475 °C embrittlement
Loss of plasticity in ferritic stainless steel / From Wikipedia, the free encyclopedia
Duplex stainless steels are a family of alloys with a two-phase microstructure consisting of both austenitic (face-centred cubic) and ferritic (body-centred cubic) phases. They offer excellent mechanical properties, corrosion resistance, and toughness compared to other types of stainless steel. However, duplex stainless steel can be susceptible to a phenomenon known as 475 °C (887 °F) embrittlement or duplex stainless steel age hardening, which is a type of aging process that causes loss of plasticity in duplex stainless steel when it is heated in the range of 250 to 550 °C (480 to 1,020 °F). At this temperature range, spontaneous phase separation of the ferrite phase into iron-rich and chromium-rich nanophases occurs, with no change in the mechanical properties of the austenite phase. This type of embrittlement is due to precipitation hardening, which makes the material become brittle and prone to cracking.