Estudo do desempenho operacional e da morfologia do cordão de solda depositado com arames tubulares autoprotegidos com adição de níquel utilizados na soldagem subaquática molhada

Abstract

Underwater wet welding has a wide application in the repair and maintenance of structures designed for oil extraction, offshore stations or platforms, the naval industry and nuclear reactors. The SMAW process is the most widely used technique due to its simplicity of operation. However, the FCAW process has become a widely accepted alternative due to its greater productivity, in addition to obtaining similar results in relation to the quality of the weld bead deposited with the SMAW process. Therefore, the aim of this work is to conduct an operational study and characterize the morphology of weld seams made using the FCAW process. Therefore, the aim of this work is to conduct an operational study and characterize the morphology of weld seams made using the FCAW process. For this purpose, two self-shielded tubular wires with nickel added (60% and 70% nickel by weight) were manufactured. Subsequently, weld beads were deposited in the flat position, and an experimental matrix was run with three factors, to change the polarity, type of tubular wire and operating condition (air welding, wet welding at 0.3 and 30 m depth). As a result, the stability of the process decreased dramatically at the highest level of operating condition. It was found that the average value of the current coefficient of variation increased in wet welding at 0.3 m compared to air welding. Subsequently, the constriction of the arc due to hydrostatic pressure caused greater difficulty in maintaining the arc. Furthermore, the type of tubular wire with the highest nickel content in DCEN polarity at 30 m was the experimental treatment with the greatest instability. In addition, the increase in heat input due to the change from air welding to wet welding and the subsequent increase in depth showed a positive correlation with the penetration of the weld bead.