Avaliação dos efeitos do metal de adição no processo de solda a arco elétrico sobre um aço patinável

Abstract

The welding process is present in about 90% of the industries, metalworking, civil construction, oil and gas. Among the diverse range of processes, MIG / MAG welding is distinguished, which is the first option for most of the needs of metal joints in the industry. The feature of automatic supply of consumables on the joint to be welded makes the process more agile and competitive in the commercial scenario. The intense industrial demand for safety, quality and productivity makes the researches extend to the theme, working with new materials (metal base, addition metal, consumables), optimization of processes, equipment, among others. The application of materials with greater mechanical and chemical resistance bring the need for the use of consumables and processes that accompany these trends and maintain the properties after welding, as in the case of the steels that have as characteristic the resistance to atmospheric corrosion. In this work the welding of the ASTM A588 steel with two addition metal alternatives (ER70S-6 and ER80S-G) and twelve conditions of welding parameters were evaluated. Qualification tests were performed to validate welding parameters, including radiography, folding and traction. After the solder qualification, microhardness, micrograph and corrosion performance tests were carried out with the electrochemical potential versus time and potentiodynamic polarization curve in the HAZ and BM. The results on mechanical properties and corrosion resistance showed that the welding parameters were predominant in relation to the types of addition metals. It was concluded that the inadequate selection of electrical parameters is detrimental to the mechanical properties, leading to defects such as lack of fusion and incomplete filling of the joint. As for the addition metal, both ER70S-6 and ER80S-G showed similar performances to corrosion performance analyzes.