Microsoldagem em lâminas finas de aço inoxidável aisi 316l utilizando laser pulsado nd:yag
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Data
2022-09-13
Autores
Nakashima, Victor Massayuki
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O processo de soldagem laser a cada dia vem sendo mais utilizado nas indústrias manufatureiras. No processo com laser pulsado é possível realizar soldas de costura em lâminas finas, através da sobreposição dos pulsos. A soldagem de sobreposição de lâminas finas apresenta problemas típicos, tais como: distorção excessiva da junta soldada, falta de contato (folga) entre as lâminas a serem soldadas, perfuração da junta e presença de altos níveis de tensões residuais. O presente trabalho estudou a influência da energia de pulso, em um processo de soldagem laser Nd:YAG, na soldagem de lâminas finas (100 µm de espessura) de aço inoxidável austenítico AISI 316L, utilizado no revestimento de sensores que trabalham em ambiente corrosivo nas indústrias sucroalcooleira, química, petroquímica e alimentícia. Variou-se a energia de pulso de 1,0 a 2,25 J, com incremento de 0,25 J. A velocidade de soldagem (ν) e a taxa de repetição (Rr ) foram fixas em 2 mm/s e 9 Hz, respectivamente. As soldas foram realizadas com proteção gasosa de argônio com vazão de 10 l/min e largura temporal igual a 4 ms. A caracterização microestrutural das juntas soldadas foi efetuada através de suas secções transversais, com revelação dos detalhes no metal de solda por meio de ataque eletroquímico com ácido nítrico 69%, tensão de 4 V e tempo ataque de 20 s. A análise mecânica dos metais de solda foi efetuada através da realização de ensaios de microdureza Vickers e de tração. Os parâmetros geométricos do cordão como (largura, profundidade e união) aumentaram em função do aumento da energia de pulso. A dureza apresentou um aumento nos cordões de solda em relação ao metal base. O limite de resistência da junta soldada aumentou no início, apresentando em seguida um pequeno decréscimo em função do aumento da energia do pulso, sendo que a amostra com energia de pulso 1,50 J foi a que apresentou os melhores resultados. Por fim, o processo mostrou-se muito sensível à presença de folga entre as lâminas, demonstrando que, o controle da energia de pulso em processo de soldagem por laser de lâmina finas, é de fundamental importância para a geração de juntas soldadas com boas propriedades mecânicas e livres de descontinuidades.
The laser welding process is increasingly being used in manufacturing industries. In the pulsed laser process, it is possible to perform seam welds on thin blades, through the superposition of the pulses. Thin blade overlap welding presents typical problems such as: excessive distortion of the welded joint, lack of contact (gap) between the blades to be welded, perforation of the joint and presence of high levels of residual stresses. The present work studied the influence of pulse energy, Nd: YAG laser welding process, on the welding of thin blades (100 µm thick) of AISI 316L austenitic stainless steel, used in the coating of sensors that work in a corrosive environment in the sugar and ethanol industries. , chemical, petrochemical and food. The pulse energy was varied from 1.0 to 2.25 J, with an increment of 0.25 J. The welding speed (ν) and repetition rate (Rr) were fixed at 2 mm/s and 9 Hz, respectively. The welds were performed with argon gas shielding with a flow rate of 10 l/min and a temporal width equal to 4 ms. The microstructural characterization of the welded joints was carried out through their cross sections, revealing the details in the weld metal by electrochemical etching with 69% nitric acid, voltage of 4 V and etching time of 20 s. The mechanical analysis of the weld metals was performed by performing Vickers microhardness and tensile tests. The geometric parameters of the bead (width, depth and union) increased as the pulse energy increased. The hardness showed an increase in the weld beads in relation to the base metal. The strength limit of the welded joint increased at the beginning, then showed a small decrease as a function of the increase in pulse energy, and the sample with pulse energy of 1.50 J showed the best results. Finally, the process proved to be very sensitive to the presence of gap between the blades, demonstrating that the pulse energy control in the thin blade laser welding process is of fundamental importance for the generation of welded joints with good properties. mechanical and free of discontinuities.
The laser welding process is increasingly being used in manufacturing industries. In the pulsed laser process, it is possible to perform seam welds on thin blades, through the superposition of the pulses. Thin blade overlap welding presents typical problems such as: excessive distortion of the welded joint, lack of contact (gap) between the blades to be welded, perforation of the joint and presence of high levels of residual stresses. The present work studied the influence of pulse energy, Nd: YAG laser welding process, on the welding of thin blades (100 µm thick) of AISI 316L austenitic stainless steel, used in the coating of sensors that work in a corrosive environment in the sugar and ethanol industries. , chemical, petrochemical and food. The pulse energy was varied from 1.0 to 2.25 J, with an increment of 0.25 J. The welding speed (ν) and repetition rate (Rr) were fixed at 2 mm/s and 9 Hz, respectively. The welds were performed with argon gas shielding with a flow rate of 10 l/min and a temporal width equal to 4 ms. The microstructural characterization of the welded joints was carried out through their cross sections, revealing the details in the weld metal by electrochemical etching with 69% nitric acid, voltage of 4 V and etching time of 20 s. The mechanical analysis of the weld metals was performed by performing Vickers microhardness and tensile tests. The geometric parameters of the bead (width, depth and union) increased as the pulse energy increased. The hardness showed an increase in the weld beads in relation to the base metal. The strength limit of the welded joint increased at the beginning, then showed a small decrease as a function of the increase in pulse energy, and the sample with pulse energy of 1.50 J showed the best results. Finally, the process proved to be very sensitive to the presence of gap between the blades, demonstrating that the pulse energy control in the thin blade laser welding process is of fundamental importance for the generation of welded joints with good properties. mechanical and free of discontinuities.
Descrição
Palavras-chave
Soldagem, Laser Nd:YAG, AISI 316L, Microdureza, Ensaio de tração, Lâminas finas, Welding, Nd:YAG Laser, Microhardness, Traction test, Thin blades