The Master´s thesis focuses on the possibilities of using MAG welding on carbon steel 1.1221(C60E) without using preheating. It researches the effect of basic welding parameters on the final characteristics with the goal being to find a welding seam without defects, without using preheating.

Orientador: Afonso Lopes / Resumo: Na concepção do projeto e na fabricação de equipamentos, deve-se preocupar com a energia incorporada e com a quantidade de emissão de gases de efeito estufa (GEE), de modo a atender às exigências ambientais, cada vez mais requeridas por organismos internacionais. Este trabalho teve como objetivo calcular a energia incorporada (MJ) e a emissão de GEE (kg CO2e) na fabricação de equipamentos para beneficiamento de algodão, considerando a matéria-prima, a hora trabalhada e a energia elétrica consumida. O trabalho foi realizado na análise de três equipamentos de uma usina de beneficiamento de algodão. Os referidos equipamentos foram fabricados com tecnologia nacional por uma empresa localizada no interior do Estado de São Paulo. O primeiro equipamento, alimentador extrator automático, teve emissão de 6,57 CO2e kg-1 e energia incorporada de, 102,54 MJ kg-1; o segundo equipamento, descaroçador, teve emissão de 6,82 CO2e kg-1 e energia incorporada de 107,64 MJ kg-1; e o terceiro equipamento, prensa hidráulica, teve emissão de 5,05 CO2e kg-1 e energia incorporada de 78,73 MJ kg-1. Verifica-se a relevância dos materiais metálicos, principalmente do aço-carbono e a importância da energia elétrica consumida no cálculo de energia incorporada. O tempo homem/hora não foi relevante nos resultados de emissão de CO2e kg-1 e energia incorporada. / Abstract: In conception of design and manufacturing equipment it must be concerned with the embodied energy and greenhouse gas emissions (GHG), in order to meet the environmental requirements, which are increasingly required by international organizations. This paper aimed to calculate the embodied energy (MJ) and the emission of GHG (kg CO2e) in the manufacture of equipment for cotton processing, considering the raw material, the hour worked and the consumption of electric energy. The study analyzed three equipments of a plant of cotton benefit. These equipments were manufactured with national technology by a company located in the interior of the Brazilian state of São Paulo. The first equipment, automatic extractor feeder, had emission of 6.57 CO2e kg-1 and embodied energy of 102.54 MJ kg-1; the second equipment, ginning machine; had emission of 6.82 CO2e kg-1 and embodied energy of 107.64 MJ kg-1, and the third equipment, hydraulic press; had emission of 5.05 CO2e kg-1 and embodied energy of 78.73 MJ kg-1. Then was verified the relevance of metallic materials, mainly carbon steel and the importance of consumption of electric energy in the calculation of embodied energy. The man/hour time was not relevant in the results of CO2e kg-1 emission and embodied energy. / Doutor

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Fracture path transition, from interfacial fracture to a pulled button, in peel tests of spot welds in SAE 1039 steel was evaluated to determine the controlling material properties. Welds were tested in the as welded condition and after tempering at various temperatures to develop a range of hardness and strength in the weld metal. Two transitions were found, from complete interfacial fracture to partial interfacial and from partial interfacial fracture to a pulled button. Samples tempered at less than 350 °C exhibited complete interfacial fracture while those tempered at 500 °C or higher pulled full buttons. Each transition was accompanied by a large increase in the energy absorbed during fracture. Both partial and complete interfacial fracture occurred by intergranular fracture along prior austenite grain boundaries. Optical microscopy utilizing a tint etch indicated that austenite existed as films on prior austenite grain boundaries of samples tempered at less than 500 °C and TEM confirmed that these films were austenite. Weld metal toughness was found to control the fracture path. If fracture initiation was delayed until the applied load caused plastic deformation of the coupons pulled button fracture occurred. Fracture initiation prior to plastic deformation of the coupons resulted in interfacial or partial interfacial fractures. A small secondary hardening peak was observed in samples tempered at 450 °C. Secondary hardening, which normally results from alloy carbide precipitation, was due to AlN precipitation in this aluminum killed plain carbon steel. / Ph. D.