Outokumpu’s new high-temperature, price-stable Therma 4622Nb™ grade ready to roll

Introduced in early 2024, Therma 4622Nb™ is a stabilized, high-chromium ferritic grade with excellent high-temperature properties such as creep and corrosion resistance. This price-stable grade is ideal for a wide variety of applications including automotive and industrial exhaust systems, furnaces, and burner nozzles.

Containing no nickel, Therma 4622Nb™ is a highly cost-competitive and price-stable grade compared to equivalent nickel-alloyed austenitic grades high service temperatures such as EN 1.4828. 

“Eliminating nickel helps to avoid the price volatility typically associated with austenitic grades,” says Juha Kela, Senior Product Manager, Outokumpu. “This grade is ideal for price-sensitive applications that require excellent high-temperature properties and good corrosion resistance combined with good weldability, formability, and machinability.” 

Smart alloying with niobium (Nb) and silicon (Si) enables good creep resistance up to temperatures of 1000 C, while the high typical chromium content of 21% gives Therma 4622Nb™ good overall corrosion resistance. The grade has successfully passed multiple corrosion-resistance tests including salt spray and short and long-term climate change tests. In addition, Therma 4622Nb™ has good resistance to cyclic oxidation. 

Good formability and machinability, plus excellent weldability

Therma 4622Nb™ can be formed using typical processes including folding, bending, and drawing. The grade also has improved machinability and polishability compared to austenitic grades thanks to its lower work hardening. This speeds up machining processes and enables longer tool life. Therma 4622Nb can be easily welded with conventional methods, using argon or helium-based based shielding gases and 316L filler metals, and exhibits less welding distortion due to the excellent heat transfer properties. 

Availability, standards, and approvals

Therma 4622Nb is available as cold rolled coil and sheets, and in thicknesses of 0.5 – 2.0 mm and widths up to 1250 mm. The grade is covered by the ASTM 240/A240M, ASME SA-240/S-240M, PED Directive 2014/68/EU, and EN 10028-7standards. EN 10088-2 is expected to be published in the near future.