# UNS S31600 Forgings (316 / 1.4401)

**UNS S31600 is the standard molybdenum-bearing austenitic stainless steel: 16.0 to 18.0% chromium, 10.0 to 14.0% nickel and 2.00 to 3.00% molybdenum, with carbon held at 0.08% maximum. The molybdenum is what separates it from Type 304 and gives it resistance to pitting and crevice attack in chloride-bearing media.**

Jiangyin Jiangnan Metal Co., Ltd. forges this grade at its works in Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. The steel is melted on site by electric arc furnace, ladle furnace and vacuum oxygen decarburisation, then forged or ring-rolled, heat treated, machined and tested without leaving the plant, so the certificate traces a shipped part back to its melt number rather than to a purchased billet.

| Field | Detail |
|---|---|
| UNS | S31600 |
| AISI type | 316 |
| EN number | 1.4401 |
| EN name | X5CrNiMo17-12-2 |
| Old British BS | 316S31 (En 58H, 58J) |
| Swedish SS | 2347 |
| Japanese JIS | SUS 316 |
| Forging specification | ASTM A182 F316 |
| Low-carbon variant | S31603, 316L, 1.4404 |
| High-carbon variant | S31609, 316H |
| Supplier | Jiangyin Jiangnan Metal Co., Ltd. |
| Plant | No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China |
| Telephone | +86 189 2135 9659 |
| Email | sales@steelforgepieces.com |
| Page | https://www.steelforgepieces.com/Stainless-Steel/UNS-S31600.html |

Designation comparisons follow the Atlas Steels grade comparison for 316 and are functionally similar materials, not a schedule of contractual equivalents.

## Chemical composition

Weight per cent. The two columns differ only in the silicon limit: 0.75% for flat-rolled product under ASTM A240, 1.00% for forgings under ASTM A182 F316.

| Element | Min | Max (A240) | Max (A182 F316) |
|---|---|---|---|
| Carbon | - | 0.08 | 0.08 |
| Manganese | - | 2.00 | 2.00 |
| Silicon | - | 0.75 | 1.00 |
| Phosphorus | - | 0.045 | 0.045 |
| Sulfur | - | 0.030 | 0.030 |
| Chromium | 16.0 | 18.0 | 18.0 |
| Nickel | 10.0 | 14.0 | 14.0 |
| Molybdenum | 2.00 | 3.00 | 3.00 |
| Nitrogen | - | 0.10 | 0.10 |
| Iron | Balance | | |

Melting route for this grade: electric arc furnace, ladle furnace, then vacuum oxygen decarburisation where low carbon or tight nitrogen control is called for. Electroslag remelting is available where improved cleanliness or segregation control is specified.

## Mechanical properties

Room-temperature minima, solution annealed. Requirements follow the product form, so state the governing specification when enquiring.

| Property | ASTM A182 F316 (forgings) | ASTM A240 and A479 |
|---|---|---|
| Tensile strength | 515 MPa (75 ksi) | 515 MPa (75 ksi) |
| Yield strength, 0.2% offset | 205 MPa (30 ksi) | 205 MPa (30 ksi) |
| Elongation | 30% in 50 mm or 4D | 40% in 50 mm |
| Reduction of area | 50% | Not specified |
| Hardness, max | Per order and test plan | 217 HB / 95 HRB |

Some datasheets list a compressive strength of 170 MPa for this grade. ASTM specifies no compressive strength for austenitic stainless steel, and 170 MPa is the minimum yield strength of 316L (S31603). It is a transcription error, not a design value.

## Physical properties

Typical values for 316, 316L and 316H, after the Atlas Steels grade data sheet.

| Property | Value |
|---|---|
| Density | 8,000 kg/m3 |
| Elastic modulus | 193 GPa |
| Thermal expansion, 0 to 100 C | 15.9 um/m.C |
| Thermal expansion, 0 to 538 C | 17.5 um/m.C |
| Thermal conductivity at 100 C | 16.3 W/m.K |
| Specific heat, 0 to 100 C | 500 J/kg.K |
| Electrical resistivity | 740 nOhm.m |
| Solution treatment | 1010 to 1120 C, cool rapidly |

S31600 cannot be hardened by thermal treatment. Strength above the annealed minima comes only from cold work.

## Corrosion and heat resistance

Performance is good across a wide range of atmospheric environments and corrosive media, generally better than Type 304. The limits matter, because the grade is specified past them more often than any other stainless.

- It is commonly called the standard marine grade but is not resistant to warm sea water. In many marine environments it shows surface corrosion as brown staining, particularly at crevices and rough surface finishes.
- It is subject to pitting and crevice corrosion in warm chloride environments and to stress corrosion cracking above about 60 C.
- It is considered resistant to potable water with up to about 1,000 mg/L chloride at ambient temperature, falling to about 500 mg/L at 60 C.
- Oxidation resistance is good in intermittent service to 870 C and continuous service to 925 C.
- Continuous use between 425 and 860 C is not recommended where later aqueous corrosion resistance matters, because of carbide precipitation.
- Heavy welded sections require post-weld annealing for full corrosion resistance. 316L does not.

