Application of Response Surface Method in Optimization of Impact Toughness of EN24Steel.

Rohit Pandey1, Rahul Davis2 1Research Scholar (M.Tech), Department of Mechanical Engineering, Shepherd School of Engineering and Technology 2Assistant Professor, Department of Mechanical Engineering, Shepherd School of Engineering and Technology SHIATS,, Allahabad, Uttar Pradesh, India E-mail- Địa chỉ email này đã được bảo vệ từ spam bots, bạn cần kích hoạt Javascript để xem nó.

DOE 29

Abstract—

Impact testing methodology is findings the applications for determining the impact strength of the different materials. Oneof the most important characteristics of structural steels, toughness is assessed by the Charpy V-notch impact test.

The objective of the research was to maximize the impact toughness by selecting various combinations of Charpy Impact test parameters.

In this paper, experiments were carried out to Study the Effect of Thermal Treatments (annealing, cryogenic treatment and tempering) on Impact Toughness.

Cryogenic treatment (CT) is the supplementary process to conventional heat treatment process in steels, by deep– freezing materials at cryogenic temperatures to enhance the mechanical and physical properties of materials being treated.

For this purpose, the temperature was used -196oC as deep cryogenic temperature.

The effects of cryogenic temperature (deep), cryogenic time (kept at cryogenic temperature for 36 hr) on the wear behavior of EN24 steel were studied. The findings showed that the cryogenic treatment decreases the retained austenite and hence improves the wear resistance and hardness.

The process has various advantages like increase in hardness, increase in wear resistance, reduced residual stresses, fatigue resistance, increased dimensional stability, increased thermal conductivity, toughness, by transformation of retained austenite to martensite, the metallurgical aspects of etacarbide formation, precipitation of ultra- fine carbides, and homogeneous crystal structure.

The findings show that the cryogenic treatment improves the wear resistance and hardness of EN24 steel. En24 steel is generally used in the hardened and tempered condition to achieve an optimum combination of hardness and ductility.

In the present study, heat treatment process of En24 steel was done which includes Annealing and Tempering at high temperature.

The specimens tempered at different temperatures (in the range 473–823 K) exhibited decreasing hardness with increase in tempering temperature. Response surface methodology was adopted in designing the experiments for three factors with 27 levels. 

Keywords—

EN24 Steel, Impact Toughness, Thermal Treatment, Cryogenic Treatments, Hardness, Austenite, Martensite, Carbide formation, Tempering, Wear Resistance.