Super Duplex 2507 / 1.4410 stainless steel

What Super Duplex 2507 / 1.4410 is

2507 / 1.4410 is a super duplex stainless steel. The structure is two-phase – ferrite and austenite in the same material – which gives higher strength and better chloride resistance than the austenitic 316L, at the price of stricter welding. The step from Duplex 2205 to 2507 is a higher PREN and higher strength for aggressive chloride, seawater and demanding process duty. It is bought on W.Nr. and condition: the certificate states X2CrNiMoN25-7-4 and 1.4410, whatever the drawing calls it.

Delivery condition and dimensions

We source Super Duplex 2507 from European partners as round bar, plate, flat bar, seamless tube and welded tube, cut to your sizes and ship the certificate with the goods. Typical condition: solution annealed. Standard: X2CrNiMoN25-7-4. From a single cut piece to larger lots – without minimum charge, so you do not have to buy a whole merchant length to get what you need. Dimensions and availability are confirmed on enquiry – state form, dimension, length and quantity.

Heat treatment and strength

2507 is supplied solution annealed – that is the condition the certificate shows. The strength comes from the two-phase structure, not from quenching and tempering, so there is no +QT purchase as with a martensitic grade. No mechanical table is published here: the values that apply are those the mill certifies for the delivered heat and dimension. If a particular test or condition has to be documented, it must be specified before we order.

Sawing and machining

Sawing of bar and flat to length, cutting of plate to size, tube to dimension. State the form – not just the W.Nr. – together with Ø or thickness, length and quantity. Machining takes place in the solution-annealed condition in which the material is supplied.

Welding

Super duplex comes with demanding welding requirements and requires controlled welding. It is not a 316L you “upgrade” without a procedure – the procedure, filler and heat input are the fabricator's responsibility, and they must be in place before 2507 is specified. If the job is routine 316L workshop welding, 2507 is the wrong starting point.

Certificates and documentation

Super Duplex 2507 can be supplied with a material certificate to EN 10204, depending on the producer, dimension and the requirements specified for the delivery. On stainless steel, the analysis and the delivery condition are what the certificate shows. If a particular test or a specific condition has to be documented, it must be specified before we order. EN 10204 3.1 can be supplied on a wide range of our materials.

International designations

The same grade appears under several names. The certificate carries the designation the mill has issued – state the one the drawing requires on the enquiry.

• X2CrNiMoN25-7-4 / 1.4410 – EN designation and Werkstoffnummer
• 2507 – trade name for the same grade
• UNS S32750 – American designation, cross-referenced to 1.4410
• F53 – designation used in American forging specifications for the same grade

Limits and alternatives

2205 when 2507 is overkill. 316L when duplex is more than the task calls for. Not a 316L you “upgrade” without a procedure. 1.4501 when the Cu-W variant is specified – close to 2507 in PREN, but a different EN line and a different W.Nr. on the certificate. 1.4547 when a 6 % Mo austenite is the designation the drawing knows.