🔬 What Is 253MA Stainless Steel?
This article covers the metallurgy, properties and applications of 253MA stainless steel. For product dimensions, available forms and quotation, see the 253MA forged parts product page.
253MA stainless steel (designated UNS S30815 in the United States and EN 1.4835 in Europe) is an austenitic, heat-resistant stainless steel engineered for continuous or cyclic service in oxidizing, high-temperature environments. It was developed by Avesta Sheffield — now part of Outokumpu — as a cost-effective replacement for alloy grades 310 and 446, using silicon and rare earth metals (REM), primarily cerium, to deliver superior oxidation protection through a distinct metallurgical mechanism.
The designation "253MA" is a trade name. "253" loosely references its chromium (~21%) and nickel (~11%) target levels; "MA" stands for Modified Austenite — reflecting the nitrogen and rare earth additions that distinguish it from conventional chromium-nickel grades.
253MA maintains both oxidation resistance and structural strength above 900°C — its rare-earth-modified oxide scale makes it the preferred alloy for the 900–1100°C oxidizing service range across petrochemical, power generation, cement, and furnace industries worldwide.
⚙ Key Metallurgical Fact
The cerium addition (~0.05 wt%) creates a mixed Cr₂O₃–CeO₂ oxide scale that adheres more tightly during thermal cycling than a pure chromia scale — the primary reason 253MA outperforms Grade 310S in intermittent service.
🌐 Global Designations & Equivalents
253MA stainless steel is sold under multiple international designation systems. You may encounter any of the following for the same alloy:
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Table 1: International Equivalents for 253MA Stainless Steel
| System | Designation | Region / Authority |
|---|
| Trade Name | 253MA / Therma 253 MA | Outokumpu (Global) |
| UNS Number | S30815 | USA — ASTM / SAE |
| EN Material No. | 1.4835 | Europe — EN / DIN |
| Swedish Standard | SS 2368 | Sweden — SIS |
| ASTM Standards | A182 / A240 / A476 / A479 / A473 | USA — ASTM International |
| DIN Near-Equivalent | 1.4893 | Germany |
📌 Procurement Tip
Always request the material certificate to EN 10204-3.1 (manufacturer's own lab — Jiangsu Liangyi standard) or EN 10204-3.2 (independent third-party inspection, available on request). These are the internationally recognised traceability standards for critical forged alloy components.
⚗️ Chemical Composition of 253MA (UNS S30815)
The performance of 253MA stainless steel is rooted in its precisely balanced chemistry. The table below reflects nominal and permissible ranges per the UNS S30815 specification:
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Table 2: 253MA (UNS S30815) Chemical Composition — Weight %
| Element | Min % | Max % | Role |
|---|
| Chromium (Cr) | 20.0 | 22.0 | Primary oxidation resistance — forms Cr₂O₃ scale |
| Nickel (Ni) | 10.0 | 12.0 | Austenite stabilizer; lower than 310 for better sulfidation resistance |
| Silicon (Si) | 1.4 | 2.0 | Enhances scale adhesion with REM additions |
| Nitrogen (N) | 0.14 | 0.20 | Solid-solution strengthener at elevated temperature |
| Rare Earth Ce/La | 0.03 | 0.08 | Signature element: anchors oxide scale, prevents thermal spalling |
| Carbon (C) | — | 0.10 | Low to minimise sensitisation at grain boundaries |
| Manganese (Mn) | — | 0.80 | Austenite stability; minor deoxidation |
| Iron (Fe) | Balance | Matrix / base metal |
💡 Why Lower Nickel Is Advantageous
253MA's moderate nickel content (10–12% Ni) gives better sulfidation resistance versus Grade 310 (19–22% Ni) in SO₂ or H₂S-containing combustion gases — extending service life in refinery heaters, waste incinerators and biomass boilers at lower alloy cost.
📊 Mechanical Properties
Room-temperature properties for 253MA (UNS S30815) in the solution-annealed condition:
600
MPa — Min. Tensile
UTS at room temp.
