Por: nathália mello mascarenhas paixão (Centro federal de educação tecnológica de minas gerais (cefet-mg)), maíza souza conrado (Centro federal de educação tecnológica de minas gerais (cefet-mg)), wagner sade (Centro federal de educação tecnológica de minas gerais (cefet-mg)), marcelo ferreira (Centro federal de educação tecnológica de minas gerais (cefet-mg))
Resumo:
Calendering is a mechanical formation process of great industrial relevance, since metal parts made out of this process – usually of tubular geometry – are applied in the
fabrication of silos, eolic towers structure, tubes and plumbing of the construction sector etc. The present work has proposed to analyze the hardness and the microstructure of calendered metal parts of SAE 1020 and SAE 1045 carbon steels and the effects of heat treatments on these. The low carbon steel part – SAE 1020 – was annealed for tension relief, and the medium carbon steel part – SAE 1045 – was quenched and then tempered. The hardness of both metal parts was measured and compared for three different moments: before the calendering, after it and after the heat treatment. Likewise, the microstructure of the metal plates was observed in these three distinct moments. The results have shown that the calendered metal plates had a higher hardness, comparing with the plates in the initial stage. SAE 1045 steel has presented higher hardness after quenching and tempering, while SAE 1020 steel has suffered huge hardness decrease after the annealing, due to tension relief and grain growth. It is possible to conclude that the application of quenching followed by tempering is valid for the increase of mechanical resistance of calendered SAE 1045 steel parts. Regarding the low carbon steel plates, the annealing process has caused a huge decrease in its hardness. Therefore, it is possible to conclude that the annealing process is not valid for the SAE 1020 steel, since the tension relief comes together with an expressive hardness decrease, that makes the steel part inappropriate for many uses.
