Evaluation of Mechanical Properties of Medium Carbon Low Alloy Forged Steels by Polymer Quenching

Medium carbon low alloy forged steels were investigated (EN18, EN19, EN 24, and EN25) with respect to their mechanical properties by polymer quenching. The effect of polyethylene glycol (PEG) H−(O−CH2−CH2)n−OH as a quenchant was studied by varying polymer concentration (10% and 30%) to investigate the mechanical properties and their metallographic structures. The study was carried out on the medium carbon low alloy forged steels in heat treated condition by hardening in the polymer quenchant. The quenched samples were step tempered at 575⁰C and at 220⁰C sequentially for 60 min each. Hardness, tensile strength, Charpy impact strength and metallographic were carried out on the untreated and heat treated specimens. The step tempering process of the specimen gives the high strength with high hardenability. The specimen quenched in the polymer solution exhibited the best mechanical properties, viz., as received samples. The mechanical properties are found increased in the polymer quenchant because of the slow and uniform cooling rate of the polymer. The microstructural examination of the specimens were found to have justified reason for the increment recorded in some of the mechanical properties, as it displayed a high proportion of the martensitic phase. (paper)