ASTM A182 F347 Forgings: Rolled Rings, Flanges, Shafts, Discs and Bars
UNS S34700 | EN 1.4550 | X6CrNiNb18-10 | ASME SA-182 F347 | Alloy 347. Forged to drawing by Jiangyin Jiangnan Metal Co., Ltd.
ASTM A182 Grade F347 is a niobium-stabilised 18Cr-9Ni austenitic stainless steel forging grade, UNS S34700. It is specified for flanges, fittings, valves and other forged pressure parts in high-temperature service. Niobium combines with carbon to form niobium carbide, which keeps chromium in solution and gives resistance to intergranular corrosion after exposure to the chromium carbide precipitation range of 800-1500 °F (427-816 °C).
We forge F347 as rolled rings, flanges, shafts, discs, sleeves, bushings, tube sheets, nozzles and round bars. Material is EAF + VOD melted, with ESR remelt available. Parts are solution annealed, ultrasonically tested, and supplied with EN 10204 3.1 or 3.2 certification.
Chemical Composition of ASTM A182 F347
| Element | C | Mn | Si | P | S | Cr | Ni | Nb (Cb) | Fe |
|---|---|---|---|---|---|---|---|---|---|
| Limit | 0.08 max | 2.00 max | 1.00 max | 0.045 max | 0.030 max | 17.0-20.0 | 9.0-13.0 | 10 x C min, 1.00 max | Bal. |
No molybdenum is specified for F347. If your drawing calls for molybdenum, the grade is a different one: see A182 F44 or 904L. Some published S34700 tables covering sheet and pipe practice show Cr 17.0-19.0. We forge to the specification edition named on the purchase order. Tighter sulfur (0.015 % max) and restricted niobium heats can be melted on request.
Mechanical Properties of ASTM A182 F347
| Property | Imperial | Metric |
|---|---|---|
| Tensile strength, min | 75 ksi | 515 MPa |
| Yield strength (0.2 % offset), min | 30 ksi | 205 MPa |
| Elongation in 2 in. [50 mm] or 4D, min | 30 % | 30 % |
| Reduction of area, min | 50 % | 50 % |
| Brinell hardness | Not specified by A182 for this grade | |
For sections over 5 in. [130 mm] in thickness the minimum tensile strength is 70 ksi [485 MPa]. One tension test is made per heat for austenitic grades, and specimens are taken only after all heat treatment is complete.
Heat Treatment of A182 F347 Forgings
| Stage | Requirement |
|---|---|
| After hot working | Cool below 1000 °F [538 °C] before heat treating |
| Heat treat type | Solution treat and quench |
| Solutioning temperature | 1900 °F [1040 °C] minimum |
| Cooling media | Liquid |
| Quench below | 500 °F [260 °C] |
The upper temperature matters as much as the lower one. Solution annealing above 1950 °F [1065 °C] may impair resistance to intergranular corrosion in F347 and the other stabilised grades after later exposure to sensitizing conditions. Where a purchaser requires it, a lower temperature stabilisation anneal is applied after the initial solution anneal, under ASTM A182 Supplementary Requirement S10. Our furnaces are recorder equipped and the thermal chart is filed with the heat records.
Melting and Forging Practice
ASTM A182 requires stainless steels to be melted by electric furnace, with optional separate degassing and refining, by vacuum furnace, or by either route followed by vacuum or electroslag consumable remelting. Our standard route for F347 is EAF + VOD. ESR remelt is available where the application calls for better cleanliness and ingot homogeneity, which is common for rotating parts and thick section pressure components. Enough discard is taken to keep the material free from piping and undue segregation, and forgings are worked as close to the specified shape and size as the tooling allows.
Corrosion Performance and Grade Selection
Alloy 347 gives general corrosion resistance comparable to Type 304. It was developed for service in the chromium carbide precipitation range of 800-1500 °F (427-816 °C), where unstabilised grades such as 304 are subject to intergranular attack. Within that band the overall corrosion resistance of Alloy 347 is better than Alloy 321, and 347 also performs somewhat better in strongly oxidising environments up to 1500 °F (816 °C). Refineries have used the grade for many years under polythionic acid service conditions.
Since F347 carries no specified molybdenum, its pitting and crevice resistance is that of the 18-8 family. Stabilisation protects against sensitization, not against chlorides. For chloride-bearing or immersed service, look at A182 F51, F53 and F55 duplex grades, or 904L.
F347 compared with neighbouring grades
| Grade | UNS | Stabiliser | Where it fits |
|---|---|---|---|
| A182 F321 | S32100 | Titanium | General cyclic hot duty. Titanium can burn out across the welding arc. |
| A182 F347 | S34700 | Niobium | Severe cyclic hot duty. Stabilisation survives welding. Polythionic acid service. |
| 321H / 347H | S32109 / S34709 | Ti / Nb, controlled C | Creep governed design above 538 °C. |
| A182 F44 | S31254 | None | 6 % Mo super austenitic. Chloride and seawater duty. |
A182 F347 Forged Products We Manufacture
Rings and Rolled Sections
Rolled rings, forged rings, retaining rings, valve seat rings and flange rings, made on our ring rolling and open-die lines.
Flanges and Pressure Parts
Forged flanges, tube sheets, nozzles, bodies, valve blocks and covers for ball, gate, globe, check and plug valves.
Shafts, Bars and Rotating Parts
Forged shafts, eccentric shafts, spindles, crankshafts, round bars, gear blanks and rolls for turbines, compressors and gearboxes.
