Zanardi Austempering: steel and cast iron heat treatment

Subcontracting of austempering heat treatments on all grades of austempered ductile iron (ADI), isothermal ductile iron (IDI), austempered grey iron (AGI) and austempered steel.

Lighter, high-performance, sustainable components

We offer the market a single point of contact, providing our support starting from the definition of the product’s chemical composition

We have been performing our in-house austempering heat treatment since 2001: in 2019 we began to offer our services as a subcontractor, supporting European foundries in defining the desired product requirements and transversal optimisation of the austempering process.

Since the early 2000s we have invested both internally and in research to acquire the necessary expertise on ADI processing. Recent investments in hi-tech machinery for mechanical processing have allowed us to propose our services to other foundries in search of a partner able to process castings, and also support our clients in defining processing parameters and selecting the most suitable tools.

Thanks to the modern equipment in our metallography lab, we are also able to provide complete certification for the austempered material.

High-performing austempering treatment systems

For the austempering heat treatment, and therefore the production of cast parts in austempered ductile iron (ADI), we use three AFC-Holcroft UBQA furnaces measuring 36″ x 72″ x 36″
Internal dimensions of heat treatment baskets:
840 x 1705 x h890 mm
Installed heat treatment capacity: 10.000 t
Weight range: da 1 Kg a 1000 Kg

These modern and efficient heat treatment systems ensure the stability of the process combined with the quality and repeatability of the material’s characteristics.

The main benefits offered by austempered materials/h3>

Austempered materials are highly resistant and demonstrate excellent fatigue behaviour. By providing excellent benefits in terms of lightness of mechanical components, they promote environmental sustainability and are also competitive in terms of production costs.
From a design point of view, austempered materials offer excellent flexibility and, with the Zanardi Austempering brand, we offer cast iron and steel manufacturers targeted support in defining the chemical analysis, with the aim of minimising the use of alloys and the complexity of metallurgical management.

Austempered Ductile Iron

The mechanical properties of Austempered Ductile Iron (ADI) make it an excellent alternative to cast, forged and welded steel, because it reduces the weight of the components.
This materials offers a unique combination of fatigue strength, wear resistance, toughness, lightness, and flexibility in the design of the components, while maintaining good machinability .

Isothermal Ductile Iron

Isothermal Ductile Iron (IDI) is obtained by heat treating cast parts in ferritic spheroidal graphite iron (GJS400-15) through isothermal hardening in a salt bath. This process increases the flow stress and strength of the material without compromising its elongation while ensuring consistency in the mechanical properties as the thickness varies. This makes the material suitable for components which require high levels of static and fatigue strength. The IDI grade is an exclusive Zanardi Fonderie S.p.A patent.

Austempered Grey Iron

Grey austempered lamellar graphite cast irons (AGI), known as Austempered Grey Irons (AGI), are obtained starting from traditional grey cast iron through an austempering process similar to the one used for spheroidal graphite irons. These cast irons offer comparable, if not greater, mechanical strength and elongation at break to that of compacted graphite iron (CGI), together with exceptional thermal conductivity and vibration damping characteristics.

Austempered steel

Ausferritic steel is a very interesting solution for components that require wear and impact resistance, such as agricultural tools. Even though the carbon content in the matrix stays the same as that of the chemical composition of the steel, the presence of silicon increases its mobility by allowing the formation of an ausferritic structure (acicular ferrite and carbon-stabilised austenite). When the silicon content is not sufficient, however, the carbon combines with the iron forming carbides, thus producing bainite. Bainitic steel, with its combination of wear resistance and fatigue strength, can be used in a wide range of industrial components, such as mower blades, clips, transmission gears, etc.

Foundries can count on our extensive experience in austempering

The Austempering heat treatment is a flagship service offered for more than 30 years by Zanardi Fonderie, which, since 2019, has also worked as a subcontractor on behalf of European foundries.

Our company offers the market the heat treatment of spheroidal graphite iron castings, guaranteeing the possibility to achieve all grades of austempered ductile iron (ADI) in compliance with international standards (ISO17804, EN1564 and ASTMA897/A897M). It also offers European foundries its own heat treatment to obtain isothermal ductile iron (IDI), one of our patented materials.

We also offer our austempering service for third parties

Austempered ductile iron (ADI) offers clients a valid alternative to steel parts, maximising value for money in numerous applications.

Thanks to the experience acquired in the in-house production of austempered ductile iron ADI, Zanardi Fonderie offers targeted support to client foundries, starting from the definition of the material’s chemical analysis, with the aim of minimising the use of alloying elements and complexity of the metallurgical process.

For 30 years we have been investing in the research and development of austempering as a technological innovation in the field of ferrous materials. We actively collaborate with important academic institutes such as WZL/RWTH Aachen University, Technische Universitat Munchen, University of Trento, University of Padua, EIT Raw Materials and participate in international committees for the material’s standardisation.

Design, co-design, research and development at the service of clients

Thanks to our experience in austempering and use of the most modern software, we are able to support foundries in defining the most appropriate chemical composition for the development of new parts in spheroidal graphite iron (ADI).

We work with the following software:

  • PoE CAD
  • Magmasoft

We perform fatigue strength tests to determine:

  • Rotating-bending fatigue
  • Axial fatigue
  • Bending fatigue

Material certification in our metallography laboratory

Our metallography lab is equipped to provide complete certification of the austempered material. We are able to perform internal mechanical tests, micrographic analysis, hardness tests and resilience tests up to +40 °C.

We issue certificate 3.1B for material certification and use the following machinery to test the materials:


  • Optical microscope
  • SEM

Mechanical properties

  • Machines to test tensile strength

Hardness range

  • Durometers to measure the hardness value


  • Charpy Pendulum to measure resilience even at -40°C.

Case History

Real cases explaining the development of client projects