Influência do pó de cromo sobre as propriedades mecânicas e morfológicas do revestimento duro produzido por soldagem GMAW-MAG

Abstract

In order to provide better mechanical properties to low and medium carbon steels, hard coating is commonly used from welding. This technique occurs through several processes, using materials based on hard materials, where SMAW, FCAW and GMAW / MAG stand out. The GMAW / MAG process is widely used in industries due to its high productivity and operational simplicity. In this study we sought to join elements of the three processes to produce a coating with geometry and suitable mechanical and morphological properties. For this purpose a powder (flux in the FCAW process) was produced from the coated electrode OK 83.58 which was included in the GMAW / MAG welding process with semi-automatic electric arc, the strands being deposited in ASTM A-36 steel plates. It was observed that the variation of welding parameters directly influences the geometry and penetration of the bead and the melting of the powder. In tests carried out varying tension and welding speed a cord with satisfactory appearance and dilution was reached. The hardness reached values above 50 HRC in some samples, while the maximum microhardness was 4 times higher in the coating when compared to the base metal, since the lowest mass loss reached a value of 124 mg. These values are related to the precipitation of Cr7C3 type carbides on a eutectic matrix present in all samples tested.