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http://cml.postech.ac.kr/. 1 µm. Surface 1 Surface 2. 50 µm. Srinivasan & Wayman, 1968. s. d. c. r. 1. 50 µm. Bhadeshia and Waugh, 1981. Takahashi and Bhadeshia. 2. 1. 0. 300. 400. 500. Fe-0.4C wt%. Decarburisation
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Surface 1 Surface 2 50 µm Srinivasan & Wayman, 1968
s d c r 1
2 1 0 300 400 500 Fe-0.4C wt% Decarburisation time / s Temperature / °C
Temperature Ae3' T' o x Carbon in austenite
TRIP-assisted steel Fe-0.29C-1.41Si-1.42Mn wt% (Jacques, 2001)
Growth is diffusionless. Strain energy must be accounted for.
Summary The mechanism of transformation is displacive. Transformation temperature higher than martensite. Bainite grows without diffusion. But carbon then escapes into the residual austenite. Shape deformation plastically accommodated. Sub-unit mechanism of growth
Think of bainite as martensite which tempers during transformation
DISPLACIVE RECONSTRUCTIVE
Summary Mechanism of transformation is displacive but carbon must partition during growth. Pairs of plates grow together to minimise strain.