Influência Da Pré-Deformação Plástica, Da Temperatura E Do Tempo De Aquecimento No Envelhecimento Do Aço Bh220 Através De Planejamento De Experimentos

Abstract

ResumoAços Bake Hardening são aços laminados a frio com envelhecimento controlado. Estes aços caracterizam-se pela boa conformação e por apresentarem aumento de resistência mecânica devido à deformação e ao envelhecimento por tratamento térmico. Nesse trabalho corpos de prova de tração do material BH220 foram submetidos à pré-deformações que variam de 0% a 9% por tração uniaxial e posteriormente submetidos a tratamento térmico realizado em temperaturas que variam de 140°C a 210°C com tempos de aquecimento entre 5 minutos e 45 minutos. Foi confirmado que as temperaturas de envelhecimento, na faixa estudada, alteraram a variação do limite de escoamento devido ao fenômeno de difusão que é termicamente ativado. Verificou-se que o tempo de aquecimento, dentro do intervalo testado, não causou grandes variações nos resultados e a deformação foi a variável que maior contribuiu para o aumento de propriedade mecânica. Palavras-chave: Aço BH220; Bake hardening; Work hardening; Planejamento de experimentos. INFLUENCE OF PLASTIC PRE DEFORMATION, TEMPERATURE AND HEATING TIME IN THE AGING TREATMENT OF THE BH220 STEEL THROUGH DESIGN OF EXPERIMENTS AbstractBake Hardening steels are cold rolled steels with controlled aging. These steels are characterized by a good formability and an increase in the strength due to the aging that occurs during heat treatment. In this study, tensile test specimens of the BH200 steel were submitted to pre deformations ranging from 0% to 9% by uniaxial tension, subsequently they were subjected to an aging heat treatment performed at temperatures varying from 140°C to 210°C, in heating times between 5 minutes and 45 minutes. It has been confirmed that the aging temperatures, in the range studied, modified the yield point due to the phenomenon of diffusion, which is thermally activated. In the results, it is possible to verify that the heating time, within the range tested, it is not significant and the deformation was the largest variable that contributed to the increase of mechanical properties.

Active aging awareness and well-being among older adults in Portugal

“…However, the results from the Active Ageing Index (AAI) project indicate that Portugal's score was still 2.2 points lower than the EU average in 2018, being particularly low in the 'participation in society category' (10). The country has been making important strides, namely with the nomination of a working group to develop the National Strategy for Active and Healthy Aging (ENEAS), but there is still room for improvement (11,12).…”