Development of YS 500MPa class TMCP steel plates for offshore structures

Akihiko Kojima, Akihito Kiyose, Yoshio Terada, Atsuhiko Yoshie, Ryuji Uemori, Shuji Aihara, Shiroh Imai, Yuzuru Yoshida, Toshihiko Adachi, Kazuaki Tanaka, Takao Nakashima

Research output: Contribution to conferencePaperpeer-review

5 Citations (Scopus)


New steel manufacturing technology has been developed to attain excellent crack tip opening displacement (CTOD) properties in a heat affected zone (HAZ) as well as yield strength (YS) of 500MPa in base metal. In the new steels, the HAZ microstructure near a weld fusion line is markedly refined by utilizing not only the formation of intragranular ferrite (IGF) but the strong retardation of austenite (here in after " γ ") grain growth. The IGF grows radially from oxides in the same way as in titanium-oxide bearing steels (TiO steels). The γ grain growth retardation is due to the pinning effect by fine particles including ultrafine oxides. Since these oxides dispersed in the steels are chemically stable even near the fusion line, the microstructure control is possible and the HAZ microstructure can be remarkably refined. Based on the new technology, YS 500MPa class thermomechanical control process (TMCP) steel plates with a low carbon equivalent and a 63.5mm thickness for offshore structures have been manufactured and tested. The steel plates have satisfied the required strength and low-temperature toughness of the base metal. They have also exhibited excellent CTOD properties and Charpy impact properties of joints welded by flux cored arc welding (FCAW) with 0.7kJ/mm and welded by submerged arc welding (SAW) with 3.5kJ/mm, as well as good weldability. The newly developed YS 460MPa and YS 500MPa class TMCP steel plates are being mass produced for offshore structures.

Original languageEnglish
Number of pages9
Publication statusPublished - 2001
Externally publishedYes
Event20th International Conference on Offshore Mechanics and Arctic Engineering; Materials - Rio de Janeiro, Brazil
Duration: Jun 3 2001Jun 8 2001


Other20th International Conference on Offshore Mechanics and Arctic Engineering; Materials
CityRio de Janeiro

All Science Journal Classification (ASJC) codes

  • Ocean Engineering
  • Energy Engineering and Power Technology
  • Mechanical Engineering


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