Estudo comparativo da microestrutura e microdureza do aço 1045 utilizando os tratamentos térmicos

Abstract

Steel is a widely used metallic alloy in the industry due to its versatility, mechanical strength, and ability to undergo heat treatment to meet different applications. SAE 1045 steel, in particular, is a medium-carbon steel with good mechanical strength and moderate machinability, commonly used in the manufacturing of shafts, gears, and structural components. This study aimed to analyze the microstructural changes and microhardness variations of SAE 1045 steel subjected to different heat treatments. Five samples were prepared, one without heat treatment for characterization and four subjected to annealing, normalizing, quenching, and tempering. The heat treatment was performed in a JUNG furnace, model LT 83013. The samples underwent manual grinding, polishing with alumina, and chemical etching with 5% Nital for observation under an OLYMPUS optical microscope, model CX31. Microhardness was measured using a SHIMADZU microhardness tester, model HMV, with a load of 4.903 N and an application time of 15 seconds. The results showed that annealing significantly reduced the material's hardness, while quenching led to a significant increase in microhardness due to martensite formation. Tempering partially reduced hardness, balancing strength and ductility. The obtained values are consistent with the literature, highlighting the influence of heat treatments on the mechanical properties of SAE 1045 steel.