Caracterização das barras de aço CA-50 produzidas no Brasil
Reinforced concrete (RC) structures, as for example bridges, can be subjected to fatigue. Reinforcement steel bars (rebars) are determinant in the fatigue strength of reinforced concrete elements. This strength can be influenced by its microstructural aspects as grains type and size as well as surfa...
| Autor principal: | Bodanese, Ana Letícia |
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| Formato: | Trabalho de Conclusão de Curso (Graduação) |
| Idioma: | Português |
| Publicado em: |
Universidade Tecnológica Federal do Paraná
2020
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| Assuntos: | |
| Acesso em linha: |
http://repositorio.utfpr.edu.br/jspui/handle/1/14362 |
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| Resumo: |
Reinforced concrete (RC) structures, as for example bridges, can be subjected to fatigue. Reinforcement steel bars (rebars) are determinant in the fatigue strength of reinforced concrete elements. This strength can be influenced by its microstructural aspects as grains type and size as well as surface geometry. These aspects depends on the rebar fabrication process. Few studies can be found in the Brazilian literature regarding the rebar microstructural characteristics and none reference are found on the surface roughness. This works aims to investigate the microstructure of CA-50 rebars of different Brazilian manufacturers by metallographic analyses and it relates to the fabrication process. Microhardness Vickers and tensile strength are measured. Surface roughness is investigated using two techniques: Scanning Electron Microscopy followed by photo stereometry for 3D surface roughness reconstruction and roughness meter. With both techniques the roughness is quantified through a stress concentration factor, parameter commonly used for fatigue life prediction of metallic components. The analysis of metallography allowed to verify that of the bars of steel produced today, some undergoes the process of tempering and tempering and others only by the hot rolling. The Vickers microhardness values were consistent with the microstructure identified in the bars. In the analysis of the tensile strength, the higher values of yield stress and rupture are obtained in the samples with higher amount of perlite. Some steel bars did not reach the minimum values of flow voltage as established in the Brazilian standards.In relation to roughness, the two techniques present very different values for stress concentration factor. |
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