NLMK DanSteel A/S (Frederiksvaerk, Denmark):

Goli-Oglu E. A., Cand. Eng., Process Developer, e-mail: ego@dansteel.dk

Bokachev Yu. A., Managing Director

E-mail (common): info@dansteel.dk

NLMK Group (Lipetsk, Russia):

Polunina L. V., Head of Metall Science and Metal Physics Laboratory, e-mail: polunina_lv@nlmk.ru

Klimenko E. S., Engineer of Metall Science and Metal Physics Laboratory

The article is devoted to production of heavy plates for pressure vessels with specified elevated temperature properties at the 4200 mm heavy plate mill of NLMK DanSteel. Two technologies which meet the requirements of a number of European standards for boiler steels were used in this research. Combination of conditions related to certain mechanical properties and their changes under alternative technologies are taken into consideration. Heavy plates with minimum yield strength of 355 MPa from C-Mn steel and C-Mn steel with Nb were under investigation. The article presents data showing the effect of manufacturing technologies and micro-alloying on the grain size and the homogeneity of the steel in its fi nal microstructure as well as tensile characteristics in the temperature range from 20 to 450 °C and impact energy at temperature from +20 to –60 °C. It is concluded that the technology with differential Nb alloying depending on thickness level and impact requirements at negative temperature in longitudinal and transversal directions is the most expedient. The article presents an explanation, how it is possible to choose the best production technology and chemical composition in order to produce steel plates of a certain required quality and thickness, thereby reducing production costs per ton and increase profitability of boiler steel production. 

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