Journal of Welding and Joining

  • 제20권6호
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  • Pages.809-815
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  • 2002
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  • 2466-2232(pISSN)
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  • 2466-2100(eISSN)
대한용접접합학회 (The Korean Welding and Joining Society)
권호 표지

저탄소 박판강재의 레이저 용접과정에서 열영향부에 존재하는 탄화물 입자의 분해 거동

Dissolution of Carbide Particles at the Heat Affected Zone of Laser Welded tow Carbon Steel

  • 발행 : 2002.12.01
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초록

Metallurgical behavior of laser welded cold rolled low carbon steel was investigated. Welding was performed with CW Nd:YAG laser system. Applied laser power, travel speed and nitrogen blowing pressure were 720W CW, 17mm/s and 196kPa, respectively. According to the test results, many carbide particles were observed on the base metal surface that was polished and etched with nital solution. The carbide particles at the welding heat affected zone were thought to be dissolved during welding process. Microstructural inspection revealed that dissolved carbide particles formed mixed phase of very fine martensite and bainite. Test results also demonstrated that the hardness of matrix remained constant value of around 160Hv over the welding heat affected zone. Dissolved carbide particles, however, showed higher average hardness values of around 276Hv near the fusion boundary and 700Hv at the welding heat affected zone of 0.4mm apart from the fusion line. It was considered that care should be given to minimize the test error when measuring the hardness value since many of the dissolved particles were so small that it was not easy to aim the indentor of the testing machine just on the objects.

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참고문헌

  1. Muneharu Kutsuna. Atsuo Kikuchi: Thermal cycle and microstructures in laser welding of carbon steel, IIW Doc .. IV-597-93 (1993)
  2. Isao Masumoto, Muneharu Kutsuna, Chen zhong Xiao: Some special structures of HAZ by laser welding. Proc. of the International Conference Joining of Metals. JOM-3 (1993). 256-260
  3. Ki Chol Kim. Eui Pak Yoon: Metallurgical characteristics of C02 laser welded structural steel, Jour. of the Joining of Materials. 4, 2 (1992), 60-67
  4. Muneharu Kutsuna, Kazuo Uetani: Consideration on CCT diagram for estimation of microstructure and hardness of laser welds of low carbon steels, Preprints of the National Meeting of J.W.S. No. 63 (1998), 278-279 (in Japanese)
  5. Muneharu Kutsuna, Yasuhiro Kondoh: Study on microstructure and phase transformation of laser welds of ultra low carbon steels, Pre prints of the National Meeting of J.W.S. No. 58 (1996). 188-189 (in Japanese)
  6. Muneharu Kutsuna. Yasuhiro Kondoh: Study on microstructure and hardness of laser welds of carbon steels, Preprints of the National Meeting of J.W.S. No. 57 (1995), 420-421 (in Japanese)
  7. Muneharu Kutsuna, Atsuo Kikuchi: Microstructural change of HAZ heated and cooled rapidly in laser welding of carbon steels, Preprints of the National Meeting of J.W.S. No. 46 (1990), 108-109 (in Japanese)
  8. Koichi Yasuda, Yasushi Kitani: Metallurgical Characteristics of laser weld metal for heavy plate, Quarterly Journal of the J. W. S. 18, 1 (2000), 95-101 (in Japanese)
  9. Masahiro Ohara, Yasunobu Miyazaki: Microstructure and hardness of laser welded steel sheets, Preprints of the National Meeting of J.W.S. No. 62 (1998), F9-F12 (in Japanese)
  10. Muneharu Kutsuna, Kazuo Uetani, Yasuhiro Kondoh. Effect of cooling rates on phase transformation of ultra low carbon steels welds, Preprints of the National Meeting of J.W.S. No. 60 (1997), 90-91 (in Japanese)
  11. Muneharu Kutsuna, Kazuo Uetani: Effect of cooling rates and chemical composition on hardness of laser welds of ultra low carbon steels, Preprints of the National Meeting of J.W.S. No. 61 (1997), 362-363 (in Japanese)
  12. Tomohiro Tsuchida, Seiji Katayama, Akira Matsunawa: Microstructural features and hardnesses of laser welded carbon steels, Preprints of the National Meeting of J.W.S. No. 61 (1997). 364-365 (in Japanese)
  13. A. V. Surkov, V. V. Kovalev: Special features of the metallurgy of laser welding, Welding Production, May (1984), 15-16
  14. P. R. Strutt. Microstructural refinement of hard iron base materials by laser and electron beam surface melting, Metals Forum. 4, 1 (1981), 117-122
  15. E. A. Metzbower.: Laser beam welding-Thermal profiles and HAZ hardness, Welding Journal. July (1990). 272s-278s
  16. M. F. Ashby, K. E. Easterling: A first report on diagrams for grain growth in welds, Acta Metal!. 30 (1978), 1969-1978
  17. J. C. Ion. K. E. Easterling, M. F. Ashby: A second report on diagrams of microstructure and hardness for heat-affected zones in weld. Acta metall.. 32, 11 (1984), 1949-1962
  18. M. F. Ashby, K. E. Eastering: The transformation hardening of steel surface by laser beams: Hypo-eutectoid steels, Acta metall., 32, 11 (1984), 1935-1948