Abstract
The results of researches of possibilities of increasing the mechanical properties of pig iron with ball-bearing graphite of brand FCD-50 by the combined heat treatment are described. The scheme of multistage heat treatment, the characteristic feature of which is the operation of cooling in liquid nitrogen, is proposed. The use of such a scheme allows for increased HRC hardness characteristics. The study of the microstructure of cast iron treated with this scheme has proved the efficiency of the cryogenic heat treatment stage and determined its rational regimes.To match or approximate the properties of steel, the mechanical properties of this ductile cast iron 50 (FCD-50) must be enhanced by methods such as ACTDI (austemper cryogenic and temper Ductile Iron). In this procedure, the FCD-50 specimen is inserted into the electric kitchen heater at 350 °C (room temperature), heated to 600 °C and held at this temperature for 45 minutes. Next, the specimen is heated to 900 °C and held at this temperature for 1 hour (temperature austenisation). Then, the specimen is placed in furnace 2 at 3,000 °C for 45 minutes (austempering process). The specimen subsequently is cooled in liquid nitrogen. In this study, additional specimens were obtained for hardness and microstructure tests. The as-cast test yielded a hardness value of 18.39 HRC. In the hardness test for the ACTDI process, 12 hours of submersion yielded the highest hardness result of 24.25 HRC. In terms of the changes in microstructure after soaking changes, the amount of perlite present in the specimen was greater than that of ferrite, and the arrangement of graphite nodules was better than that of the as-cast material.
Highlights
Known as nodular cast iron, spheroidal graphite iron (S.G. iron) and spherulitic iron, has the best mechanical propertieswhen compared to other types of cast iron
The aim of this study was to improve the mechanical properties of ductile cast iron (FCD-50)
The ACTDI process resulted in increased hardness and microstructure changes in ductile cast iron (FCD-50) as listed in the hardness data table (Table 1)
Summary
Known as nodular cast iron, spheroidal graphite iron (S.G. iron) and spherulitic iron, has the best mechanical propertieswhen compared to other types of cast iron. For both motor vehicles and production machinery, component–component machines have been developed as indicated by field data. The mechanical properties of cast iron fall short. The components of these machines that contain cast iron graphite round include gears, shafts, piston rings, and cylinder liners and heads. Improved ductile cast iron can be used as a steel partner to meet the need for reinforcing steel
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