Evaluation of Mechanical Properties of Medium Carbon Low Alloy Forged Steels Quenched in Water, Oil and Polymer

摘要

Medium carbon low alloy forged steels (EN 18, EN19, EN 24, and EN25) have been investigated with respect to their mechanical properties after heat treatment. For heat treatment solutionizing temperature of 855°C with a soaking period of 60 min was used. Thereafter quenching was carried out in three media, viz., Step water, oil and polymer (polyethylene glycol) separately. The quenched samples were step tempered at 575°C and at 220°C sequentially for 60 min each. Hardness, tensile strength, Charpy impact strength and metallographic were carried out on the untreated and heat treated specimens. The heat treated specimens showed higher hardness (10-30%), higher strength (20-100%) and higher impact energy (20-160%). The specimens quenched in poly ethylene glycol exhibited the best mechanical properties. The heat treated specimens had a structure of fine tempered martensite with small amount of bainite.