The Effect of Cryogenic Treatment on W360 and E38K Hot Work Tool Steels

Abstract

The present study examines the impact of cryogenic treatment (CT) on W360 and E38K hot work tool steels used in forging dies, subjected to conventional heat (HT) and CTs followed by double tempering treatment. Results reveal that CT facilitates the transformation of retained austenite from 4.9% and 2.5% for W360 and E38K steels, respectively, into martensite to an undetectable limit. Also, when compared to HT, CT at -180 degrees C results in about 3 times higher amount of the carbide precipitation for both steel types. In contrast, a slight increment in the hardness values with decreasing treatment temperature is observed. Notch impact test results indicate higher impact energy with lower CT temperatures, particularly notable in W360 steel. Although both steel types exhibit almost similar impact energy values at room temperature, E38K steel has approximate to 100% higher energy at 350 degrees C. DCT-treated samples show improved wear resistance at lower cryogenic temperatures. Cryotreated W360 steel displays nearly 25% less wear rate than cryotreated E38K steel. The study underscores the suitability of W360 and E38K steels for hot work applications, with CT enhancing their mechanical and microstructural performance, particularly in W360 steel due to its higher carbide density. The cryogenic treatment facilitates the transformation of retained austenite to martensite to an undetectable limit, with about 3 times higher amount of the carbide precipitation for both steel types. Both steel types exhibit almost similar impact energy values at room temperature, but E38K steel has 2 times higher energy at 350 degrees C. Cryotreated W360 steel displays nearly 4 times less wear rate than cryotreated E38K steel.image (c) 2024 WILEY-VCH GmbH