Stainless steels for high service temperatures

The Therma range covers heat-resisting stainless steels for use in applications with high service temperatures. A common feature of these Outokumpu high temperature steels is that they are designed primarily for use at temperatures exceeding approximately 550 °C/ 1020 °F. The range covers both austenitic and ferritic steels.

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Therma range for high service temperatures

The Therma range contains heat- and creep-resisting stainless steels with excellent oxidation and creep resistance for use in applications with high service temperatures (≥ 550°C/1020°F).

Austenitic heat- and creep-resisting stainless steels have resistance to carburizing and nitriding/low oxygen hot gas and higher creep strength, in general.

Therma 253 MA/4835 (EN 1.4835) is an austenitic heat-resisting stainless steel with excellent oxidation and creep resistance in cyclic conditions and is best employed in high temperatures up to 1100°C/2012°F.

Therma 310S/4845 (EN 1.4951) is an austenitic heat- and creep-resisting stainless steel with excellent oxidation resistance in mildly cyclic conditions and is best employed in high temperatures up to 1050°C/1920°F.

The ferritic heat-resisting stainless steels Therma 4713 (EN 1.4713) and Therma 4724 (EN 1.4724) have good resistance to sulfur-containing hot gases and lower thermal expansion compared to nickel-alloyed grades. Therma 4713 and Therma 4724 are best employed in temperatures up to 800°C/1470°F and 850°C/1560°F, respectively.

See the full list of Therma grades below

Outokumpu Therma grades

Therma 253 MA stainless steel

Therma 253 MA is 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

Product forms

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

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Therma 310S/4845 stainless steel

Therma 310S/4845 is 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 S31008

Microstructure Austenitic

Typical applications

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

Product forms

Datasheet

Download Therma range datasheet

Typical chemical composition, % by mass

C 0.05

Cr 25.5

Ni 19.1

Mo -

N -

Others -

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Therma 4950

A austenitic creep resisting stainless steel for use in temperature up to 1000°C

EN 1.4950

ASTM type 309S

ASTM UNS S30908

Microstructure Austenitic

Typical applications

  • Furnaces

Product forms

Chemical composition, % by mass

C 0.06

Cr 22.3

Ni 12.3

Mo -

N -

Others -

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Therma 4951

A austenitic creep resisting stainless steel for use in temperature up to 1050°C

EN 1.4951

ASTM type 310S

ASTM UNS S31008

Microstructure Austenitic

Typical applications

  • Furnaces

Product forms

Chemical composition

C 0.05

Cr 25.5

Ni 19.1

Mo -

N -

Others -

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Therma 4878

A austenitic heat resisting stainless steel, stabilized 304, for use in temperatures up to 800°C

EN 1.4878

ASTM type -

ASTM UNS -

Microstructure Austenitic

Typical applications

  • Heating elements

Product forms

Chemical composition, % by mass

C 0.05

Cr 17.3

Ni 9.1

Mo -

N -

Others Ti

Please remove item from comparison before you can add another one

Therma 316H

A high carbon 316 version for use at elevated temperatures

EN -

ASTM type 316H

ASTM UNS S31609

Microstructure Austenitic

Product forms

Chemical composition, % by mass

C 0.04

Cr 17.1

Ni 10.1

Mo 2.1

N -

Others -

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Therma Alloy 800/800H/800T

Outokumpu Therma Alloy 800/800H/800T is a series of high-temperature alloys design for high creep strength, resistance to carburization, oxidation, and other types of high-temperature corrosion. Therma Alloy 800 series (EN 1.4876/1.4958/1.4959 UNS, N08800/N08810/N08811) are stabilized austenitic alloys with high Nickel and Chromium content as well as controlled additions of Carbon, Titanium and Aluminum. Additionally, grain size is controlled for improved creep strength properties.

EN 1.4876 1.4958 1.4959

ASTM UNS N08800 N08810 N08811

Microstructure Austenitic

Typical applications

  • General high-temperature service
  • Steam/hydrocarbon reformers
  • Ethylene pyrolysis
  • Acetic anhydride cracking furnaces
  • Heat exchangers
  • Heating element sheaths
  • High temperature process equipment

Product forms

Datasheet

Download Therma 800 datasheet

Typical chemical composition, % by mass

C <0.10

Cr 21

Ni 31

Mo -

N -

Others Ti, Al

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Therma 4713 stainless steel

Therma 4713 is 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

Product forms

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 

Please remove item from comparison before you can add another one

Therma 4724 stainless steel

Therma 4724 is 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

Product forms

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

Please remove item from comparison before you can add another one

Therma 304H/4948 stainless steel

Therma 304H/4948 is an austenitic Core 304/4301 variant with improved high-temperature creep strength that is best employed in temperatures up to 750°C/1380°F. It offers good formability and weldability.

EN 1.4948

ASTM type 304H

ASTM UNS S30409

Microstructure Austenitic

Typical applications

  • Tubes
  • Pressure vessels
  • Valves and flanges

Product forms

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 -

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Therma 321H/4878 stainless steel

Therma 321H/4878 is 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

Product forms

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 

Please remove item from comparison before you can add another one

Therma 347H stainless steel

Therma 347H is 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

Typical applications

  • 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

Product forms

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

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Therma 4828 stainless steel

Therma 4828 is 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

Product forms

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

Please remove item from comparison before you can add another one

Therma 309S/4833 stainless steel

Therma 309S/4833 is 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

Typical applications

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

Product forms

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 -

Please remove item from comparison before you can add another one

Therma 314/4841 stainless steel

Therma 314/4841 is 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

Product forms

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

Please remove item from comparison before you can add another one

Go directly to Outokumpu Therma grades

Standards and approvals

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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