Microstructural and Mechanical Properties of Hot Deformed AISI 4340 Steel Produced by Powder Metallurgy

Abstract

In this work, AISI 4340 steel was produced by powder metallurgy. Samples were sintered at 1150oC for 90 min. and then cooled in the furnace. Except to those in the as-sintered condition, one of the produced samples was homogenized at 1150oC for 1 h and then cooled in air. Other samples were deformed at the temperature range of 1150-930oC and deformation rate of 30 and 60% followed by cooling in sand, air and water mediums. The grain size gradually decreased depending on the deformation rate or cooling rate in AISI 4340 steel. Small grains occurred due to completely recrystallization at 60% deformation rate. Density and hardness also increased by the increase in deformation rate. The results showed that hot deformation is a process that is capable of improving the properties of AISI 4340 steel produced by powder metallurgy without rising the addition of alloying elements.