Analisis Pengaruh Variasi Temperatur Pemanasan dan Media Pendingin Quenching Terhadap Sifat Mekanik Baja AISI 1045

Abstract

This study investigates the effects of austenitizing temperature variations (850°C, 900°C, and 950°C) and different quenching media, including water, used SAE 40 oil, and SAE 10 hydraulic oil, on the microstructure and mechanical properties of AISI 1045 steel. The analysis focused on cooling rate, phase transformation, microstructure formation, and mechanical behavior using the Continuous Cooling Transformation (CCT) diagram. The results show that water quenching provides the fastest cooling rate, producing a martensitic structure with the highest hardness (527–612 BHN), Ultimate Tensile Strength (UTS) of 1986 N/mm², and very low elongation (<1%), indicating brittle behavior. Quenching with used SAE 40 oil forms a bainitic structure with balanced mechanical properties, including UTS values of 967–1776 N/mm² and elongation of 4–10%, indicating improved ductility. Meanwhile, SAE 10 hydraulic oil produces the slowest cooling rate, resulting in ferrite–pearlite structures with lower hardness (256–291 HB), lower tensile strength, and the highest elongation (16.56%). These findings confirm that quenching media strongly influence the microstructure and mechanical properties of AISI 1045 steel.