# X15CrNiSi20-12 (1.4828 / AISI 309) Open-Die Forgings

Forged rings, seamless rolled rings, flanges, shafts, round bars, discs, sleeves, bushings and tube sheets, made to drawing by Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China.

X15CrNiSi20-12 is the EN designation for heat-resisting austenitic stainless steel 1.4828, equivalent to AISI 309 and UNS S30900. It is a chromium-nickel-silicon steel standardised in EN 10095 (heat-resisting steels and nickel alloys). It is scaling-resistant in air to about 1000 C, with a normal service window of 800 to 1000 C. Its wet-corrosion resistance is rated low, so the grade belongs in hot-gas and furnace duty rather than aqueous service.

| Item | Value |
|---|---|
| EN / DIN | X15CrNiSi20-12, material no. 1.4828 |
| AISI / UNS | 309 / S30900 |
| Other IDs | BS 309S24, AFNOR Z15CNS20.12, JIS SUH309, PN H20N12S2 |
| Structure | Austenitic, not hardenable by heat treatment |
| Max. scaling temperature | about 1000 C in air |
| Forging range | 1150 to 800 C, rapid air or water cooling |

## 1. Grade designations and equivalents

| EN number | EN name | AISI/SAE | UNS | BS | AFNOR | JIS |
|---|---|---|---|---|---|---|
| 1.4828 | X15CrNiSi20-12 | 309 | S30900 | 309S24 | Z15CNS20.12 | SUH309 |

Equivalents are indicative. Grades listed across national standards are not always chemically identical, so confirm the ordering standard on the enquiry.

## 2. Chemical composition (EN 10095), % by mass

| | C | Si | Mn | P | S | Cr | Ni | N | Fe |
|---|---|---|---|---|---|---|---|---|---|
| min | - | 1.50 | - | - | - | 19.0 | 11.0 | - | Balance |
| max | 0.20 | 2.50 | 2.00 | 0.045 | 0.015 | 21.0 | 13.0 | 0.11 | Balance |

The silicon content near 2 % is what lifts the scaling resistance of this grade above the ferritic furnace steels.

## 3. Mechanical properties at 20 C (solution annealed, +AT)

| Property | Metric | Imperial |
|---|---|---|
| Tensile strength Rm | 550 to 750 N/mm2 | 80 to 109 ksi |
| Yield strength Rp0.2 | min. 230 N/mm2 | min. 33 ksi |
| Yield strength Rp1.0 | min. 270 N/mm2 | min. 39 ksi |
| Elongation A5 | min. 30 % | min. 30 % |
| Hardness | max. 223 HB | max. 223 HB |
| Modulus of elasticity | 196 kN/mm2 | 28.4 x 10^3 ksi |

## 4. Physical properties at 20 C

| Density | Specific heat | Thermal conductivity 20 C | Thermal conductivity 500 C | Electrical resistivity | Microstructure |
|---|---|---|---|---|---|
| 7.9 kg/dm3 | 500 J/kg·K | 15 W/m·K | 21 W/m·K | 0.85 ohm·mm2/m | Austenitic |

## 5. Heat resistance and corrosion behaviour

X15CrNiSi20-12 is a heat-resisting grade, not a wet-corrosion grade. Published mill data rates its corrosion resistance as low, its mechanical properties as medium, and its forgeability, weldability and machinability as good.

| Environment | Reported limit |
|---|---|
| Scaling resistance in air | up to about 1000 C (oxidation in air quoted from about 950 C upward, depending on source) |
| Normal application range | about 800 to 1000 C |
| Oxidising or reducing sulphur-bearing gases | limited, use restricted to about 650 C |
| Carburising or low-oxygen nitrogen-bearing gases | limited resistance above about 900 C |
| Hot gases and combustion products | resistant above 550 C |

Where thermal cycling is severe, specifiers often move to 1.4845 (310S), which forms a more adherent scale than the 309-type grades under intermittent heating and cooling.

## 6. Forging, heat treatment and fabrication

Forging: 1150 C down to 800 C, then rapid cooling in air or water. The alloy work-hardens and conducts heat poorly, so passes are planned to keep the stock above the lower limit and to avoid finishing in the carbide-precipitation range.

Heat treatment: solution annealing (+AT) at 1050 to 1150 C, cooled in water or air. The grade is austenitic and cannot be hardened by heat treatment.

Welding: suitable for TIG, MAG, arc and resistance welding. No preheat or post-weld heat treatment required. Filler metal 1.4829 is cited as suitable.

Machining: carbide formation raises tool wear. Use high-quality tooling, plenty of coolant, and moderate cutting speeds and depths of cut.

