Outokumpu Therma range

Stainless steels for high service temperatures

The Therma range contains heat-resisting stainless steels for use in applications with high service temperatures (≥550°C/1020°F). Ferritic stainless steels have resistance to sulfur containing hot gases and lower thermal expansion. Austenitic stainless steels have resistance to carburizing and nitriding/low oxygen hot gas and higher creep strength.

Key grades

Therma 253 MA 

An austenitic stainless steel with excellent oxidation and creep resistance in cyclic conditions that is best employed in temperatures up to 1150°C/2100°F. There is a slight susceptibility to embrittlement during continuous operation between 600–850°C/1110–1560°F.

Therma 310S/4845

An austenitic product with very good oxidation resistance in general and good oxidation resistance in mildly cyclic conditions that is best employed in temperatures up to 1050°C/1920°F. There is a slight susceptibility to embrittlement during continuous operation between 600–900°C/1110–1652°F.

We believe in the world that lasts forever

Why Therma range

  • Ferritics are resistant to sulfur-containing hot gases and have lower thermal expansion than austenitics.
  • Austenitics are resistant to carburizing and nitriding/low-oxygen hot gases. They also have higher creep strength than ferritics.
  • Due to their higher creep strength and oxidation resistance, Therma MA (micro alloyed) stainless steels give you a longer product lifecycle.
     
  • Why Outokumpu

    • Outokumpu is a global leader in stainless steel, and innovator of the first stainless steels in the world.
    • A strong customer focus, sustainability, and technical excellence are at the heart of everything we do.
    • As a customer you benefit from our strong R&D and technical support.

    Why stainless steel

    • The durability of stainless steel means that it is not only the best, but also the most economically sustainable choice for a wide range of applications.
    • All of our products are made from an average of 85% recycled material and are fully recyclable at the end of their lifecycles.

    Outokumpu Therma stainless steel grades

    Therma 253 MA

    Description An austenitic stainless steel with excellent oxidation and creep resistance in cyclic conditions that is best employed in temperatures up to 1150°C/2100°F. There is a slight susceptibility to embrittlement during continuous operation between 600–850°C/1110–1560°F.

    EN 1.4835

    ASTM type -

    ASTM UNS S30815

    Microstructure Austenitic

    Typical applications

    • Oil industry equipment
    • Conveyor belts
    • Refractory anchors
    • Expansion bellows
    • Radiant tubes
    • Rotary kilns
    • Exhaust manifolds
    • Power generation applications
    • Cyclone dip tubes
    • Impact separators
    • Bell furnaces
    • Muffle furnaces
    • Automotive exhaust components
    • Tube shields
    • Heat treatment trays
    • Dampers
    • Recuperator tubes
    • Large-scale bakery ovens
    • Valves and flanges

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechnanical properties, physical properties and fabrication

    Typical chemical composition, % by mass

    C 0.09

    Cr 21.0

    Ni 11.0

    Mo -

    N 0.17

    Others Si, Ce

    Therma 310S/4845

    Description An austenitic product with very good oxidation resistance in general and good oxidation resistance in mildly cyclic conditions that is best employed in temperatures up to 1050°C/1920°F. There is a slight susceptibility to embrittlement during continuous operation between 600–900°C/1110–1652°F

    EN 1.4845

    ASTM type 310S

    ASTM UNS S31800

    Microstructure Austenitic

    Typical applications

    • Furnace equipment
    • Oil industry equipment
    • Heat treatment baskets
    • Heat exchangers
    • Steam boilers
    • Thermowells
    • Automotive components
    • Valves and flanges

    Typical chemical composition, % by mass

    C 0.05

    Cr 25.5

    Ni 19.1

    Mo -

    N -

    Others -

    Therma 4713

    Description A ferritic low-alloyed stainless steel best employed at 550–800°C/1020– 1470°F when you need higher mechanical loading compared to other ferritic grades. Offers good resistance against sulfur attack compared to nickel-alloyed grades. 

