Third. 3. EUTECTIC TRANSFORMATION AND NUCLEATION OF CAST IRON Both gray cast iron and ductile iron are EUTECTIC FE-C alloys, and eutectic transformation is the most important step in the solidification process. Although primary austenite is precipitated in hypoeutectic cast iron, eutectic cast iron, and hypereutectic cast iron, however, the eutectic transformation does not rely […]
Morphology of primary AUSTENITE DENDRITE The Crystal Lattice of austenite is face-centered cubic. When the AUSTENITE is nucleated and grown directly from the liquid iron, the AUSTENITE is stable only when the surface energy is minimum and octahedral crystal is formed. Then, because the concentration gradient of solute in the liquid iron at the edge […]
Second. Primary AUSTENITE DENDRITE IN CAST IRON Due to the mechanical properties, Gray cast iron is usually hypoeutectic, and there will be primary austenite dendrite in solidification structure. Under the condition of special properties of cast iron (such as high thermal conductivity and good shock absorption), gray cast iron with near Eutectic or hypereutectic composition […]
2. UNIDIRECTIONAL NUCLEATION In the solidification process of the metal-nonmetal system, the nonmetallic substance can be the core of metal solidification, while metal cannot be the core of nonmetallic substance solidification, which is called One-way nucleation.
The final properties of iron castings are mainly determined by the structure formed during solidification. For example, the thermal properties of gray iron are affected by the shape, size, and quantity of graphite in its structure. The mechanical properties depend on the number of primary Austenite Dendrites, the morphology of graphite and the size of […]