GB/T 4237 015Cr20Ni18Mo6CuN S31252 Stainless Steel Plate Supplier
GB/T 4237 015Cr20Ni18Mo6CuN: what it is and who uses it
015Cr20Ni18Mo6CuN is the Chinese counterpart of UNS S31254 (254 SMO type): Mo 6.00–6.50%, N 0.18–0.25% and Cu 0.50–1.00%. A minimum PREN above 42 puts it in the 6Mo super austenitic class for seawater and bleach plant service.
How to read the name: under GB/T 20878 the leading ‘015’ is the carbon code (here C ≤0.020%), then Cr20 = about 20% chromium; Ni18 = about 18% nickel; Mo6 = about 6% molybdenum; Cu = copper added; N = nitrogen added. S31252 is the unified numeric code (ISC) used in GB/T 4237-2015.
SHH STEEL produces and exports austenitic stainless plate from China, works as a sales agent for leading stainless mills, and runs its own processing warehouse for cutting and surface finishing. 015Cr20Ni18Mo6CuN is part of our GB/T 4237 stainless plate range; for comparison, see our AISI 254 SMO page.
How 015Cr20Ni18Mo6CuN performs in corrosive service
Super austenitic grades are chosen when 316L and 317L pit or crevice-corrode: seawater, bleach plant filtrates, hot brines, sulfuric and phosphoric acids with chloride.
PREN of 015Cr20Ni18Mo6CuN from the GB/T 4237 limits: 42.2 – 44.1. PREN is a ranking tool for pitting in chlorides, not a guarantee; temperature, crevices, deposits and weld finish matter as much.
Intergranular corrosion testing is not compulsory for this grade in GB/T 4237-2015; when required, the method (GB/T 4334, ASTM A262 or A923 for duplex) and acceptance are agreed in the order.
For critical service, order ASTM G48 Method A (ferric chloride pitting) or Method C/E (critical pitting temperature) tests on the plate heat. We arrange them at the mill or an independent laboratory.
If service is harsher than 015Cr20Ni18Mo6CuN can handle, the next step up in this batch is GB/T 4237 015Cr24Ni22Mo8Mn3CuN S32652.
Heat analysis limits for 015Cr20Ni18Mo6CuN
| Element | 015Cr20Ni18Mo6CuN heat analysis, % (Table 15) | Why it matters |
|---|---|---|
| C | ≤ 0.020 | Carbon. Low values protect welds from carbide precipitation; higher values add hot strength or hardenability. |
| Si | ≤ 0.80 | Silicon. Deoxidizer; in heat-resistant grades it builds a protective scale. |
| Mn | ≤ 1.00 | Manganese. Deoxidizer; in Mn-bearing grades it replaces nickel and keeps nitrogen in solution. |
| P | ≤ 0.030 | Phosphorus. Impurity, kept low for toughness and weld cracking resistance. |
| S | ≤ 0.010 | Sulfur. Impurity; low sulfur improves pitting resistance, hot workability and polishability. |
| Cr | 19.50 – 20.50 | Chromium. Forms the passive film; the main driver of corrosion and oxidation resistance. |
| Ni | 17.50 – 18.50 | Nickel. Stabilizes austenite, improves toughness and resistance to reducing acids. |
| Mo | 6.00 – 6.50 | Molybdenum. Raises pitting and crevice resistance in chlorides (×3.3 in PREN). |
| Cu | 0.50 – 1.00 | Copper. Improves resistance to sulfuric acid and, in ferritics, general corrosion and formability. |
| N | 0.18 – 0.25 | Nitrogen. Strengthens, stabilizes austenite and adds pitting resistance (×16 in PREN). |
| PREN (Cr + 3.3Mo + 16N) | 42.2 – 44.1 (minimum – mid-range) | Calculated from the limits above, not a requirement of GB/T 4237 |
Values are maximum unless a range is given. The mill reports the ladle (heat) analysis on the certificate; this is the figure to compare with Table 15.