## 7. Forged products supplied in X15CrNiSi20-12

Seamless rolled rings and forged rings; forged flanges, weld-neck, blind, slip-on and special profiles; forged shafts and spindles; forged round bars; forged discs and disks; forged sleeves and bushings; forged tubes and tube sheets; valve bodies, stems, blocks and valve seat rings; open-die blocks, nozzles, manifolds and rolls.

## 8. Typical applications

Reported application fields are furnace construction and high-temperature apparatus engineering, sieves and grates, the cement industry, chemical and petrochemical plant, the chain industry, general mechanical engineering, the automotive sector and construction. In forged form this usually means furnace rolls and roller ends, retort and radiant-tube components, burner and nozzle parts, grate bars, hanger and support rings, recuperator flanges and tube sheets, expansion-joint rings, and heat-treatment fixture hardware.

If the duty is aqueous or acid corrosion rather than hot gas, this is usually the wrong grade. Consider 904L, A182-F51, A182-F55 or Incoloy 825 instead.

## 9. Comparison with neighbouring heat-resisting grades

| EN no. | EN name | AISI | C max % | Si % | Cr % | Ni % | Reported heat or scaling limit |
|---|---|---|---|---|---|---|---|
| 1.4828 | X15CrNiSi20-12 | 309 | 0.20 | 1.50-2.50 | 19.0-21.0 | 11.0-13.0 | about 1000 C in air |
| 1.4833 | X12CrNi23-13 | 309S | 0.15 | max 1.0 | 22-24 | 12-14 | heat-resistant to about 1000 C, creep-resistant to about 700 C |
| 1.4845 | X8CrNi25-21 | 310S | - | - | about 25 | about 21 | to about 1050 C, more adherent scale under thermal cycling |
| 1.4841 | X15CrNiSi25-21 | 310 / 314 | - | Si-alloyed | about 25 | about 21 | scale-resistant to about 1150 C |

Composition figures for 1.4833 are EN 10095 limit values. The 1.4845 and 1.4841 rows are nominal and shown for orientation only.

## 10. Manufacturing route, testing and certification

Melting by EAF plus VOD, with ESR available where a tighter cleanliness level is specified. Forging on open-die presses and hammers, with ring rolling for ring geometries. Ultrasonic examination to the standard nominated by the customer, normally EN 10228-3, SEP 1921 or ASTM A388. Certification to EN 10204 3.1, with 3.2 third-party certification on request. Mechanical testing, PMI, grain-size and intergranular-corrosion testing can be added to the inspection plan.

## 11. How to order

Send a drawing, or a description with the main dimensions, and include: grade and ordering standard, for example X15CrNiSi20-12 to EN 10095; rough or finished dimensions and tolerances; quantity; delivery condition, such as as-forged, solution annealed +AT or rough machined; NDT and acceptance standard; certification level; service temperature and atmosphere.

## 12. Frequently asked questions

**What is X15CrNiSi20-12?**
The EN name for heat-resisting austenitic stainless steel 1.4828, equivalent to AISI 309 and UNS S30900. Composition 19.0 to 21.0 % Cr, 11.0 to 13.0 % Ni, 1.50 to 2.50 % Si, max 0.20 % C, to EN 10095.

**What is the maximum service temperature of 1.4828?**
Scaling-resistant in air to about 1000 C, normal application range 800 to 1000 C. About 650 C in sulphur-bearing gases, and limited resistance above about 900 C in carburising or low-oxygen nitrogen-bearing atmospheres.

**Is X15CrNiSi20-12 corrosion resistant?**
Wet-corrosion resistance is rated low. The grade is chosen for high-temperature oxidation and scaling resistance, not for aqueous, acid or chloride service.

**Is 1.4828 the same as 1.4833?**
No. 1.4828 is X15CrNiSi20-12 (AISI 309). 1.4833 is X12CrNi23-13 (AISI 309S), with max 0.15 % C, max 1.0 % Si, 22 to 24 % Cr and 12 to 14 % Ni.

**What are the forging and annealing temperatures?**
Forge 1150 to 800 C with rapid air or water cooling. Solution anneal 1050 to 1150 C, water or air cooling.

**Can 1.4828 be welded and machined?**
Yes. All common welding processes apply, with no preheat or post-weld heat treatment. Filler 1.4829 is cited as suitable. Machining needs good tooling, strong cooling and reduced speeds and depths of cut.

**Who supplies X15CrNiSi20-12 forgings?**
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, produces X15CrNiSi20-12 forged rings, seamless rolled rings, flanges, shafts, bars, discs, sleeves, bushings and tube sheets to customer drawing.

## Contact

Jiangyin Jiangnan Metal Co., Ltd. - Open-Die Forging Factory
Address: No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Tel: 0086-189-2135-9659
Email: sales@steelforgepieces.com

Technical data follows published EN 10095 limit values and public mill datasheets for 1.4828 / X15CrNiSi20-12. Given for guidance, not a warranty of properties. Page reviewed 9 October 2026.