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Home > News > Some tips about iron-chromium-aluminium alloys

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Some tips about iron-chromium-aluminium alloys
2011-04-01

Those are alloys of chemical composition Fe + Cr + Fe with some additional elements and rare earth so as Yttrium, zirconium, Titan, Cerium, and Lanthanum which confer them:
•    An excellent resistance to oxidation under heat
•    A limitation of intergranular oxidation
•    A good life time

Alloys in question are:
Resistohm 125 – 135 – 140 – 145 – Y
Their metallurgical structure confers them nevertheless a cold plasticity lower than austenitic alloys (NiCr).
Advantages of FeCrAl compared with NiCr:
•    A higher resistivity (until 1.44 ohm mm²/m)
•    A temperature of use higher in the air (1300°C against 1200 °C for Resistohm 80)
•    A higher charge rate
•    A good resistance to sulphurous and carbonaceous atmospheres
•    A lower density which means: with an equal weight of material a more important number of elements (a cheaper unit price)
However:
•    A less important plasticity and a more difficult shaping
•    Mechanical behaviour limited and embrittlement after first heat
•    Possibility of corrosion more important because of the iron
•    Phenomenon of “path” more important (striction and elongation of the resistances)

Constraints:
 
•    Pre-oxidation often necessary
•    Minimal content in alumina of the supports: 60 % without iron oxide
•    In furnaces under atmosphere, initial coat of protective oxide to regenerate periodically

 

Related products: Nichrome resistance heating alloy, FeCrAl resistance heating alloy