Outokumpu Supra 316L/4404
Producer-specific selection of low-carbon CrNiMo stainless steel, with product-form strength data, corrosion boundaries and fabrication requirements.
Tags: materials, stainless-steel, producer-products
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Product identity
At 20°C, Outokumpu's EN 10088-2 Supra 316L/4404 table gives 240 MPa 0.2% proof strength for cold-rolled coil and sheet and 220 MPa for hot-rolled coil and sheet or quarto plate. Its separate ASTM A240 table lists 170 MPa for those forms. Select the table for the ordered specification. Outokumpu Supra Tables 5–6
Supra 316L/4404 is Outokumpu's low-carbon, molybdenum-alloyed austenitic stainless steel identified as EN 1.4404, ASTM Type 316L and UNS S31603. The producer describes improved resistance to intergranular corrosion after welding and supplies multiple forms and surface finishes. Those designation associations identify the product; they do not prove that a particular shipment is certified to every listed standard. Outokumpu: Supra product range
The live range page lists typical composition of 0.02% C, 17.2% Cr, 10.1% Ni and 2.1% Mo by mass for 4404. These are typical values, not acceptance ranges or the measured composition of a heat. Other Supra products, including 4432, 4435 and 316plus, have separate identities and formulations. Outokumpu: grade entries and chemistry
For substitution, compare the actual specification, required corrosion performance, mechanical condition and fabrication route. A shared ASTM family name does not establish identical producer products or suitability for the same duty.
Strength depends on form and standard
The Supra range datasheet's Table 5 gives the following 20°C values according to EN 10088-2 for 316L/4404:
| Supplied form | Rp0.2 | Rp1.0 | Tensile strength Rm |
|---|---|---|---|
| Cold-rolled coil/sheet, C | 240 MPa | 270 MPa | 530–680 MPa |
| Hot-rolled coil/sheet, H | 220 MPa | 260 MPa | 530–680 MPa |
| Quarto plate, P | 220 MPa | 260 MPa | 520–670 MPa |
Its separate ASTM A240 table lists 170 MPa Rp0.2, 485 MPa tensile strength and 40% A50 elongation for C/H/P. Preserve these separate standard bases; verify the applicable edition, thickness range and ordered condition before contractual use. Outokumpu: Supra range datasheet, Tables 5–6
These entries are not allowable stresses for a pressure vessel, welded joint or fatigue-loaded bracket. A design record should identify the code, temperature, stress basis, joint efficiency and any forming or welding effects. Do not combine the highest value from each standard into a synthetic material specification.
Illustrative distinction: a 100 mm² net section under a uniformly distributed 10 kN axial load has nominal stress 10,000/100 = 100 MPa. Comparing that number with a room-temperature proof-strength entry is only an initial calculation. It excludes bending, stress concentration, buckling, weld behavior, fatigue, corrosion loss and the design code's required margins.
Corrosion and service environment
Outokumpu's corrosion guidance explicitly identifies standard austenitic 4404 as susceptible to chloride-induced stress corrosion cracking. It describes chloride SCC as commonly associated with elevated temperature, while also documenting cracking at lower temperatures in some environments. There is no universal safe-temperature cutoff implied by the grade name. Outokumpu: corrosion resistance, SCC discussion
The same guidance treats pitting, crevice corrosion, intergranular attack and corrosion fatigue as different mechanisms. Its PRE composition index screens pitting resistance; it does not establish a service pressure, lifetime or immunity to cracking. Outokumpu: corrosion mechanisms and PRE
For a tank or wetted fabrication, describe fluid composition, chloride concentration, pH, temperature, cleaning chemicals, deposits, crevices and exposure time. Include residual and applied stress. Assess shutdown and cleaning conditions as well as normal operation. A material that performs acceptably in a clean flowing fluid may need a different assessment at a stagnant gasket interface.
Forming, machining and welding
Outokumpu's range guidance describes high work hardening in Supra austenitics, hardening through cold working rather than heat treatment, and machining that benefits from sharp tooling and a rigid setup. Welding guidance favors matching or slightly over-alloyed fillers where equivalent weld properties are required. Outokumpu: Supra fabrication guidance
Qualify tooling, springback, surface damage and dimensions on the actual stock and rolling direction.
Surface restoration and release
The producer's post-fabrication guidance explains that pickling removes oxide scale and the chromium-depleted surface layer. It distinguishes this from chemical passivation and says that properly pickled stainless does not require an additional chemical passivation step simply to improve corrosion resistance. Grinding and blasting also require control of contamination from previously used tools or media. Outokumpu: post-fabrication treatment
Specify the required surface result and a qualified treatment procedure. Cosmetic brightness alone does not demonstrate removal of weld-related damage. Account for dimensional and finish changes when choosing a treatment, and use the treatment supplier's current handling and waste instructions.
A useful release record links the heat/certificate and ordered condition to the drawing, fabrication procedure, surface treatment and final inspection. Keep raw-material certification separate from proof that the finished component meets its service requirements.
Source applicability
The Supra range PDF prints 1561EN:4, November 2022. The linked live producer pages do not state a technical revision date. The PDF URL's modified=20251117111951 parameter is not treated as an edition. Obtain the applicable controlled document and standard edition for procurement; this page's review date records when these sources were consulted.