Avaliação de Revestimentos à base de Inconel 625 depositados através do Processo de Soldagem GMAW em aço API 5L X70 utilizando Planejamento Fatorial

Abstract

Concern for the environment has motivated several studies on the use of new materials to extend the life of equipment operating in harsh environments in the oil sector. One alternative that has been used is the application of coatings with high corrosion resistance welding process materials. The objective of this study was to evaluate the effects of different welding parameters on the geometric characteristics, dilution, microhardness, microstructure and corrosion resistance of the coatings with Inconel 625 alloy deposited on the API 5L X70 steel used in oil pipelines to transport plate. The parameters were optimized using the factorial statistical experimental design for analysis of process parameters, and the results analyzed by Response Surface Methodology (RSM). Three deposits were carried out ½ overwrite process GMAW (Gas Metal Arc Welding), followed by cross-sectional analysis of samples for the geometrical and metallographic characteristics. For the analysis corrosion, the coating surface being machined to have a height of 3 mm according to Standard N-1707 Petrobrás coating. The electrochemical behavior of the coating surface (Inconel 625) was investigated at room temperature in NaCl solution using the technique of linear potentiodynamic polarization and electrochemical impedance spectroscopy. To reveal the corrosion resistance of the coatings, featuring some important parameters were considered, such as: the polarization resistance (Rp) and the corrosion potential (Ecorr). The results showed dilution values D (%) ranging from 12.77% to 24.88% in the maximum levels (18.99 KJ/cm) and minimum (8.34 KJ/cm) welding power, and the amounts the most important of 12.77%. As to the corrosion resistance, the results were more satisfactory for the highest level of welding power.