• Title/Summary/Keyword: 레이저 용접

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Laser Weldability and Formability of Hot Rolled Steels for Hydroforming Applications (하이드로포밍용 열연 강재의 레이저 용접성 및 성형 특성)

  • Lee Won-Beam;Lee Jong-Bong
    • Journal of Welding and Joining
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    • v.22 no.6
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    • pp.19-24
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    • 2004
  • The laser welding and its analysis of thin-sheet carbon steels were carried out with high power $CO_{2}$ laser. The main factor of weld quality of laser welding is gap and edge quality. This work was preformed to focus on the gap tolerance problem during laser welding. First, bead on plate welding of thin sheet was examined to investigate the effect of laser welding variables, and to obtain optimum welding condition. Butt welding was also carried out to show the effect of gap on the laser weldability of thin sheet. In order to investigate the effect of gap on formability of welded thin sheet, LDH test was caried out. At high welding speed, the partial penetration was obtained by low heat input. Otherwise, porosity was formed in the bead at low weld speed because of too much heat input. The optimum welding condition of welding was derived from bead width, penetration and hardness property. The maximum gap tolerance on laser welding was observed to be about 0.2mm. This gap size has good relationship with beam size of laser spot(about 0.3mm). The formability of welded sheet was about $80{\%}$ value of base metal and the gap size has not affected on the formability, although weld quality is dependent on the gap size.

A Study on the Feasibility of Partial Penetration Laser Welding for the Lap Joint of 390MPa High Strength Steel Sheets (390MPa급 고장력강판의 경치기 레이저 용접에서 부분용입 용접의 적용 가능성에 대한 연구)

  • 이경돈;박기영;김주관
    • Journal of Welding and Joining
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    • v.20 no.2
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    • pp.95-101
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    • 2002
  • After high power lasers are avaliable in the commercial market, the number of applications of the laser welding has been increased in manufacturing industries. Although the tailored blank laser welding of butt jointed steel sheets is well known recently in the automotive industries, the lap joint laser welding is a new technology to the automotive manufacturing people as well as the design people. But the deep penetration laser welding seems to be preferred to the partial penetration welding for the lap joint welding in the automotive manufacturers because the partial penetration is a serious deflect for the butt joint. In this study, the feasibility of partial penetration welding fur the lap joint $CO_2$ laser welding was studied fur the 1mm thick 390MPa high strength steel sheets for automotive bodies. The process window of the lap joint partial penetration welding was obtained from experiments with the gap size and the welding speed as process parameters. The partial penetration welding was found excellent on the basis of the tensile shear strength and sectional geometry. The bead width, input energy Per volume, tensile-shear strength, deformation energy and the sectional geometries after tensile-shear tests of partial penetration welded specimens are compared with those of full penetration welded specimens with a series of gaps and welding speeds.

Finite Element Analysis on the Improvement of Residual Deformation of the Part After Pulse Laser Welding of Circular Cover (원형 커버의 펄스 레이저 용접 후 부품 잔류변형 개선에 관한 유한요소해석)

  • Kim, Kwan-Woo;Cho, Hae-Yong
    • Journal of Welding and Joining
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    • v.33 no.6
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    • pp.60-66
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    • 2015
  • Molten zone shape of pulse laser welding is affected by welding conditions such as beam power, beam speed, irradiation time, pulse frequency, etc. and is divided into conduction type and keyhole type. It is necessary to design heat source model for irradiation of laser beam in the pulse laser welding. Shape variables and the maximum energy density value of the heat source model are different depending on the molten zone shape. In this paper, pulse laser welding simulation for joining of cylindrical part and circular cover was carried out. The heat source model for pulse laser beam with circular path was applied to the heat input boundary condition, radiative and conductive heat transfer were considered for the thermal boundary condition. For each phase, thermal and mechanical properties according to temperature were also applied to analysis. Analytical results were in good agreement with the molten zone size of specimen under the same welding conditions. So, the reliability of the welding simulation was verified. Finally, the improvements for reducing residual deformation after cover welding could be reviewed analytically.

