The phenomenon that quenched boron and the boron in steel cluster to austenite grain Boundaries is non-equilibrium grain boundary clustering. By the way of resolving no isothermal diffusion equation, a mathematical expectation for non-equilibrium grain boundary clustering has been derived, and the relationship among measure of boron depleted zone, quenching temperature, cooling rate, activation energy and diffusion coefficient of non-equilibrium grain boundary clustering has been established. The ...