• Journal of Welding and Joining
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• v.9 no.4
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• pp.69-74
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• 1991

The Plasma Arc Cutting Method using high density and hight temperature beam is well applicable to the cutting of the nonferrous metal (Al alloy ) and stainless steel which are unable to be cut by the use of the oxy-fuel gas. This study focalizes on the cutting phenomena of the plate of (mm) thickness, since the cutting phenomena of thick plates have been rather thoroughly studied. In this study the cutting groove, adhesive phenomena of dross, surface roughness were measured according to the variation of cutting speed and compared with the case of mild steel plates. The result showed that the kerf width variation of Al alloy was similar to the case of mild steel, while that of the stainless steel differed from the mild steel. In the adhesive phenomena of dross, 6(mm) thick plates of Al alloy showed a difference from those of thick plates, but the stainless steel was similar to thick plates. The surface roughness variation of Al alloy wias minimum at 67 cm/min, while that of stainless steel was at 30cm/min.

• Journal of Welding and Joining
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• v.28 no.1
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• pp.47-53
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• 2010

In recent time there is vigorous requirement for the use of thick steel plate in various industrial fields including shipbuilding industry. Especially, with the continual increases in marine transportation volumes on a global scale, the steel of container ships has become thicker and thicker with the increased size of ships. In addition, the brittle crack arrestability of heavy thick plates was big issue, in recently. In this study, crack arrest test were conducted in order to investigate the crack arrestability of thick plates for shipbuilding steels, where test plate thicknesses were 50mm and 80mm. This paper introduces the brittle crack arrestability of heavy thick plates with thickness effect for shipbuilding.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.3-5
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• 2007

In recent time there are vigorous requirement for the use of thick steel plate in various industrial fields including shipbuilding industry. Especially, with the continual increases in marine transportation volumes on a global scale, the steel of container ships have become thicker and thicker with the increased size of ships. In addition to, the brittle crack arrestability of heavy thick plates were big issue, in recently. In this study, crack arrest test were conducted in order to investigate the crack arrestability of thick plates for shipbuilding steels, where test plate thickness were 50mm and 80mm. This paper introduce the brittle crack arrestability of heavy thick plates for shipbuilding.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.169-176
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• 2018

Removal of angular deformation induced during the welding of butt joints in thick steel plates needs expert skill and is costly. To reduce deformation, proper joint designs are studied with a prediction of deformation prior to welding. However, as the thickness of a plate increases, a predictive analysis of the welding process is more difficult, especially if there is an increase in the number of welding passes in the joint. In this study, a numerical model with the finite element method (FEM) was developed to analyze the angular deformation in the multi-pass welding of butt joints of plates made of AH32 steel that had a thickness of up to 100 mm. A series of numerical simulations were then performed based on the developed model to predict the deformations for thick plates. With the results obtained by the analyses, this study suggested optimal X-shape grooves for the butt joints of thick plates to minimize the angular deformation. As the thickness of the plate increased to 100 mm, the ratio of the depth of the front-side groove to that of the back-side groove should be gradually increased to nearly 1:3.

• Steel and Composite Structures
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• v.21 no.3
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• pp.517-536
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• 2016

Thick steel plate is commonly found with mega steel structures but its properties have not been fully explored. Grade Q345GJ-C steel plate with thickness ranging from 60 mm to 120 mm are studied in this paper. Both the static and cyclic performance of material in different directions (horizontal and through-thickness directions) and locations (outer surface, 1/4 thickness and mid-depth) are experimentally obtained. The accumulative damage during cyclic loading is also calculated by using bilinear mixed hardening (BMH) constitutive relationship together with the Lemaitre's damage model. Results show that the static properties are better at the outer surface of thick steel plates than those at mid-depth. Properties in through-thickness direction are similar to those at mid-depth in the horizontal direction. The cyclic performance at different locations of a given plate is similar within the range of strain amplitude studied. However, when damage parameters identified from monotonic tensile tests are included in the numerical simulation of cyclic loading tests, damage is found accumulating faster at mid-depth than close to outer surface.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.92-93
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• 2006

