Effect of Melting Techniques on Ductile Iron Castings Properties
نویسنده
چکیده
Ductile iron is one of the most important engineering materials, in view of its excellent castability, signifi cantly better mechanical properties and low cost [1, 2]. It represents the fastest growing segment of the iron market. In the medium term, it is to be expected that the market share of nodular iron will level off at 40 % to 45 % [3]. Achieving the full potential of ductile iron requires superior metallurgical process control, as well as the highest levels of skill in melting the ductile iron base, spheroidizing and inoculation [4]. The fi rst step of the production of ductile iron castings is the careful selection of the charge materials. Manganese and chromium have the most infl uence on all mechanical properties [5]. For this reason, their concentration in metal is of particular importance. These elements arise in the charge from steel scrap, iron units and returns. It is recommended practice to purchase steel scrap so that the average Cr content remains below 0,1 percent. Ideally, the same advice would be given for Mn but, unfortunately, all steel scraps contain Mn, the majority being at the 0,5 percent level. The amount of steel scrap in the charge must be that The study was designed to investigate the effects of the charge, melting conditions, nodularizing and inoculation on the ductile iron castings properties. Results showed that the temperature and holding time of the melt in an induction furnace and the intensity of spheroidizing effect on the carbon and residual magnesium contents in the ductile iron castings. The same grade of ductile iron may be obtained using different chemical compositions. The castings of ductile iron will be ferritic as-cast only when large amount of pig iron in the charge and in addition some-steps inoculating treatment are used.
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