310
MPa — Min. Yield
0.2% proof stress, annealed
40
% — Min. Elongation
In 50 mm gauge length
95
HRB — Hardness
Typical Rockwell B, annealed
7.8
g/cm³ — Density
Similar to standard austenitic
15.6
W/m·K
Thermal conductivity at 100°C
Elevated-Temperature Tensile Properties
253MA's nitrogen addition provides solid-solution strengthening that remains active at temperatures where conventional grades have degraded:
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Table 3: 253MA Tensile Properties at Elevated Temperatures (Annealed)
| Temperature | 0.2% Proof Stress | Tensile Strength | Elongation |
|---|
| 20°C (RT) | 310 MPa | 600 MPa | 40% |
| 400°C | 175 MPa | 430 MPa | 38% |
| 700°C | 130 MPa | 280 MPa | 36% |
| 900°C | 90 MPa | 160 MPa | 50% |
| 1000°C | 60 MPa | 100 MPa | 55% |
🌡️ High-Temperature Behavior
Oxidation Resistance Up to 1100°C
253MA resists oxidation up to 1100°C (2012°F) continuously and ~1150°C intermittently. The cerium addition creates an adherent Cr₂O₃–CeO₂ scale that stays bonded during thermal cycling — preventing the chromium depletion that limits conventional grades. This is the key reason 253MA is preferred over 310S for batch furnace and cyclic-heating applications.
Creep Resistance
Creep — time-dependent plastic deformation under sustained load at elevated temperature — is the critical failure mode for furnace hangers, heat exchanger tubes and support structures above 700°C. 253MA's nitrogen content (0.14–0.20%) significantly improves creep rupture strength compared to nitrogen-free grades like 304H or 310S.
Sulfidation & Carburization Resistance
In SO₂/H₂S-containing atmospheres, 253MA's lower Ni content (10–12% vs 19–22% in Grade 310) provides better resistance to sulfide attack. Silicon also assists in forming a barrier scale that slows carbon ingress in carburizing atmospheres.
⚠ Embrittlement Risk
253MA shows mild susceptibility to sigma-phase embrittlement during long-term service at 600–850°C. Heating above 1050°C fully dissolves sigma phase and restores impact toughness. Consider this in design for components cycling through this range.
🔨 The 253MA Forging Process
Forging is the optimal manufacturing route for 253MA (UNS S30815) components in critical service — refining grain structure, closing porosity and producing directional properties impossible in castings.
01
Melting — ESR or VIM+ESR
High-quality input material is produced by Electro-Slag Remelting (ESR) or VIM+ESR. ESR removes non-metallic inclusions and produces a homogeneous ingot with consistent rare-earth distribution throughout the cross-section — the foundation of uniform oxidation performance in the finished forging.
02
Ingot Heating
Ingots are heated to the forging window of 1050–1200°C (1920–2190°F). Extended soaking must be avoided — 253MA is susceptible to excessive austenite grain growth during prolonged holds, which degrades impact toughness of the finished forging.
03
Hot Forging
Forging is performed between 1100°C and a minimum finish temperature of 900°C (1650°F). Working within this window achieves grain refinement while maintaining adequate deformability. Below 900°C, 253MA work-hardens rapidly and risks surface cracking.
04
Solution Annealing
Full solution annealing at 1050–1150°C for 10–15 min per 25 mm, followed by rapid air or water cooling, dissolves carbides and secondary phases to restore maximum corrosion resistance, toughness and oxidation performance.
05
Testing, NDE & Certification
Each heat lot includes: chemistry by OES/ICP (with REM content confirmed), mechanical testing (tensile, Charpy impact) and NDE (UT, PT or MT per specification). EN 10204-3.1 certificates are issued as standard; EN 10204-3.2 third-party inspection is available on request.
🔧 Welding & Fabrication
253MA has good weldability by standard austenitic stainless processes. Low carbon (max 0.10%) reduces sensitisation risk in the heat-affected zone.
