GB/T 4237 07Cr18Ni11Nb S34779 Stainless Steel Plate Supplier

07Cr18Ni11Nb is 347H: carbon 0.04–0.10% with Nb 8 × C to 1.00%. It is the creep-resistant stabilized grade for boilers and refinery heaters.

How to read the name: under GB/T 20878 the leading ’07’ is the carbon code (here C 0.04–0.10%), then Cr18 = about 18% chromium; Ni11 = about 11% nickel; Nb = niobium added. S34779 is the unified numeric code (ISC) used in GB/T 4237-2015. Older drawings and Chinese buyers may still write the pre-2007 name 1Cr19Ni11Nb.

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. 07Cr18Ni11Nb is part of our GB/T 4237 stainless plate range; for comparison, see our ASTM A240 Type 347H page.

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.

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.

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 07Cr18Ni11Nb limits. Deviations apply to one side of a range only, never to both sides in the same heat.

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.

In 07Cr18Ni11Nb the stabilizing element forms carbides that are more stable than chromium carbide, so chromium stays in solution even when the steel passes through 450–850 °C. The standard sets the minimum ratio: Nb: 8 × C – 1.00.

The ratio works only if carbon and nitrogen are measured and titanium or niobium is high enough. Check the certificate: for a 0.05% C heat, Ti ≥5×C means Ti ≥0.25%; many buyers ask for a margin above the minimum.

Compared with the low-carbon route (GB/T 4237 022Cr19Ni10 S30403 and GB/T 4237 022Cr17Ni12Mo2 S31603), stabilized grades keep more strength above 500 °C, which is why boiler and refinery designers still use them.

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.

Recommended heat treatment for 07Cr18Ni11Nb (GB/T 4237-2015 Annex C): ≥ 1 095 °C, water quench or other rapid cooling.

A stabilizing anneal at about 870–900 °C after welding can be added for parts that will see 450–850 °C service.

Stabilized grades are bought for intergranular corrosion resistance after welding or after service in the 450–850 °C sensitization range. General corrosion resistance is similar to 304 (or 316 for Mo grades).

PREN of 07Cr18Ni11Nb from the GB/T 4237 limits: 17.0 – 18.0. 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.

If service is harsher than 07Cr18Ni11Nb can handle, the next step up in this batch is GB/T 4237 07Cr17Ni12Mo2 S31609.

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: ASTM A240 Type 347H, ASME SA240 347H, AISI 347H. See also our ASTM A240/A240M and JIS G4305 plate lists.

Weld stabilized grades with Nb-stabilized filler (ER347 / E347) — titanium does not transfer well across the arc, so ER321 is rarely used. For 316Ti use ER318 or ER316L.

Knife-line attack can occur in a narrow band next to the fusion line if the part sees 450–850 °C service after welding. If that is the case, ask for a stabilizing anneal (around 870–900 °C) in the procedure.

Cutting: we cut 07Cr18Ni11Nb 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.

Where the stabilized chemistry pays off:

• Boiler superheater and reheater parts
• Hydrocracker and reformer internals
• Steam headers
• High-temperature pressure vessels

Buyers specifying 07Cr18Ni11Nb for these jobs often compare it with GB/T 4237 06Cr18Ni11Nb S34778 and GB/T 4237 07Cr17Ni12Mo2 S31609; the comparison table on this page shows the differences.

International grade pages for the alternatives mentioned above: ASTM A240 Type 347, AISI 321H, ASTM A240 Type 316H.

The table compares 07Cr18Ni11Nb with the grades buyers most often weigh it against. Strength values are GB/T 4237-2015 minimums; PREN is calculated from the minimum chemistry.

Order coarse grain (grade 7 or coarser) and note that reheat cracking can occur in thick welded 347H; follow a qualified PWHT or stress-relief procedure if the code requires one.

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.

Weight: plate mass in kg/m² = thickness (mm) × density (7.93 g/cm³). A 10 mm 07Cr18Ni11Nb plate weighs about 79.3 kg/m²; a 1 500 × 6 000 × 10 mm plate about 714 kg.

• Heat chemical analysis on every heat; product analysis by agreement
• Tensile test (Rp0.2, Rm, A) per batch
• Hardness test
• Grain size, grade 7 or coarser (GB/T 6394), when ordered
• 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.

• Standard and edition: GB/T 4237-2015
• Grade and code: 07Cr18Ni11Nb (S34779); 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.

07Cr18Ni11Nb is a mainstream grade at Chinese stainless mills. We supply it from our own stock and processing warehouse, and by mill order from major producers such as TISCO and Baosteel Stainless, for which we act as a sales agent. Stock plate ships in about 1–2 weeks after cutting; mill orders typically take 30–60 days depending on thickness and rolling schedule.

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.

GB/T 4237 07Cr18Ni11Nb (S34779) is a stabilized austenitic plate grade, known internationally as 347H. It is defined by Table 15 chemistry (C 0.04 – 0.10, Cr 17.00 – 19.00, Ni 9.00 – 13.00) and Table 20 properties of at least 205 MPa proof strength and 515 MPa tensile strength. Typical uses include boiler superheater and reheater parts, hydrocracker and reformer internals and steam headers. Order coarse grain (grade 7 or coarser) and note that reheat cracking can occur in thick welded 347H; follow a qualified PWHT or stress-relief procedure if the code requires one.

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 07Cr18Ni11Nb plate from stock and by mill order, cut to size and finished in our own warehouse, with EN 10204 3.1 certificates. For related grades see GB/T 4237 06Cr18Ni11Nb S34778 and GB/T 4237 07Cr19Ni11Ti S32169, our GB/T 4237 category and the ASTM A240 Type 347H page. Send your sizes and quantities for a quotation.