Este trabalho tem por objetivo a avaliação da influência e os benefícios obtidos com a utilização... more Este trabalho tem por objetivo a avaliação da influência e os benefícios obtidos com a utilização de mobiliário de distribuidor na Aços Villares-Usina de Mogi das Cruzes. Os benefícios esperados são: remoção de inclusões e aumento do rendimento da máquina de lingotamento contínuo. A metodologia empregada neste trabalho consistiu no modelamento matemático preliminar para projeto do mobiliário, utilização sistemática do conjunto Ripple Pad e Diques e finalmente análise dos resultados em remoção de inclusões e em ganhos de rendimento. Considerando-se o nível de inclusões obtido com a utilização sistemática do sistema Ripple Pad com diques, obteve-se uma redução de cerca de 30% na rejeição de peças finais em casos de aplicações críticas. Obteve-se, também, uma redução consistente de descartes da ordem de 10% em relação ao material descartado em seqüenciais mistos, proporcionando ganhos de rendimento com a implementação do sistema.
The characteristics of Mould fluxes have been improved in recent years, in order to meet the rigo... more The characteristics of Mould fluxes have been improved in recent years, in order to meet the rigorous demands of the continuous casting of steel. The most important improvements in mould fluxes have been focused on the prime requirements of the continuous casting process, i.e., better surface quality of the solid steel, higher productivity and minimum environmental impact. In order to keep abreast of these trends, a F- free mould flux has been developed and tested in a European steel plant(1). In this paper, preliminary results obtained with this mould flux has recently been used in a Brazilian billet-casting machine and preliminary results are presented describing its impact on steel productivity.
The characteristics of Mould fluxes have been improved in recent years, in order to meet the rigo... more The characteristics of Mould fluxes have been improved in recent years, in order to meet the rigorous demands of the continuous casting of steel. The most important improvements in mould fluxes have been focused on the prime requirements of the continuous casting process, i.e., better surface quality of the solid steel, higher productivity and minimum environmental impact. In order to keep abreast of these trends, a Ffree mould flux has been developed and tested in a European steel plant. In this paper, preliminary results obtained with this mould flux has recently been used in a Brazilian billet-casting machine and preliminary results are presented describing its impact on steel productivity.
Resumo O impacto de alguns elementos microligantes no tamanho de grão e nas propriedades mecânica... more Resumo O impacto de alguns elementos microligantes no tamanho de grão e nas propriedades mecânicas obtidas em diferentes rotas de processamento foi estudado neste trabalho para uma laminação de barras de aços especiais, special bar quality em inglês, SBQ. Esse estudo compreende as etapas iniciais da metodologia para o desenvolvimento de um modelo capaz de prever o comportamento da microestrutura e as propriedades mecânicas obtidas em processos de laminação de barras, que é pouco difundido para aços microligados. Foram testadas duas variações de aços microligados, com diferentes percentuais de Nb e Ti A rota de processamento mostrou um papel fundamental para a obtenção de melhores propriedades mecânicas nos aços testadosum aprimoramento considerável foi observado quando o material foi laminado seguido uma sequência termo-controlada. Palavras-chave: Barras de aços especiais; Aços microligados; Laminação termocontrolada.
Resumo A influência dos parâmetros termomecânicos e da adição de elementos microligantes na relaç... more Resumo A influência dos parâmetros termomecânicos e da adição de elementos microligantes na relação processo, microestrutura e propriedades de chapas laminadas, do aço DIN 20MnCr5 foi o objetivo de estudo deste trabalho. Os testes foram desenvolvidos em escala piloto, no laboratório de processos metalúrgicos do IPT. Foram testadas variações de composição química, condições de laminação e taxas de resfriamento. Ocorreu alongamento dos grãos austeníticos para os materiais processados por laminação termomecânica e refino de grão e aumento de limite de escoamento para os aços microligados, tanto na condição de laminação convencional, quanto na condição de laminação termomecânica. Palavras-chave: Barras de aços especiais; Aços microligados; Laminação termocontrolada.
Microalloyed steels have been intensely studied as an alternative to increase strength by grain r... more Microalloyed steels have been intensely studied as an alternative to increase strength by grain refinement and/or precipitation hardening. Long steel products have a wide range of opportunities to apply well-defined principles of controlled rolling (CR) in order to increase strength and toughness with reduced costs. To evaluate the effect of microalloying elements as Nb and Ti with thermomechanical treatment, three conditions were tested: DIN 20MnCrS5 with hot rolling (HR), DIN 20MnCrS5 with Nb and CR and DIN 20MnCrS5 with Nb+Ti and CR. Austenitic grain size, obtained by direct quenching after rolling, has shown a decrease 32% with Nb addition, and 29% when Nb and Ti was added. Controlled rolling generated higher grain refinement and pancacked grains near the surface. When comparing ferritic grain size, controlled rolling plus niobium and titanium additions resulted in significant reduction of 35%. Yield strength increased 15% with microalloying and CR and more than 350% in impact t...
