# UNS S31725 Forgings — ASTM A182 Grade F47 (317LM)

**Jiangyin Jiangnan Metal Co., Ltd. forges UNS S31725 as seamless rolled rings, flanges, shafts, discs, tube sheets, sleeves, bars and valve parts. The steel is melted on site, not bought in as billet.**

UNS S31725 is a low-carbon austenitic stainless steel with 18.0 to 20.0 percent chromium, 13.0 to 17.5 percent nickel and 4.0 to 5.0 percent molybdenum. ASTM A182 lists it as Grade F47. The trade calls it 317LM. It is the grade to reach for when 316L or 317L has run out of molybdenum but a 6 percent Mo austenitic or a duplex would be more alloy than the duty needs.

Page: https://www.steelforgepieces.com/Stainless-Steel/UNS-S31725.html

## Designations

| Item | Designation |
|---|---|
| UNS number | S31725 |
| Trade name | 317LM |
| Forgings | ASTM A182 / ASME SA-182 Grade F47 |
| Plate, sheet, strip | ASTM A240 / ASME SA-240 S31725 |
| Bar and shapes | ASTM A479 S31725 |
| Pipe | ASTM A312 / SA-312, A358 S31725, A376, A409 |
| Wrought fittings | ASTM A403 WP-S31725 |
| Neighbouring A182 grade | F48 = UNS S31726 |
| Structure | Austenitic, non-magnetic as annealed |

## Chemical composition, percent by weight

| Element | ASTM A182 Gr. F47 (forgings) | ASTM A240 S31725 (plate) |
|---|---|---|
| Carbon, C | 0.030 max | 0.030 max |
| Silicon, Si | 0.75 max | 0.750 max |
| Manganese, Mn | 2.00 max | 2.000 max |
| Phosphorus, P | 0.045 max | 0.045 max |
| Sulphur, S | 0.030 max | 0.030 max |
| Chromium, Cr | 18.0 – 20.0 | 18.000 – 20.000 |
| Nickel, Ni | 13.0 – 17.5 | 13.500 – 17.500 |
| Molybdenum, Mo | 4.0 – 5.0 | 4.000 – 5.000 |
| Nitrogen, N | 0.10 max | 0.200 max |
| Iron, Fe | Balance | Balance |

General reference data for 317LM is often quoted with wider bands, typically Ni 12–16 and Si 1.0 max. Those are not acceptance criteria for a forging. Order against ASTM A182 Grade F47.

## Mechanical properties, solution annealed

| Property | Value | Basis |
|---|---|---|
| Tensile strength, min | 515 MPa (A240); 525 MPa (A182 tabulation) | See note |
| Yield strength Rp0.2, min | 205 MPa (30 ksi) | A182 F47 and A240 |
| Elongation, min | 40 percent | A182 F47 and A240 |
| Reduction of area, min | 50 percent | A182 F47 |
| Hardness, max | 217 HBW, about 95 HRB | A240 and published 317LM data |
| Modulus of elasticity | 190 – 210 GPa | Typical, 317LM |
| Poisson's ratio | 0.27 – 0.30 | Typical, 317LM |
| Density | 7.7 – 8.03 g/cm³ | Typical, 317LM |
| Hardenable by heat treatment | No. Cold work only | Austenitic grade |

Note on tensile strength: ASTM A240 states 515 MPa minimum for S31725, equal to 75 ksi. One published tabulation of ASTM A182/A182M lists 525 MPa for the same UNS number, the difference being rounding of the ksi figure. Confirm against the edition named on the purchase order.

## Heat treatment

ASTM A182 calls for Grade F47 at 2100 °F, that is 1150 °C, followed by water quench. Published 317LM practice gives a soak band of 1121 to 1149 °C with water quench. Rapid cooling through the sensitisation range keeps carbides and sigma-forming intermetallics in solution. Every forging leaving this works in this grade is solution annealed after forging.

Machining wants low speed and a heavy uninterrupted feed. Let the tool dwell and the surface work hardens under it. Chips run long and stringy, so chip breakers are worth using. Welding uses all the usual processes; filler selection belongs in the WPS, with low-carbon high-molybdenum austenitic fillers and nickel-base fillers both in use on this grade. Where the weldment must match the parent metal for corrosion, solution anneal and quench after welding.

