14 Jul New Standard – Founding. Ausferritic spheroidal graphite cast irons. Classification.
BS ISO 17804:2020 Founding. Ausferritic spheroidal graphite cast irons. Classification.
Ausferritic spheroidal graphite cast iron is a cast alloy, iron, carbon and silicon based, carbon primarily in the form of spheroidal graphite particles. Compared with the spheroidal graphite cast iron grades, four material grades combine high strength, ductility and toughness properties while two grades combine higher strength with wear resistance as a result of ausferrite matrix structures.
The document deals with the classification of ausferritic spheroidal graphite cast irons in accordance with the mechanical properties of the material. The mechanical properties of these ausferritic spheroidal graphite cast irons depend on their structure, e.g. the form of the graphite and the structure of the matrix.
The required structure is developed by selecting the appropriate composition and subsequent processing.
The mechanical properties of the material can be evaluated on machined test pieces prepared from:
— separately cast samples with an appropriate gating system, able to provide metallurgical conditions similar to those of the castings they represent;
— samples cast in the mould alongside the casting, with a joint running system, hereafter called “side-by-side cast samples”;
— samples cast onto either the casting or the running system, hereafter referred to as “cast-on samples”;
— samples cut from a casting (only by agreement between the manufacturer and the purchaser, the agreement specifying, in particular, the conditions of sampling and the values to be obtained).
Two grades of ausferritic spheroidal graphite cast iron are specified in accordance with their hardness. These cast irons are used in applications where high abrasion resistance is required (e.g. mining, earth moving and manufacturing industries).
Five grades of ausferritic spheroidal graphite cast iron are specified by their mechanical properties. When, for these grades, hardness is a requirement for the application, an annex provides the means for determining appropriate hardness ranges.
Some ausferritic spheroidal graphite cast iron grades can be used for pressure equipment.
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