EFFECT OF CRYOGENIC TREATMENT ON EN8 STEEL USED FOR PRESS TOOL

Abstract

Cryogenic Treatment is an additional process to conventional heat treatment in material processing technology. Not like coatings of superior materials over other metals, it is a onetime process that affects the entire section of the component. Cryogenic treatments are considered to be a good way to reduce the retained austenite content and increase the performance of tools. In this study cryogenic treatment is applied on EN8 steel which is used as a press tool, subsequently determining its properties by means of hardness test and microscopic observation. Furthermore, optimization of tools (normal and cryogenic), pressure and stroke length has been done using Response Surface Methodology (RSM) based desirability function for the minimization of surface roughness and maximization of stamping depth. Pneumatic powered normal and cryogenic EN8 tools are observed under specific operating conditions. Obtained hardness values of EN8 before and after cryogenic treatment are 223 BHN and 310 BHN respectively. Also retained martensite structure is obtained which improves its surface properties. Furthermore, a fatigue life analysis has been carried out to examine the effect of cryogenic treatment on the life cycle of the same tools. Fatigue analysis proved that life cycle has been improved tremendously after cryogenic treatment.