• Title/Summary/Keyword: Laser overlap welding

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The Characteristics of Continuous Waveshape Control for the Suppression of Defects in the Fiber Laser Welding of Pure Titanium Sheet (II) - The Effect According to Control of Overlap Weld Length - (순 티타늄 박판의 파이버 레이저 용접시 결함 억제를 위한 연속의 출력 파형제어 특성(II) - 중첩부 길이변화에 따른 영향 -)

  • Kim, Jong-Do;Kim, Ji-Sung
    • Journal of Welding and Joining
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    • v.34 no.6
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    • pp.69-74
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    • 2016
  • Because the pure titanium has superior corrosion resistance and formability compared with different material, it is widely used as material of welded heat exchanger. When the welding of heat exchanger is carried out, certain area in which welding start and end are overlapped occurs. The humping of back bead is formed in the overlap area due to partial penetration. Thus in this study, the experiments were carried out by changing the length and wave shape of overlap area, and then the weldabiliay was evaluated through the observation of microstructure, the measurement of hardness and tensile-shear strength test in the overlap area. When overlap length was 9.8mm, humping bead was suppressed. The microstructure of overlap area coarsened and its hardness increased due to remelting. As a result of tensile-shear strength test in the overlap area according to applying the wave shape control, it was confirmed that the overlap area applied wave shape control had more excellent yield strength and ductility.

Effect of Coating Weight on the Laser Weldability in the Welding of Aluminized Steels (레이저용접에서 알루미늄 도금량이 용접성에 미치는 영향)

  • Kim Ki Chol;Cha Joon Ho
    • Korean Journal of Materials Research
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    • v.14 no.1
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    • pp.1-8
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    • 2004
  • Laser weldability of aluminized steels for deep drawing application has been investigated. Test coupons for Nd:YAG laser welding and $CO_2$ laser welding were prepared trom the commercial steels. According to the test results, total penetration and back bead width of aluminized steels were sensitive to the welding conditions. Bead width at the half thickness of the overlap joint, however, was rather constant. Laser weldability of aluminized steels was superior to that of zinc coated steel. Weld microstructure revealed that overlap zone adjacent to the fusion line was filled with coated materials, which was thought to be desirable to protect weld from crevice corrosion. The aluminum coated materials was also found in the weld metal. Practically no spattering was observed in the laser welding of aluminized steels even when the welding was performed without joint gap. In the welding of zinc coated steel, however, spattering was so severe that it was difficult to get the acceptable weld. Bead quality of aluminized steel laser weld was smooth and stable.

Laser Welding Characteristics of Aluminum and Copper Sheets for Lithium-ion Batteries (자동차 이차전지 제조를 위한 알루미늄과 무산소동의 레이저 용접특성)

  • Kang, Minjung;Park, Taesoon;Kim, Cheolhee;Kim, Jeonghan
    • Journal of Welding and Joining
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    • v.31 no.6
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    • pp.58-64
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    • 2013
  • Several joining methods involving resistance welding, laser welding, ultrasonic welding and mechanical joining are currently applied in manufacturing lithium-ion batteries. Cu and Al alloys are used for tab and bus bar materials, and laser welding characteristics for these alloys were investigated with similar and dissimilar material combinations in this study. The base materials used were Al 1050 and oxygen-free Cu 1020P alloys, and a disk laser was used with a continuous wave mode. In bead-on-plate welding of both alloys, the joint strength was higher than the strength of O tempered base material. In overlap welding, the effect of welding parameters on the tensile shear strength and bead shape was evaluated. Tensile shear strength of overlap welded joint was affected by interfacial bead width and weld defect formation. The tensile-shear specimen was fractured at the heat affected zone by selecting proper laser welding parameters.

An experimental study on the fracture of Nd:YAG laser welded amorphous foils (Nd:YAG 레이저를 이용한 비정질 박판 용접부의 파괴에 대한 실험적 연구)

  • 이건상
    • Laser Solutions
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    • v.3 no.3
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    • pp.31-37
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    • 2000
  • In this paper, the possibilities of the laser overlap spot welding were studied to utilize the advantageous properties of amorphous metal foils. In order to estimate the usage of amorphous metals foils as structural members, the tensile shear strength and the fracture features were investigated. Although the crystalline zone on the surface was formed, it was not the direct cause of the fracture of the weld. The fracture of the weld resulted from the geometry discontinuity between the workpiece and the protrusion zone, which was formed during the weld process. The vein pattern - the typical feature of the fracture of the amorphous metal - was formed on the fracture surface. The tensile shear stress was reached to 1200 N/㎟ (2-foils overlap welding) and 900 N/㎟ (10-foils overlap welding), whereas the tensile strength of the workpiece was 1500-2000 N/㎟.

