Fechral Cr23Al5

Cold-drawn wire from the alloy Cr23Al5 is used for heating and resistance elements. Fechral enclose high electric resistance and low temperature coefficient of the electric resistance and high strain-sensitive, high ductility and high heat-resistance. This resistance alloy is used at temperature to 1330 °C in oxidative, sulphur atmospheres and others.

High oxidation and corrosion stability of the most common manufacturing aggressive mediums was conditioned by the nature chemically inert, thick superficial protective oxide layer on basis of Al2O3. Nickel alloys as against, in contrast to fechral ,for example, neither be used in sulfur mediums not СA-containing atmosphere at 800-950 °C, because at simultaneous oxidation and carburetion, on theirs surfaces have destruction protective oxide with combining "green mould".

Field of applications:

Electric heating of the furnaces are for all branches of industry, household appliances etc. Used in high temperature electric furnaces, firing furnaces and fire drying furnaces, different electric heaters having enhanced, creep resistance, ductility, (including after long exploitation), stability of the form and increased term of exploitation.

Foreign fechrales have higher maximum temperature of operation and more durable compare to nichrome and ferrochrome. Moreover, the fechrals have more stable temperature coefficient of electric resistance, let keep the heating temperature.

Technical information:

Cold-drawn wire from the alloy Cr23Al5 is produced in soft annealed condition diameter 0.1-10 mm according to DIN 17470.

Limiting deflections in diameter of the wire not exceed ±0.100 mm, and the oval of the wire is not more than half of the field tolerance in diameter.

Chemical composition of alloy and typical mechanical and physical properties of the alloy Cr23Al5 are in the table:

Chemical composition, % :
С	≤ 0,05
Cr	20 - 23
Аl	5 - 6
Si	< 0,5
Mn	<0,5
Zr	< 0,3
Y	mах 0,1
Ti,Ca,N2	< 0,1 Σ
Fe	basis

Typical mechanical and special properties:
Tensile Strength, MPa	650-740
Yield Strength, МPа	470-570
Elongation, %	18-34
Density, g/сm3	7,15
Curie point	~600 °C
Melting temperature	1500 °C
Specific electric resistance Оm/mm2/m at 20°C	1,39
Transmissibility in conditions absolute oxidation	0,70

Durability of the alloy, tested the method G, at temperature 1300 °C, compose not less 100 hours.

Advantages:

• High temperature of exploitation – to1330 °C, against 1200 °C for Cr20Ni80.


• High melting temperature - 1500 °C, against 1400 °C for Cr20Ni80.


• Term of employment in 2-4 times longer than nichrome.


• Not high density - 7.15 g/сm3 against 8.4g/сm3 for Cr20Ni80, let economize to 18% on the weight.


• The best corrosion - resistance in the air, vacuum, argon, sulfur and carbon content mediums, water steam.


• High yield strength, let use the wire minimum diameter in connection less changed square cross-section at the coiling.


• High specific resistance – 1.39 Оm_mm2/m against 1.12 for Cr20Ni80.


• Electric resistance does not depend from different forms of heat influence and cold warping.


• Unique correlation of tensile strength or yield strength (~0.5), let use this sphere elasto-plastic deformation.