Interfacial reactions in white iron/steel composites

The interfacial phenomena occurring when a white iron of low melting point is cast onto a steel substrate are considered. Such layered composites offer the prospect of combining the toughness of steel and the wear-resistance of a white cast iron into a single structure. It is shown that an epitaxial interfacial layer of austenite is precipitated onto the steel substrate from the liquid phase, and that the thickness of the layer can be controlled by soak time at 1250 °C. Significant mass transfer of carbon takes place through this layer into the steel substrate.

► Joints made between high chromium cast iron and steel by a kiln casting process.
► Key phenomenon is the formation and growth of an interfacial layer of austenite.
► Details of the process revealed by in situ observation in confocal microscope.
► Growth of layer controlled by counter-current mass transfer of carbon and iron.