Avaliação da resistencia a cavitação em ligas inoxidaveis auteniticas - cavitec e inconel 625 - depositadas pelo processo MIG

Abstract

The study evaluated the cavitation resistance of two austenitic stainless steel alloys, Cavitec and Inconel 625, deposited on an ASTM A743-CA6NM martensitic stainless steel substrate by MIG welding. Cavitation is a critical challenge in hydromechanical equipment, such as turbines, due to the nucleation and collapse of vapor bubbles, which cause localized deformations and material removal. The results showed that the Cavitec alloy coating has superior cavitation resistance compared to the Inconel 625 alloy. The improved resistance of the alloy is attributed to its low stacking fault energy (SFE), which allows for greater energy absorption before fatigue failure. The microstructural analysis of Cavitec revealed a more effective energy absorption mechanism, characterized by the formation of superficial twins. This behavior is directly related to the material's SFE and the γ→ε→α’ martensitic transformation, which consumes more energy to occur. On the other hand, Inconel 625 showed an incubation period of approximately 4 hours. Its lower resistance is justified by its high SFE, which promotes a direct γ→α’ martensitic transformation, without the intermediate phase, making it less resistant to fatigue wear. In addition, the microstructure of Inconel 625 is characterized by the precipitation of carbides, which act as critical points for cavitation wear. The study concluded that the Cavitec alloy is suitable for environments subject to cavitation, highlighting the importance of low SFE and twinning deformation mechanisms.