Characteristics of Plasma Emission Signals in Fiber Laser Welding for API Steel (I) - Variation of Signals by Measuring Conditions - (API강재의 화이버레이저 용접시 유기하는 플라즈마의 방사특성 (I) - 측정조건에 따른 광신호의 변화 -)

  • Kim, Jong-Do;Lee, Chang-Je;Lee, Mok-Young
    • Journal of Welding and Joining
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    • v.28 no.6
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    • pp.51-57
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    • 2010
  • Fiber laser is a heat source which is introduced recently, and so has a little researched data compare with conventional laser processing. Moreover basic data for welding monitoring are also insufficient. Therefore, in this study, the change of signal with measuring position and angle of plasma emission signals were analysed as a basic experiment for real time monitoring in fiber laser welding. As a result, the signals measured from the side, front and rear had the biggest intensity at $60^{\circ}$, and frequency peak to reflect the behavior of keyhole and swing of plasma by shield gas was detected at $45{\sim}60^{\circ}$. However, both intensity of signal and the result of FFT for monitoring were satisfied at the angle of $45^{\circ}$ from the side.

Hot Wire Laser Welding of Multilayer for Narrow Gap - Analysis of Wire Melting/Transfer and Arc Formation Phenomenon by High Speed Imaging - (내로우 갭 적용을 위한 핫와이어 송급 레이저용접 - 고속촬영을 통한 와이어 용융/이행 현상과 아크 포메이션 분석 -)

  • Kim, Kyounghak;Bang, Hansur;Bang, Heeseon;Kaplan, Alexander F.H.;Nasstrom, Jonas;Frostevarg, Jan
    • Journal of Welding and Joining
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    • v.34 no.5
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    • pp.26-32
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    • 2016
  • In this study, Hot-wire laser welding (HWLW) without keyhole which deposits filler material by feeding hot wire into the process zone has been performed to increase process performance. From the analysis of High Speed Imaging (HSI), for higher voltage, the process is prone to arc formation and drop transfer, which is disagreeable transfer mode. It is necessary that arc formation and drop (globular) transfer should be avoided by lower voltage. Therefore, continuous wire melting and transfer mode is preferred when adopting this process. The HWLW technique has high potential in terms of performance, precision, robustness and controllability for thick section of narrow gap.

Applicability Study of 2-pass Laser Welding on Galvanized Steel Sheets (아연도금강판 겹치기 용접부에 대한 2패스 레이저용접 적용성 연구)

  • Ahn, Young-Nam;Kang, Minjung;Kim, Cheolhee
    • Journal of Welding and Joining
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    • v.34 no.4
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    • pp.55-61
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    • 2016
  • During laser overlap welding of galvanized steel sheets, explosion of weld pool by the high pressure zinc vapor induces weld defects like porosity and blowhole. In this study, laser 2-pass welding was implemented to prevent the weld defects. Through the 1st pass welding, zinc layers on the faying surfaces were removed when proper heat input was applied. Excessive heat input could result in explosion even during the 1st pass welding and insufficient heat input could not remove enough region of zinc layer for the 2nd pass welding. Coating weights of $45g/m^2$ and $60g/m^2$ were considered and for both cases sound welds without weld defects could be achieved. In spite of 2-pass welding, softening of weld and heat affected zone was not observed and Zn coating was not diluted into the weld metal.

Effect of Hot-stamping Heat Treatment on Microstructure and Hardness in TWB Laser Joints of Al-Si-coated Boron Steel and Zn-coated DP Steel (Al-Si 도금된 보론강과 Zn 도금된 DP강의 TWB 레이저 용접부 미세조직과 경도에 미치는 핫 스탬핑 열처리의 영향)

