Improved high silicon ductile iron alloys

Currently, the demand for parts manufactured with cast iron has increased due to its technological properties and, above all, its great economic competitiveness. This fact, along with the economic downturn in Europe and the aggressive competition of countries such as China or India, has forced researchers to optimize the properties of these materials and develop new types of cast iron alloys with innovative features. These new materials have huge potential when applied to the manufacturing of components where, until now, steel or other alloys have been used, incurring their associated higher production costs.

Among new materials with improved mechanical properties development, one of the most interesting groups is the as-cast ductile irons with high Silicon contents (2.8-4.2 wt.%). The new version of the standard EN 1563 (2012) includes the required properties for some grades related to these kind of materials. Nevertheless, this standardisation is still limited and foundries still have not adopted these materials in their manufacturing processes. This is mainly due to the lack of knowledge of their structural and mechanical properties, machining response, etc.

IK4-AZTERLAN Technological Centre is carrying out a wide study on these materials with the aim of optimising their properties through variations in their chemical composition. Another interesting area of this investigation is the manufacturing of prototype-components that, after being characterized, will provide essential process information for the foundries interested in these types of materials.

The already obtained results have confirmed the great industrial applicability of iron alloys with high Silicon content. However, some processing parameters with important influence on properties must be checked in order to avoid the appearance of defects during solidification of the cast alloys. These defects are related to graphite degenerations and to the contraction capability of the solidifying alloys. These materials will definitely become an improved alternative to the cast iron grades which are traditionally used in foundries.