A study of isochronal austenitization kinetics in a low carbon steel

Rem: Revista Escola de Minas

Maximiano Maicon Batista Lopes²  André Barros Cota¹ 

[1] ,Federal University of Ouro Preto REDEMAT

关键词: austenite formation;    kinetics;    low carbon steel;    formação da austenita;    cinética;    aço baixo carbono;   

DOI  :  10.1590/S0370-44672014000100009

来源: SciELO

【 摘 要 】

The austenite formation under isochronal conditions in Nb microalloyed low carbon steel was studied by means of dilatometric analysis and the data was adjusted to the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation, for different heating rates and for three initial microstructures. It was shown that the kinetics of austenitization of a pearlite+ferrite structure is faster than that of martensite (tempered martensite) at a heating rate of 0.1ºC/s. For heating rates higher than 0.1ºC/s, the kinetics of austenitization of a martensite structure is faster than of pearlite+ferrite one. The K parameter of the JMAK equation increases with the heating rate for the three previous microstructures and it is greater for the initial microstructure composed of ferrite+pearlite. At lower heating rates, the formation of austenite in this steel is controlled by carbon diffusion, independently of the initial microstructure. At higher heating rates, the formation of austenite from an initial microstructure composed of pearlite and ferrite is controlled by interface-controlled transformation.

【 授权许可】

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