Effect of Palm Oil and Water Emulsion Quenchants on Mechanical Characterization of Quenched EN 19 Steel

– The present investigation emphasizes on mechanical characterization of medium carbon low alloy hardened treated EN 19 steels. Preparation of emulsified palm oil and water quenchant is done by the ultrasonication process. Varying the different percentages of emulsified quenching media can improve the mechanical properties of the steel. Hardening treatment is carried out at 800, 850, and 900 °C in the furnace at 1, 2, and 3 h holding times, quenching in 25, 50 and 75% oil solutions. The design of the experiment, the Taguchi method, is used for statistical analysis based on Taguchi L9 experiments. Hardness, tensile and impact tests were carried out. The hardness value and the tensile strength of the samples increased after heat treatment, while the impact decreased strength in reducing the oil content in the solution. The solution containing a 50% of blended quenchant shows better tensile strength values, whereas the samples which were quenched in a solution containing 25 % percentage of oil with a shorter isothermal holding time showed better impact strength. Microstructure reveals the formation of martensite and ANOVA and regression analysis show better hardness and tensile strength with increasing the heating temperature from 800 to 900 °C and a reduction in the impact strength. It is also observed that an increase in oil content in the quenchants content, the transformed hardness and strength decrease with the increase in toughness.