Aplicação de tratamento termomecanico a um aço bainitico microligado com niobio, titanio e boro

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

The influence of different conditions of controlled rolling and cooling was studied, simulating the industrial process of hot strip mill. This simulation aimed the investigation of microstructure formation and mechanical properties of a low carbon bainitic steel microalloyed with niobium, titanium and boron. In addition to the analysis of process parameters, the influence of boron on the material properties was evaluated. The experiments were performed in a thermomechanical processing laboratory, using a 25 HP FENN reversible rolling mill. The samples were initially reheated to 1200°C, kept at this temperature for one hour, and then rolled in the region of high temperature austenite (1150°-1050° C) with 50% of total reduction in three passes, followed by one step of deformation at low temperatures, corresponding to the region of non-recrystallization of austenite. In this stage, three rolling temperature ranges and cumulative reductions were used. After rolling, the samples were submitted to either air or accelerated cooling and then slow cooled , simulating the coiling processo For the latter step, three initial temperatures were applied. The experimental results indicated that increasing the cumulative reduction and lowering the finishing pass temperatures improve the material toughness, with a slight decrease on the Yield Stress and Tensile Strength. Increasing the cooling rate and reducing the coiling temperature, improved the mechanical strength with no significant deterioration on the impact properties. Finally, the importance of boron addition was confirmed for the development of bainitic steels

ASSUNTO(S)

laminação (metalurgia) aço - metalurgia aço de alta resistencia

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