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Table 4: Recommended Filler Metals for Welding 253MA (UNS S30815)
| Process | Filler | Notes |
|---|
| GTAW / TIG | ER 253MA (ER S30815) | Best match; preferred for root passes and thin-wall tubing |
| GMAW / MIG | ER 253MA | Fill and cap passes in thicker sections |
| SMAW / Stick | E 253MA | On-site repair and maintenance welding |
| SAW | 253MA wire + flux | High-volume production welding of heavy sections |
Key Guidelines
Preheat: Not required. Interpass temperature: Keep below 150°C to minimise HAZ grain growth. PWHT: Not mandatory; full solution anneal at 1050–1150°C recommended for critical applications above 900°C. Machining: Use sharp positive-rake carbide tooling; maintain consistent cut depth; apply cutting fluid to manage work-hardening.
🏭 Industrial Applications
253MA forged parts (UNS S30815) are specified across a wide range of high-temperature industries due to their superior oxidation resistance, creep strength and competitive cost:
🔥
Heat Treatment Furnaces
Radiant tubes, muffle tubes, furnace rolls, kiln furniture, retorts and structural hangers.
⛽
Petrochemical & Refinery
Tube hangers, burner tips, reformer basket components, heat exchanger heads, expansion bellows.
⚡
Power Generation
Boiler components, superheater tube hangers, steam generator internals, FGD system parts.
🏗️
Cement & Lime Industry
Kiln nose rings, grate cooler components, burner pipes, preheater cyclone parts.
🍬
Sugar & Food Processing
Evaporator internals, heat exchangers and vapor pipelines in moderate-temperature corrosive environments.
🛢️
Oil & Gas
Downhole tool components, wellhead fittings, drilling rig parts and pipeline fittings at elevated temperatures.
⚙️
Pumps & Compressors
Impellers, diffuser rings, pump casings and shaft sleeves in hot gas compressors and process pumps.
🧪
Chemical Processing
Reactor vessel internals, agitator shafts, crystallizer components and centrifuge bowls.
Common product forms include flanges, seamless rolled rings, discs, round bars, shafts and near-net shapes in a wide range of dimensions and weights. Each form is produced to customer drawing and specification.
⚖️ 253MA vs Other Grades
Understanding where UNS S30815 (253MA) sits relative to comparable alloys:
Property
Grade 310S
253MA (S30815) ★
Grade 304H
Max. Cont. Temp.
1050°C
1100°C Best
870°C
Cyclic Oxidation
Good
Superior Best
Moderate
Creep @ 900°C
Moderate
Higher (N) Best
Low
Nickel Content
19–22%
10–12% ✓
8–11%
Sulfidation Resist.
Moderate
Better Best
Poor >700°C
Relative Cost
High
Medium ✓
Low
253MA vs 316L: When to Upgrade
For service above 600–700°C, 316L lacks the required oxidation resistance and creep strength. 253MA is the correct specification. 316L remains preferred for room-temperature chloride corrosion environments.
When to Consider Alternatives
For sustained service above 1100°C continuous, consider Alloy 600, Alloy 800H or Alloy 230. For extreme creep above 1000°C, Alloy 617 or 740H are appropriate. 253MA is optimal for the 900–1100°C oxidizing range.
📋 Standards & Certifications
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Table 5: Standards Applicable to 253MA (UNS S30815) Forgings
| Standard | Scope | Relevance |
|---|
| ASTM A182 | Forged fittings, valves, flanges | Primary forging standard; S30815 listed |
| ASTM A479 | Stainless bars and shapes for boilers | Forged bar supply condition |
| ASTM A473 | Stainless steel forgings | Directly applicable to forged shapes |
| EN 10204-3.1 | MTC — manufacturer's own lab | Standard document with all Jiangsu Liangyi forgings |
| EN 10204-3.2 | MTC — independent third-party | Available on request for critical pressure equipment |
| NACE MR0175 / ISO 15156 | Sour service — H₂S environments | Relevant for oil & gas applications |
| PED 2014/68/EU | European Pressure Equipment Directive | Required for pressure parts shipped to EU projects |
🏭 Jiangsu Liangyi Certification
Jiangsu Liangyi Co., Limited holds ISO 9001:2015 quality management system certification. All 253MA forgings are supplied with EN 10204-3.1 material test certificates as standard. Independent EN 10204-3.2 third-party inspection is available on request — please state this requirement at the RFQ stage.
