a group company of MITSUBISHI STEEL MFG. CO., LTD.
Immediately after quenching, martensite is untempered, but untempered martensite is usually undesirable because it is brittle (practically no ductility). So the steel will be typically tempered to restore some level of ductility (tempered martensite). In modern Advanced High Strength Steels (AHSS) retained austenite may transform into martensite (the steel "TRIPS") as a result of the application of strain. This is desirable because the transformation requires the absorption of energy. Such steels may be used in automotive applications to manage crash energy.
I hope this helps.
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