The effect of varying quenching media on cooling time and microstructures of leaf spring steel AISI 5160

Abstract

The mechanical properties of the material is affected by the microstructure, and the microstructure is determined by the cooling time. This research aims to evaluate the effect of varying quenching media on cooling time and microstructures of leaf spring steel AISI 5160. The leaf spring steel AISI 5160 was heat-treated at 850 oC for 30 minutes and was cooled in the varying quenching media. The quenching media were oil, water, water 1 L + soap 10 g, water 1 L + soap 15 g, water 1 L + soap 25 g, water 1 L + urea 10 g, water 1 L + urea 15 g, water 1 L + urea 25 g sand, air, and furnace. The cooling times were calculated by newton’s law of cooling and heating equation, the microstructures were observed by an optical light microscope, and the percentages of martensite and retained austenite in the material were calculated by Optimas software. The results show that the fastest cooling time is 20.20 s cooled in water 1 L + urea 25 gr, and the longest cooling time is 82800 s cooled in the furnace. The microstructures of the material were martensite and retained austenite when the materials are cooled in a water and oil base quenching media. The microstructures were ferrite and pearlite when the materials are cooled in air, sand, and the furnace. The lowest percentage of the martensite is 78.4 % cooled in oil quenching media, and the highest percentage of the martensite is 94.4 % cooled in water + urea 25 g.