Overview

253 MA is a heat-resistant austenitic chromium-nickel stainless steel with high silicon and nitrogen contents and a rare-earth (cerium) micro-addition, developed for high-temperature service where oxidation resistance, creep strength and long-term structural stability are essential. This datasheet presents the material within the American standard system.

It resists oxidation in air up to about 1150 °C (2100 °F) and provides superior service to the 25Cr-20Ni (310-type) grade in carbon-, nitrogen- and sulphur-bearing atmospheres. Its comparatively low nickel content gives an advantage in reducing sulphidising atmospheres relative to high-nickel alloys. The high chromium and silicon, together with the nitrogen and cerium, give good oxide-scale stability and adherence, high elevated-temperature (creep) strength and excellent resistance to sigma-phase precipitation: cerium suppresses oxide-scale spallation during thermal cycling, silicon forms a protective sub-scale that slows oxygen diffusion, and nitrogen provides solid-solution strengthening. The fully austenitic structure gives excellent toughness, even down to cryogenic temperatures. The most suitable temperature range is about 850–1100 °C; prolonged use in the 600–850 °C range can lead to structural changes (embrittlement).

Typical applications include industrial-furnace components and linings, radiant tubes, muffles and retorts, annealing baskets and heat-treatment fixtures, heat exchangers and recuperators, burner components, and other equipment for high-temperature oxidizing or thermally-cycled service. Resistance to oxidizing/reducing sulphur-bearing gases and to aqueous corrosion is limited.

1. Physical Properties

Values per manufacturer (Outokumpu) / reference data, solution-annealed condition.

2. Chemical Composition (wt %)

Composition per ASTM A240.

Nominal: 21Cr-11Ni with ~1.6% Si, ~0.17% N and a rare-earth (cerium) microaddition. Cr + Si + N + Ce together give oxide-scale stability, creep strength and sigma-phase resistance — a service limit of ~1150 °C, higher than the 153 MA / 304-type grades.

3. Mechanical Properties

Typical room-temperature properties, solution-annealed condition.

The nitrogen addition gives high elevated-temperature (creep) strength, while the fully austenitic structure provides excellent toughness from cryogenic to elevated temperatures. Optimum service is ~850–1100 °C. Values are typical or specified minima; confirm against the mill test certificate.

4. Oxidation and High-Temperature Resistance

5. Heat Treatment

An austenitic stainless steel; it cannot be hardened by heat treatment. Strength is increased only by cold work.

Solution Anneal approximately 1020–1120 °C (commonly ~1080 °C), followed by rapid cooling in water or air, to dissolve carbides and secondary phases and produce a uniform austenitic structure with optimum oxidation and creep behaviour.

Prolonged exposure in the ~600–850 °C range can cause structural changes (embrittlement); ductility can be restored by re-solution-annealing followed by rapid cooling. The cerium and nitrogen additions help resist sigma-phase precipitation.

6. Weldability and Joining

Has good weldability and can be joined by submerged-arc, plasma-arc, flux-cored-arc, shielded-metal-arc, gas-tungsten-arc and gas-metal-arc processes. A matching or over-alloyed heat-resistant filler (matching 253-type composition) is used; preheating is not required.

No preheat required. Keep heat input controlled; solution anneal after welding where maximum high-temperature performance is required.

7. Machinability and Fabrication

Machining Guidelines

Forming Processes

8. Applications

9. Available Product Forms and Standards

Heat-resistant Si-N-Ce austenitic stainless steel (21Cr-11Ni). UNS S30815; ASTM A240 / A213 / A312; ASME SA213. Tradename / type: 253 MA.

10. Comparison with Related Alloys (Trade-Name System)

Next：S30815