HARDNESS AND MICROSTRUCTURE OF 0.60%C STEEL HARDENED IN TRANSESTRIFIED NEEM OIL

The hardness, impact strength and microstructure of 0.60%C plain carbon steel quenched-hardened in transesterified neem oil (TN) are reported in the study. Fresh neem oil (FN) was transesterified using methanol. Afterwards, steel samples normalized and then austenitized at 850oC for 40 minutes and then quenched in TN, FN and SAE40. The quenchant used as bench mark was SAE40. The as-quenched samples’ hardness and impact strength tested. Additionally, microstructural analysis on the as-quenched samples was carried out. TN-quenched sample exhibits higher hardness and impact strength as compared to FN-quenched parts. In all the quenched samples, martensite and retained austenite were observed. The investigation shows that TN gives good combination of hardness and impact strength. Therefore, TN is recommended to be used as quench medium for 0.60%C (AISI 1060) steel

Cooling Rate Observation in Quenching Process Using Carbon Nanofluids for S45C Carbon Steel

Quenching process is the most important step in steel heat treatment as this process will determine the properties of the steel such as strength and hardness. Different cooling rate and thermal conductivity provided by the quench medium affect strongly to the mentioned steel properties. Recently, studies for nanoparticle added in the quench medium are developing rapidly. This nanoparticle added fluid is known as nanofluid and could affect the thermal property of the quench medium which ultimately changes the properties of the steel. The nanoparticle composition in nanofluid will affect its thermal property. In this research, carbon was used as the nanoparticle. The composition variations were 0.1, 0.3, and 0.5 weight percent in 100 ml distilled water. Pure distilled water was also used as a comparison control. Planetary ball-mill were utilized for 15 hours at 500 rpm to produce nanosized carbon particle. Field-Emission Scanning Microscope (FE-SEM) and Energy Dispersive X-Ray (EDX) were used to check the particle size, shape and purity of the carbon nanoparticles. These nanofluids were then used to quench S45C carbon steels samples annealed at 1000°C for 1 hour. Samples were attached with a thermocouple which connected to temperature data logger to observe the cooling rate of the quench medium. The quenched samples were be tested to get the information of hardness and metallography analysis for supporting data.