Comparison of wet and dry milling on carbon biomass as dispersed particle in quench medium for steel heat treatment application

Abstract

Particle dispersion in the quench medium can alter its properties, particularly its thermal conductivity. Modulating the quench medium’s thermal conductivity can impact the steel’s hardness after heat treatment. In this study, micron-sized particles of carbon biomass derived from coconuts were obtained by milling the biomass via wet and dry methods. The milling duration for both methods was 10, 15, and 20 h, while the speeds were 250, 500, and 750 rpm for each duration. Particle size analysis revealed that dry milling could decrease the particle size by up to 60% from its initial size, whereas wet milling could only decrease it by up to 43%. A thermal conductivity test was conducted on the water-based quench medium supplemented with milled particles, demonstrating an increase in thermal conductivity up to 0.68 W mK−1 and 0.83 W mK−1 for dry and wet milling, respectively. All steel quenched with particle-added quench medium showed a hardness up to 21% higher than steel quenched with distilled water. The increase in hardness suggests that the cooling rate during quenching was faster because of the additional dispersed particle, determined by the quench medium’s thermal conductivity.