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Austempering

Austempering is ideal for parts that have both flexibility and fatigue strength, such as springs.
The steering knuckle is made of ADI material and is austempered.
It is used in automotive parts that are sensitive to impact.

It is a type of heat treatment applied to ferrous metals. Its most well-known applications are steel and cast iron. As a result of this process, a bainitic structure is formed in steel materials, while stabilized austenite is formed together with acicular ferrite containing high amounts of carbon in cast irons. This austenite is also called ausferrite.

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In classical oil hardening (quenching), the parts are quickly cooled below the martensite initial temperature, while in austempering, the parts are kept at a temperature above the martensite initial temperature (260-370°C) for a while and cooled in air.

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The structure created is more flexible, has higher toughness and shock resistance.

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It has application areas in many places such as automotive, defense and heavy truck industry. In the aviation industry, landing gear main struts are hardened by austempering.

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Due to the good specific strength properties of cast iron materials (ADI) suitable for austempering, it allows the production of lighter parts than steel or even aluminum.

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Applied materials,

  • Medium and high carbon steels

    • SAE 1095, 4140, 4340, 50CrV4​

  • Classified according to ISO 17804

    • NAME 800, 900, 1050, 1200, 1400 and 1600

  • Nodular graphite cast irons

    • EN-GJS-350-22, EN-GJS-500-7 and EN-GJS-900-2​

  • Gray cast irons​

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CQI-9 Table A is used for this heat treatment technique in the automotive industry.

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