1.4828 (X15CrNiSi20-12) is an austenitic heat-resistant stainless steel standardized under EN 10095:1999, equivalent to AISI 309 / UNS S30900. With 19–21% chromium, 11–13% nickel, and a deliberate 1.5–2.5% silicon addition, it delivers outstanding oxidation resistance in continuous service up to 1050°C — the highest temperature rating of any standard austenitic grade in its cost class.
Unlike general-purpose stainless grades such as 304 or 316, 1.4828 is purpose-built for a single priority: reliable performance at extreme heat. Its silicon-enhanced oxide scale dramatically outperforms lower-silicon grades in cyclic thermal service, making it the dominant material choice for industrial furnace components, high-temperature conveyors, ceramic kiln hardware, and petrochemical process equipment worldwide.
This guide provides the complete technical reference for 1.4828 — covering chemical composition, mechanical and physical properties, oxidation resistance mechanisms, forging and heat treatment parameters, welding guidance, machining strategy, international grade equivalents, and industrial applications. Engineers and buyers looking to source custom 1.4828 X15CrNiSi20-12 forged parts can find full product details, available shapes, and request a quotation via our dedicated product page.
Designation, Standards & International Equivalents
1.4828 carries multiple designations across global standards systems. Knowing these equivalencies is essential for international procurement, multi-standard project specifications, and cross-border supply chain verification.
| Standard System | Designation | Standard Reference | Notes |
|---|---|---|---|
| European (EN) | 1.4828 / X15CrNiSi20-12 | EN 10095:1999 | Primary reference standard for this guide |
| American (AISI/UNS) | AISI 309 / UNS S30900 | ASTM A276 / A240 | Carbon limit up to 0.20% (same as 1.4828) |
| American (low-C variant) | AISI 309S / UNS S30908 | ASTM A276 / A240 | Carbon limited to ≤ 0.08% for improved weldability |
| French (AFNOR) | Z17CNS20-12 | NF A36-209 | Direct equivalent |
| Italian (UNI) | X16CrNi23-14 | UNI 6901 | Slight Ni variation; functionally equivalent |
| Russian (GOST) | 20KH20N14S2 | GOST 5632 | Direct equivalent; widely used in CIS projects |
| Japanese (JIS) | SUH309 | JIS G4312 | Heat-resistant steel classification |
AISI 309 (equivalent to EN 1.4828) allows carbon up to 0.20%, while AISI 309S limits carbon to ≤ 0.08%. When specifying by AISI designation, always confirm whether 309 or 309S is intended — particularly for welded fabrications where sensitization risk matters. When specifying by EN designation, 1.4828 specifically maps to the higher-carbon 309 variant.
Chemical Composition
Every element in the 1.4828 composition serves a defined structural or protective function at elevated temperature. The specification per EN 10095:1999 is as follows:
| Element | Range (%) | Function at High Temperature |
|---|---|---|
| Carbon (C) | ≤ 0.20 | Contributes to high-temperature strength via carbide precipitation; intentionally higher than 304/316 |
| Chromium (Cr) | 19.0 – 21.0 | Forms primary Cr₂O₃ protective scale; main oxidation barrier up to 1050°C |
| Silicon (Si) | 1.5 – 2.5 | Creates SiO₂ sublayer that anchors the Cr₂O₃ scale; dramatically improves cyclic oxidation performance |
| Nickel (Ni) | 11.0 – 13.0 | Stabilizes fully austenitic structure; improves toughness and resistance to thermal shock |
| Manganese (Mn) | ≤ 2.0 | Secondary austenite stabilizer; aids hot workability during forging |
| Nitrogen (N) | ≤ 0.11 | Solid solution strengthener; improves creep resistance at sustained high temperature |
| Phosphorus (P) | ≤ 0.045 | Controlled residual; excess weakens grain boundaries at high temperature |
| Sulfur (S) | ≤ 0.015 | Controlled residual; low level preserves intergranular corrosion resistance |
The Role of Silicon: The Defining Design Choice in 1.4828
Silicon content of 1.5–2.5% is the single most important feature that distinguishes 1.4828 from standard 309 grades and from lower-alloy austenitic steels. At elevated temperature, silicon preferentially oxidizes at the metal/scale interface to form a thin, continuous SiO₂ sublayer directly beneath the primary Cr₂O₃ scale. This sublayer physically anchors the chromia to the base metal, dramatically reducing the tendency for scale to spall or delaminate during thermal cycling.
