THE INFLUENCE OF HEAT TREATMENT IN MECHANICAL PROPERTIES AND MICROSTRUCTURE OF THE SAE 1045 STEEL

Adriel Magalhães Souza¹; Fernando Ferreira Del Monte¹; Renato de Camargo Bortholin²

¹ Universidade de Franca; ² Instituto Federal de Educação, Ciência e Tecnologia - Araraquara

doi:10.20906/CPS/COB-2015-1215

Resumo

Currently through the understanding of the composition and microstructure of the materials, the usage of proper synthesis and processing has enable the existence of a wide range of applications for the metals and its alloys; always with the purpose of optimizing the cost-performance relationship. Thus, a microestructure-composition-property-processing correlation is extremely important in order to obtain a greater performance. Heat treatments can be considered the set of operations performed in order to alter their mechanical properties, without altering the geometry of the final product. The purpose of this study is to verify the influence of the martemper, quenching in brine, normalizing and annealing treatments in the mechanical properties and in the microstructure of SAE 1045 steel. The results found an increase of over 350 % in hardness and virtually double the necessary strength to break the test specimens treated with tempering. The processes of martempering and quenching in brine made the samples brittle, thus the items that needed more strength to be broken, consequently had less elongation. Normalizing has not shown significant increases in hardness nor in the strength necessary to break the pieces, when compared to the tempered ones. Annealing has increased the tenacity, making them more brittle, and therefore, with extremely low hardness. The metallograpy was able to prove the alterations in the microstructures with the mechanical properties resulting from each process. The result found also supports the statement that heat treatment is an excellent method for altering the mechanical properties, hence, justifying the wide range of usage of such material in several types of project.

Palavras-chave: heat treatment; mechanical tests and metallography; steel 1045