DOI QR코드

DOI QR Code

Effect of Groove Conditions on the Mechanical Properties of Welds Produced by the Combined Welding Process of Flux Cored Arc and Electro Gas in EH36 TMCP Steel Plate for Hull Structures

선체구조용 EH36 TMCP 후판의 FCAW 및 EGW 조합 용접부 기계적 성질에 미치는 개선조건의 영향

  • Kim, Kihyuk (Plate Research Team, Plate Business Division, Dongkuk Steel) ;
  • Kim, Kiwon (Dept. of Material Science Engineering, Pusan National Univ.) ;
  • Sim, Hoseop (Plate Research Team, Plate Business Division, Dongkuk Steel) ;
  • Bae, Kangho (Plate Research Team, Plate Business Division, Dongkuk Steel) ;
  • Hong, Hyunuk (Dept. of Metallurgy and Materials Engineering, Changwon National Univ.) ;
  • Park, Byunggyu (Plate Research Team, Plate Business Division, Dongkuk Steel)
  • 김기혁 (동국제강 후판사업본부) ;
  • 김기원 (부산대학교 융합학부) ;
  • 심호섭 (동국제강 후판사업본부) ;
  • 배강호 (동국제강 후판사업본부) ;
  • 홍현욱 (창원대학교 신소재공학부) ;
  • 박병규 (동국제강 후판사업본부)
  • Received : 2015.08.05
  • Accepted : 2015.09.09
  • Published : 2015.10.01

Abstract

Characterization of microstructures and mechanical properties of 83mm thickness EH36-TM welds produced by the combined flux cored arc (FCA) and electro gas (EG) welding processes has been studied with the two different groove conditions, single-V (SV) and double-V (DV) bevels. The welding consumables used for FCA and EG welding processes were ASME/AWS A5.29 (E81T1-K2) and A5.26 (EG72T), respectively. Experimental results showed that all the mechanical properties of welds such as tensile property, CVN toughness and Vickers hardness met IACS requirements. The tensile strength of EG welded plates were reduced by approximately 4% (DV: 3.8%, SV: 4.2%) compared to the base metal. The hardness value of SV-beveled weld metal was slightly lower than that of DV-beveled one. There were no significant differences as per welding groove conditions except for the weld metal. In addition, at the fusion line, the toughness of SV condition was 20J lower and the weld metal was 40J lower than DV condition, respectively. On the basis of microstructural analysis, grain boundary ferrite (GBF) structures for SV condition were 2 times higher volume fraction than for DV condition and their packet sizes were coarsened to almost double. It was thus suggested that the GBF volume fractions and packet sizes in the weld metal of EH36-TM steel plates are the most important factors affecting the mechanical properties of the combined FCA and EG welded joint. Nevertheless, all the results of welds with both DV and SV conditions were found to be excellent.

Keywords

References

  1. D. S. Kim, Welding techniques and welding consumables for shipbuilding and offshore fabrication, Proceedings of the Welding Metallurgy Symposium of KWJS, Summer (2008) 5-23 (in Korean)
  2. T. W. Jang, J. H. Moon, D. R. Yoon, High speed welding present and future in shipbuilding assembly stage, Journal of KWJS, 22 (6) (2004), 14-18 (in Korean)
  3. K. H. Kim, B. G. Park et al, Microstructures and mechanical properties of electro-gas arc welded zone as per welding consumables for EH36-TMR plate, Proceedings of the Conference of KWJS, 49 (2008) 66 (in Korean)
  4. R. A. Ricks, P. R. Howell, G. S. Barritte, J. Mater. Sci. 17 (1982), 732-740 https://doi.org/10.1007/BF00540369
  5. Babu, S. S. The mechanism of acicular ferrite in weld deposits. Current Opinion in Solid State and Materials Science, 8 (2004) 267-278 https://doi.org/10.1016/j.cossms.2004.10.001
  6. A. Kojima, Development of high HAZ toughness steel plates for box columns with high heat input welding, Nippon Steel Techical Report, 90 (2004) 39-44 (in Japanese)
  7. Bhadeshia, H. K. D. H., Svensson, L. E. and Gretoft B., A model for the development of microstructure in low-alloy steel (Fe-Mn-Si-C) weld deposits, Acta Metallurgica, 33 (1985) 1271-1283 https://doi.org/10.1016/0001-6160(85)90238-X
  8. J. S. Lee J. O. Yun, S. H. Jeong, C. G. Park, Y. H. An, The study about characteristics of welding consumable and weld metal for EGW, Journal of KWJS, 28 (2) (2010) 79-83 (in Korean)