Bead characterization on FCAW welding of a basic tubular wire

摘要

This work aimed to study the effect of some operational conditions on the characteristics of beads produced by a Brazilianmade basic tubular wire (ASME SFA-5.20: E71T-5/E71T-5M), 1.2 mm in diameter, intended for welding common structural carbon steels with low and medium levels of carbon. Welding tests were carried out, in a flat position, on thick plates (12 mm thick) of common low-carbon steel using a source operating in constant voltage mode and with continuous monitoring of the arc current, arc voltage, and feed speed (fusion) values for the wire. The composition of the shielding gas (75%Ar-25%CO_2 and 100%CO_2), the electrode polarity (positive and negative), and the wire feed speed (7 and 9 m/min) were varied. The other welding parameters were kept fixed, including the energized lengths of the electrode (16 mm) and the arc (3.5 mm). The effects of the operational conditions on the main characteristics of the bead were evaluated including its geometry (penetration, reinforcement, width, welded area, deposited area and dilution), presence of discontinuities, microstructure, and hardness. For the basic wire, the operational conditions with the highest productivity (the highest deposit rate) associated with a bead with suitable characteristics for welding thick plates of structural steels were assessed.