Analysis of Mechanical Properties of EN 24 Steel After Austempering and Martempering

Abstract

:- The mechanical properties of steel decide its applicability for a particular condition. Heat treatment processes are commonly used to enhance the required properties of steel. The present work aims at experimentally investigating the effects of normalizing, Austempering and timed quenching on AISI 4340 steel. The material was machined to ASTM standards and then different tests like microstructure analysis, hardness test, impact test, and were carried out after the heat treatment processes. All the tests were carried out in the mechanical workshops and laboratories under the supervision of their respective faculty, at the MIT campus, Manipal. It was found that normalized steel was least hard and while timed quenched steel was hardest. The ASTM grain size affirmed these results by displaying a similar trend. An increase in brittleness was observed with the increase in hardness, with the timed quenched specimen displaying the least impact strength.

Heat treatment is necessary to obtain the required mechanical and physical properties for a material to make it suitable for fabrication. For this reason, the knowledge of heat treatment is necessary to suitably condition the material for the subsequent stages of manufacture, or in the case of semi-finished component to impart the desired mechanical and physical properties such as increased strength, toughness and wear resistance. Heat treatment is also resorted to relieve internal stresses and to soften hard metals in order to improve machinability. The outstanding advantage of steel as an engineering material is due to its versatility. Its properties can be controlled and changed at will by the heat treatment. Thus, if steel is to be formed into some intricate shape, it can be made very soft and ductile by the heat treatment, if, on the other hand, it is to resist water, it can be heat treated to a very hard, wear-resisting condition.