Time-Dependent Austempering of High Carbon Steel using Epoxidized Cotton Seed Oil

Abstract

The work seeks to ascertain the potential of austempering time on the microstructure and mechanical properties of high carbon steel using epoxidized cotton seed oil bath. Five sets of high carbon steel (HCS) samples were heated to an austenitizing temperature of 830°C in the furnace, soaked at that temperature for 1 hour and quenched interruptedly at a temperature of 310°C in epoxidized cotton seed oil (ECO) bath for 15 – 75 minutes (at regular intervals of 15 minutes for different samples’ sets). Subsequently, samples air-cooled at ambient temperature. Hounsfield tensometer, Indentec universal hardness tester and Izod impact tester were used to determine the mechanical properties of the austempered samples. From the outcome of the investigation, appreciable improvement was noted in tensile strength (1210 N/mm2), hardness (397 HBN) and impact strength (12.1 J/mm) of the austempered samples. Further, samples were subjected to metallographic sample preparation, succeeded by microstructural examination using scanning electron microscope (SEM). The structures observed to be majorly bainite. The austempering time of 15 minutes produced the outstanding combination of mechanical properties.