In recent time there are vigorous requirement for the use of thick steel plate in various industrial fields including shipbuilding industry. Application of TMCP steel plates, especially, is increase progressively. As a welding process for thick steel plate assembly high heat input welding method is used. However, HAZ softening of TMCP steel plates has a possibility to reduce the strength of welded joint. In this study, therefore, tensile strength of TMCP welds had softened HAZ was examined using numerical calculation and experiment.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4637-4641
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• 2023

For nuclear decommissioning applications, a study was conducted to investigate the feasibility of using a laser for long-distance cutting in complex structures. Cutting tests were performed on stainless steel plates with thicknesses ranging from 10 mm to 30 mm at distances of 300 mm-700 mm from the laser head, using a laser power of 6 kW. Remarkably, the 10 mm and 20 mm thick stainless-steel plates were successfully cut at a distance of 700 mm from the head. Based on the trends observed in the results, it is anticipated that these thicknesses could also be cut at distances of approximately 1 m. Similarly, the 30 mm thick stainless-steel plate was effectively cut at a distance of 500 mm from the head. To evaluate the amount of secondary waste generated, the kerf width was measured. Due to the long-distance cutting, the average kerf width ranged from 6 mm to 16 mm. Despite the wider kerf width, long-distance cutting holds promise for efficiently handling hard-to-reach targets in nuclear decommissioning scenarios.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.103-103
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• 2009

As the size of containership increased over 14,000TEU, thick steel plate with high strength has been used. The plate thickness increased over 70mm and yield strength of the steel plate was around $47kg_f/mm^2$. Many researchers reported that the thick welded plate has low crack arrest toughness. They noticed the crack arrest ability is dependent on the plate thickness. In other words, brittle crack propagates straightly along the welded line and make abrupt fracture in the thick plate which causes low $K_{ca}$. In this study, the other factors, especially welding heat input, to cause low crack arrest toughness was investigated for thick steel plate welds. EH grade steel plates were used in this study and 50 to 80 thick plates were tested to confirm thickness sensitivity. Electro gas welding (EGW) and flux cored arc welding (FCAW) were adopted to prepare the welded joints. Temperature gradient ESSO test was performed to measure $K_{ca}$ values with the variation of welding variables. As a result of this study, regardless of plate thickness, welding heat input to cause welding residual stress around crack path is a key factor to control the brittle crack propagation in welded joints.

• Structural Engineering and Mechanics
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• v.44 no.6
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• pp.735-751
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• 2012

Although being one of the most popular strengthening techniques in reinforced concrete beams, the use of steel plates bonded to the soffit raises problems of ductility. This study aims at investigating the influence of the use of perforated steel plates instead of solid steel plates on the ductility of reinforced concrete beams. A total of nine reinforced concrete beams were tested. In addition to an unplated beam, eight beams with perforated steel plates of two different thicknesses (3 mm and 6 mm) were subjected to monotonic loading. Effect of bonding the plates to the beams with anchor bolts and with additional side plates bonded to the sides of the beam with and without anchors is also investigated. The use of bolts in addition to epoxy was found to greatly contribute to the ductility and energy absorption capacity of the beams, particularly in specimens with thick plates (6 mm) and the use side plates in addition to the bottom plate was found to be ineffective in increasing the ductility of a concrete beam unless the side plates are attached to the beam with anchors bolts. The thickness of the plate was found to have little effect on the bending rigidity of the beam.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.3
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• pp.279-287
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• 2021

For application in nuclear decommissioning, underwater laser cutting studies were conducted on thick stainless-steel plates for various cutting directions using a 6 kW fiber laser. For cutting along the horizontal direction with horizontal laser irradiation, the maximum cutting speed was 110 mm·min^-1 for a 48 mm thick stainless-steel plate. For cutting along the vertical direction with horizontal laser irradiation, a maximum speed of 120 mm·min^-1 was obtained for the same thickness, which confirmed that the cutting performance was similar but slightly better. Moreover, when cutting with vertically downward laser irradiation, the maximum cutting speed was 120 mm·min^-1 for a plate of the same thickness. Thus, the cutting performance for vertical irradiation was nearly identical to that for horizontal irradiation. In conclusion, it was possible to cut thick stainless-steel plates regardless of the laser irradiation and cutting directions, although the assist gas rose up due to buoyancy. These observations are expected to benefit laser cutting procedures during the actual dismantling of nuclear facilities.