Industrial equipment — furnaces, kilns, heat treatment lines — undergoes repeated thermal cycles between ambient and operating temperature. Each cycle creates differential thermal expansion between the oxide scale and the metal substrate. Without the silicon anchor, scale delaminates and exposes fresh metal, accelerating oxidation per cycle. With the silicon anchor, mass loss per cycle drops measurably, directly extending component service life.
Mechanical Properties
Room Temperature Properties (Solution Annealed + Quenched)
| Property | Value | Test Condition |
|---|---|---|
| Tensile Strength (Rm) | ≥ 550 MPa | Solution annealed + quenched |
| 0.2% Proof Strength (Rp0.2) | ≥ 230 MPa | Solution annealed + quenched |
| Elongation at Break (A) | ≥ 30% | Gauge length = 5.65√S₀ |
| Hardness | ≤ 230 HB | Solution annealed + quenched |
| Modulus of Elasticity | 210 GPa | Room temperature (20°C) |
Elevated Temperature Short-Term Tensile Properties
| Temperature | Rp0.2 (MPa) | Rm (MPa) | Application Context |
|---|---|---|---|
| 200°C | ~165 | ~480 | Steam lines, low-temp process piping |
| 400°C | ~135 | ~420 | Industrial process heaters |
| 600°C | ~120 | ~370 | Furnace structural elements |
| 800°C | ~95 | ~280 | Core furnace operating zone |
| 1000°C | ~45 | ~95 | Approaching service limit |
Temperature range of concern: 600–850°C. Prolonged exposure in this range causes sigma-phase (σ-phase) precipitation at grain boundaries. Sigma-phase is hard and brittle; it does not significantly affect elevated-temperature strength but causes severe loss of room-temperature impact toughness and ductility upon cooling.
This has two critical engineering implications: (1) forgings and weld assemblies must be cooled rapidly through 600–850°C — never slow-cooled; (2) components designed for continuous service in this band require specific engineering review before 1.4828 is specified. Intermittent or short-duration exposure at these temperatures is generally tolerable.
Physical Properties
21 W/m·K at 500°C
Key thermal note: Unlike carbon and low-alloy steels, thermal conductivity of 1.4828 increases with temperature (15 → 21 W/m·K from 20°C to 500°C). This has practical implications for thermal gradient calculations in thick-section forgings during heat treatment: heating rates and temperature uniformity estimates based on carbon steel data are not directly applicable to 1.4828.
Oxidation & Corrosion Resistance
The oxidation protection mechanism in 1.4828 operates through a two-layer system that provides robust protection in oxidizing atmospheres up to 1050°C in continuous service:
At elevated temperature, chromium preferentially oxidizes at the surface to form a dense, adherent chromia (Cr₂O₃) layer. This is the primary oxygen diffusion barrier. The 19–21% Cr level in 1.4828 ensures rapid, complete scale formation and active self-repair if the scale is mechanically disrupted.
Silicon migrates to the metal/scale interface and oxidizes to form a thin, continuous SiO₂ sublayer directly beneath the Cr₂O₃. This sublayer physically pins the chromia scale to the base metal, preventing delamination during thermal cycling. This mechanism is unique to silicon-bearing grades and is the core performance advantage of 1.4828 over standard 309.
When scale is damaged by thermal shock, mechanical impact, or unplanned process excursions, the chromium in the alloy re-oxidizes rapidly at temperature to restore full protective coverage. This self-healing capability is critical for equipment subject to unplanned shutdowns or intermittent operation.
H₂S / SO₂ atmospheres above 650°C: Sulfidation attacks penetrate the protective oxide scale, causing rapid internal metal loss. Do not specify 1.4828 for sulfur-bearing process streams above 650°C without dedicated corrosion engineering assessment.
Carburizing atmospheres above 900°C: Carbon uptake at the surface depletes the chromium reservoir needed to maintain the protective oxide, progressively degrading oxidation resistance.
