Abstract
Cast iron was the first man-made composite. Due to its properties and its competitive price, it remains the most important molten material to this day. The production of nodular cast iron components involves melting steel, pig iron, machining returns, such as chips and alloy irons, and currently production consumes up to 70wt.% of recyclable waste. Currently aiming at reducing costs and to reduce environmental impacts, steel scrap has been used; one of the most important components used in the nodular cast iron process is the steel scrap of the automotive industries. Nevertheless, the development of technological steels through the addition of chemical elements to meet a specific application and efficient separation would be expensive and time consuming. Indeed, there is an increasing difficulty in acquiring low alloy steel for the production of nodular cast iron. The chemical elements present in the steel scrap may favor the appearance of unwanted phases and particles that alter the mechanical properties. Further research showed that the shape of graphite precipitates in cast iron is very sensitive to small variations in melt composition. The present study evaluated the effect of the addition of the main elements present in recyclable steels such as chromium, molybdenum and nickel in levels between 0.50wt.% and 1.0wt.% in the formation of phases and in the characteristics of the graphite nodules. The use of alloy elements added intentionally and process changes to obtain specific properties are the objects of study in this work. While nickel was evenly distributed in the matrix, chromium and molybdenum formed carbides in the contours of eutectic cells. In addition, chromium strongly favored the formation of perlite in nodular cast iron and molybdenum, the martensite.
Published Version
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