The Weldability of $6mm^t$ Primer-coated Steel for Shipbuilding by $CO_2$ Laser( I ) - Effects of Primer Coating Condition and Gap Clearance -

$6mm^t$조선용 프라이머 코팅강판의 $CO_2$레이저 용접성( I ) - 프라이머 코팅조건과 갭 간극의 영향 -

  • Kim Jong-Do (Division of Marine System Engineering, Korea Maritime University) ;
  • Park Hyun-Joon (Graduate School, Korea Maritime University)
  • 김종도 (한국해양대학교 기관시스템공학부) ;
  • 박현준 (한국해양대학교 대학원)
  • Published : 2005.06.01

Abstract

Recently the application of laser welding technology has been considered to shipbuilding structure. However, when this technology is applied to primer coated steel, good quality weld beads are not easily obtained. Because the primer-coated layer caused the spatter, humping bead and porosity which are main part of the welding defect attributed to the powerful vaporizing pressure of zinc. So we performed experiment with objectives of understanding spatter and porosity formation mechanism and producing sound weld beads in 6mmt primer coated steels by a $CO_2$ CW laser. The effects of welding parameters; defocused distance, welding speed, coated thickness and coated position; were investigated in the bead shape and penetration depth on bead and lap welding. Alternative idea was suggested to suspend the welding defect by giving a reasonable gap clearance for primer coated thickness. The zinc of primer has a boiling point that is lower than melting point of steel. Zinc vapor builds up at the interface between the two sheets and this tends to deteriorate the quality of the weld by ejecting weld material from lap position or leaving porosity. Significant effects of primer coated position was lap side rather than surface. Therefore introducing a small gap clearance in the lap position, the zinc vapor could escape through it and sound weld beads can be acquired. In conclusion, formation and suspension mechanism of the welding defects was suggested by controling the factors.

Keywords

References

  1. 新美 友治, 夏見 文章 : $CO_{2}$ レ-ザ容接の自動車ポデイ-ヘの應用, 第28回レ-ザ熱加工硏究完全論文集(1992), 171-184 (in Japanese)
  2. 泰山 正則, 高橋 通泰, 福井 部の耐食性及び諸特性, 第147回 溶接治金資科, 第157回溶接法資科, 第24高エネルギ-ビ-ム資科(1997), (in Japanese)
  3. H. SIMIDZU, F. YOSHINO, S. KATAYAMA and A. MATSUNAWA : Pulsed Nd:YAG Laser Spot Welding of Aluminum Alloys, Proceedings of LAMP'92, Nagaoka (June, 1992), 511-516
  4. I. NORRIS, T. HOULT, C. PETERS and P. WILEMAN : Material Processing with a 3kW Nd:YAG Laser, Proceedings of LAMP'92, Nagaokat(June. 1992), 489-494
  5. J. D. Kim and Y. S. Kim : The State of In-Process Quality Monitoring Technology in Laser Welding, The Korean welding society 18-4 (2000), 433-440 (in Korean)
  6. G. Marinoni. A. Maccagno, E. Rabino : Technical and economic comparison of laser technology with the conventional technologies for welding, Proc. 6th Int. Conr. Lasers in Manufacturing, (1989), 105-120
  7. PA Hilton : ND:YAG and $CO_{2}$ laser welding of complex geometries, ICAEO(2002)
  8. N. C. Sekhar. J. D. Russell. N. A. McPherson : Autogenous ND:YAG laser welding of 6mm thick dissimilar steels, ICALEO(2002)
  9. Hongping Gu. Robert Mueller : Hybrid welding of galvanized steel sheet, ICAEO(2002)
  10. G. S. Booth, D. S. Howse, A C. Woloszyn, E. D. Howord : Applying laser-arc hybrid welding thchnology for land pipelines, IWC, (2002), 169-175
  11. Ulrich Dilthey, Hanno Keller : Laser arc hybrid welding, IWC, (2002), 162-168
  12. Se-Hwan Lee, Massood A. Rahimi. Charles E. Albright, Walter R. Lempert : Development of combind welding with an electric arc and low power CO laser, IWC, (2002), 176-180
  13. Hongping Gu : A new method of laser lap welding of zinc-coated steel sheet, ICALEO(2000), 1-6
  14. R. Akhter, M.M.Gualini : Mathematical Modeling of the Laser Spot Weling of Zinc Coated Steel in Lap Configuration, ICAKEO(1998), 207-216
  15. J. Heyden, K. Nilsson and C. Magnusson: Laser welding of zinc coated steel, Proc. 6th Int. Conf. Lasers in Manufacturing, (1989), 93-104
  16. M. M. S. Gualini : Laser welding of zinc coated steels. An old problem with a possible solution, ICALEO, (2002)
  17. Katayama Seiji, Wu Yushen. Matsunawa Akira : Laser weldability of zinc-coated steels, ICALEO (2002)
  18. Jong Hyun Suh, To Hoon Kim, Byung Kil Yu, Kyoung Don Lee : A Study of Tailored Blank Welding between Mild Steel and Zn-coated Steel Sheets by $CO_{2}$ Laser Beam, The Journal of Korean Society of Laser Processing 1-1 (November, 1998), 4-10 (in Korean)
  19. J. Suh, Y.H. Han, J.O. Kim, S.H. Yoon : Laser Beam Welding and Formability of Zn-Coated Steel Plates, Proceeding of the 5th Symposium on Laser Materials Processing (October, 1994), 153-166 (in Korean)
  20. Kyoung Don Lee, Ki Young Park and Ju Gwan Kim : Effects of Gap and the Speed on the Lap-Joint $CO_{2}$ Laser Welding of Automotive Steel Sheet, Journal of the Korean Welding Society 20-4 (August, 2002), 510-515 (in Korean)