Per: Jaqueline Polezi Mazini (iFES), André Itman Filho (Ifes), Breno Mendes Rabelo Ávila (Ifes), Dirceu da Silva Junior (Ifes), Pedro Gabriel Bonella de oliveira (USP)
Abstract:
High strength and low alloy steels are widely used in petroleum pipes manufacturing, because presents mechanical properties according to API standard. The main manufacturing process for these steels is the controlled rolling, however, for complex geometry parts, forging is preferred. In this case, quenching and tempering heat treatments are necessary to reach the desired properties. Besides mechanical and high-pressure requests which the pipes must support, these materials must still resist seawater corrosion. In this context, the current work goal is to evaluate the microstructure, impact and corrosion resistance of two microalloyed steels with different niobium and molybdenum content. Initially two steels ingots were forged and subsequently subjected to quenching followed by tempering treatments. From the tempering curve, an average temperature of secondary hardening range, according to literature results, was selected to impact and potentiodynamic polarization tests. The results show that the steel with highest niobium content delivers higher impact and corrosion resistance, while the steel with higher molybdenum content delivers higher hardness.