GOLI-OGLU Eugene NLMK-Dansteel

Spoluautoři BOKACHEV Yuriy

Thermomechanical controlled processing (TMCP) is used in production of heavy plates of low carbon microalloyed structural steels with strength grade of S420 - S460. Final thickness of plates can be up to 100 mm and the plates are used in welded constructions such as bridges, offshore units and wind turbines. For such big final thickness TMCP can be very complicated process as it is necessary to ensure a high uniformity of mechanical properties and proper formation of final microstructure (grain refinement). During the process a number of things are to be taken into consideration, for example, unequal temperature and deformation conditions in different layers. Unequal conditions occur because of a large temperature gradient and uneven accumulation of deformation throughout the thickness of material. The report presents the results of research in temperature and deformation conditions (throughout the thickness) in the γ- and γ+α- regions during thermomechanical processing of thick 80-100 mm plates. The example of production at NLMK-DanSteel (4200-mm plate mill) under different TM technological conditions demonstrates the level of uniformity of the microstructure as well as the level of anisotropy of yield strength, tensile strength, ductility and toughness at low temperatures (till minus 60 °C). Cold resistance (throughout the thickness) in 80-100 mm plates produced with different TM conditions was also investigated.