Effect of the Heat-Treatment Process on the Mechanical and Microstructure Properties of EN8 Steel

1. Introduction

EN8 is unalloyed medium carbon steel that has better mechanical properties and also good machinability than mild steel (M et al., 2019). EN-8 steel (also called AISI 1040 steel or 080M40) has been extensively used in automobile crankshafts, power transmission shafts, and gears (Prabhu et al., 2019). Heat treatment refers to the process of heating a metal and then cooling it to room temperature in order to improve its properties, life, and durability, and it may be used for almost anything. Heat-treated materials become softer, making them easier to shape. It can make components stiffer by making them harder. It may provide a hard topography to comparatively soft materials to improve wear properties. It has the potential to produce corrosion-resistant skin, which aids in the protection of components that could otherwise decay. It may also harden brittle items. Heat-treated components are essential for the effective operation of automobiles, spacecraft, and various heavy equipment. Numerous processes of heat treatment comprise normalizing, annealing, hardening, tempering and hardening (Srivastava et al., 2021). Annealing consists of heating and holding at a proper temperature followed by cooling at a suitable rate. It is often applied on steel or iron materials to soften, enhance the grains and increase elongations (Kazdal Zeytin et al., 2011). In normalizing, the substance is heated to the austenitic temperature and followed by air cooling. It is generally carried out to attain a pearlite matrix and increase the strength and hardness (Chandra Kandpal et al., 2021). Hardening is commonly used to increase the hardness of the materials by heating to a definite temperature and subsequently cooling rapidly to room temperature. Tempering is mostly desired to increase the ductility and toughness of the materials (Chang et al., 2020).