Product analysis vs heat analysis
A check analysis drilled from the finished plate may differ slightly from the heat analysis. GB/T 4237 refers to GB/T 222 for the permitted deviations; the table applies them to the 015Cr20Ni18Mo6CuN limits. Deviations apply to one side of a range only, never to both sides in the same heat.
| Element | Heat analysis limit (%) | Permitted deviation | Product analysis limit (%) |
|---|---|---|---|
| C | ≤ 0.020 | +0.005 | ≤ 0.025 |
| Si | ≤ 0.80 | ±0.05 | ≤ 0.85 |
| Mn | ≤ 1.00 | ±0.03 | ≤ 1.03 |
| P | ≤ 0.030 | +0.005 | ≤ 0.035 |
| S | ≤ 0.010 | +0.005 | ≤ 0.015 |
| Cr | 19.50 – 20.50 | ±0.20 (min) / ±0.25 (max) | 19.30 – 20.75 |
| Ni | 17.50 – 18.50 | ±0.15 | 17.35 – 18.65 |
| Mo | 6.00 – 6.50 | ±0.10 | 5.90 – 6.60 |
| Cu | 0.50 – 1.00 | ±0.03 (min) / ±0.05 (max) | 0.47 – 1.05 |
| N | 0.18 – 0.25 | ±0.01 (min) / ±0.02 (max) | 0.17 – 0.27 |
Where the table says ‘by agreement’, the deviation is not tabulated for that content level and should be agreed in the contract, usually by reference to ASTM A480 Table A1.1.
Mechanical properties at room temperature
| Property | 015Cr20Ni18Mo6CuN (Table 20) |
|---|---|
| Proof strength Rp0.2, MPa | ≥ 310 |
| Tensile strength Rm, MPa | ≥ 655 |
| Elongation A, % | ≥ 35 |
| Hardness HBW | ≤ 223 |
| Hardness HRB | ≤ 96 |
| Hardness HV | ≤ 225 |
Values apply to plate in the delivery heat-treated condition, tested transversely per GB/T 228.1. Hardness is checked by one method chosen by the mill.
Cross-reference to other standards
| Standard system | Equivalent / closest grade |
|---|---|
| China GB/T 4237-2015 | 015Cr20Ni18Mo6CuN (S31252) |
| ASTM A240/A240M | S31254 |
| EN 10088-2 | X1CrNiMoCuN20-18-7 / 1.4547 |
| JIS G4304 (hot rolled) | SUS312L |
| Common name | 254 SMO-type 6Mo |
Equivalent grades are close in chemistry and properties but are never identical: limits on carbon, nitrogen and residual elements differ. For dual or multiple certification the heat must meet every standard named on the order, and we confirm that from the heat chemistry before quotation.
Related pages: AISI 254 SMO, ASTM A240 Type 904L. See also our ASTM A240/A240M and JIS G4305 plate lists.
Where this grade sits on the super austenitic ladder
The high-alloy austenitics of GB/T 4237 step up in molybdenum and nitrogen. Pitting resistance follows PREN closely; nickel mainly helps in acids and against phase precipitation.
| Grade | Mo, % | N, % | PREN min |
|---|---|---|---|
| GB/T 4237 015Cr21Ni26Mo5Cu2 S31782 | 4.00 – 5.00 | ≤ 0.10 | 32.2 |
| 015Cr20Ni18Mo6CuN S31252 | 6.00 – 6.50 | 0.18 – 0.25 | 42.2 |
| GB/T 4237 015Cr20Ni25Mo7CuN S38926 | 6.00 – 7.00 | 0.15 – 0.25 | 41.2 |
| GB/T 4237 022Cr21Ni25Mo7N S38367 | 6.00 – 7.00 | 0.18 – 0.25 | 42.7 |
| GB/T 4237 022Cr24Ni17Mo5Mn6NbN S34553 | 4.00 – 5.00 | 0.40 – 0.60 | 42.6 |
| GB/T 4237 015Cr24Ni22Mo8Mn3CuN S32652 | 7.00 – 8.00 | 0.45 – 0.55 | 54.3 |
015Cr20Ni18Mo6CuN: 254 SMO-type 6Mo.
