56. Growth is diffusionless. Strain energy must be accounted for.
57. Takahashi and Bhadeshia
59. Oka and Okamoto
60. Ohmori and Honeycombe
61. 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 Summary
62. Think of bainite as martensite which tempers during transformation
65. DISPLACIVE RECONSTRUCTIVE
72. Watson and McDougall, 1973
76. Mechanism displacive but carbon must partition during growth. Pairs of plates grow together to minimise strain. Summary
77. Nucleation of martensite, bainite, Widmanstätten ferrite
78. x Gibbs free energy Carbon Thermodynamics G m x m G
80. T h G N
81. Bhadeshia, 1981 Each point represents a different steel Nucleation function G N
82. The nucleation of bainite must involve the partitioning of carbon Why does the required free energy vary linearly with T?