To modify the surface structure of AISI 1005 steel and its properties without any dimensional loss, different plasma surface treatments were performed at low temperatures (500 °C) in this study. The samples were subjected to single plasma treatments including: nitriding (N5% and N3%), carburizing (CE) and ferritic nitrocarburizing (NC) and to duplex treatments of nitriding followed by carburizing (N5%+CE and N3%+CE) and ferritic nitrocarburizing followed by carburizing (NC+CE). The gas mixture used for these treatments was varied as follows: nitriding (5%N 2 +95%H 2 and 3%N 2 +97%H 2 ), carburizing (5%CH 4 +95%H 2 ) and ferritic nitrocarburizing (5%N 2 +1.5%CH 4 +93.5%H 2 ). A microstructural characterization of the samples was carried out using optical and scanning electron microscopy in addition to XRD analysis. Microhardness testing was also performed. The XRD analysis showed a stabilization of the outermost cementite layer for all of the carburizing treatments. The results show that a greater hardness increase was achieved for the nitriding treatment as well as a more regular compound layer. However, a greater depth of hardening was obtained in samples with NC+CE and N5%+CE, which extended to the hardened depth to 800 μm.

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Sintered self-lubricating components may present inappropriate mechanical properties despite their excellent tribological properties. In general, alloying elements are used to improve these properties, but with a cost increase. As an alternative, surface enrichment (or surface alloying) with alloying elements may be applied. This study developed and characterized sintered composite materials surface-enriched with nickel or molybdenum. The results showed that the surface enrichment process is useful for increasing the tribomechanical properties. The Mo-enriched samples presented superior tribological results. Compared with the reference samples (not enriched), the Mo-enriched specimens showed an increase of 4,954% in scuffing resistance, lower friction coefficient (0.09), and reduced wear rate (68% and 96% lower for the specimen and the counter body). These results were mainly attributed to microstructural modification.

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ResumoO desenvolvimento dos aços inoxidáveis significou um grande avanço na fabricação de materiais resistentes à corrosão. Dentre os aços inoxidáveis desenvolvidos, estão os aços inoxidáveis duplex (AID). Os AID são aços de baixo teor de carbono, ligados principalmente ao cromo, níquel e molibdênio que possuem composição balanceada, de modo a se obter uma microestrutura mista, com frações volumétricas aproximadamente iguais de ferrita e austenita. Este artigo apresenta uma visão geral sobre os aços inoxidáveis duplex, começando com um resgate do contexto histórico, dos processos de fabricação, da classificação, passando pelas propriedades mecânicas e metalúrgicas e finalizando com as principais aplicações desse material. Palavras

ResumoO tratamento de austenitização é de fundamental importância para a qualidade do aço Hadfield, já que é o tratamento que garantirá a total austenitização do material. Dentre as variáveis que devem ser controladas estão à temperatura de tratamento e velocidade de resfriamento. O presente trabalho aborda um estudo de caso sobre o controle da temperatura dentro do forno de tratamento térmico bem como o comportamento da temperatura da água na piscina durante o resfriamento do material. Palavras-chave: Tratamento térmico, Aço Hadfield. CASE STUDY: BEHAVIOR OF WATER TEMPERATURE OF THERMAL COOLING POOL IN THE AUSTENITIZING TREATMENT HADFIELD STEEL AbstractThe austenitizing treatment is of fundamental importance to the quality of Hadfield steel, because is the that treatment will ensure the complete austenitizing of the material. Among the variables that must be controlled are the treatment temperature and the cooling rate. This paper presents a case study on the control of the temperature inside the heat treatment furnace and the behavior of the pool water temperature during the cooling of the material.

ResumoA produtividade de uma linha de moldagem numa fundição é determinada pela vida de banca dos moldes. No processo com resina fenólica alcalina (Alphaset), a cura ocorre devido à reação de polimerização entre a resina e o catalisador orgânico ester. O tempo no qual a reação de polimerização ocorre é influenciado por dois fatores: temperatura e a relação entre a quantidade de resina e catalisador (vazão mássica). Esse estudo procura estabelecer um entendimento entre estes dois fatores no tempo de banca, estabelecendo o mais predominante, para que assim possa-se aperfeiçoar o processo utilizando a quantidade adequada de resina e catalisador, sem perder a produtividade. Para avaliar o efeito da temperatura no tempo de banca foi realizado o teste de gel time com a resina em diversas temperaturas. Para avaliar a variação da vazão mássica da resina devido as diferentes condições de temperaturas foi realizado o ensaio com o Copo Ford. Observou-se que o tempo de polimerização da resina reduz exponencialmente com o aumento da temperatura da resina, sendo o inverso verdadeiro também. O teste com o Copo Ford mostrou que a vazão da resina é muito sensível a temperatura, aumentando quase 40% num acréscimo de 10 o C na temperatura. Palavras-chave: Resina; Vazão mássica; Fundição. STUDY OF BEHAVIOR POLYMERIZATION RESIN ALKALINE ESTER WITH TEMPERATURE CHANGE AbstractThe productivity in a casting molding line in is determined by the bank of life of the molds. In Alphaset process healing occurs because of the polymerization reaction between the resin and the catalyst. The time at which the polymerization reaction occurs is influenced by two factors: the relationship between temperature and the amount of resin and catalyst (mass flow). This study wishes to establish an understanding between these two factors in the banking time, establishing the most prevalent, so we can optimize the process using the best type of resin and catalyst, without losing productivity. To evaluate the effect of temperature on the bank time was conducted the gel time test with the resin at different temperatures. To evaluate the variation of mass flow of resin due to the different conditions of temperature was carried out the test Ford Cup. It was observed that the resin polymerization time decreases exponentially with increasing temperature of the resin, and the opposite is also true. The Ford Cup test showed that the flow of the resin is very sensitive to temperature, increasing almost 40% with in a 10°C increase in temperature.

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