ISSN 2594-5297
56° Seminário de Laminação e Conformação de Metais — vol. 56, num.56 (2019)
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Abstract
Usiminas Steel Plant in Ipatinga installed an accelerated cooling device named CLC (Continuous On-Line Control) in the year 2011, enabling it to supply steels produced by TMCP technology. There are various gains in terms of quality and productivity associated to the application of such technology. However, the flatness control becomes crucial because large thermal stresses may be generated due to thermal heterogeneity during the fast cooling when the austenite phase decomposes mostly into ferrite and bainite. In literature there is lack of knowledge regarding a full understanding of the relation among cooling conditions and plate flatness. Therefore, this work has focused on the effect of the cooling strategy for API steels, aiming at optimizing flatness and keeping the mechanical properties within the specified ranges. The starting point was dilatometer tests, where cooling conditions such as start cooling temperature, SCT, finish cooling temperature, FCT, and cooling rate, CR, were changed in order to evaluate their effect on microstructure and hardness. Those laboratory conditions supposed to give the best results were transposed to industrial scale, so as to produce experimental lots of plates with five different cooling strategies. It was shown the possibility to find a cooling profile that guarantees the balance between mechanical properties and flatness requirements. The influence of cooling strategy on flatness was explained by the varied heat transfer regimes occurring from hot steel surface to the ambient.
Usiminas Steel Plant in Ipatinga installed an accelerated cooling device named CLC (Continuous On-Line Control) in the year 2011, enabling it to supply steels produced by TMCP technology. There are various gains in terms of quality and productivity associated to the application of such technology. However, the flatness control becomes crucial because large thermal stresses may be generated due to thermal heterogeneity during the fast cooling when the austenite phase decomposes mostly into ferrite and bainite. In literature there is lack of knowledge regarding a full understanding of the relation among cooling conditions and plate flatness. Therefore, this work has focused on the effect of the cooling strategy for API steels, aiming at optimizing flatness and keeping the mechanical properties within the specified ranges. The starting point was dilatometer tests, where cooling conditions such as start cooling temperature, SCT, finish cooling temperature, FCT, and cooling rate, CR, were changed in order to evaluate their effect on microstructure and hardness. Those laboratory conditions supposed to give the best results were transposed to industrial scale, so as to produce experimental lots of plates with five different cooling strategies. It was shown the possibility to find a cooling profile that guarantees the balance between mechanical properties and flatness requirements. The influence of cooling strategy on flatness was explained by the varied heat transfer regimes occurring from hot steel surface to the ambient.
Keywords
TMCP, Accelerated cooling, API steels, Microstructure and flatness
TMCP, Accelerated cooling, API steels, Microstructure and flatness
How to refer
Paiva, Fabricio Mazola da Silva;
Santos, Antonio Adel dos;
Buono, Vicente Tadeu Lopes;
Gandra, Carmos Antonio.
INFLUENCE OF ACCELERATED COOLING CONDITIONS ON MICROSTRUCTURE AND FLATNESS OF API STEEL HEAVY PLATES
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p. 51-61.
In: 56° Seminário de Laminação e Conformação de Metais,
São Paulo,
2019.
ISSN: 2594-5297
, DOI 10.5151/2594-5297-32315
