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선급용 고강도 극후물재의 취성파괴 정지 성능에 관한 연구
안규백,류강묵,박준식,정보영,김태수,이종섭,An, Gyu-Baek,Ryu, Kang-Mook,Park, Joon-Sik,Jeong, Bo-Young,Kim, Tae-Su,Lee, Jong-Sub 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.1
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.
유한요소법과 초음파 메카트로닉스 시스템에 의한 강도적 불균질 이음부의 노치위치에 따른 균열발생 한계 조건
안규백,방한서,풍전정남,An Gyu-Baek,Bang Han-Sur,Toyoda Masao 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.6
It has been well hewn that ductile fracture of steels is accelerated by triaxial stresses. The characteristics of ductile crack initiation in steels are evaluated quantitatively using a two-parameters criterion based on equivalent plastic strain and stress triaxiality. The present study focuses on the effects of strength mismatch, which can elevate plastic constraint due to heterogeneous plastic straining, on the critical condition for ductile fracture initiation usinga two-parameter criterion. Fracture initiation testing has been conducted under static loading using notched round bar specimens which had different notch locations. This study provides the fundamental clarification of the effect of strength mismatching and effect of notch location on the critical condition to ductile crack initiation from notch root using fuite element method and ultrasonic-mechatronics system. The critical condition of ductile crack initiation from notch root of strength mismatched tensile specimens under static loading appeared to be almost the same as those of homogeneous tensile specimens with circumferential sharp notch specimen. Also, the effect of notch location in mismatched specimens was estimated using finite element(FE) analyses.
피로강도 향상을 위한 표면마찰교반법의 가공조건 및 비드형상
박정웅,안규백,김흥주,조병철,Park, Jeong-Ung,An, Gyu-Baek,Kim, Heung-Ju,Jo, Byeong-Cheol 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.4
Burr grinding, Tungsten Inert Gas (TIG) dressing, ultrasonic impact treatment, and peening are used to improve fatigue life in steel structures. These methods improve the fatigue life of weld joints by hardening the weld toe, by improving the bead shape, and by creating the compressive residual stress. In this study, a new post-weld treatment method improving the weld bead shape and metal structure at the welding zone using Friction Stir Processing (FSP), a welding process, is proposed to enhance fatigue life. For that, a pin-shaped tool and processing condition employing Friction Stir Processing (FSP) is established through experiments. Experimental results revealed that fatigue life is improved by around 50% compared to as-welded fatigue specimens by reducing the stress concentration at the weld toe and by generating a metal structure finer than that of flux-cored arc welding (FCAW).
고유변형도법에 의한 두께 25mm 맞대기용접부의 두께방향의 잔류응력측정
박정웅,안규백,우완측,허승민,Park, Jeong-Ung,An, Gyu-Baek,Woo, Wanchuck,Heo, Seung-Min 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.4
Overlay welding is carried out to improve the corrosion resistance, wear resistance and heat resistance on the surface of the chemical plant and steelmaking plant structures. In overlay welding, control of the bead size and the temperature distribution of weldment are particularly important because that is directly connected to the improvement of quality and productivity. The aim of this study is to model the welding heat source that is very useful to analyze the bead size and temperature distribution of weldment. To find the welding heat source model, numerical analyses are performed by using FE software MSC-marc.
박준식,정보영,안규백,이종봉,Park, Joon-Sik,Jung, Bo-Young,An, Gyu-Baek,Lee, Jong-Bong 대한용접접합학회 2007 대한용접·접합학회지 Vol.25 No.4
선박의 고강도화 및 극후물화가 진행됨에 따라 선체 구조물의 파괴 특성에 대한 관심이 높아지고 있으며, 최근 균열정지의 관점에서 취성균열 정지특성에 대한 연구가 활발히 이루어지고 있다. 기존의 연구결과에 따르면 65mmt 이상의 극후물 용접부에 대해서 취성균열 정지특성의 저하가 발생할 가능이 있다고 보고되고 있으며, 취성균열 정지특성이 우수한 강재의 개발 이외에 용접부 보강재의 부착, 보수 용접 실시 등 개선 방안을 마련하기 위한 다양한 연구가 진행되고 있다. 그러나 극후물 용접부 취성균열 전파기구에 관한 규명은 현재 전무한 실정이며, 강재 두께의 영향 이외에 용접 입열량 용접부 잔류응력 등의 효과가 복합적으로 검토되어야 한다. 아울러 극후물 용접부 균열정지 파괴인성의 평가, 대형파괴시험을 대체할 소형시험법의 개발 및 검증 등에 관한 연구가 요구된다.