Hollow and Machined Blanks
Forged sleeves, bushings, discs, hollow bars, forged tubes and pipe blanks, rough or finish machined to drawing.
Typical service applications
Aerospace piston engine manifolds and expansion joints. Refinery hot circuits and polythionic acid service. Chemical processing and heat exchanger components. Pulp and paper digesters, liquor tanks and paper machines. Oil and gas production, including subsea and deepwater systems. Compressor, nitrogen generator and power generation parts. Food processing equipment and storage. Pharmaceutical and biochemical production. Thermal oxidisers in waste treatment. Shipbuilding and heavy machinery.
Testing, Inspection and Certification
Ultrasonic examination is carried out to the acceptance standard named on the order: ASTM A388, EN 10228-3 or SEP 1921. Intergranular corrosion testing to ASTM A262 practices is available where a project specifies it, along with PMI, impact testing, hardness survey and dimensional reports. Each heat is released with EN 10204 3.1 certification as standard, or EN 10204 3.2 witnessed by a third party such as TUV, SGS, BV, Lloyd's or DNV. Parts are hard stamped with grade, heat number, drawing number and our mark, and traceability runs from ingot to despatch.
Equivalent Grades and Designations
| UNS | ASME | EN / Werkstoff | EN name | JIS | BS | Legacy US |
|---|---|---|---|---|---|---|
| S34700 | SA-182 F347 | 1.4550 | X6CrNiNb18-10 | SUS 347 | 347S31 | 18-8 Cb |
Columbium (Cb) is the former US name for niobium (Nb), and both older drawings and the ASTM tables still use it. Components often ordered alongside F347 forgings are ASTM A312 TP347 pipe and A403 WP347 wrought fittings.
How to Order
Send a drawing, or the finished dimensions, and we will quote rough forging weight, price and lead time, usually within 24 hours. Please include:
- Grade and specification edition, for example A182 F347, or 347H where creep stresses govern the design
- Rough forged or finish machined condition, with machining allowance if known
- Quantity, and whether the order is a one-off or a repeat schedule
- Melting route, EAF + VOD or with ESR remelt
- NDT acceptance standard and class
- Certification level, EN 10204 3.1 or 3.2, and the name of the third party if applicable
- Supplementary requirements such as ASTM A262 testing or restricted chemistry
- Delivery destination and required date
ASTM A182 F347 Frequently Asked Questions
What is ASTM A182 F347?
ASTM A182 Grade F347 is a niobium-stabilised 18Cr-9Ni austenitic stainless steel forging grade, UNS S34700, covered by ASTM A182/A182M for forged flanges, fittings, valves and parts in high-temperature pressure service. Niobium combines with carbon to form niobium carbide, so chromium stays in solution and the steel resists intergranular corrosion after exposure to the 800-1500 °F (427-816 °C) sensitization range.
What is the chemical composition of A182 F347?
Per ASTM A182 Table 2: C 0.08 % max, Mn 2.00 % max, Si 1.00 % max, P 0.045 % max, S 0.030 % max, Ni 9.0-13.0 %, Cr 17.0-20.0 %, and niobium (columbium) at a minimum of 10 times the carbon content, 1.00 % max. No molybdenum is specified.
What are the mechanical properties of A182 F347?
Minimum tensile strength 75 ksi (515 MPa), minimum yield strength 30 ksi (205 MPa), minimum elongation 30 % in 2 in. or 4D, and minimum reduction of area 50 %. For sections over 5 in. (130 mm) thick the minimum tensile strength is 70 ksi (485 MPa). Brinell hardness is not a specified requirement for this grade in A182.
What heat treatment is required for A182 F347?
Solution treat and quench from a minimum of 1900 °F (1040 °C), liquid quenched to below 500 °F (260 °C). Forgings are cooled below 1000 °F (538 °C) after hot working. Solution annealing above 1950 °F (1065 °C) may impair resistance to intergranular corrosion after later sensitizing exposure, so the upper temperature has to be controlled. A lower temperature stabilisation anneal can be added when specified.
What is the difference between A182 F347 and A182 F321?
The stabilising element. F347 uses niobium, F321 uses titanium. Niobium transfers through the welding arc while titanium tends to burn out, so F347 weld metal stays stabilised. In the chromium carbide precipitation range of 800-1500 °F the overall corrosion resistance of Alloy 347 is better than Alloy 321, and 347 also performs somewhat better in strongly oxidising environments up to 1500 °F (816 °C). We forge both grades.
Can A182 F347 be used in seawater or chloride service?
It is not the right choice. F347 has no specified molybdenum, so its pitting and crevice corrosion resistance is that of the 18-8 family, and stabilisation guards against sensitization rather than chloride attack. For chloride-bearing or immersed service, use duplex grades such as F51, F53 and F55, or the 6 % Mo grades F44 and 904L.
Who manufactures ASTM A182 F347 open-die forgings?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We produce A182 F347 rolled rings, flanges, shafts, discs, sleeves, bushings, tube sheets and bars to customer drawing, EAF + VOD or ESR melted, solution annealed, ultrasonically tested to ASTM A388, EN 10228-3 or SEP 1921, and certified to EN 10204 3.1 or 3.2. Contact +86 189-2135-9659 or sales@steelforgepieces.com.
Technical data on this page is stated per ASTM A182/A182M Tables 1, 2 and 3 for Grade F347 (UNS S34700). Confirm requirements against the specification edition cited in your purchase order.