Effect of Polymer Quenchants on the Toughness and Hardness of Different Medium Carbon Low Alloy Steels.

Abstract

In the present study, medium carbon low alloy (MCLA) steels like AISI 5140 (EN18) and AISI 4140 (EN19) are treated in different quenching media under solutionizing temperature of 855°C. Quenched in SAE 250 oil, polyethylene glycol (PEG) (10% and 30%), and water. The quenched samples are step-tempered at 575°C and at 220°C sequentially with 60 minute soaking time. BHN, YS, UTS and tensile toughness are determined for the untreated and heat-treated samples. It is found that there is an excellent correlation, with correlation coefficients of 0.97. The standard generalized equation for these two steels are established. Tensile toughness = 19000 + 12 BHN- 215 El. The study revealed that the PEG is better in terms of cost, fire-resistant and biodegradable. 30% polymer quenched samples result in better tensile toughness properties as compared to 10% polymer quenched samples.