• Title, Summary, Keyword: 입열량

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The behavior of boron segregation according to heat input in the weld CGHAZ of low alloyed steel (용접 입열량에 따른 저합금강 용접부 CGHAZ의 보론 편석거동 분석)

  • Kim, Sang-Hoon;Lee, Jong-Ho;Lee, Kyung-Sub;Hwang, Byoung-Chul;Lee, Chang-Gil;Lee, Chang-Hee
    • Proceedings of the KWS Conference
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    • pp.60-60
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    • 2009
  • 본 연구는 보론이 첨가된 저합금강 용접 열영향부에서의 보론 편석 거동 연구를 위해 보론이 10ppm 첨가된 저합금강을 이용하여 다양한 용접 입열량 및 외부 응력에 따른 용접부 CGHAZ의 보론 편석거동을 분석하였다. 이를 위해 Gleeble 시스템을 이용하여 다양한 입열량에 따른 CGHAZ를 열 및 열-응력 사이클을 통하여 재현하였다. 재현된 시편의 미세조직은 OM을 통하여 분석하고, 보론의 편석거동을 SIMS와 PTA 분석법을 통하여 분석하였다. 그 결과 입열량에 따른 보론의 편석 거동은 최초 입열량이 증가함에 따라 보론의 편석이 증가하다가 다시 감소하였는데 이는 비평형 편석 후 고온에서 유지시간이 길어짐에 따라 back diffusion 발생에 따른 영향으로 판단된다. 또한 외부 응력에 의한 보론 편석 거동 분석 결과, 용접 열 사이클 중 작용하는 외부 응력에 의해 결정립계 편석 감소하였는데 이는 외부 응력에 의한 오스테나이트 결정립 크기 감소에 따른 결정립계 증가의 영향으로 판단된다.

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The effect of heat input and PWHT on the mechanical properties and microstructure of HSB600 steel weldments with GMAW (HSB600강 가스메탈아크용접부에서 입열량과 용접후 열처리가 기계적 특성과 미세조직에 미치는 영향)

  • Ju, Dong-Hwi;Jang, Bok-Su;Lim, Young-Min;Koh, Jin-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.5
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    • pp.1939-1946
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    • 2012
  • High performance steel for bridges requires higher performance in tensile and yield strength, toughness, weldability, etc. The purpose of this study is to investigate the weldability of HSB 600 steel. The effects of heat input (1.4~3.2kJ/mm) and postweld heat treatment (PWHT, $600^{\circ}C$, 40hr.) on the TMCP HSB600 steel weldments made by GMAW process were investigated. The tensile strength and hardness of as-welded specimens decreased with increasing heat input. Charpy V-notch impact energy did not show any significant difference by postweld heat treatment. The fine-grained acicular ferrite was mainly formed in the 2.1kJ/mm of heat input while polygonal and side plate ferrites were dominated in the high inputs. Meanwhile, tensile strength and hardness of PWHT weldments decreased due to the coarsening and globularization of ferrite microstructure and reduction of residual stresses with increasing heat inputs. However, there was no significant difference in the impact energy absorption.

The effect of Heat input and PWHT on the microstructure and mechanical properties of HSB600 steel weldments (HSB600강 GMA 용접부에서 입열량과 용접후 열처리가 미세조직과 기계적 특성에 미치는 영향)

  • Koh, Jin-Hyun;Kim, Nam-Hoon;Jang, Bok-Su;Ju, Dong-Hwi;Lim, Young-Min
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.12
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    • pp.5405-5411
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    • 2011
  • The effects of heat input (1.5~3.6 kJ/mm) and post weld heat treatment (PWHT, $600^{\circ}C$, 40hr.) on the TMCP HSB600 steel weldments made by GMAW process were investigated. The tensile strengths and hardness of as-welded specimens were decreased as heat input increased, but CVN (Charpy V-Notch) impact energy did not show any differences. The fine-grained acicular ferrite was mainly formed in the low heat input while polygonal and side plate ferrites were dominated in the high heat inputs. Meanwhile, tensile strength and hardness of PWHT weldments were decreased due to the coarsening and globular of microstructure as well as reduction of residual stresses.

Development of Real Time Calorimetry System for Neutral Beam (중성입자 빔의 실시간 열량 측정시스템 개발)

  • Seo, Min-Seok;Yoon, Byeong-Joo;Oh, Byung-Hoon
    • Proceedings of the KIEE Conference
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    • pp.1702-1703
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    • 2007
  • KSTAR(Korea Superconducting Tokamak Advanced Research)의 보조 가열장치 중에 하나인 중성입자 빔 가열장치의 열량을 실시간으로 측정할 수 있는 시스템을 개발하였다. 실시간으로 열량을 측정하기위해 중성입자 빔 발생장치의 말단에 위치한 열량계(Calorimeter)의 냉각수 입 출구 온도를 온도센서 중의 하나인 열전대를 이용하여 측정하고 이를 열량 측정을 위해 개발한 알고리듬을 이용하여 실시간으로 중성입자 빔의 열량으로 연산한다. 연산된 열량은 사용자 인터페이스 화면에 출력하여 매 실험마다 열량계에 입사된 열량을 실시간으로 확인이 가능하도록 하였다.

