• The Journal of the Petrological Society of Korea
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• v.18 no.3
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• pp.195-209
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• 2009

Juwangsan area($107.4km^2$) has been designated as the twelfth National Park in 1976, because it has magnificent aspect and seasonally spectacular landscapes. Juwang valley($9,177.5m^2$) has been designated as Noted Scenery No. 11 in 2003, because it has the same topographical landscape as rock domes, rock cliffs, caves, waterfalls and plunge pools. The most spectacular landscapes are exhibited in the densely welded zone of the Juwangsan Tuff. The rock cliffs generated from vertical joints in the densely welded zone, in which there are the same many rock cliffs as Geupsudae, Haksodae, Sinseondae, Mangwoldae, Giam and Byeongpungbawi, three caves such as Juwanggul, Mujanggul and Yeonhwagul in the cliff. The cliffs and caves are landscapes that were generated from vertical joints in the densely welded zone, and the rock domes and waterfalls are landscapes of erosional vertical joint planes in the zone. The vertical joints are columnar joints formed during cooling of the Juwangsan Tuff. Therefore the topographical features cause the cooling columnar joints that are vertically intersected in the densely welded zone of the Juwangsan Tuff.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.3
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• pp.30-34
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• 2006

We investigated fatigue crack growth behavior in laser-welded sheet metal caused by a single applied overload The fatigue specimens were made using butt jointed cold rolled sheet metal that was welded with a $CO_2$ laser, The effects of the specimen thickness and overload ratio were determined from fatigue crack propagation tests, These tests were performed in such a way that the fatigue loading was aligned parallel to the weld line while the crack propagated perpendicular to the weld line, Overload ratios of 1.0, 1.5, and 2. 0 were applied near the tip of the fatigue crack at points located 6, 4, and 2 mm from the weld line. The specimens were either 0.9 or 2.0 mm thick. The size of the plastic zone at the crack tip due to the single applied overload was also determined using finite element analysis.

• Steel and Composite Structures
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• v.1 no.3
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• pp.269-282
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• 2001

In this paper the results of an experimental program devoted to the assessment of the cyclic behaviour of full scale, European type, beam-column subassemblages with welded connections are presented. Six tests (five cyclic and one monotonic) have been carried out on three different series of specimens, encompassing a total of eighteen tests. The three specimen series have been designed with the aim of defining the effect of the column size on the connection behaviour, under different applied loading histories. The tests have evidenced the effect of the column size and panel zone design and of the applied loading history on the cyclic behaviour and failure modes of the connections.

• Transactions of the Korean Society of Mechanical Engineers
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• v.6 no.3
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• pp.232-238
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• 1982

The behavior of corner crack propagation by unidirectional plane bending fatigue was investigated in the butt welded joints of SS41 and SM50 steel plates including an edge through-thickness notch. The properties of fatigue crack propagation were inspected in the weld metal, heat-affected zone, and base metal of the welded joints. Main results obtained are as follows; (1) When a plate with an edge through-thickness notch is loaded by plane bending fatigue in indirection, the 2 variant corner cracks on the upper and lower edge of the plate are initiated and propagated respectively from the notch. (2) In case of a specimen containing a corner crack, it is more reasonable to estimate the crack propagation rate by area of fracture surface than by crack surface length. (3) The rate of fatigue crack propagation becomes faster in the following order; weld metal, heat-affected zone, and base metal. (4) The specimen including reinforcement shape is rapidly failed throughout bond due to effect of its shape when the repeated load exceeds a certain cycle.

• Journal of the Korean institute of surface engineering
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• v.42 no.1
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• pp.34-40
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• 2009

In the study, it was carried out dissimilar metal welding on materials for Al ship. The electrochemical and mechanical characteristics evaluated for specimen welded by ROBOT. The hardness of welding zone is lower than those of heat affected zone and base metal. At the result of tensile test, the specimen welded with ER5183 welding material presented excellent property compared with ER5556. The polarization trend for the base metal and welding metal showed the effects of concentration polarization due to oxygen reduction and activation polarization due to hydrogen generation. At the Tafel experiments result, the corrosion density in welded with ER5183 welding material presented the lowest value.

