INVESTIGATING THE EFFECT OF WATER, VEGETABLE OIL AND BRINE SOLUTION ON AUSTENITE TEMPERATURE OF 0.3% CARBON STEEL.

This study investigates the influence of different quenching media water, vegetable oil, and brine solution on the mechanical properties of 0.3% carbon steel. Specimens were heated to an austenitizing temperature of 950 °C, soaked for 60 minutes, and subsequently quenched in the selected media. The resulting properties were evaluated through hardness, tensile, and compression tests, using an impact testing machine and universal testing machine at the Mechanical and Civil Engineering Workshop of Auchi Polytechnic. Tensile Test Results: Brine-quenched specimens exhibited the highest ultimate tensile strength (760 MPa) and yield strength (600 MPa) but with low ductility (12%) and brittle fracture. Water quenching achieved 720 MPa UTS, 580 MPa YS, and 18% elongation, showing moderate brittleness. Vegetable oil quenching yielded the lowest strength (680 MPa UTS, 550 MPa YS) but the highest ductility (22%), indicating better toughness. The hardness test showed that brine quenching gave the highest hardness value of 60 HRC, followed by water quenching with 55 HRC, while vegetable oil quenching produced 50 HRC. Although brine provided maximum hardness, it also induced brittleness and cracking, whereas vegetable oil achieved a better balance between hardness and ductility. Compression Test: Brine quenched specimens recorded the highest ultimate compressive strength at 870 MPa, followed by water (820 MPa) and vegetable oil (729 MPa). Strain at failure was 14% for brine, 16% for water, and 20% for oil, confirming vegetable oil’s superior ductility under compression. Overall, brine solution maximizes hardness and strength but results in brittle behavior, water provides a balanced combination, while vegetable oil offers better toughness and ductility at the expense of peak strength.