INFLUENCE OF PVC AND ALUMINUM COATINGS ADDITION IN E-7018 ELECTRODE TO THE MOLTEN ZONE OF ASTM A36 STEEL
microstructure, molten zone, PVC films, aluminum, E-7018
The shielded metal arc welding (SMAW) presents competitive advantages that this union process as one of most important in industrial scale. However, the humidity absorption is a problem that requires special cares to stock the electrodes. Trying to control this problem, PVC films and aluminum ink coatings were applied in E-7018 electrodes to weld ASTM SA36 steel. In this paper was realized a comparative study among different welded samples: E-7018, pure and with coating, and using BRH4-R electrode. The molten zone characterization of these samples is a sequential continuation of the works developed by RAMOS (2015) and SOUZA (2017). Through the optical and scanning electron microscopies, it was observed that the molten zone microstructure, in all samples, is composed by Widmanstatten, acicular and polygonal ferrite, upper bainite, ferrite-carbine aggregates and, in some regions, MA micro-constituent. The EBSD technique, in addition to the others methods, confirmed that the welding using BRH4-R electrode formed coarser grains than the others samples. Acicular ferrite grains were found in all samples, and the BRH4-R provided less formation of acicular ferrite, while there is no difference among the E-7018 pure and covered by aluminum or PVC.