Microalloyed steels have been intensely studied as an alternative to increase strength by grain r... more Microalloyed steels have been intensely studied as an alternative to increase strength by grain refinement and/or precipitation hardening. Long steel products have a wide range of opportunities to apply well-defined principles of controlled rolling (CR) in order to increase strength and toughness with reduced costs. To evaluate the effect of microalloying elements as Nb and Ti with thermomechanical treatment, three conditions were tested: DIN 20MnCrS5 with hot rolling (HR), DIN 20MnCrS5 with Nb and CR and DIN 20MnCrS5 with Nb+Ti and CR. Austenitic grain size, obtained by direct quenching after rolling, has shown a decrease 32% with Nb addition, and 29% when Nb and Ti was added. Controlled rolling generated higher grain refinement and pancacked grains near the surface. When comparing ferritic grain size, controlled rolling plus niobium and titanium additions resulted in significant reduction of 35%. Yield strength increased 15% with microalloying and CR and more than 350% in impact toughness, even at-40°C.
Microalloyed steels have been intensely studied as an alternative to increase strength by grain r... more Microalloyed steels have been intensely studied as an alternative to increase strength by grain refinement and/or precipitation hardening. Long steel products have a wide range of opportunities to apply well-defined principles of controlled rolling (CR) in order to increase strength and toughness with reduced costs. To evaluate the effect of microalloying elements as Nb and Ti with thermomechanical treatment, three conditions were tested: DIN 20MnCrS5 with hot rolling (HR), DIN 20MnCrS5 with Nb and CR and DIN 20MnCrS5 with Nb+Ti and CR. Austenitic grain size, obtained by direct quenching after rolling, has shown a decrease 32% with Nb addition, and 29% when Nb and Ti was added. Controlled rolling generated higher grain refinement and pancacked grains near the surface. When comparing ferritic grain size, controlled rolling plus niobium and titanium additions resulted in significant reduction of 35%. Yield strength increased 15% with microalloying and CR and more than 350% in impact toughness, even at-40°C.
The characteristics of Mould fluxes have been improved in recent years, in order to meet the rigo... more The characteristics of Mould fluxes have been improved in recent years, in order to meet the rigorous demands of the continuous casting of steel. The most important improvements in mo uld fluxes have been focused on the prime requirements of the continuous casting process, i.e., better surface quality of the solid steel, higher productivity and minimum environmental impact. In order
The characteristics of Mould fluxes have been improved in recent years, in order to meet the rigo... more The characteristics of Mould fluxes have been improved in recent years, in order to meet the rigorous demands of the continuous casting of steel. The most important improvements in mo uld fluxes have been focused on the prime requirements of the continuous casting process, i.e., better surface quality of the solid steel, higher productivity and minimum environmental impact. In order
This work aims to evaluate the influence and benefits obtained with the utilization of tundish fu... more This work aims to evaluate the influence and benefits obtained with the utilization of tundish furniture at Aços Villares - Mogi das Cruzes Plant. The expected benefits are inclusion removal and yield improvement in the continuous casting machine. The methodology employed in this work consisted in preliminary mathematical modeling of the system for the furniture project, the systematic Ripple Pad and dams utilization and finally the analysis of results in terms of inclusion removal and yield improvements. Considering the level of inclusions obtained with the systematic utilization of the system Ripple Pad and dams, a reduction around 30% in rejection of final products was obtained for critical applications. Consistent reduction around 10% in the discharge for sequencial casting of different steel grades was also obtained, providing yield improvement.
Resumo O objetivo do presente trabalho é avaliar o efeito da adição de Nb na determinação da Temp... more Resumo O objetivo do presente trabalho é avaliar o efeito da adição de Nb na determinação da Temperatura de Têmpera ótima (TTo), para se obter a maior fração de austenita retida possível, em aços tratados por Tempera e Partição e comparar este resultado com o modelo teórico. Duas ligas, uma delas com adição de Nb, foram submetidas à ciclos térmicos em dilatômetro. As frações de austenita retida foram determinadas por difração de raios X e a distribuição de fases por EBSD. Foi observado que a presença do Nb altera a distribuição de fases, favorecendo a formação de austenita retida.
Uploads
Papers by José Bolota