![\"\"](\"\/wp-content\/uploads\/2025\/01\/arrow-down.svg\"){kind=icon}
<\/p>\n<\/p>\n
in Duplex<\/span><\/p>\n<\/h1>\n Duplex stainless steels contain 2 types of microstructures, austenite<\/a> and ferrite<\/a>. Hence the name duplex.<\/p>\n<\/div>\n Sigma phase leaves the material in a stage with unfortunate material properties and must be prevented. Sigma phase forms primarily at 800-850C, but is able to form at temperature between 600 and 1000C, and will do so at varying rates, depending on the specific alloy. Please refer to the below TTT (Time-Temperature-Transformation) diagram for SAF2205 and the speed of which foreign phases forms.<\/p>\n For example, then chromium nitrides, chi-phase and carbides forms if a part made from SAF2205 is held at 800C for more than 1 min. The critical \u03c3-phase precipitation will form after approximately 16 min.During our tests, Zeron100 SuperDuplex alloy proved worst results as it initiated formation of \u03c3-phase after 3.5 min. at 850C.<\/p>\n<\/div>\nPreventing \u03c3-Phase Precipitation with Expanite\u00ae Treatments. <\/h2>\n
\nIn simple terms, the combination of these two phases is what causes duplex alloys to be highly sensitive with respect to the formation of the so-called \u201cSigma phase\u201d (\u03c3-phase), because the \u03c3-phase primarily will form in the boundary between austenite and ferrite, growing into the ferrite.<\/p>\n![\"Preventing](\"\/wp-content\/uploads\/2025\/02\/Sigmaphase.png\")
<\/p>\n
\n
![\"Sigma](\"\/wp-content\/uploads\/2025\/05\/CL_3-1.jpg\")
<\/p>\n