• Journal of the Korean Society of Safety
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• v.2 no.3
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• pp.5-11
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• 1987

In this study, a mild steel (SS41) of the carbon steel, a spring steel (SUP-9), and stainless steel (SUS 304) of the special gceel, etc, are adopted as the experimental materrials and are weded by $CO_2$(SS41, SUP-9), TIG (SUS304), respectively. And the residual stress distribution and fracture behavior at the welded zone are examined according to annealing temperatures of four section involving as welded. As a consequence, the best annealing temperatures that the residual stress is removed enough and mechanical properties are very suitable are at 90$0^{\circ}C$ (SS41), 75$0^{\circ}C$ (SUP-9), 110$0^{\circ}C$ (SUS 304), respectively.

• International Journal of Railway
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• v.2 no.4
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• pp.175-179
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• 2009

The welding deformation and its prediction method at the HAZ (Heat-Affected Zone) are presented in this paper. The inherent strain method is well known as analytical method to predict welding deformation of large scale welded structure. Depend on the size of welding deformation in welding joints, the fatigue life, the stress concentration factor and the manufacturing quality of welded structure are decided. Many welded joints and its manufacturing control techniques are also required to railway rolling stock and its structural parts such as railway carbody and bogie frame. Proposed methods in this paper focus on the two different the inherent strain area at HAZ. This is main idea of proposed method and it makes more reliable result of welding deformation analysis at the HAZ.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.152-154
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• 2005

Austenitic stainless steel has good weldability but is sensitive to hot cracking such as solidification crack and liquation crack. In this study, the specimens of dissimilar metals made between austenitic stainless steel and Al-brass were welded by GTAW process using four different filler metals. Cracks were detected in the heat-affected zone of the stainless steel when welded with CuAl, CuSn and NiCu filler metals, but no cracks were detected a Ni filler metal was used. The cracks propagated along the grain boundary in the heat affected zone near the fusion line to base metal of 316L stainless steel. The cracks were located inside the weld bead with very fine hairline crack. All cracks initiated at the fusion line and moved forward in the base metal. From energy dispersion spectroscopy (EDS), Cu peak was detected only in the crack-opening area.

• International Journal of Korean Welding Society
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• v.1 no.2
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• pp.45-50
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• 2001

This paper presents application of neutron diffraction technique to the measurement of residual stresses in the T-type 20 m thick welded stainless steel plates(100$\times$50 $mm^2$ and 50$\times$50 $mm^2$). The High Resolution Powder Diffractormeter of the Korea Atomic Research Institute was utilized in the measurement. The power of nuclear reactor was 24 MWt and the measured reflection in the 220 plane (2$\theta$）was $92.66^{\circ}$. Poisson ratio of 0.265 and elastic constant of 211 GPa were applied to the calculation of stresses and strains. Three directional components such as normal, transverse, and longitudinal stresses were measured. The results showed that three components were tensile and became compressive along the y axis in the zone away from the welded center. The compressive stresses became tensile in the zone away from the center line of x axis. This may be due to the balance effect caused by the net stress to keep the specimen shape flat.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.1
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• pp.9-15
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• 2024

In this study, the mechanical properties of friction stir welded A6061-T6 were evaluated. This material is used as a battery pack case material for electric vehicles. The Vickers hardness, tensile strength, and yield stress of the friction stir welding (FSW) specimen were all smaller than those of the base metal specimen. As the heat input increased, the nugget zone widened, and there were differences in hardness according to the base metal zone, heat affected zone, thermal-mechanical affected zone, and nugget zone. Mechanical properties were not proportional to heat input, and the thermal-mechanical affected zone on the advancing side was the smallest in all conditions. This is because the material flow speed increased on the advancing side, where the welding direction and the tool rotation direction were the same, forming a distinct boundary with mechanical deformation.