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A novel process of welding GMAW-CW (Gas Metal Arc Welding-Cold Wire) had been developed with it resemblance to the GMAW (Gas Metal Arc Welding), the GMAW-CW has an additional wire fed into de weld pool, allowing better deposition rates, while maintaining weld characteristics. However, there is a more complex situation related to the HAZ (Heat Affected Zone) and weld geometry prediction than the GMAW conventional. The welding energy is a high metallurgical important parameter because together with the geometric characteristics of the gasket and the preheat level is decisive in thermal cycles imposed to the material, and therefore in the possible microstructural transformations and behavior of the joint. The behavior of representative curves of thermal cycling reflects important aspects regarding the conditions used in welding. Usually such factors as the type of process, use or non- pre or post- heating, heat input, multipass welding, are able to establish differences in the form of a heat cycle curve. In this work, it was applied the dual ellipsoidal model of heat input, adapted to the GMAW-CW and compared to the same model over the GMAW, using existing experimental data and predicting the HAZ dimensions in function of weld and welding parameters. The results found had less than 10% error from experimental data in a more refined version of the model, whereas the difficulties to predict cold wire addition influences were not trivial.

Resumo Juntamente com o crescimento da indústria naval brasileira surgiram problemas provenientes dos processos de produção na forma de distorções e tensões residuais. Neste trabalho foi estudada a influência de procedimentos de soldagem (sequência e direção de soldagem e uso do passe reverso) e modos de transferência (MAG-CC, MAG-STT e MAG-CW) Palavras-chave: Distorções. MAG. MAG-STT. MAG-CC. Cold Wire. Abstract: The Growth in the Brazilian shipbuilding industry brought on numerous problems in the production line. Some of these problems are related to the manufacturing process, welding process, due to residual stress and distortions. In the present paper, the influence of the welding procedure (sequence and direction of welding and the use of back weld) was studied. Different welding processes with different transfer modes (GMAW-CC, GMAW-TT and GMAW-CW)were also used. These changes were made to observe the influences on the amplitude of the distortions. All the welds were made using the ER70S-6 electrode and pure CO 2 as a shielding gas with the short circuit transfer mode. The results showed that the most important variable is the direction of welding, which is related to the level of restriction of the panels welded. The effect of the welding sequence presented on the values of distortion produced were minor. The panels produced using the back welding procedure presented small values of distortion however, the procedure showed to be inefficient. It was also observed that the level of distortion for the processes GMAW-CC and GMAW-STT showed similar values. On the other hand the values of distortion in the panel welded using the GMAW-CW process presented the lowest values. Key-words: Distortion. GMAW. GMAW-STT. GMAW-CC. Cold Wire. IntroduçãoO processo de soldagem é o principal responsável pelo surgimento das imperfeições de fabricação [1], contudo, não se pode desconsiderar que as formas de transporte e armazenamento das chapas contribuem com uma parcela na distorção final dos painéis enrijecidos de estruturas navais. As estruturas navais são constituídas, basicamente, de painéis enrijecidos, que formarão blocos e estes darão forma às construções. Os painéis são formados pela união de chapas que são enrijecidas pelo processo de soldagem de reforços longitudinais e transversais. Para que haja o processo de união, deve ser aplicado calor, porém, uma parcela desse calor não homogêneo, aplicado ao material durante a soldagem, gera uma expansão térmica ao redor da área do cordão de solda. Esse efeito pode ser visualizado na Figura 1. A barra central aquecida na Figura 1A representa o cordão de solda depositado, já na Figura 1B é feito um comparativo entre o mecanismo de barras e uma placa soldada. Como o cordão, inicialmente, é a única parcela da placa aquecida, irá se expandir com um determinado nível de energia e as regiões ao redor tenderão a se manter imóveis, bloqueando a dilatação. Em um segundo momento, na fase de resfriamento, a placa irá se contrair e, novamente, as regiões ao redor irão restringir essa...