Título

SPHEROIDIZATION CYCLES FOR 4140H STEEL AFTER COLD DRAW

SPHEROIDIZATION CYCLES FOR 4140H STEEL AFTER COLD DRAW

Autoria

Lima, Lara Fernandes Rocha Barbosa

DOI

10.5151/2594-5327-40038

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Resumo

The spheroidization treatment consists of long time at adequate temperatures for the formation of spherical carbides in a ferritic matrix, in order to increase its ductility and decrease the hardness. However, this is a treatment with very slow kinetics, impairing its viability for production on an industrial scale. Therefore, it was studied the effect of prior cold deformation on the rate of spheroidization and differences on microstructure after subcritical and intercritical annealing of 4140H steel. It was observed that the intercritical route has a faster drop in the hardness of the steel, even though the carbide does not seem as fragmented as the subcritical routes ones. It was also observed that in the subcritical route it is not very noticeable change in microstructure between 2 and 4h of soak time, when the coarsening of the carbides started happening, but it was observed a continuously drop in hardness in this stage of spheroidization.

 

The spheroidization treatment consists of long time at adequate temperatures for the formation of spherical carbides in a ferritic matrix, in order to increase its ductility and decrease the hardness. However, this is a treatment with very slow kinetics, impairing its viability for production on an industrial scale. Therefore, it was studied the effect of prior cold deformation on the rate of spheroidization and differences on microstructure after subcritical and intercritical annealing of 4140H steel. It was observed that the intercritical route has a faster drop in the hardness of the steel, even though the carbide does not seem as fragmented as the subcritical routes ones. It was also observed that in the subcritical route it is not very noticeable change in microstructure between 2 and 4h of soak time, when the coarsening of the carbides started happening, but it was observed a continuously drop in hardness in this stage of spheroidization.

Palavras-chave

Spheroidization; subcritical; intercritical; cold draw; 4140H;

Spheroidization; subcritical; intercritical; cold draw; 4140H;