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Alleima® 253 MA* is an austenitic, chromium-nickel stainless steel alloyed with nitrogen and reactive elements and suitable for a wide range of high-temperature applications, such as recuperators in steel mills and PCI lances for blast furnaces.
The grade provides excellent performance for example, in environments with isothermal and cyclic oxidation, carburizing atmospheres and different combustion and flue gases as well as in salt and metal melts. Alleima® 253 MA can be used at temperatures up to 1150°C (2100°F), depending on the service parameters and application
Alleima® 253 MA has very high resistance to oxidation, especially under cyclic conditions, due to the addition of reactive elements, such as cerium (Ce). The high mechanical strength of Alleima® 253 MA allows for thinner tube wall constructions compared with using materials of the ASTM 310 type. Despite the material's high strength, ductility is not reduced, and good formability is maintained.
One of Turkey's largest steel producers wanted to reduce energy consumption, prolong the service life of furnace recuperators and simultaneously increase production. To make it possible, the recuperators, essential for recovering outgoing heat from the furnaces, had to be able to run at higher temperatures. The challenge was to find a steel grade, which could resist these higher temperatures and meet the new energy reduction, service life and production demands.
After contact with material experts from Alleima, the customer decided to install tubes in Alleima® 253 MA into four recuperators. The changeover to Alleima® 253 MA made it possible to run the recuperators at higher temperatures, thus saving substantially on energy/fuel consumption. At the same time, a production increase of 60% has been achieved.
The old carbon steel tubes in the recuperators lasted about 3 years. The new tubes in Alleima® 253 MA have, so far, been running for 8 years without problems (2012).
* 253 MA is a trademark owned by Outokumpu OY.