Halogen-containing atmospheres: Chlorine and fluorine compounds attack chromia scales at elevated temperature. Specialist alloys are required for such environments.
Grade Comparison: 1.4828 vs. Related Steels
The following comparison covers the grades most frequently evaluated alongside 1.4828 in heat-resistant applications. Each column represents the decisive technical parameters for grade selection:
Selection rule of thumb: When continuous service temperature is below 1050°C and budget does not justify the high Ni/Cr premium of 1.4841, 1.4828 is the optimal engineering choice. Its silicon content closes the cyclic oxidation gap against lower grades and positions it as the cost-efficient workhorse of the heat-resistant steel category. For applications consistently exceeding 1050°C, the upgrade to 1.4841 forged parts is necessary.
Forging Parameters & Hot Working Guidance
1.4828 responds well to open die forging and seamless ring rolling when correct thermal parameters are observed. As a fully austenitic grade, it work-hardens more readily than ferritic or martensitic alternatives, making temperature control throughout the forging sequence critical for achieving the required grain structure and mechanical properties.
| Parameter | Value / Guidance |
|---|---|
| Forging Start Temperature | Maximum 1150°C — do not exceed; grain coarsening accelerates above this |
| Minimum Finish Temperature | 800°C — abandon forging and reheat if below this; cold working below 800°C risks cracking |
| Preheat Strategy | Gradual heating to 900°C before raising to forging temperature; avoid rapid thermal shock of large sections |
| Post-Forge Cooling | Rapid air cool or water quench through 600–850°C sigma-phase range — NEVER slow-cool through this range |
| Post-Forge Heat Treatment | Solution anneal at 1050–1150°C + water or air quench strongly recommended to fully restore microstructure |
| Work Hardening Behavior | Austenitic; work-hardens faster than ferritic grades — reheating between passes may be needed for heavy reductions |
| Max Single-Piece Weight | 30,000 kg (Jiangsu Liangyi capability) |
| Max Seamless Ring OD | Up to 5,000 mm |
| Max Forged Bar Diameter | Up to 1,200 mm |
Slow cooling of 1.4828 forgings through the 600–850°C range consistently produces sigma-phase embrittlement that severely reduces room-temperature impact toughness. This is not a theoretical risk — it is a predictable, reproducible metallurgical outcome that must be managed by procedure, not by chance. Water quenching after solution annealing is standard practice for all impact-critical 1.4828 forgings.
For custom-dimensioned components, Jiangsu Liangyi manufactures rings, discs, shafts, flanged shapes, blanks, and bespoke profiles per customer drawings. Every batch is delivered with full EN 10204 3.1 MTC documentation covering chemical analysis, tensile testing, Charpy impact results, hardness, heat treatment records, and NDT results. Full product specifications, available dimensions, and inquiry forms are on the 1.4828 forging parts product page.
Welding 1.4828 / X15CrNiSi20-12
1.4828 offers good weldability — a practical advantage over many higher-alloy heat-resistant grades. All standard fusion welding processes are applicable without significant restrictions:
| Welding Parameter | Guidance |
|---|---|
| Applicable Processes | GTAW (TIG), GMAW (MIG), SMAW (MMA), FCAW, Resistance welding — all suitable |
| Oxyacetylene (OFW) | Not recommended — risk of carburization from flame and porosity in weld pool |
| Preheat Temperature | Not required under normal conditions; optional 50–100°C for very thick sections (>100 mm) |
| Filler Metal — Standard | AWS ER309 / E309 — matches base metal composition; correct choice for most applications |
| Filler Metal — Low Carbon | AWS ER309L / E309L — use when sensitization risk exists (post-weld service in 425–870°C range without PWHT) |
| Interpass Temperature | Maximum 150°C recommended to limit heat input to the HAZ |
| Post-Weld Heat Treatment | Not required in most applications; where performed, full solution anneal (1050–1150°C + quench) is preferred over partial stress relief |
| Post-Weld Cooling | Allow slow cooling from weld temperature before any quench; do not immediately water-quench a hot weldment |
Sensitization risk: The relatively high carbon content of 1.4828 (up to 0.20%) means chromium carbide (Cr₂₃C₆) can precipitate at grain boundaries if the weld metal or HAZ is held in the 425–870°C sensitization range. For components that cannot be fully solution-annealed post-welding and that will operate in a corrosive or oxidizing environment in this temperature range, specify 309L or 309S filler to reduce residual carbon and minimize sensitization tendency.
