Quenching of Cast Iron with a High Copper Content

The structure, hardness, and microhardness of hypoeutectic white cast iron alloyed with copper after quenching at 1000 and 1120 degrees C is studied. Features of cupric inclusion separation are detected and its size distribution is shown. After quenching the structure consists of martensite, residual austenite, and vermicular graphite. A decrease in the size and volume fraction of globular cupric inclusions is detected, along with the complete dissolution of nanoscale cupric inclusions, which are located in the ferrite of pearlite colonies. The result of these structural changes is a 30% increase in iron hardness. Cast iron quenching at 1120 degrees C is followed by an increase in the austenite volume fraction to 69%. This effect is due to a decrease in the volume fraction of graphite and a corresponding increase in the carbon content in gamma-Fe. Cupric inclusions are located mainly along boundaries of austenitic grains.