2. A carbon
concentration of 0.8% was targeted on the surface of the
specimens and the carburizing time was selected as 3, 5
and 7.5 hours at the process temperature of 1173 K
(900°C), in order to obtain different case depths. After
quenching in oil, all specimens were tempered at 453 K
(180°C) for one hour. A set of specimens were also austenitized at 1173 K (900°C) for 30 minutes in a controlled atmosphere avoiding decarburization at the surface. Following oil quenching, these specimens were
tempered at 453 K (180°C) for one hour.