# Z12CN25-20 Forgings — 25Cr-20Ni Heat-Resistant Steel

AFNOR Z12CN25-20, close equivalent of 1.4845 / X12CrNi25-21 / AISI 310S / UNS S31008.

Z12CN25-20, also written Z12CN25.20 or Z 12 CN 25-20, is the AFNOR designation for a 25% chromium / 20% nickel austenitic heat-resistant stainless steel, specified at max 0.15% C, 23.0-26.0% Cr and 18.0-21.0% Ni. It resists scaling in air and oxidising atmospheres up to about 1050 C.

Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu, China, produces this grade as forged rings, seamless rolled rings, flanges, shafts, round bars, discs, sleeves, bushings, forged tubes and tube sheets to customer drawing, with EN 10204 3.1 or 3.2 certification. Every item is made to order, so price and lead time are quoted against the drawing.

Supplier: Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Tel +86-189-2135-9659. Email sales@steelforgepieces.com.

## Equivalent grades

| Standard | Designation | C max | Cr | Ni | Mn max | Si max | P max | S max |
|---|---|---|---|---|---|---|---|---|
| AFNOR | Z12CN25-20 | 0.15 | 23.0-26.0 | 18.0-21.0 | 2.0 | 1.0 | 0.040 | 0.030 |
| EN / SEW | X8CrNi25-21, X12CrNi25-21, 1.4845 | 0.10 | 24.0-26.0 | 19.0-22.0 | 2.0 | 1.5 | 0.045 | 0.015 |
| ASTM / AISI | 310S, UNS S31008 | 0.08 | 24.0-26.0 | 19.0-22.0 | 2.0 | 1.5 | 0.045 | 0.030 |
| DIN | X16CrNi25-20, 1.4843 | 0.20 | 22.0-25.0 | 19.0-22.0 | 2.0 | Si 1.5-2.5 | 0.045 | 0.030 |
| BS | 310S24 | 0.15 | 23.0-26.0 | 19.0-22.0 | 2.0 | 1.0 | 0.045 | 0.030 |
| GOST | 20Kh23N18 | 0.20 | 22.0-25.0 | 17.0-20.0 | 2.0 | 1.0 | 0.035 | 0.020 |
| PN | H23N18 | 0.20 | 22.0-25.0 | 17.0-20.0 | 1.5 | 1.0 | 0.045 | 0.030 |

Composition in % by mass, from the Virgamet grade cross-reference for 1.4845 / AISI 310S.

Other designations in the same family: Z8CN25-20, Z12CN26-21, X6CrNi25-20 (1.4951), X22CrNi25-20, CSN/STN 17255, SUS 310S, F-331, 12NiCr250, 06Cr25Ni20, 0Cr25Ni20, TP310S, TP310H, UNS S31009, AMS 5521, AMS 5572, AMS 5577, AMS 5651, AMS 7490.

Z12CN25-20 permits up to 0.15% carbon, roughly double the 0.08% ceiling of AISI 310S, so the grade is also cross-referenced to the higher-carbon AISI 310H. Higher carbon raises creep strength but lowers resistance to intergranular attack after sensitisation. State the governing standard at enquiry stage.

## Mechanical and physical properties

| Property | Value |
|---|---|
| Tensile strength, Rm | 500-700 MPa (Tachart quotes an upper bound of 750 MPa) |
| Yield point, Re | min 210 MPa |
| Elongation, A | min 33% (Tachart: 35%) |
| Hardness | max 192 HB |
| Modulus of elasticity, E | 196 GPa |
| Thermal capacity, cp 20-100 C | 500 J/kg·K |
| Linear expansion coefficient | 15.0 x 10^-6 K^-1 |
| Thermal conductivity | 14.7 W/m·K |

Room-temperature values, supersaturated condition. Data from Virgamet (1.4845) and the Tachart datasheet for X12CrNi25-21.

### Creep limit and creep strength (MPa)

| Property | 600 C | 700 C | 800 C | 900 C |
|---|---|---|---|---|
| Creep limit R1/1 000 h | 100 | 45 | 18 | 10 |
| Creep limit R1/10 000 h | 90 | 30 | 10 | 4 |
| Creep strength Rz/1 000 h | 170 | 80 | 35 | 15 |
| Creep strength Rz/10 000 h | 130 | 40 | 18 | 8.5 |
| Creep strength Rz/100 000 h | 80 | 18 | 7 | 3 |

Data from Virgamet, 1.4845 / X8CrNi25-21.

