ADI Treatments Ltd.

ADI is a most versatile material, enabling innovative solutions to new and current problems.

By selecting precise heat treatment parameters a specific set of properties can be achieved. The lower hardness ADI castings are used in structural applications, often where weight and cost reduction are important.

Wear resistance is superior to steel at any given hardness level, making the higher hardness grades ideal for mining, construction, agricultural and similar high abrasion applications.

ADI competes favourably with steel components, especially for heavy-duty parts where reliability is paramount.

It is used to upgrade from standard ductile irons, and as a substitute for manganese steel and nickel-hard materials.

When strength is required ADI is particularly cost-effective: tensile and yield values are twice those of standard ductile iron; fatigue strength is 50% higher and it can be enhanced by shot peening or fillet rolling.

With its high strength-to-weight ratio ADI can even replace aluminium when reduced section sizes are acceptable.

Because the carbon rich austenite phase is stable in Austempered Ductile Iron it enhances the bulk properties.

ADI is produced by heat treating ductile cast iron; sometimes with the additon of small amounts of copper, nickel and molybdenum to improve hardenability. The heat treatment parameters are carefully selected for the application.

Castings are first austenitised to enrich the austenite with carbon, then quenched rapidly to avoid the formation of pearlite. Austempering brings about the nucleation and growth of acicular ferrite, accompanied by the rejection of carbon into the austenite.

The resulting microstructure, known as “Ausferrite”, gives ADI special properties.

Ausferrite exhibits twice the strength for a given level of ductility compared to the pearlitic, ferritic or martensitic structures formed by conventional heat treatments.

Because the carbon rich austenite phase is stable in ADI it enhances the bulk properties. Furthermore, as the austenite is thermodynamically stable, it can undergo a strain-induced transformation when locally stressed, producing islands of hard martensite that enhance wear properties. This behaviour contrasts with that of the metastable austenite retained in steels, which can transform to martensite at room temperature. 

All heat treatments create dimensional change but with ADI this effect can be minimsed. The process is isothermal which means that components of the same incoming chemistry will grow the same way every time.

Batch-to-batch and part-to-part, your components will have predictable growth from the Austempering process. That means you can design the dimensional change into your component and let it grow to its tolerance.

The final properties (grades) of the ADI are governed by the austempering temperature and duration.

Based on customer input, our proprietary computer models can make accurate material and process selections and predict these properties. We can then assist the design engineer to find the optimum and most efficient solutions.

The Austempering of Grey Iron forms AGI, a material with excellent damping and wear resistance. Current applications include cylinder liners and bearing collars.

Carbidic ADI (CADI) is a new material formed with a matrix of ausferrite and carbides to add strength and wear resistance to ductile iron parts. The result is a premium, engineered iron with longer life and greater wear resistance than ADI 1400 (EN1564).

Applications for CADI are to be found in off-highway vehicles, agricultural equipment, railroad car, truck, construction, mining, general industrial, material handling, and ground engaging components.

Ductile Cast Iron undergoes a remarkable transformation when subjected to the austempering heat process.

A new microstructure (ADI) results with capability superior to many traditional, high performance, ferrous and aluminium alloys.
To optimise ADI properties for a particular application the austempering parameters must be carefully selected and controlled.

Castings are first austenitised to dissolve carbon, then quenched rapidly to the austempering temperature to avoid the formation of deleterious pearlite or martensite.

While the casting is held at the austempering temperature nucleation and growth of acicular ferrite occurs, accompanied by rejection of carbon into the austenite.

The resulting microstructure, known as “Ausferrite”, gives ADI its special attributes.

Ausferrite exhibits twice the strength for a given level of ductility compared to the pearlitic, ferritic or martensitic structures formed by conventional heat treatments.

Because the carbon rich austenite phase is stable in Austempered Ductile Iron it enhances the bulk properties.

Furthermore, while the austenite is thermodynamically stable, it can undergo a strain-induced transformation when locally stressed, producing islands of hard martensite that enhance wear properties.

This behaviour contrasts with that of the metastable austenite retained in steels, which can transform to brittle martensite at room temperature.