    EN 1.4713

    ASTM type -

    ASTM UNS -

    Microstructure Ferritic

    Typical applications

    • Furnace equipment
    • Air heaters
    • Annealing boxes
    • Conveyor belts
    • Thermowells

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechnanical properties, physical properties and fabrication

    Typical chemical composition, % by mass

    C 0.06

    Cr 6.5

    Ni -

    Mo -

    N -

    Others Al, Si 

    Therma 4724

    Description A ferritic low-alloyed product with improved oxidation resistance in temperatures up to 850°C/1560°F.

    EN 1.4724

    ASTM type -

    ASTM UNS -

    Microstructure Ferritic

    Typical applications

    • Furnace equipment
    • Thermal boiler components
    • Grids
    • Burner nozzles
    • Conveyor belts
    • Thermowells

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechnanical properties, physical properties and fabrication

    Typical chemical composition, % by mass

    C 0.07

    Cr 12.5

    Ni -

    Mo -

    N -

    Others Al, Si

    Therma 4742

    Description A ferritic stainless steel with very good oxidation resistance in temperatures up to 1000°C/1830°F, but which begins to be subject to embrittlement at temperatures above 950°C/1740°F.

    EN 1.4742

    ASTM type -

    ASTM UNS -

    Microstructure Ferritic

    Usage

    • Grids
    • Burner nozzles
    • Conveyor belts
    • Chains
    • Machine parts
    • Cement processing equipment

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechnanical properties, physical properties and fabrication

    Typical chemical composition, % by mass

    C 0.07

    Cr 17.5

    Ni -

    Mo -

    N -

    Others Al, Si 

    Therma 304H/4948

    Description An austenitic Core 304/4301 variant with improved high-temperature creep strength that is best employed in temperatures up to 750°C/1380°F. Offers good formability and weldability.

    EN 1.4948

    ASTM type 304H

    ASTM UNS S30409

    Microstructure Austenitic

    Typical applications

    • Tubes
    • Pressure vessels
    • Valves and flanges

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechnanical properties, physical properties and fabrication

    Typical chemical composition, % by mass

    C 0.05

    Cr 18.1

    Ni 8.3

    Mo -

    N -

    Others -

    Therma 321H/4878

    Description An austenitic heat resisting stainless steel with comparable wet corrosion resistance to Core 321/4541 that is best employed in temperatures up to 850°C/1560°F

    EN 1.4878

    ASTM type 321H

    ASTM UNS -

    Microstructure Austenitic

    Typical applications

    • Furnace equipment
    • Case hardening boxes
    • Valves and flanges

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechnanical properties, physical properties and fabrication

    Typical chemical composition, % by mass

    C 0.05

    Cr 17.3

    Ni 9.1

    Mo -

    N -

    Others Ti 

    Therma 347H

    Description An austenitic heat resisting stainless steel with excellent long-term creep resistance at at 550–600°C/1020–1110°F and comparable wet corrosion resistance to Core 347/4550.

    EN -

    ASTM type 347H

    ASTM UNS S34709

    Microstructure Austenitic

    Usage

    • Oil refineries
    • Fired heater tubes
    • Boiler casings
    • Pressure vessels
    • Reactor vessels
    • Welded tubes
    • Fittings
    • Stack liners
    • Tanks for storing organic chemicals
    • Furnace heating elements
    • Tanks for thermal storage
    • Valves and flanges

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechanical properties, physical properties and fabrication.

    Typical chemical composition, % by mass

    C 0.05

    Cr 17.5

    Ni 9.5

    Mo -

    N -

    Others Nb

    Therma 4828

    Description An austenitic heat resisting stainless steel with improved oxidation resistance in temperatures up to 1000°C/1830°F. There is a slight susceptibility to embrittlement during continuous operation atbetween 600–850°C/1110– 1560°F.

    EN 1.4828

    ASTM type -

    ASTM UNS -

    Microstructure Austenitic

    Typical applcations

    • Furnace equipment (especially supporting parts)
    • Annealing and hardening boxes
    • Air heaters
    • Exhaust systems
    • Automotive components such as turbochargers
    • Valves and flanges

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechanical properties, physical properties and fabrication.

