UNS S32750 (1.4410)

UNS S32750 is a super duplex stainless steel designed to offer very high strength and exceptional corrosion resistance in demanding environments. It has a balanced microstructure of roughly equal parts ferrite and austenite, which gives it superior resistance to pitting, crevice corrosion, and stress corrosion cracking compared to standard stainless steels. The biggest difference is that super duplex has a higher Molybdenum and Chromium content. This gives the material greater strengh when compared to other stainless steel grades.

UNS S32750 usually costs more to produce than standard duplex grades like 1.4462 (UNS S31803). Its raw materials are more expensive, and the melting and processing steps must be carefully controlled to keep the right phase balance. Even so, S32750 is still cheaper than high-performance austenitic or nickel-based alloys that offer similar corrosion resistance. This makes super duplex a cost-effective option when you need high strength and long-term durability, helping lower overall lifecycle costs despite its higher initial price.

Composition: UNS S32750 contains a high percentage of chromium (around 25%), molybdenum (about 3.6%), and nickel (approximately 7%), along with other elements like nitrogen and iron. This composition gives it superior resistance to corrosion. It is especially notable in environments that are highly corrosive or prone to chloride stress corrosion cracking.

Super Duplex Structure: This steel is classified as “super duplex” because it has a dual-phase microstructure—about 50% austenite and 50% ferrite. This combination provides excellent mechanical properties, such as high strength and good resistance to both pitting and crevice corrosion.

Corrosion Resistance: UNS S32750 is highly resistant to corrosion in aggressive environments, including sea water, acids, and chloride-rich solutions. It is often used in applications where standard stainless steels might not perform well. Specifically, it is suitable for offshore oil and gas rigs, chemical processing plants, and desalination plants.

Mechanical Properties: It has excellent strength compared to standard austenitic stainless steels, making it suitable for applications that require both strength and corrosion resistance.