### Alternatives and the reason for choosing them

| Grade | Reason over 316 |
|---|---|
| 316L | Heavy welded sections, or service in the carbide precipitation range |
| 316Ti | Better resistance around 600 to 900 C |
| 316N | Higher strength than standard 316 |
| 317L | Higher chloride resistance than 316L at similar stress corrosion resistance |
| 904L | Much higher chloride resistance at elevated temperature, good formability |
| 2205 (A182 F51) | Much higher chloride resistance at elevated temperature and higher strength |
| A182 F44 | Six per cent molybdenum austenitic for severe chloride duty |

## Product forms in S31600

Each item is forged from one piece of steel melted on site. No welding, no casting, no purchased billet of unknown origin.

| Form | Typical use | Limit and equipment |
|---|---|---|
| Seamless rolled rings | Flange rings, bearing races, gear ring blanks, slewing rings | To OD 6,000 mm on the 6 m radial-axial mill; from OD 50 mm by upset and punch |
| Forged flanges and nozzles | Pressure vessels, heat exchangers, piping to ASME B16.5 and B16.47 | A182 F316 acceptance |
| Discs, tube sheets, covers | Heat exchangers, vessel closures, blind flanges | To 5,000 mm machined diameter |
| Round bars and blocks | Machining stock, valve stems, fasteners | Forged, rough turned or peeled |
| Shafts and spindles | Pumps, mixers, compressors, gearboxes, eccentric shafts | To 14,000 mm turned length; 15 m well furnace for vertical quench |
| Sleeves, bushings, cylinders | Subsea equipment, pulp and paper, chemical plant | To 1,600 mm dia x 10,000 mm, CNC deep-hole drilled |
| Valve and wellhead parts | Bodies, bonnets, seat rings, stems, blocks, manifolds | API 6A and NACE MR0175 / ISO 15156 on request |

Applications include chemical and petrochemical plant, petroleum refining including polythionic acid service, pulp and paper digesters and liquor tanks, food processing and storage, pharmaceutical production, offshore and onshore oil and gas equipment, air compressors and nitrogen generators, valve parts, shipbuilding and general heavy machinery.

## Testing and certification

Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388 as specified. Liquid penetrant inspection, positive material identification, intergranular corrosion testing to ASTM A262 and ferrite measurement are available on request. Certificates are issued to EN 10204 3.1, or 3.2 with third-party inspection by TUV, SGS, BV or Lloyd's. The works holds CCS, BV, DNV, LR and NK approvals. Heat treatment is recorded on furnace charts tied to the melt number.

## Ordering

| Item | Detail |
|---|---|
| Minimum order | 10 kg, no minimum piece count |
| Lead time | 20 to 60 days |
| Maximum ring | OD 6,000 mm |
| Maximum single piece | 30,000 kg |
| Delivery condition | As forged, rough machined or finish machined |

To quote we need a drawing or the finished dimensions, the quantity, the governing specification such as ASTM A182 F316 or ASTM A479 S31600, the certificate level, any NDT requirement, the delivery condition and the destination port.

## Questions

**Is UNS S31600 the same as 316 stainless steel?**
Yes. S31600 is the Unified Numbering System designation for AISI Type 316, also 1.4401 or X5CrNiMo17-12-2 in Europe, 316S31 in the old British system and SUS 316 in Japan. As a forged pressure part it is ordered as ASTM A182 Grade F316.

**What is the difference between S31600 and S31603?**
Carbon and strength. S31600 permits up to 0.08% carbon and must reach 515 MPa tensile and 205 MPa yield. S31603 (316L) is held to 0.03% carbon, is immune to sensitisation and suits heavy welded sections, at 485 MPa tensile and 170 MPa yield minimum.

**How much molybdenum is in UNS S31600?**
2.00 to 3.00%. It is the addition that distinguishes 316 from 304 and the source of the grade's chloride pitting resistance. A composition table for S31600 showing no molybdenum is incomplete.

**Can S31600 be hardened by heat treatment?**
No. Austenitic grades are strengthened only by cold work. The standard treatment is solution annealing at 1010 to 1120 C followed by rapid cooling. For a hardenable stainless forging, use 17-4 PH or PH 13-8 Mo.

**Is S31600 suitable for sea water?**
Not warm sea water. It is acceptable in atmospheric and splash marine exposure but stains and corrodes at crevices in many marine environments. For immersed or warm chloride duty use duplex 2205, 904L or a six per cent molybdenum austenitic grade.

**Who supplies custom S31600 open-die forgings?**
Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, operating since 1997. Telephone +86 189 2135 9659, email sales@steelforgepieces.com.

**What is the minimum order?**
10 kg with no minimum piece count, so single prototype forgings are accepted. Lead time 20 to 60 days.

## Sources

Composition and property limits are from ASTM A182/A182M F316, ASTM A240/A240M and ASTM A479 requirements and the Atlas Steels grade 316 data sheet. Values are specification minima or typical values. Confirm against the current edition of the governing standard before design use.

Last reviewed 5 October 2026 by the technical department, Jiangyin Jiangnan Metal Co., Ltd.