Machining 1.4828 — Practical Guidance
1.4828 machines similarly to AISI 304 stainless in terms of tooling strategy but is somewhat more demanding. The five behaviors below must be managed to achieve productive, quality cutting:
- Rapid work hardening: 1.4828 work-hardens aggressively when the tool dwells without cutting. Any rubbing, hesitation, or interrupted cutting creates a hardened surface layer that accelerates tool wear. The tool must always be in active cutting contact — no pausing mid-pass, no allowing the spindle to coast through a cut.
- Stringy, long chips: Unlike carbon steels that produce manageable chips, 1.4828 produces long, stringy chips that can wrap around the tool, workpiece, or spindle. Chip breaker geometries are essential on turning and milling inserts.
- Heat concentration at the tool tip: Low thermal conductivity traps heat at the cutting zone rather than conducting it away through the workpiece. Use ample flood coolant (not mist), sharp tooling with positive rake angles, and monitor tool temperature closely.
- Carbide tooling mandatory: HSS tooling wears too rapidly on 1.4828 at productive cutting speeds. Use coated carbide inserts — TiAlN or AlTiN coatings are preferred for their thermal resistance. Replace inserts more frequently than you would for carbon steel.
- Reduce cutting speed by 20–30% versus 304 parameters: To compensate for work hardening, increase chip load (feed per tooth/revolution) to ensure each cutting edge is actively removing material rather than rubbing a hardened surface.
Industrial Applications of 1.4828 Forged Parts
The combination of 1050°C oxidation resistance, adequate high-temperature load-bearing capability, established weldability, and competitive cost against higher-alloy grades makes 1.4828 the dominant material in several major industrial sectors:
1.4828 (X15CrNiSi20-12) fills a clear and well-defined engineering niche: when a project demands reliable oxidation resistance to 1050°C in a grade that can be forged, welded, and machined at competitive cost, 1.4828 is the correct specification. Its silicon-enhanced scale adhesion makes it genuinely superior to standard 309 in cyclic thermal service, and its Cr-Ni content decisively outperforms 304 for any sustained high-temperature duty. For temperatures consistently above 1050°C, the upgrade to 1.4841 is warranted. For everything below that threshold, 1.4828 earns its position as the global industry standard in heat-resistant austenitic forgings.
Sourcing 1.4828 Forged Parts — Complete Specification Checklist
A complete procurement specification for 1.4828 forgings must include the following elements to ensure the supplier delivers to the correct standard with full traceability:
- Material designation and standard: State "1.4828 per EN 10095" or "AISI 309 per ASTM A276/A240" — not just a trade name or grade number without the governing standard.
- Heat treatment condition: Specify "solution annealed and quenched." State quench medium (water or air) when impact toughness at low temperatures is a design criterion.
- Dimensional drawing: Provide a full dimensional drawing with all tolerances; state the governing dimensional standard (EN, ASME, API, customer standard).
- Mechanical test requirements: Define minimum values for Rm, Rp0.2, elongation (A%), Charpy impact energy at a specified test temperature, and hardness range.
- NDT requirements: Specify UT acceptance class per EN 10228-3 or equivalent; include MT if surface-breaking discontinuities must be detected and reported.
- Certification level: EN 10204 3.1 MTC as standard minimum. Specify 3.2 (third-party inspector co-signature) for nuclear, critical pressure-retaining, or otherwise regulated applications.
- Chemical analysis scope: Require both ladle and product analysis. Include tramp elements (Cu, Co, Sn) if your end-use code or customer specification requires them.
Jiangsu Liangyi Co. Limited is an ISO 9001:2015 certified manufacturer of 1.4828 (X15CrNiSi20-12) forged parts — open die forgings and seamless rolled rings from 30 kg to 30,000 kg with ring ODs to 5,000 mm. EN 10204 3.1 MTC is supplied as standard. Submit drawings to sales@jnmtforgedparts.com for a no-cost engineering review and quotation.