Application of Response Surface Method in Optimization of Impact Toughness

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 eta-carbide 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 tempere