Welding and fabrication of 015Cr20Ni18Mo6CuN
Weld super austenitic plate with over-alloyed nickel-base filler (ERNiCrMo-3, ERNiCrMo-10 or ERNiCrMo-13 class). Matching filler leaves Mo-depleted dendrite cores that pit before the parent metal.
Heat input ≤1.5 kJ/mm, interpass ≤100 °C, full argon back purge, and pickling of the whole weld zone. Avoid autogenous (no-filler) GTAW on wetted surfaces.
Cutting: we cut 015Cr20Ni18Mo6CuN by plasma (up to about 150 mm), laser (thin plate) or waterjet, and remove the heat-affected edge by machining where the drawing requires it.
How 015Cr20Ni18Mo6CuN plate is heat treated
Recommended heat treatment for 015Cr20Ni18Mo6CuN (GB/T 4237-2015 Annex C): ≥ 1 150 °C, water quench or other rapid cooling.
Super austenitic plate must be quenched fast from the solution temperature to keep sigma and chi phases out of the structure. Hot-formed heads are re-annealed at the same temperature.
What the standard covers for this grade
| Item | GB/T 4237-2015 requirement / SHH STEEL supply |
|---|---|
| Standard | GB/T 4237-2015 Hot rolled stainless steel plate, sheet and strip (current edition, replaces GB/T 4237-2007) |
| Grade / unified code | 015Cr20Ni18Mo6CuN / S31252 |
| Steel class | Austenitic |
| Chemical composition | Table 15 (heat analysis); product analysis per GB/T 222 |
| Mechanical properties | Table 20 |
| Product forms | Hot-rolled thick plate (3.0 – 200 mm in the standard), hot-rolled wide strip and cut plate (2.0 – 25.4 mm) |
| Our usual thickness range | 3 – 50 mm |
| Delivery condition | ≥ 1 150 °C, water quench or other rapid cooling |
| Surface | Hot rolled, heat treated, pickled (No.1 / 1D) as standard; ground or polished by agreement |
| Density | 8.0 g/cm³ |
| Certificate | EN 10204 3.1 mill certificate; 3.2 with third-party inspection on request |
Sister grades on the same standard are listed under GB/T 4237; cold-rolled sheet of the same chemistry is ordered to GB/T 3280, and all our plate lines sit in stainless steel sheets and plates.
Applications of 015Cr20Ni18Mo6CuN plate
Severe-service applications:
- Seawater cooling systems, condensers and desalination plants
- Offshore firewater and ballast systems
- Pulp bleach plant washers and towers
- FGD absorbers in high-chloride conditions
- Food processing with hot brines
- Tall oil and chloride-bearing chemical processes
Buyers specifying 015Cr20Ni18Mo6CuN for these jobs often compare it with GB/T 4237 015Cr20Ni25Mo7CuN S38926 and GB/T 4237 022Cr25Ni7Mo4N S25073; the comparison table on this page shows the differences.
International grade pages for the alternatives mentioned above: ASTM A240 Type 2507.
015Cr20Ni18Mo6CuN compared with related grades
The table compares 015Cr20Ni18Mo6CuN with the grades buyers most often weigh it against. Strength values are GB/T 4237-2015 minimums; PREN is calculated from the minimum chemistry.
