Kinetics and Microstructural Control

· Carbon content controls the temperature at which martensite starts to form (M_S) and also the morphology of this non-equilibrium material as shown on the phase diagram opposite.
· Because of the speed of the reaction, carbon atom diffusion does not take place during the transformation. The super-saturaturation of the low temperature structure with carbon causes the distortion to body-centered-tetragonal.

From: Smith, "Structure & Properties of Engineering Alloys,"
McGraw Hill (1981)