Nichrome alloys of grades Х20Н80 and Х15Н60 are widely used in modern industry precision alloys of chromium and nickel with high electrical resistance.
Nickel (Ni) is the base metal in these alloys. Its share in nichrome is 55-78%. In second place in terms of quantity is chromium (Cr) - 15-23%. The remaining components of nichrome Х20Н80 and Х15Н60 are silicon (Si), manganese (Mn), aluminum (Al), sulfur (S), iron (Fe), carbon (C), titanium (Ti), phosphorus (P).
The properties of nichrome are determined by its main components - chromium and nickel.
Nickel tends to dissolve a large number of other metals in itself, while maintaining good ductility. Also, this metal has high corrosion resistance in liquid and gaseous media and, as noted above, has good ductility and heat resistance. Chromium, in turn, has high heat resistance, hardness and is also resistant to corrosion.
Thus, nichrome combines good heat resistance, heat resistance and ductility, as well as high corrosion resistance. The heat resistance property determines the maximum operating temperatures of nichrome.
Thus, the thermal resistance threshold for Kh20N80 nichrome is determined at 1200 ° C (depending on the wire diameter or the thickness of the nichrome strip), for the Kh15N60 alloy the thermal destruction threshold is at the level of 1125 ° C.
The more nickel in nichrome, the higher the maximum operating temperature of the resulting alloy. Another noteworthy property of nichrome is plasticity. It belongs to the category of technological properties that show what types of processing (stamping, welding, turning, drawing, etc.) a given material can be subjected to.
Nichrome has good plasticity, which makes it possible to obtain such types of products as nichrome tape and nichrome wire, including very thin wire. To obtain nichrome wire, metal pressure treatment is used - drawing.
It is worth noting the most important physical properties of nichrome - a low temperature coefficient of electrical resistance and a high specific electrical resistance. These properties, together with high heat resistance, determined the use of nichrome in the form of a tape and wire for the manufacture of high-temperature heating elements.
Nichrome wire and nichrome tape are mainly used in electrical engineering. It is used for the manufacture of electric heaters, electric heating elements that operate for a long time in air at temperatures up to 1250 ° C, in wire and strip resistors, rheostats in heating devices. It is also recommended to use nichrome in the manufacture of heaters for high reliability electrothermal equipment.