| Grade (GB/T 4237) | Key chemistry, % | PREN min | Rp0.2 min, MPa | Rm min, MPa |
|---|---|---|---|---|
| 015Cr20Ni18Mo6CuN S31252 | C ≤ 0.020, Cr 19.50 – 20.50, Ni 17.50 – 18.50, Mo 6.00 – 6.50, N 0.18 – 0.25, Cu 0.50 – 1.00 | 42.2 | 310 | 655 |
| GB/T 4237 015Cr20Ni25Mo7CuN S38926 | C ≤ 0.020, Cr 19.00 – 21.00, Ni 24.00 – 26.00, Mo 6.00 – 7.00, N 0.15 – 0.25, Cu 0.50 – 1.50 | 41.2 | 295 | 650 |
| GB/T 4237 022Cr21Ni25Mo7N S38367 | C ≤ 0.030, Cr 20.00 – 22.00, Ni 23.50 – 25.50, Mo 6.00 – 7.00, N 0.18 – 0.25, Cu ≤ 0.75 | 42.7 | 310 | 655 |
| GB/T 4237 015Cr24Ni22Mo8Mn3CuN S32652 | C ≤ 0.020, Cr 24.00 – 25.00, Ni 21.00 – 23.00, Mo 7.00 – 8.00, N 0.45 – 0.55, Mn 2.00 – 4.00 | 54.3 | 430 | 750 |
| GB/T 4237 015Cr21Ni26Mo5Cu2 S31782 | C ≤ 0.020, Cr 19.00 – 23.00, Ni 23.00 – 28.00, Mo 4.00 – 5.00, N ≤ 0.10, Cu 1.00 – 2.00 | 32.2 | 220 | 490 |
| GB/T 4237 022Cr25Ni7Mo4N S25073 | C ≤ 0.030, Cr 24.00 – 26.00, Ni 6.00 – 8.00, Mo 3.00 – 5.00, N 0.24 – 0.32, Cu ≤ 0.50 | 37.7 | 550 | 795 |
Weld only with over-alloyed nickel filler (ERNiCrMo-3 or ERNiCrMo-13 class); a matching filler would lose pitting resistance through Mo segregation. Solution anneal at 1 150 °C or above if the plate has been hot formed.
Surface options and cut-to-size service
| Finish | Description | Availability for this grade |
|---|---|---|
| No.1 / 1D | Hot rolled, heat treated, pickled; the GB/T 4237 standard surface | Standard |
| Shot-blasted + pickled | Uniform matte for welded structures | On request |
| Ground | Ground surface for defect removal or UT | On request |
| 2B / BA | Cold-rolled finishes (ordered as GB/T 3280 sheet, not hot-rolled plate) | Sheet only |
Our warehouse cuts plate to size (plasma, laser, waterjet, saw), bevels weld edges, polishes and applies PVC protective film. Processed plate ships with the original mill heat number marked. Ask for cut pieces of other stainless steel products at the same time to consolidate freight.
Dimensions and plate weight
| Dimension | Typical supply |
|---|---|
| Thickness | 3 – 50 mm |
| Width | 1 000 / 1 219 / 1 250 / 1 500 / 1 800 / 2 000 mm; wider by mill order |
| Length | 2 000 / 2 438 / 3 000 / 6 000 mm or cut to size |
| Flatness | Per GB/T 4237; ≤15 mm per metre for plate up to 25 mm unless agreed tighter |
| Thickness tolerance | Per the GB/T 4237 dimensional tolerance tables (normal or higher accuracy as ordered) |
| Edge | Mill edge or cut edge |
Weight: plate mass in kg/m² = thickness (mm) × density (8.0 g/cm³). A 10 mm 015Cr20Ni18Mo6CuN plate weighs about 80.0 kg/m²; a 1 500 × 6 000 × 10 mm plate about 720 kg.
Inspection, tests and mill certificates
- Heat chemical analysis on every heat; product analysis by agreement
- Tensile test (Rp0.2, Rm, A) per batch
- Hardness test
- ASTM G48 pitting test when specified
- Ultrasonic testing (NB/T 47013.3 or ASTM A578) when specified
- Positive material identification (PMI) on every plate leaving our warehouse
- Visual and dimensional inspection; third-party inspection (SGS, BV, TÜV, Intertek) at the buyer’s request
Certificates follow EN 10204 3.1 as standard. Where plate is also certified to ASME SA240 or ASTM A240, both standards are shown on one certificate.
Mill sourcing and lead time
015Cr20Ni18Mo6CuN is produced by a small number of Chinese mills with the melting and heat treatment capability for it. We place mill orders for it through the producers we represent and do not usually hold it in stock. Expect about 45–90 days, with minimum quantities per thickness; we can combine small quantities into one rolling where the mill allows.
Every plate is traceable to its heat number, and copies of the mill certificates stay on file for repeat orders and audits. The same mills also supply our ASTM A240, ASME SA240, JIS G4305 and AISI plate ranges, so mixed-standard orders can ship together.