  • Jung, Byung-Hun;Kong, Jong-Pan;Kang, Chung-Yun
    • Korean Journal of Metals and Materials
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    • v.50 no.3
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    • pp.224-232
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    • 2012
  • In this study, the effect of hot-stamping heat treatment on the microstructure and hardness of TWB(Tailor Welded Blank) laser joints in Al-Si-coated boron steel and Zn-coated DP(Dual Phase)590 steel was investigated. In the TWB joints without heat treatment, hardness profiles showed local hardness deviation near the fusion zone. However, there was no hardness deviation in the heat treated specimen and its hardness was higher than that of the one without the heat treatment, due to a fully martensite microstructure. In the TWB joints of both the boron and DP steels, the maximum hardnesses were observed at the HAZ(Heat Affected Zone) near the base metal, and the hardness decreased gradually to the base metal. In the heat treated joints, the hardnesses of the HAZ and the base metal of the boron steel side were similar to the maximum hardness of the weld, while those of the HAZ and the base metal of the DP steel side were higher than the maximum hardness.

Laser Welding Analysis for 3D Printed Thermoplastic and Poly-acetate Polymers (3차원 광경화성 수지와 폴리아세테이트 수지의 레이저 접합해석)

  • Choi, Hae Woon;Yoon, Sung Chul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.7
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    • pp.701-706
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    • 2015
  • In this study, experimental and computer simulation results are compared and analyzed. Three-dimensional (3D) fabricated matrices from an MJM 3D printer were joined with poly-acetate thermoplastic polymers using a diode laser. A power range of 5-7 W was used to irradiate the boundary of two polymers. The heated polymers flowed into the matrices of the 3D fabricated structure, and reliable mechanical joining was achieved. Computer simulation showed the temperature distribution in the polymers, and flow direction was estimated based on the flux and temperature information. It was found that the more than the minimum energy threshold was required to effectively join the polymers and that two scans at low-speed were more effective than four scans at high speed.

Fabrication of semiconductor optical switch module using laser welding technique (반도체 광스위치 모듈의 제작 및 특성연구)

  • 강승구
    • Korean Journal of Optics and Photonics
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    • v.10 no.1
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    • pp.73-79
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    • 1999
  • Semiconductor optical switch modules of 1$\times$2, 1$\times$4, and 4$\times$4 types for 1550 nm optical communication systems were fabricated by using laser welding technique, embodying in 30-pin butterfly package. For better coupling efficiency between switch chip and optical fiber, tapered fibers of 10~15mm lens radii were used, which provided up to 60% optical coupling efficiency. With the help of new laser hammering process, we could recover the lost optical power almost completely up to average 82% of initially obtained power. The fabricated optical switch modules showed good thermal stability of less than 5% degradation even after 200 times thermal cycling test. The 2.5 Gbps optical transmission characteristics of the 4$\times$4 switch module showed low sensitivities of less than -30dB for all possible switching paths. The transmission penalties of 1$\times$2 switch module at $10^{-10}$ BER were 0.6dB and 0.7dB for 50Xm and 90 Km optical fibers, respectively.

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The Characteristic of Residual Stress and Fracture Toughness on The Welded Joint of HT50 by Laser Welding (50kg급 고장력강 레이저용접부의 용접잔류응력 및 파괴인성 특성)

  • Ro, Chan-Seung;Bang, Han-Sur;Ko, Min-Sung;Kim, Sung-Ju;Kim, Ha-Sig
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.10a
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    • pp.93-96
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    • 2003
  • Laser beam welding process is a relatively new process in comparison with arc welding process, but it is expected to apply widely because of the many advantages, and research and development of that process is being progressed actively for the practical use. the application of this welding process has been restricted due to the high initial investment and the need of precise processing against the material, but cost reduction and thick plate welding in high speed have become practial by recent technological development, and this welding process to not only small parts in automobile, machinery and physicochemical field, but also a large structure and pipe line are being applied. In order to utilize this welding process appropriately to a steel structure, the properties of welding residual stresses and fracture toughness in welded joints are to be investigated for relibilty. On this study, after performing the finite element analysis, thermal and residual stress properties have been examined to the general structural steel (HT50) by laser beam welding. Besides, the property of fracture toughness has been investigated by the Charpy impact test and 3-points bending CTOD test carried out in the range of temperature between $-60^{\circ}C$ and $20^{\circ}C$. From the research results it is revealed that the maximum residual stress appears in the center of plate thickness and the fracture toughness is influenced by strength mis-match.

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