METHOD OF LOW-ALLOY NODULAR CAT-IRON CASTING THERMAL TREATMENT

摘要

In order to reach a high strength and the plastic parameters of cast pieces, these are austenized at a temperature of 880 to 950 degrees C, whereupon they undergo an incomplete isothermal decomposition of austenite at the transformation temperature of 240 to 420 degrees C with the subsequent after cooling. The transition of cast pieces from the austenization ambient into the ambient, in which, the incomplete isothermal decomposition takes place, lasts for 5 to 20 seconds.The introduced method is applied with cast pieces in a basic composition of 3.0 to 3.7 percent of carbon, 2.0 to 3 percent of silicon, 0.2 to 0.5 percent of manganese, 0.01 to 0.07 percent of phosphor, 0.01 to 0.04 percent of sulphur, 0.04 to 0.08 percent of magnesium and the cast pieces contain, aside from the vanadium, also one of the alloying elements of nickel, molybdenum or copper. The cast piece processed in this way display altogether high mechanical properties, which enable their use in much stressed components.