ADI (Austempered Ductile Iron)
ADI is a cast iron material in which the carbon appears as nodules and the structure matrix consists of ausferrite. This ausferrite is a fine-grained mixture of ferrite and stabilised austenite which is a guarantee for the high hardness and ductility of ADI.
In ADI the chemical composition is laid down according to the relevant wall thickness of the material. In general it is aimed to achieve the following analysis:
|3,5 – 3,7||1,9 – 2,3||0,6 – 1,0||0,6 – 2,5||0,15 – 0,3|
With this composition, and depending on the form which the metallic matrix has, the material has an expected tensile strength of Rm = 800 to 1400 N/mm². ADI is an alloyed form of spheroidal cast iron, in combination with a special form of heat treatment.
THE PROPERTIES OF ADI/CONCLUSIONS
Excellent possibilities – opening up new perspectives to all designers. The correct material selection will result in:
- High strength levels
- Concurrent ductility
- High fatigue resistance
- High durability
- Improved sound dampening
- Greater freedom of design
- Accuracy when machining to final dimensions
- Lower prices than normal ductile and case-hardened steel with similar and better properties!
- high values for static and dynamic strengh
- High hardening
- Low notch sensitivity
- High fatigue resistance due to cold work-hardening
- Choice of geonetrical design forms
- Good sound dampening properties
- Good machinability