Browse > Article

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

김기철 (포항산업과학연구원)
조흥규 (포항산업과학연구원)
정호신 (부경대학교)
Publication Information
Journal of Welding and Joining / v.20, no.6, 2002 , pp. 809-815 More about this Journal
Abstract
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.
Keywords
Low carbon steel; Sheet steel; Phase change; Laser welding; CW Nd:YAG laser; Welding heat affected zone;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Muneharu Kutsuna. Atsuo Kikuchi: Thermal cycle and microstructures in laser welding of carbon steel, IIW Doc .. IV-597-93 (1993)
2 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)
3 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)
4 M. F. Ashby, K. E. Easterling: A first report on diagrams for grain growth in welds, Acta Metal!. 30 (1978), 1969-1978
5 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)
6 A. V. Surkov, V. V. Kovalev: Special features of the metallurgy of laser welding, Welding Production, May (1984), 15-16
7 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
8 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
9 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)
10 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
11 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
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 P. R. Strutt. Microstructural refinement of hard iron base materials by laser and electron beam surface melting, Metals Forum. 4, 1 (1981), 117-122
14 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)
15 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)
16 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)
17 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)
18 E. A. Metzbower.: Laser beam welding-Thermal profiles and HAZ hardness, Welding Journal. July (1990). 272s-278s