  A compositionally-graded steel composed of martensite with 0.4%C on the
centre and bainite with 0.1%C on the surface was manufactured by partial
decarburization. It is reported that the as quenched material can be cold
rolled up to an equivalent strain of 1.5 without cracks. The mechanical
properties of the cold-rolled material exhibits up to 2.5 GPa strength and
ductility. A simple mechanical model is developed to predict the stress state
after rolling of the graded structure explaining the good ductility of the
present high strength materials.
