Effect of Different Cooling Conditions on Grain Refinement and Mechanical Properties of Low Carbon Steel: A Comprehensive Evaluation

Low-carbon steel's characteristics are mostly dictated by critical cooling rate, recrystallization temperature, and cooling medium. Higher cooling temperatures increase the possibility of coarse grain development in the martensite structure. Lower cooling rates, on the other hand, encourage the development of tiny grains inside a martensite and pearlite structure that is evenly distributed. The cooling medium directly impacts the material's microstructure. Several cooling media were employed in this investigation, including boiling water, SAE 15W-30 oil, freezing water, and water at room temperature. The fluid's viscosity mostly influences the cooling rate; finer grains result from higher viscosity. The temperature must be lowered below the critical cooling rate to enhance hardening, encourage the growth of fine grains, and lessen strain and residual stresses. Mechanical tests, including microstructure analysis, hardness, tensile, and impact tests, are performed on the specimen to assess its suitability for specific applications.