What to put on a 015Cr20Ni18Mo6CuN purchase order
- Standard and edition: GB/T 4237-2015
- Grade and code: 015Cr20Ni18Mo6CuN (S31252); add the equivalent if dual certification is needed
- Thickness × width × length, quantity in pieces or tonnes
- Thickness tolerance class and flatness if tighter than standard
- Surface finish and protective film
- Tests beyond the standard (IGC, UT, impact, ferrite, PMI, grain size)
- Certificate type (EN 10204 3.1 / 3.2) and inspection body
- Marking, packing (wooden cases, steel pallets) and delivery terms
Send the list to SHH STEEL and we return a quotation with mill, lead time and stock options. Other grades from the same standard can be combined in one shipment; browse GB/T 4237 plate grades.
FAQ
- Is 015Cr20Ni18Mo6CuN equivalent to 254SMO?
- Yes, it is the GB/T 4237 grade corresponding to UNS S31254 (254 SMO type), EN 1.4547 and JIS SUS312L. GB/T 4237-2015: Cr 19.50–20.50%, Ni 17.50–18.50%, Mo 6.00–6.50%, N 0.18–0.25%; 310 MPa proof and 655 MPa tensile minimum.
- What is the chemical composition of 015Cr20Ni18Mo6CuN?
- Under GB/T 4237-2015 Table 15, 015Cr20Ni18Mo6CuN (S31252) has C ≤ 0.020, Cr 19.50 – 20.50, Ni 17.50 – 18.50, Mo 6.00 – 6.50, N 0.18 – 0.25, Cu 0.50 – 1.00. Phosphorus is limited to ≤0.030% and sulfur to ≤0.010%.
- What are the mechanical properties of 015Cr20Ni18Mo6CuN plate?
- GB/T 4237-2015 Table 20 requires for 015Cr20Ni18Mo6CuN: proof strength Rp0.2 ≥310 MPa, tensile strength ≥655 MPa and elongation ≥35%, hardness ≤223 HBW. Values apply to plate in the delivery heat-treated condition.
- Is 015Cr20Ni18Mo6CuN stainless steel magnetic?
- Not in the annealed condition. 015Cr20Ni18Mo6CuN is austenitic, so annealed plate is essentially non-magnetic; cold work can induce slight magnetism, mostly at cut and bent edges.
- What thickness of 015Cr20Ni18Mo6CuN plate can you supply?
- Under GB/T 4237 we supply 015Cr20Ni18Mo6CuN hot-rolled plate in 3 – 50 mm, widths up to 2 000 mm (wider by mill order), cut to size in our warehouse. Thinner material is cold-rolled sheet to GB/T 3280.
- What is the PREN of 015Cr20Ni18Mo6CuN?
- Using PREN = Cr + 3.3Mo + 16N and the GB/T 4237-2015 limits, 015Cr20Ni18Mo6CuN has a PREN of about 42.2 at minimum chemistry and 44.1 at mid-range.
Conclusion
GB/T 4237 015Cr20Ni18Mo6CuN (S31252) is a super austenitic / high-alloy austenitic plate grade, known internationally as 254 SMO-type 6Mo. It is defined by Table 15 chemistry (C ≤ 0.020, Cr 19.50 – 20.50, Ni 17.50 – 18.50, Mo 6.00 – 6.50, N 0.18 – 0.25, Cu 0.50 – 1.00) and Table 20 properties of at least 310 MPa proof strength and 655 MPa tensile strength. Typical uses include seawater cooling systems, condensers and desalination plants, offshore firewater and ballast systems and pulp bleach plant washers and towers. Weld only with over-alloyed nickel filler (ERNiCrMo-3 or ERNiCrMo-13 class); a matching filler would lose pitting resistance through Mo segregation.
Before ordering, state the standard edition, the grade name with its code, and any extra tests, so that the mill certificate matches your design documents. SHH STEEL supplies 015Cr20Ni18Mo6CuN plate by mill order through the producers we represent, cut to size and finished in our own warehouse, with EN 10204 3.1 certificates. For related grades see GB/T 4237 015Cr20Ni25Mo7CuN S38926 and GB/T 4237 022Cr21Ni25Mo7N S38367, our GB/T 4237 category and the AISI 254 SMO page. Send your sizes and quantities for a quotation.
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