Resumo:
Due to the advance of research and development of new welding processes, it is important to
investigate the effects that the variables of entry perform on the variables of output. Therefore,
the aim of this work is to investigate the influence of the welding parameters, mainly the
shielding gas, on the GMAW STT® (Surface Tension TransferTM) derivative process applied in
the welding of the ASTM A-36 structural steel, and compare its results with the GMAW process.
For this purpose, a design of experiments was carried out, in form to evaluate the interaction
of the variables studied at all levels. In the first phase of the research, screening experiments
were conducted, using fractional factorial design, to explore the main effects of the input
variables with less quantity of runs. After, in the next phase of the project, a full factorial design
was used to responses modeling, once it did not present curvature. The welds were made in
BOP (bead on plate) using GMAW STT® welding. For the analysis of the bead geometry the
test specimens were prepared by mettalography and later submitted to optical macroscopy. The
optimal condition will be repeated in top joints and welded by GMAW and STT® process
welding, and the welded specimens prepared for the mechanical tests of traction,
microhardness, Heat Afected Zone and Penetration measurement. The variation of the
protection gas was determinant at the geometrical proprieties of the welded joint, and the STT
process shower smaller results of ZTA size than the conventional GMAW. As of Penetration,
both processes had similar response.
