The obtained microstructure of the rolled products is ferrite-pearlitic, where ferrite
grain number is 9, 10, and banding is 1 point.
The difference in the ferrite grain size between the axis and the surface does not
exceed one number, and the metal has almost the same banding across the cross section.
Such a state of microstructure in thickness of the rolled product and banding
shows that the desired result during the thermomechanical rolling and a sufficiently
effective, for this product mix, cooling of the rolled products in thickness have been
achieved. In order to determine whether the rolled products in larger thicknesses can
be manufactured, taking into account the cooling capabilities of the equipment, further
development study is required.
CONCLUSION
1. Тhe developed technology and the produced batch of hot rolling coils (6×1500
mm, steel grade S355MC) are fully in line with EN 10149-2.
2. The technical capability of TMCP rolling has been firstly confirmed for the
rolling mill 1700 at PJSC ILYICH IRON & STEEL WORKS OF MARIUPOL
(Mariupol).
3. The additional controlled air cooling for coils to 450°C has been firstly
developed and used on an industrial scale, which provides for decrease in air scale once
the thermomechanical rolling is finished and improvement of surface quality for the
customers.
4. There has been established the technical potential for further development of
the technology of thermomechanical rolling of steel grade S355MC in larger
thicknesses, and hot rolling coil production of higher strength categories.
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