupled multivariable systems, Frequently, not all the variables affecting the welding quality are known, nor may they be easily quantified. From this point of view, decoupling between the welding parameters from the welding quality is very difficult, which makes it also difficult to control the welding parameters for obtaining the desired welding quality. In this study, a neural network based on the backpropagation algorithm was implemented and adopted for the selection of gas metal arc welding parameters of the fillet joint, that is, welding current, arc voltage and welding speed. The performance of the neural network for modeling the relationship between the welding quality and welding parameters was presented and evaluated by using the actual welding data. To obtain the optimal neural network structure, various types of the neural network structures were tested with the experimental data. It was revealed that the neural network can be effectively adopted to select the appropriate gas metal arc welding parameter of fillet joints for a given weld quality.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.836-839
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• 1997

In recent years, much progress has been made in the automation of welding coped with a variety of highly flexible sensors. Among these sensors, only the eddy current sensor can detect the center location of the butt joint whose gap distance is zero. Thus, in this study the eddy current sensor is used to develop a robust and useful joint tracking system. The developed system is tested to qualify the performance of the system and seam tracking algorithm is proposed and two simulation are executed to show the performance of the proposed tracking algorithm.

• Journal of Welding and Joining
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• v.6 no.1
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• pp.28-34
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• 1988

The fatigue test was carried out to evaluate the fatigue characteristics of the accelerated cooled (ACC) TMCP steel and its welded joint. From this study, it was confirmed that ACC TMCP steel has higher fatigue strength than conventional steels. After welding, however, the fatigue strength of ACC TMCP steel was deteriorated associated with HAZ softening when weld reinforcement was removed. On the other hand, with weld reinforcement, there is no effect of HAZ softening on the fatigue strength of welded joint because it is strongly dependant on the detail weld geometry i.e., stress concentration factor. Accordingly the fatigue strength of actual welded joint increases with decreasing the stress concentration factor of welded joint, regardless of HAZ softening.

• Korean Journal of Materials Research
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• v.14 no.1
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• pp.1-8
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• 2004

Laser weldability of aluminized steels for deep drawing application has been investigated. Test coupons for Nd:YAG laser welding and $CO_2$ laser welding were prepared trom the commercial steels. According to the test results, total penetration and back bead width of aluminized steels were sensitive to the welding conditions. Bead width at the half thickness of the overlap joint, however, was rather constant. Laser weldability of aluminized steels was superior to that of zinc coated steel. Weld microstructure revealed that overlap zone adjacent to the fusion line was filled with coated materials, which was thought to be desirable to protect weld from crevice corrosion. The aluminum coated materials was also found in the weld metal. Practically no spattering was observed in the laser welding of aluminized steels even when the welding was performed without joint gap. In the welding of zinc coated steel, however, spattering was so severe that it was difficult to get the acceptable weld. Bead quality of aluminized steel laser weld was smooth and stable.

• Journal of Welding and Joining
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• v.9 no.1
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• pp.48-57
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• 1991

Welding of dissimilar materials is an area of growing importance in the automotive, aerospace, electronics medical and other domestic appliance industries. This study investigated the ultrasonic welding of dissimilar polymers. Two amorphous and two semicrystalline polymers were used, utilizing all possible welding combinations. For each combination of dissimilar materials, the weldabilitys of the joint was evaluated as a function of weld time, amplitude of vibration and pressure. The joint was also examined microscopically to analyze the melting and flow of the materials. It was generally around found that welding of amorphus polymers resulted in very poor joints. Welding of the amorphous polymers together and welding of the semicrystalline polymers together produced good joints.