Austempered Ductile Iron (ADI)
Austempered ductile iron (ADI) as an alternative to quenched and tempered steel and construction steel
Through the Austempering heat treatment we produce cast parts in austempered ductile iron (ADI) for lighter, higher performing parts
Austempered ductile iron (ADI) is one of the areas in which Zanardi Fonderie specialises, having forever focused on the search and diffusion of a material able to offer wear resistance, toughness, lightness, good machinability and ample freedom in designing parts for the agricultural and earth moving sectors, railway and forestry sectors, as well as for applications such as gear reducers, off-road and on-road vehicle suspension systems and hydraulic and fluid power parts.
Thanks to austempered ductile iron (ADI) it is possible to obtain parts with mechanical properties equivalent to those of quenched and tempered steel, but lighter and with lower manufacturing costs. At Zanardi Fonderie, austempered ductile iron ADI is heat treated in the internal Austempering department and each casting is produced in accordance with co-designs developed with the client. Today, we are able to produce all grades of austempered ductile iron (ADI) according to international standards EN 1564, ISO 17804 and ASTM A897.
Austempered ductile iron (ADI): how it’s obtained
Austempered ductile iron (ADI) is obtained through an Austempered heat treatment applied to a spheroidal graphite iron cast part. This process gives the austempered ductile iron ADI mechanical properties typical of quenched and tempered steel. By heat treating the cast parts in spheroidal graphite iron enriched by alloying elements such as copper, nickel and molybdenum, the initial untreated microstructure of the cast iron (called AS CAST) is transformed into an ausferritic microstructure, that is, containing a mix of stable austenite and acicular ferrite.
The benefits of austempered ductile iron (ADI)
Austempered ductile iron (ADI) is highly requested as an alternative to melted, welded and forged steel. Below are some of the main benefits of this material:
- Lightness: the specific weight of austempered ductile iron (ADI) is 10% lower for the same volume, compared to steel. This means vehicles can enjoy an excellent advantage by either increasing their maximum load or reducing their fuel consumption;
- Complex moulds: these can be obtained thanks to the excellent castability of austempered ductile iron ADI, which allows application of the material only where necessary;
- Wear resistance: this is a natural characteristic of austempered ductile iron ADI, which is obtained without the need for any additional surface treatments and which increases the life of the part, thus reducing the number of replacements throughout the entire service life of the machine;
- Fatigue strength: in terms of performance, it can be compared with quenched and tempered steel commonly used in modern mechanics;
- Machinability: despite the level of hardness reached by the material, after the austempering heat treatment the austempered ductile iron (ADI) can nonetheless be machined using specific tools, guaranteeing compliance with very strict tolerances.
Custom products in austempered ductile iron (ADI) according to design requirements
Austempered ductile iron (ADI) can be produced in seven distinct grades in order to respond to all application needs. Depending on the desired thickness of the cast part and grade of austempered ductile iron ADI, the right quantity of alloying elements is defined, as well as the times and temperatures of the heat treatment. This flexibility of the ductile iron heat treating process makes it possible to achieve the desired result across the entire geometry of the piece. Isothermal hardening in salt bath, typical of the Austempering heat treatment, makes it possible to obtain a consistent component from the surface to the core.
Mechanical properties of austempered ductile iron (ADI)
Rp0,2 (N/mm2 min)