EXPERIENCE IN PRODUCING HIGH-DURABILITY CAST IRON AT THE BLAGOVESHCHENSK VALVE PLANT JSC (BAZ JSC)

Abstract

The main objective of the work was to develop a technological process for manufacturing ductile iron (DI) castings that would fit into the existing production of friction wedge castings made from gray iron grade GI35. In the production of friction body castings from gray iron grade GI35, iron melting is conducted in an IST induction furnace, and metal pouring is carried out from a tea-pot ladle with a metal capacity of 700 kg. For DI production, the Sandwich process was chosen, which does not require capital investments. Inoculation was performed in the tea-pot ladle. The following inoculants were selected: spheroidizing inoculant ErgoMag-59 with fraction 1–10 mm, graphitizing inoculant ErgoSil67 with fraction 0.7–3 mm, complex inoculant MK82, steel shot – 7 kg (1.4%). The inoculants were loaded at the bottom of the ladle in a position opposite to the stream fall when releasing the melt from the furnace. The release temperature was 1440°C. Experiments showed that by varying the chemical composition of the initial iron before inoculation, it is possible to obtain DI of grades from DI40 to DI80 in the as-cast condition. Isothermal quenching of ductile iron castings of grades DI70 and DI80 will allow obtaining friction wedge castings of grade DI120.