Austempering Heat Treatment Structure

Austempering is a specialized heat treatment process used primarily for steels.

The process involves:

• Heating the steel into the austenite temperature range.
• Quenching rapidly to a temperature *above* the martensite formation temperature (M_s).
• Holding the steel at this intermediate temperature isothermally until the transformation of austenite is complete.

This controlled isothermal transformation results in the formation of a unique microstructure known as Bainite. Bainite offers a good combination of strength and toughness.

Resulting Microstructure

The specific structure obtained via the austempering process is:

• Bainite: This is the characteristic microstructure formed during austempering.

Incorrect Options Analysis

• Sorbite and Troostite: These are older terms often associated with finer pearlite structures formed at slower cooling rates than bainite.
• Martensite: This structure is formed when steel is quenched to a temperature *below* the M_s temperature, which is not the condition used in austempering.

Therefore, austempering specifically yields Bainite.