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A Study on the Welding Deformations and Residual Stresses for Circumferential Welded Cylinders (원통의 용접변형 및 잔류응력에 대한 연구)

  • K.Y. Yoo;D.S. Um
    • Journal of the Society of Naval Architects of Korea
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    • v.35 no.4
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    • pp.55-64
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    • 1998
  • Using blind hole drilling method the residual stresses and welding deflections are measured for the cylindrical shell with various heat inputs and cylinder diameters. As a result, it is verified that the axial and hoop residual stresses which are generated near the weld part of cylinders are increased, as the heat inputs and cylinder diameters are increased. And experimental results show good agreements with those of precedent researchers. In this paper, it is validated that dominant parameters, heat input Q and the dimension of cylinder h/D have some effects on the magnitude and distribution of axial and hoop residual stresses and welding deflections. The empirical equations of residual stresses and welding deflections are made by using multiple linear regression with experimental results.

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Weldability with Process Parameters During Fiber Laser Welding of a Titanium Plate (II) - The Effect of Control of Heat Input on Weldability - (티타늄 판재의 파이버 레이저 용접시 공정변수에 따른 용접특성 (II) - 입열량 제어에 따른 영향 -)

  • Kim, Jong Do;Kim, Ji Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.12
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    • pp.1055-1060
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    • 2016
  • Laser welding is a high-density energy welding method. Hence, deep penetration and high welding speed can be realized with lower heat input as compared with conventional welding. The heat input of a CW laser welding is determined by laser power and welding speed. In this study, bead and lap welding of $0.5mm^t$ pure titanium was performed using a fiber laser. Its weldability with laser power and welding speed was evaluated. Penetration, bead width, joining length, and bead shape were investigated, and the mechanical properties were examined through tensile-shear strength tests. Welds with sound joining length were obtained when the laser power and welding speed were respectively 0.5 kW and 2.5 m/min, and 1.5 kW and 6 m/min, and the weld obtained at low output presented better ductility than that obtained at high output.

Effect of Welding Heat Input on Mechanical Properties of Underwater Welded Joints of KR Grade A-1 Steel Plates (국산 선급 A-1 강판의 수중용접 입열량이 기계적 특성에 미치는 영향에 관한 연구)

  • 오세규;이종석;한상덕
    • Journal of Ocean Engineering and Technology
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    • v.1 no.1
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    • pp.120-126
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    • 1987
  • In this paper, the optimizing investigation of characteristics of underwater welding by a gravity type arc welding process is experimentally carried out by using the .phi. 4mm ilmenite type of domestic coated welding electrodes for welding the domestic marine structural steel plates of 8mm thickness in order to develop the underwater welding techniques in practical use, resulting in the quantitative analysis possibility for the relationship between the mechanical propernical properties of underwater welded joint HAZ and the welding heat input.

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Optimum Weld Heat Input in Seam SAW Joint of API-X80 Plate for High Impact Toughness (후판 API-X80 강 조관 Seam SA 용접부 인성확보를 위한 적정 용접 입열량)

  • 김충명;이종봉
    • Proceedings of the KWS Conference
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    • pp.136-137
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    • 2004
  • 석유나 가스 등의 자원을 안정적으로 수송하기 위하여 사용하는 라인 파이프는 그 사용 환경에 따라서 다양한 소재 특성을 필요로 하며, 한랭지역에서 사용되는 경우에는 낮은 온도에서도 충분한 인성을 유지할 수 있는 높은 인성을 요구하고 있다. (중략)

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Welding Characteristics on Heat input Changing of Laser Dissimilar Metals Welding (레이저 이종용접에서의 입열량 변화에 대한 용접특성)

  • Mo Yang-Woo;Shin Byung-Heon;Shin Ho-Jun;Yoo Young-Tae
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.2
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    • pp.51-58
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    • 2006
  • Laser welding of dissimilar metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research works is to investigate the influence of the process parameters, such as the welding for SM45C and STS304 with CW Nd:YAG lasers. The bead-on-plate welding tests are carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the dissimilar welding, the welding quality of the cut section, stain-stress behavior and the hardness of the welded part are investigated. From the results of the investigation, it has been shown that the optimal welding condition without defects in the vicinity of the welded area and with a good welding qualify is 1600W of the laser power, 0.85m/min of welding speed and $4{\ell}/min$ of pressure for shielding gas.