Short answer: Sigma phase is a hard, brittle intermetallic that forms in stainless and duplex steels when held in the 550-950°C range — especially in welded or high-ferrite material — embrittling the joint. Control chemistry, heat input and post-weld treatment to avoid it.
At a Glance
Where Sigma Forms
High ferrite and slow cooling in Duplex Stainless Steel Guide en Duplex Vs Super Duplex raise risk; context in Uitleg over roestvast staal en Ferritic Vs Austenitic Stainless.
Weld Control
Limit heat input and interpass temperature; manage Metal Welding Distortion Guide and inspect Weld Defects Guide under Metal Metallography Guide with Metal Ndt Guide.
QA & Supply
Document chemistry and thermal history per Mill Test Certificate Guide. HXSCO supplies low-sigma-risk grades.
Get a Quote
Tell HXSCO your requirements and we will respond with a competitive quote and lead time.
Veelgestelde vragen
A brittle Fe-Cr intermetallic that embrittles stainless/duplex steel.
Holding in roughly 550-950°C, common in slow-cooled welds.
Duplex and high-ferrite grades are most sensitive.
Control heat input, ferrite and post-weld cooling.
HXSCO supplies grades selected to limit sigma-phase risk.
Source Low-Sigma Stainless from HXSCO
HXSCO supplies duplex and austenitic grades selected to limit sigma-phase embrittlement. Send your service and quantity for a quote.