Alloy design for a low thermal expansion cast iron with enhanced mechanical properties

The effects of various alloying elements, such as Cr, Ti, V and Mo on the h ardness, the damping capacity, and the linear thermal expansion coefficient of Invar-type austenitic cast irons were investigated. A combined addition of Mo and V was found to be most effective for the improvement of hardness without deteriorating the thermal expansion behaviour and the damping capa city. The effect of carbon equivalent on specific damping capacity (SDC) an d dynamic Young's modulus was also investigated. The specific damping capac ity of low thermal expansion cast irons increased with an increase in carbo n equivalent. In the case of V and Mo addition, SDC decreased which is cons idered to be caused by an increase in the amount of carbides, The relative machinability of the Invar cast steel, Invar-type cast iron, Meehanite cast iron, and the modified Invar-type cast iron containing Mo and V was also e valuated based on the tool life test and hardness profile through the speci men thickness after machining.