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Chromel

Chromel

хромель

Chromel – a metal alloy consisting of several elements: Chromium (Cr) – the content of the order of 8.7 – 10%, nickel (Ni) – content of about 89 – 91%, impurities such as silicon (Si), cobalt (Co), manganese, copper (Cu). Nickel alloy transmits its heat resistance and resistance to corrosion, especially in a corrosive environment. The density of the alloy (Chromel) is 8710 kg / m³, the melting point of 1400 – 1500 ° C, the temperature coefficient of linear expansion – 12.8 · 10-6 ° C-1, the electric resistivity – 0.66 mO * m. Wire Chromel has a high thermoelectric power (generates an electric current in the metal to be contacted with the other site).

The disadvantages include reduced Hromel thermoelectric power during rapid cooling after annealing in the temperature range up to 600 ° C. If the wire is used in measuring devices with a source of heat above 600 ° C – metering accuracy is high enough to 10 ° C. Chromel wire the most widespread than with tape or wheel. It is used in the issuance of compensation wires, resistors, heaters and thermocouples.

Chromel T (NH9,5) and K (NH9)

Chromel NH9,5 NH9 and have high mechanical properties and heat resistance. Chromel NH9,5 used in thermocouples (positive electrode) and chromel NH9 – as compensation wires. At high temperatures, the heat resistance of chromel inferior Nichrome.

The chemical composition of chromel T and K

alloy grade

Main components,%

Impurities,%, no more than

Cr

Co

Ni

Al

Fe

Si

Mg

Mn

Chromel T (НХ9,5)

9,00-10,00

0,60-1,20

Ост

0,15        0,30       0,40      0,05      0,30

Chromel K (НХ9)

8,50-10,00

0,40-1,20

Extension

alloy grade

Impurities,%, no more than

application

Cu

Pb

S

C

P

Bi

As

Sb

Total

Chromel T (NH9,5)

0,25  0,002   0,01   0,20   0,003 0,002 0,002  0,002    1,40

Wire thermoelectrodes thermocouples

Chromel K (NH9)

Wire compensation wires

Physical and mechanical properties of chromel T (NH9,5) and K (NH9)

The melting temperature, ˚ C …………………………………… 1435

Density, g / cm3 8.7 ……………………………………………… ….

The coefficient of linear expansion at 0-1000 ˚ C α × 106 … .12,8

Thermal expansion 1m (mm) at a temperature, ