Marco Antonio dos Santos

Avaliação da microestrutura e propriedades mecânicas de metais de solda obtidos por processos de soldagem manual e automatizado utilizado na soldagem de aço API 5L X80

The objective of this work was to evaluate the heat affected zone characteristics and weld metals microstructure and mechanical properties of API 5L X80 steel welded joints, obtained for four different welding procedures using manual and automated processes. For this, plates of this steel were welded by manual Shielded Metal Arc Welding (SMAW) process with interpasses temperatures of 473 e 673 K, and using AWS E8010-G electrode as filler metals; robotized Flux Cored Arc Welding (FCAW) process, using AWS E71T-1C wire and Ar25%CO2 as consumable and mechanized Gas Tungsten Arc Welding (GTAW) process, for the root pass using AWS ER70S-3 and Ar as consumable .The microstructural analysis was related with the weld metals Charpy impact test results and with the welded joint Vickers microhardness profiles. The results indicated that weld metals obtained by automatized welding process presented a shorter and more refined heat affected zone and a weld metal with greatest Acicular Ferrite percentiles which promoted the best results of the impact test.

Optimization of submerged arc welding process parameters for overlay welding

Abstract In this work, we evaluated the influence of welding variables on weld beads applied by the submerged arc process (SAW) with conventional current, aiming future application in overlays against corrosion. Segments of steel API 5L Gr B pipe as substrate, a 1.13 mm-diameter electrode wire of nickel alloy, classification AWS ERNiCrMo-4 (Hastelloy C-276) as filler metal, and a flux neutral, basic and crowded were used. The variables voltage, wire feed speed and contact tip to work distance (CTWD) were analysed, with the remaining parameters constant by an experimental design with full factorial design in two-level and central points. Statistically significant and predictor mathematical models for response dilution and average current were obtained. However, for the response reinforcement/width, the model was characterized as statistically significant, but not predictive, and containing a lack of fit. The CTWD was the most significant variable reducing the dilution.

Otimização de Parâmetros do Processo de Soldagem Arco Submerso para Revestimentos Anticorrosivos

In this work was evaluated the influence of welding variables on weld beads applied by submerged arc process (SAW) with conventional current, aiming future application in overlays against corrosion. Segments of steel API 5L Gr B pipe as substrate, a 1.13mm-diameter electrode wire of nickel alloy, classification AWS ERNiCrMo-4 (Hastelloy C-276) as filler metal, and a flux neutral, basic and crowded were used. The variables voltage, wire feed speed and contact tip to work distance (CTWD) were analyzed, with the remaining parameters constant by a Design of Experiments with full factorial design in two-level and central points. Statistically significant and predictors mathematical models for responses dilution and average current, was obtained. However, for the response reinforcement/width, the model was characterized as statistically significant, but not predictive, and containing a lack of fit. The CTWD was the most significant variable to reducing the dilution.

Avaliação do campo de tensões residuais por difração de raios - X utilizando o método do sen²ψ em revestimentos metálicos do aço inoxidável E308-L

A aplicacao por soldagem de revestimentos metalicos de acos e ligas nobres resistentes a corrosao e uma alternativa bastante razoavel economicamente frente a fabricacao de componentes macicos nestas ligas. Entretanto ha uma carencia de informacoes sobre as alteracoes mecânico/metalurgicas causadas pelos ciclos termicos de soldagem quando da aplicacao destes revestimentos, principalmente sobre a influencia sobre o nivel de tensoes residuais , que e mister no entendimento do fenomeno da corrosao assistida por tensao. O objetivo deste trabalho foi avaliar o nivel de tensoes residuais superficiais em revestimentos do aco inoxidavel AWS E308-L T-1 aplicados pelo processo de soldagem ao Arco Eletrico com Arame Tubular sobre chapas do aco ASTM A36. As medicoes das tensoes residuais foram realizadas por um difratometro portatil de raios - X na superficie dos revestimentos e os principais resultados obtidos foram que a natureza das tensoes residuais na superficie dos revestimentos sempre se apresentou compressivas e nao observou-se uma linearidade da magnitude das tensoes residuais em funcao da energia de soldagem.