    Typical chemical composition, % by mass

    C 0.05

    Cr 19.3

    Ni 11.2

    Mo -

    N -

    Others Si

    Therma 309S/4833

    Description An austenitic stainless steel with improved oxidation resistance in temperatures up to 1000°C/1830°F. There is a slight susceptibility to embrittlement during continuous operation at 600–900°C/1110–1652°F.

    EN 1.4833

    ASTM type 309S

    ASTM UNS S30908

    Microstructure Austenitic

    Usage

    • Furnace equipment
    • Annealing boxes
    • Thermowells
    • Baffle plates
    • Pots for quenching salt
    • Valves and flanges

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechanical properties, physical properties and fabrication.

    Typical chemical composition, % by mass

    C 0.06

    Cr 22.3

    Ni 12.3

    Mo -

    N -

    Others -

    Therma 153 MA

    Description An austenitic stainless steel with excellent oxidation and creep resistance in cyclic conditions that is best employed in temperatures up to 1050°C/1920°F. This product has an excellent resistance to embrittlement.

    EN 1.4818

    ASTM type -

    ASTM UNS S30415

    Microstructure Austenitic

    Typical applications

    • Recuperators
    • Conveyor belts
    • Expansion bellows
    • Power generation applications
    • Cyclone dip tubes
    • Bell furnaces
    • Muffle furnaces
    • Automotive components
    • Tube shields
    • Heat treatment trays
    • Dampers
    • Valves and flanges

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechanical properties, physical properties and fabrication.

    Typical chemical composition, % by mass

    C 0.05

    Cr 18.5

    Ni 9.1

    Mo -

    N 0.15

    Others Si,Ce

    Therma 314/4841

    Description An austenitic heat resisting stainless steel with excellent oxidation resistance in temperatures up to 1150°C/2100°F. There is a high susceptibility to embrittlement during continuous operation at 600–900°C/1110–1652°F

    EN 1.4841

    ASTM type 314

    ASTM UNS S31400

    Microstructure Austenitic

    Typical applications

    • Furnace equipment
    • Superheater suspensions
    • Enameling grates and hardening boxes
    • Valves and flanges

    Datasheet Download Therma range datasheet for more information on corrosion resistance, mechanical properties, physical properties and fabrication.

    Typical chemical composition, % by mass

    C 0.06

    Cr 24.3

    Ni 19.2

    Mo -

    N -

    Others Si

    Standards and approvals for Therma range

    EN 10028-7 Flat products for pressure purposes – Stainless steels
    EN 10088-1 Stainless steels – Part 1: List of stainless steels
    EN 10088-2 Stainless steels – Corrosion resisting sheet/plate/strip for general and construction purposes
    EN 10088-3 Stainless steels – Corrosion resisting semi-finished products/bars/rods/wire/sections for general and construction purposes
    EN 10088-4 Stainless steel flat products, technical delivery conditions, steels for constructions
    EN 10217-7 Welded steel tubes for pressure purposes – Stainless steel tubes
    EN 10296-2 Welded circular steel tubes for mechanical and general engineering purposes - Stainless Steel tubes
    ASTM A182 / ASME SA-182   Forged or rolled alloy-steel pipe flanges, forged fittings etc. for high temperature service
    ASTM A240 / ASME SA-240 Heat-resisting Cr and Cr-Ni stainless steel plate/sheet/strip for pressure purposes
    ASTM A276 Stainless and heat-resisting steel bars/shapes
    ASTM A479 / ASME SA-479 Stainless steel bars for boilers and other pressure vessels
    Eurocode 3 / EN 1993-1-4 Design of steel structures – Part 1-4: General rules – Supplementary rules for stainless steels
    ISO 15510 Stainless steels – chemical composition

     

    The most commonly used international product standards are given in the table. For a list of standards by product, see steelfinder.outokumpu.com

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