Efeito do tipo de recozimento sobre a morfologia microestrutural e propriedades mecânicas do aço SAE 4130

Abstract

Tubular Monoblock Shafts (MTS), manufactured from SAE 4130 steel, undergo cold drawing, annealing, and cold forging processes. Annealing is a crucial step to reduce material hardness, enhance ductility, and prevent cracking during forging. The ideal microstructure after annealing consists of ferrite and pearlite, with the absence of bainite being a key factor for good formability. This study evaluated the impact of different annealing routes (full and intercritical) on the mechanical and metallurgical properties of SAE 4130 steel grade. The results showed that both routes provided similar yield strength. However, the intercritical annealing route stood out by significantly improving ductility, an essential characteristic for performance during forming processes. This improvement is associated with the presence of spheroidized pearlite in the microstructure, which contributes to greater toughness and lower hardness. Therefore, considering ductility as a key factor for the final application, intercritical annealing proved to be the most advantageous alternative, combining adequate mechanical strength with greater deformation capacity without failure.