## Service temperature

Classified as heat-resistant under EN 10095 and SEW 470.

- Air and oxidising atmosphere: up to about 1050 C
- Reducing gases with sulphur compounds in higher concentrations: about 900 C
- Reducing gases with small sulphur impurities: about 1000 C

The grade is also bought for its acid resistance in chemical apparatus for gas pyrolysis, hydrogenation and methane conversion.

## Processing

- Forging and rolling: 1150-950 C
- Hot bending of sheet components: 900-950 C
- Supersaturation: 1100-1150 C, water quench. The grade is austenitic and is not precipitation hardenable, so no ageing step applies.
- Welding: arc welding with 24-18 type electrodes, ES-24-18 class
- Melting at our works: EAF + VOD, with ESR remelting available
- Ultrasonic testing: EN 10228-3, SEP 1921 or ASTM A388
- Certification: EN 10204 3.1 or EN 10204 3.2

## Forged products

Forged rings, seamless rolled rings, flanges, shafts, eccentric shafts and crankshafts, round bars, discs and disks, blanks, sleeves, bushings, forged tubes and pipes, tube sheets, valve bodies and blocks, valve stems, valve seat rings, nozzles, gears and spindles, forged wheels, manifolds. All open-die, to customer drawing.

## Typical applications

| Industry or unit | Forged components |
|---|---|
| Fluidised bed furnaces, coal combustors | Rolled rings, shafts, grids, piping, wind boxes |
| Ore processing and steel plants | Smelter and steel melting equipment, continuous casting equipment |
| Pressure vessels, shell and tube heat exchangers | Shafts, pipes, forged tubes, tube sheets, flanges, air receivers |
| Columns, towers, tanks, silos | Shafts, flanges, rings, pipes, process modules, preheaters |
| Petroleum refining | Sleeves, discs, catalytic recovery systems, flares, recuperators, tube hangers |
| Fluid catalytic cracking units | Open-die forgings and nozzles, polythionic acid service |
| Sintering and cement plants | Burners, burner shields, feeding and discharging systems, wind boxes |
| Thermal processing | Annealing covers and boxes, burner grids, doors, fans, muffles, retorts, recuperators, walking beams |
| Oil and gas wellhead | Wellhead and Christmas tree parts, crystalliser equipment |
| Food processing and cryogenics | Forged wheels, manifolds, cryogenic structures |

## Questions

**Is Z12CN25-20 the same as 310S?**
Close, but not identical. Z12CN25-20 allows up to 0.15% C with 23.0-26.0% Cr and 18.0-21.0% Ni. AISI 310S (UNS S31008) is capped at 0.08% C with 24.0-26.0% Cr and 19.0-22.0% Ni. Because of the wider carbon range, Z12CN25-20 is also cross-referenced to AISI 310H.

**What heat treatment do the forgings receive?**
Supersaturation at 1100-1150 C with water quench. No ageing, since the grade is austenitic and cannot be precipitation hardened.

**What is the maximum operating temperature?**
About 1050 C in air and oxidising atmospheres, about 900 C in reducing gases carrying higher concentrations of sulphur compounds, about 1000 C where sulphur impurities are small.

**What is the largest ring or shaft you can forge in this grade?**
It depends on the shape and the reduction ratio required. Send the drawing, or OD x ID x height for rings and diameter x length for shafts.

**What certification comes with the material?**
EN 10204 3.1 as standard, EN 10204 3.2 third-party on request. Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388.

**How is the price decided?**
There is no list price. Each piece is forged to a drawing, so cost depends on grade, finished weight, input billet size, heat treatment, machining allowance, NDT class and quantity.

**What do you need in order to quote?**
Grade or equivalent designation, drawing or finished dimensions with machining allowance, quantity, heat treatment and NDT requirements, certificate type, destination port.

## Contact

Jiangyin Jiangnan Metal Co., Ltd. — Open-Die Forging Factory
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Tel: +86-189-2135-9659
Email: sales@steelforgepieces.com
Page: https://www.steelforgepieces.com/Stainless-Steel/Z12CN25-20.html

Technical data compiled from published grade cross-references for 1.4845 / AISI 310S. Values are typical and given for guidance, not a guarantee of properties for a specific forging. Last reviewed 11 October 2026.