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Effects of the Welding Parameters on the Weld Shape in Nd:YAG Laser Welding of STS 304L (STS 304L의 Nd:YAG 레이저 용접에서 용접조건이 용접부 형상에 미치는 영향)

  • 이형근;석한길;한현수;박울재;홍순복
    • Journal of Welding and Joining
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    • v.22 no.1
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    • pp.58-64
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    • 2004
  • The control of the weld bead shape is important in laser welding of the small parts. The effects of laser welding parameters on the weld bead shape in the pulsed Nd:YAG laser welding of STS 304L material were investigated. Shielding gas type, flow rate, pumping voltage, pulse frequency, pulse width, focal position and overlap distance were selected as laser welding parameters. Experiments were designed and conducted using the Taguchi method which was a statistical experimental method. The weld bead width, penetration, area and aspect ratio were measured and analysed as the weld bead shape properties and the welding parameters were optimized to maximize the weld aspect ratio. Weld aspect ratio were greatly affected by the pulse width, pumping voltage and pulse frequency, and somewhat by the overlap distance, and little by the shielding gas type, flow rate and focal position. A confirmation experiment were conducted using the optimized welding parameters.

Effect of Process Parameters on Bead Formation in Nd:YAG Laser Welding of Thin Steels (저탄소 박판 강재의 Nd:YAG 레이저 용접부 형성에 미치는 공정변수의 영향)

  • 김기철;허재협
    • Journal of Welding and Joining
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    • v.19 no.3
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    • pp.317-324
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    • 2001
  • This study deals with high power Nd:YAG laser welding of thin steels for small pressure vessels. Full penetration welding at the overlap joint was performed so as to assure sufficient weld strength. Results showed that mid-depth weld size reduced drastically with increasing the travel speed. Position of focus had little effect on the bead formation even though short focal system was used. However, the shape factor and the bead width had closely related with the position of focus. Based on the microstructural inspection, acceptable weld was obtained when the overlap clearance was controlled up to 20% of the base metal thickness. In the case that the joint contained more clearance than the critical value, both the tensile shear strength and the tear strength were reduced. Results also demonstrated that shielding gases were proved to play a key role as far as the bead formation characteristics was taken into consideration. Blowing dry air through 5mm in diameter nozzle produced narrower bead cross-section than that of argon or nitrogen shielding.

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Effects of Nd:YAG Laser Welding Parameters on Fatigue life of Lap Joint Structure in Stainless Steel (스테인리스강의 Nd:YAG 레이저 겹치기 용접부 피로수명에 미치는 용접변수의 영향)

  • Kim, Yang;Yang, Hyun-Seok;Park, Ki-Young;Lee, Kyoung-Don
    • Journal of Welding and Joining
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    • v.26 no.1
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    • pp.69-75
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    • 2008
  • Spot welding which use the main process for side block production of stainless steel railway vehicle is legged behind in laser welding about a quality and productivity. Although the laser welding has many potential advantages such as low heat input and aspect ratio of weld bead, its application to a new structural component still is required many engineering data including mechanical properties such as tensile, fatigue strength, etc on. Therefore, experimental analysis was carried out to understand the fatigue phenomena of different thickness stainless steel overlap joining panels by Nd:YAG laser welding. The fatigue life curves were obtained through fatigue tests with the various levels of applied load. The fatigue life is related with the parameters such as gap size and penetration depth through experiment. As the results, tensile strength and fatigue life were proportional in heat input level and gap was identified the major factor for fatigue life. Also we could know that deferent a-ferrite content at HAZ depend on welding heat input was important factor to determine a formation of initial crack and total fatigue life cycle.

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.

Lab Weldability of Pure Titanium by Nd:YAG Laser (Nd:YAG 레이저를 이용한 순티타늄판의 겹치기 용접성)

  • Kim, Jong-Do;Kwak, Myung-Sub
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.2
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    • pp.315-322
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    • 2008
  • Titanium and its alloys have excellent corrosion resistance, high strength to weight ratios and creep properties in high temperature, which make them using many various fields of application. Especially, pure titanium, which has outstanding resistance for the stress corrosion cracking, crevice corrosion, pitting and microbiologically influenced corrosion, brings out to the best material for the heat exchanger, ballast tank, desalination facilities, and so on. Responding to these needs, welding processes for titanium are also being used GTAW, GMAW, PAW, EBW, LBW, resistance welding and diffusion bonding, etc. However, titanium is very active and highly susceptible to embrittlement by oxygen, nitrogen, hydrogen and carbon at high temperature, so it needs to shield the weld metal from the air and these gases during welding by non-active gas. In this study, it was possible to get sound beads without humping and spatter with a decrease of peak power according to increase of pulse width, change of welding speed and overlap rate for heat input control, and shield conditions at pulsed laser welding of titanium plates for Lap welding.

Study on the porosity formation in the lap joint CW Nd:YAG laser welds of 6K21 aluminum alloy sheet (6K21 알루미늄 판재의 레이저 겹치기 용접 시 발생하는 기공에 관한 연구)

  • Yang, Hyun-Seok;Lee, Kyoung-Don;Kim, Yong;Park, Ki-Young
    • Laser Solutions
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    • v.11 no.3
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    • pp.16-20
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    • 2008
  • The lap Joint welding of 6K21 aluminum sheets by Nd:YAG laser were performed with an aluminum 5183 filler wire or without a filler wire. The porosity of laser welding beads were observed through an optical microscope and X-ray photography with various levels of welding speed and gap size. The porosity was observed in the gap between upper and lower sheet near a heat affected zone when autogenous welding. Decrease of welding speed and use of AA5183 filler wire reduced porosity significantly.

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