Abstract This article evaluates the effect of recrystallization annealing soaking time on the tribological behavior of cold upsetted low carbon steel. The 40% cold formed steel was subjected to annealing at 900 °C, for 10, 20, 30, 40, 50 and 60 minutes. The mechanical properties of hardness, tensile strength, yield strength and ductility, measured through specific deformation, as well as the precipitation of carbides through microstructural analysis were examined. In order to analyze the volume of removed material, the wear test was performed using a pin-on-disk tribometer according to ASTM G99. The results showed that the combination of lamellar perlite precipitation and pearlitic interlayer spacing reduction increases the mechanical strength of 1020 steel, reduces ductility, increases friction coefficient and increases wear observed by the volume of removed material increase.

Este trabalho teve por objetivo estudar o efeito do tratamento de nitretação por plasma e do revestimento de carbonitreto de titânio sob o aspecto de resistência ao desgaste de matrizes de conformação mecânica de elementos especiais de fixação. O enfoque principal está centrado na taxa de desgaste por abrasão, caracterizado pelo atrito de elementos interfaciais entre as superfícies da matéria-prima e da matriz. Foram utilizadas três matrizes de VF 800AT diferentes, das quais duas apresentavam desgaste excessivo antes do tratamento ou revestimento superficial, e uma apresentava problemas de fratura. As propriedades mecânicas foram avaliadas através de ensaios de estereoscopia, dureza, microdureza, rugosidade, metalografia óptica e eletrônica de varredura e controle dimensional por carta de Controle Estatístico de Processo - C.E.P.. No estado tratado por nitretação a plasma, as matrizes (com camada branca bastante reduzida) apresentaram menor resistência ao desgaste (maior taxa de desgaste), ao passo que a maior resistência ao desgaste foi das matrizes com revestimento de carbonitreto de titânio. Isto foi atribuído a excelente dureza do elemento titânio, juntamente com seu poder de aderência, em contraste com a fragilidade da camada branca formada pela nitretação a plasma .

This research studies the effects of plasma-nitriding and titanium carbonitriding mixtures on the wearing resistance of mechanical forming dies for special fixing elements manufacturing. The main focus is the abrasion wear rate, characterized by the friction between the surfaces of the raw material and die. Three different configurations were used for the VF 800AT steel dies, chosen among the ones that had shown high waste rates before coating. Industry and laboratory trials were performed to compare the wear behavior. The coated dies had better results in contrast with others. The plasma-nitriding dies (with a small white layer) showed lower wear resistance (higher wear rate) when compared with titanium carbonitriding dies. That was caused by the excellent hardness of the titanium carbonitriding and the good adherence.