Effect of heat treatment on microstructure behavior and hardness of en 8 steel

Abstract

EN 8 steel is an important grade of steel, used for manufacture of axles and shafts, bolts, gears, studs etc. Heat treatment is an important step in achieving desired mechanical properties and microstructure, for different applications. However, with the increase in hardness and wear resistance, machinability decreases consequently. Literature review of past works failed to achieve a good balance between hardness and machinability. In this experimental work, heat treatment methods, namely, annealing, normalizing and quenching is done on EN 8 steel, a grade of medium carbon steel. Hardness and microstructure is studied and compared. Furthermore, tempering is also conducted after each heat treatment to study its effects on hardness and microstructure. Results show that tempering after normalizing of EN 8 steel gives satisfactory hardness values. The microstructure is also found to consist of fine grains of pearlite.