Aperam and Outokumpu supply super duplex steel plates to refineries, offshore platforms, and desalination plants worldwide. Both mills melt, roll, and heat treat duplex grades to ASTM A240 and EN 10028-7, yet their production philosophies diverge in ways that matter on a specification sheet. This blog compares how each producer manufactures super duplex plate, so procurement teams can match project needs to the right source.
Why the Choice of Steel Mill Matters
The mill stamped on a material test certificate determines more than brand reputation. Melting practice and quench rate control the ferrite-austenite balance in duplex microstructure, and a shift of a few percentage points there changes toughness and corrosion resistance. Traceability from heat number to finished plate protects multi-year projects from mixed-grade shipments. Compliance with NORSOK M-630, PED 2014/68/EU, or NACE MR0175 depends on documented process control at the mill itself, and inconsistent metallurgy can surface as failure years into service.
Aperam vs Outokumpu: Key Manufacturing Differences
Manufacturing Philosophy
Aperam runs smaller batch sizes with tight process windows across its Belgium and Brazil facilities. Outokumpu operates larger integrated lines from Tornio and Sheffield, with scale and repeatability. Aperam favors tailored metallurgy for niche applications, while Outokumpu centers on volume consistency across standard grades.
Product Range and Available Grades
Aperam duplex steel plates span LDX 2101, 2205, and 2507 grades, rolled from 3mm to 100mm thickness. Outokumpu’s Forta DX and SDX lines cover the same grade family plus proprietary variants such as LDX 2404, with select facilities rolling up to 150mm. Standard sheets run 1500mm x 6000mm and 2000mm x 6000mm from both mills.
Quality Control and Testing Standards
Aperam inspects every plate through ultrasonic testing per ASTM A578 and issues 3.1 certificates under EN 10204. Outokumpu super duplex plates carry the same ultrasonic standard plus positive material identification above 25mm thickness. Outokumpu also builds intergranular corrosion testing under ASTM A923 into its standard certification rather than offering it as an add-on.
Corrosion and Mechanical Performance
Super duplex plate from both mills reaches a PREN above 40, with pitting resistance numbers hitting 42 for S32750 and 44 for S32760. Minimum yield strength is at 550 MPa for both suppliers under ASTM A240. Outokumpu’s Forta SDX shows tighter Charpy impact tolerance at minus 46°C, while Aperam’s grades match it on critical pitting temperature above 35°C in seawater.
Industry Applications
Offshore platforms, desalination plants, and pulp and paper equipment draw on plate from both mills. Aperam’s material lands in flue gas desulfurization and chemical tanker components, where niche grades suit aggressive process streams. Outokumpu’s higher volume suits structural offshore members and subsea manifolds, where tonnage and lead time matter most.
Global Availability and Supply Chain
Aperam distributes through a Europe-weighted network with centers in Belgium, France, and Brazil. Outokumpu runs a broader footprint, with stockholding partners across Europe, the Middle East, and Asia. Lead times for standard super duplex plate run 4 to 8 weeks depending on thickness and volume.
Side-by-Side Comparison Table
| Factor | Aperam | Outokumpu |
| Manufacturing approach | Smaller batches, tight process control | Large-scale integrated production |
| Product range | LDX 2101, 2205, 2507 (3mm-100mm) | Forta DX/SDX, LDX 2404 (up to 150mm) |
| Quality control | Ultrasonic testing, 3.1 certificates | Ultrasonic testing, standard PMI, ASTM A923 testing |
| Certifications | EN 10204, ASTM A240 | EN 10204, ASTM A240, NORSOK, PED |
| Typical applications | Chemical tankers, flue gas desulfurization | Offshore structures, subsea manifolds |
| Global availability | Europe and Brazil weighted | Europe, Middle East, and Asia footprint |
Which Mill Should You Choose?
Project specifications should guide mill selection ahead of brand preference. Check whether the design requires a proprietary grade like LDX 2404, available only from Outokumpu, or a niche Aperam product suited to a specific process stream. Both mills meet match certification requirements. Compare to NORSOK , PED or NACE standards. Different testing protocols. Find the right mill to match specification, procurement timeline and stock availability.
Questions to Ask Your Supplier Before Ordering
Ask which mill supplied the material, and request the mill name on the certificate itself rather than the stockist’s cover sheet. Confirm that Material Test Certificates conforming to EN 10204 3.1 or 3.2 accompany every plate, along with proof of ultrasonic and intergranular corrosion testing. Verify full heat-to-finished-product traceability, and request positive material identification reports before the order ships.
Conclusion
Aperam and Outokumpu both produce super duplex plate to ASTM A240 and EN 10028-7, but they use different batch sizes, testing procedures and distribution networks to do so. Aperam is good for projects that need niche grades and tighter batch control. Outokumpu is good for high-volume structural orders, with scale and standardized testing. Sourcing from a trusted Outokumpu duplex super steel plates through Calico Metal Alloys LLP gives engineers certified material and consistent performance in demanding offshore applications.