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Advisor(s)
Abstract(s)
Ao longo dos anos, os processos de manufatura industriais que envolvam ciclos térmicos têm crescido, sendo a soldadura um dos mais utilizados. Os métodos mais comuns que garantem fiabilidade em termos estruturais são as técnicas MAG para aços e TIG para ligas de alumínio. Entretanto, devido ao arrefecimento não controlado inerente ao processo, acaba por surgir tensões residuais nas zonas próxima ao cordão, que podem futuramente gerar problemas que levem a falhas mecânicas como trincas e até mesmo rutura.
Nessa linha, uma das soluções comerciais, de baixo custo, para aliviar este tipo de comportamento é o tratamento superficial por jateamento de granalhas, mais conhecido por shot-peening. Neste sentido, o presente trabalho tem como objetivo determinar de forma numérica, o nível de tensões residuais antes e pós processo de granalhagem, com enfoque em peças de soldadura de topo simples. Para isto, o estudo envolve componentes analíticas e numéricas para avaliar os fenômenos térmicos e estruturais pós-soldadura. Os materiais utilizados para esta pesquisa foram o aço DIN CK20 e a liga de alumínio 6082-T6, trabalhando com as respetivas propriedades termomecânicas.
Como resultado, foi verificado que o jateamento causa o alívio esperado nas tensões próximas à região do cordão, principalmente na direção σz, que se demonstrou ser o estado mais crítico. Além disso, foi utilizado um recurso na simulação térmica de soldadura para simplificar a complexidade do processo e verificou-se que os erros se encontram, em torno de 3~10% para o processo MAG e 15~18% para o TIG.
Over the years, industrial manufacturing processes involves thermal cycles have grown, being the welding one of the widely used. The most common methods that guarantee reliability in structural terms are the MAG techniques for steel and TIG for aluminum alloys. Nevertheless, due uncontrolled cooling inherent in the process, residual stresses arise close to the melt area, which in future can lead mechanical problems such as cracks and even equipment failure. Within this way, one of the low-cost commercial solution to relieve this type of behavior it is the shot blasting superficial treatment, more known as shot-peening. In this sense, the present work has the objective to numerically determine the level of residual stresses before and after shot blasting for top single weld pieces. For this, the study involves analytical and numerical components to evaluate the thermal and structural phenomena after welding. The materials used in this research were steel alloy DIN CK20 and aluminum alloy 6082-T6, working with respective thermomechanical properties. As a result, it was seen that the blasting causes the expected relief in the stresses close to the melt region, mainly in the σz direction, which has been shown to be the most critical state. In addition, a FEM feature was used in the thermal welding simulation to simplify the complexity of the process and it was verified errors of around 3~10% for the MAG process and 15~18% for TIG.
Over the years, industrial manufacturing processes involves thermal cycles have grown, being the welding one of the widely used. The most common methods that guarantee reliability in structural terms are the MAG techniques for steel and TIG for aluminum alloys. Nevertheless, due uncontrolled cooling inherent in the process, residual stresses arise close to the melt area, which in future can lead mechanical problems such as cracks and even equipment failure. Within this way, one of the low-cost commercial solution to relieve this type of behavior it is the shot blasting superficial treatment, more known as shot-peening. In this sense, the present work has the objective to numerically determine the level of residual stresses before and after shot blasting for top single weld pieces. For this, the study involves analytical and numerical components to evaluate the thermal and structural phenomena after welding. The materials used in this research were steel alloy DIN CK20 and aluminum alloy 6082-T6, working with respective thermomechanical properties. As a result, it was seen that the blasting causes the expected relief in the stresses close to the melt region, mainly in the σz direction, which has been shown to be the most critical state. In addition, a FEM feature was used in the thermal welding simulation to simplify the complexity of the process and it was verified errors of around 3~10% for the MAG process and 15~18% for TIG.
Description
Mestrado de dupla diplomação com o Centro Federal de Educação Tecnológica Celso Suckow da Fonseca - CEFET/RJ
Keywords
Tensões residuais Elementos finitos Shot-Peening Soldadura e simulação