Summary
Embrittlement refers to an upward shift of the low temperature ductile-to-brittle transition temperature in a material. Most austenitic and duplex type steels normally do not have such a ductile-to-brittle transition. However, under certain conditions such steels can also become brittle.
Degradation module “CEN.16.11753 - High Temperature Corrosion and Degradation” also addresses this damage mechanism, in lesser detail.