EFEITO DE DIFERENTES TRATAMENTOS TÉRMICOS SOBRE MICROESTRUTURA E MICRODUREZA DE UM SISTEMA AÇO C-Mn/REVESTIMENTO DE INCONEL 625
The application of C-Mn steel pipe in the oil & gas industry is quite common since starting of this industry. Even with the great evolution of the metallurgy of this type of steel over the last decades, the challenge is to overcome the corrosion severity caused by sour (H2S, CO2) species present in the petroleum and its derivates. The direct technological solution would be to replace the C-Mn steel by Ni-based superalloys and/or stainless steels. However, the high costs of these materials would make several projects impracticable. In this context, there are several initiatives in order to develop overlay and/or cladding, that means, coatings of C-Mn steels using superalloys and stainless steels. In this work, it was used an overlay deposition of Inconel 625 on the surface of a C-Mn steel using the laser process. A disadvantage of laser deposition, as it is for any deposition melting process, is the formation of a microstructural discontinuity in the steel substrate caused by the thermal cycle (HAZ = heat affected zone). In this study, different heat treatment routes were investigated aiming to eliminate the HAZ preserving the original characteristics of the substrate and of the coating.