GENERAL INFORMATION

Cold-drawn wire from alloy Fechroma®23 is intended for elements of resistance and heaters. This alloy perfectly combines high electrical resistance and the low temperature coefficient of electric resistance (TCER), a high stain responsiveness, good ductility and excellent heat resistance.

Alloy has a very high maximal working temperature (up to 1350^оС) and it is 2-4 times more durable in comparison with nichrome at operation at high temperatures (1000-1350^оС) in commonly occurring oxidizing, sulfur-containing and other environments. Alloy possesses stable TCER that allows to keep fixated heating systems temperature.

The newest manufacturing techniques of fechral Fechroma®23 provide uniform structure, uniformity of protective oxidic layer and high adhesion of this layer to a surface. In a combination with decrease of carbon level ˂0,03%, the high wire ductility, lack of tendency to intercrystalline high-temperature corrosion, high creep strength and also resistance against oxidation, sulfidization and carburizing at increased temperatures are guaranteed.    High resistance to oxidation and corrosion in the most widespread industrial oxidizing, sulfur-containing, etc. hostile environment, is caused by the nature of chemically inert, dense superficial protective layer on a basis Al₂O₃.

PROCESSING AND THERMAL PROCESSING

Fechroma® 23 can be easily processed by usual industrial technologies. The processed products have to be cleaned and not contain any impurity both before and during heat treatment.

Sulfur, phosphorus, lead and other metals with a low temperature of melting at heat treatment of Fechroma®23 can cause damages. Marking and thermometric paints and pencils, lubricants, liquids and combustible materials can be a source of similar impurity. Fuel has to contain as little sulfur as possible. Natural gas has to contain no more than 0,1% on the mass of sulfur, and the content of sulfur in liquid fuel has to be not higher than 0,5% on weight.

Carrying out heat treatment in electric furnaces is recommended (in a vacuum or inert gas) since in this case it is possible to provide exact control of parameters of temperature and to guarantee lack of impurity.

Gas furnaces are also acceptable, on condition of the low content of impurity and establishment of the atmosphere of the furnace neutral or slightly oxidizing. It is necessary to avoid fluctuation of furnace atmosphere between oxidizing and recovery and also to avoid direct impact of a flame on metal.

HOT DEFORMATION

Fechroma®23 has to be exposed to hot deformation in the range of temperatures 1050-850^оС (1920-1560^оF) with further cooling in water or on air, and passing of a temperature interval of 560-400^оС (1040-750^оF) has to be carried out fast.

Thermal bend is preferable to carry out at a temperature 200-300^оС. Top temperature 400-750^оС (390-570 ^оF) should be avoided.