🤝 What to Check When Sourcing 253MA Forgings
A
Verify the Melting Route
Ask the supplier to confirm ESR or VIM+ESR input material on the MTC. EAF-only ingots may have uneven inclusion content and inconsistent rare-earth distribution — compromising oxidation performance.
B
Specify Inspection Level at RFQ Stage
For pressure vessels and safety-critical parts, specify EN 10204-3.2 from the outset. Also define NDE scope: UT acceptance class, PT or MT method and acceptance criteria per your design code.
C
Provide a Fully Dimensioned Drawing
Supply a technical drawing with complete dimensions, tolerances, surface finish (Ra), machined vs. as-forged surfaces, test sample orientation and marking requirements. Contact Jiangsu Liangyi with your specific requirements for a capability confirmation.
D
Review the MTC Before Shipment
The material test report must include: heat/lot number; full chemistry including confirmed REM content; mechanical test results; heat treatment record; NDE results; and dimensional compliance sign-off. Only release the shipment after reviewing and accepting the full MTC.
To request a quotation for custom 253MA forgings, visit the 253MA (UNS S30815) forging specifications and quotation page or contact us directly.
❓ Frequently Asked Questions
QWhat is 253MA stainless steel and what does the name mean?
253MA is an austenitic, heat-resistant stainless steel (UNS S30815 / EN 1.4835) developed by Avesta Sheffield (now Outokumpu). "253" approximately references its chromium (~21%) and nickel (~11%) content, while "MA" stands for Modified Austenite — describing the nitrogen and rare earth additions. It is designed for continuous oxidizing service up to 1100°C (2012°F).
QWhat is the maximum service temperature for 253MA stainless steel?
253MA (UNS S30815) can be used continuously up to 1100°C (2012°F) and intermittently up to ~1150°C (2100°F), exceeding Grade 310S (1050°C) and 316L (870°C).
QWhat is the difference between 253MA, UNS S30815, 1.4835 and SS 2368?
They are all the same alloy. 253MA is the Outokumpu trade name. UNS S30815 is the US ASTM/SAE designation. 1.4835 is the European EN/DIN material number. SS 2368 is the Swedish SIS designation. All refer to identical chemical composition.
QIs 253MA stainless steel magnetic?
No. 253MA (UNS S30815) is fully austenitic in all conditions and therefore non-magnetic. Confirm with a magnet test or Feritscope measurement — a properly annealed 253MA forging should show near-zero ferrite content.
QCan 253MA forgings be used in pressure vessel and boiler service?
Yes. UNS S30815 is listed in ASTM A182 and ASTM A473 and is approved under the ASME Boiler and Pressure Vessel Code. The material certificate must reference the applicable ASTM standard and the inspection must meet the design code requirements.
QDoes 253MA require post-weld heat treatment?
PWHT is generally not required for 253MA. For demanding applications above 900°C, a full solution anneal at 1050–1150°C of the completed weldment is recommended. Recommended filler metal is ER 253MA (ER S30815) for TIG welding.
QWhat certifications does Jiangsu Liangyi hold?
Jiangsu Liangyi Co., Limited holds ISO 9001:2015 quality management system certification. All 253MA forgings are supplied with EN 10204-3.1 material test certificates as standard. Third-party EN 10204-3.2 inspection is available on request. Please specify additional inspection or certification requirements at the RFQ stage.
View 253MA (UNS S30815) Product Specifications
Jiangsu Liangyi Co., Limited manufactures custom 253MA forged parts to customer drawings — round bars, rings, discs, flanges, hubs and near-net shapes. Full dimensional and material specifications, available product forms and quotation enquiry are on our dedicated product page.
View 253MA Product Specifications & Available Forms →
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