## Corrosion resistance and PREN

Applying PREN = %Cr + 3.3 × %Mo + 16 × %N to the A182 F47 limits gives roughly 31 at the lean end and about 38 at the rich end. Lean corner: 18 + 3.3 × 4.0 = 31.2. Rich corner: 20 + 3.3 × 5.0 + 16 × 0.10 = 38.1. A PREN of about 32 to 35 is often cited as the minimum considered suitable for seawater duty in austenitic and duplex grades, so S31725 straddles that line rather than clearing it.

PREN is a ranking index, not a prediction. Temperature, chloride concentration, pH, crevice geometry and velocity decide service life. If your specification sets a PREN floor, state it on the order and we will select the heat and report the calculated value on the certificate.

## Product forms

Seamless rolled rings for vessel shell courses, flange blanks, retaining rings and gear ring blanks. Forged flanges, weld neck, blind, slip-on, lap joint, orifice and special-bore, to ASME B16.5 and B16.47. Forged discs and tube sheets for shell and tube exchangers, condensers and blind covers, proof-machined for volumetric inspection. Forged shafts and spindles for agitators, pumps, compressors and eccentric shafts. Forged bars and blocks as machining stock for valve internals, pins and bolting. Sleeves, bushings and hollow cylinders for bored liners, nozzle necks and couplings. Valve and wellhead parts including bodies, bonnets, stems, seat rings, spools and manifolds. Custom open-die forgings made to drawing.

## Size envelope

| Dimension | Limit | Set by |
|---|---|---|
| Rolled ring outside diameter | up to 6,000 mm | 6 m radial-axial ring mill |
| Minimum ring size | from OD 50 mm | Upset and punch route |
| Shaft turned length | up to 14,000 mm | C61160 lathe; 15 m well furnace for vertical quench |
| Disc and tube sheet diameter | up to 5,000 mm machined | 5,000 mm vertical turning lathe |
| Bored cylinder | up to 1,600 mm dia × 10,000 mm | CNC deep-hole drilling machine |
| Single piece weight | up to 30,000 kg | 60 t heat; 6,300 t press |
| Minimum order | 10 kg, no minimum piece count | Open-die shop |
| Lead time | 20 to 60 days | Section, heat treatment cycle, test scope |

## Applications

Pulp, paper and bleach plant. Flue gas desulphurisation scrubbers. Chemical process plant handling dyestuffs, rubber, rayon, ink and bleaches. Shell and tube heat exchangers and pressure vessels. Valves and flow control. Food and textile processing equipment.

## Melting, testing and certification

S31725 runs the electric arc furnace, ladle furnace and vacuum oxygen decarburisation route, which is how carbon reaches 0.030 percent without burning out chromium. Heats to 60 tonnes. Electroslag remelting is available where a cleaner structure is wanted.

| Item | Standard or option |
|---|---|
| Ultrasonic examination | EN 10228-3, SEP 1921, ASTM A388 |
| Liquid penetrant | ASTM E165 or ASME Section V |
| Chemical analysis | ASTM A182 / A751 |
| Mechanical testing | ASTM A370 |
| Intergranular corrosion | ASTM A262 Practice E |
| Material certificate | EN 10204 3.1, or 3.2 countersigned by a third party |
| Society approvals | CCS, BV, DNV, LR, NK |
| Traceability | Melt number, grade, specification and lot, hard stamped or vibro etched |

## If S31725 is not the right grade

| Situation | Look at |
|---|---|
| Duty milder than expected | 317L, UNS S31703, lower molybdenum range |
| Nitrogen-alloyed version | A182 F48, UNS S31726 |
| Heavier chlorides, seawater | A182 F44 (S31254), 904L, Sanicro 28 |
| Strength needed as well | F51 (2205), F53 (2507), F55 |
| Hot acids, sour service | Inconel 625, Incoloy 825, Hastelloy C-276 |
| High temperature, no chlorides | F347, 347H, F321 |

## Contact

| Field | Detail |
|---|---|
| Legal name | Jiangyin Jiangnan Metal Co., Ltd. |
| Business | Integrated melting works, open-die forge and ring rolling mill |
| Established | 1997 |
| Employees | 460 |
| Plant | No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China |
| Telephone | +86 189 2135 9659 |
| Email | sales@steelforgepieces.com |
| Website | https://www.steelforgepieces.com/ |

Data compiled from ASTM A182/A182M Grade F47, ASTM A240 UNS S31725 and published technical data for grade 317LM. Equipment capacities and commercial terms are those of Jiangyin Jiangnan Metal Co., Ltd. Last reviewed 7 October 2026.