Mechanical Properties Assessment of Structural Carbon Steel Welded Joints by Means of Submerged Arc Welding Process with Single Arc and Double Arc (Tandem-Arc)

Abstract

Faced with an economic scenario where competition is increasingly intense, the search for processes, techniques and welding equipment that provide gains in productivity is a requirement to ensure the competitiveness of companies in the market. With the development and adoption of new technologies it is possible to innovate the conventional processes, optimizing the performance and increasing their productivity, without detriment to the required quality requirements. The process of submerged arc welding allows the obtainment of welded joints of excellent quality and productivity and, with the use of multiple wires, it is possible to increase the deposition rate even further. However, the use of multiple wires implies the need for higher currents and, even with increasing welding speed, the heat input increases considerably, which can affect the tenacity of the joint. Thus, in welded structures where there are impact requirements it becomes necessary to evaluate the effects of high heat inputs. In this work the strength of two welded joints in ASTM A36 carbon steel was compared by the submerged arc process, the first being welded with single arc and the other with double arc (Tandem-Arc). After welding, the test pieces were submitted to tensile stress treatment (TTAT) and subjected to tensile tests, folding, Charpy impact, Vickers hardness profile, macrographic examination and microstructural characterization performed using optical microscopy. The results obtained in all tests were considered satisfactory and approved, thus showing that it is possible to use the Tandem-Arc process in the welding of carbon steels when there are impact requirements.

Key-words:
Submerged arc welding; Tandem-Arc; Toughness; Charpy V-Notch test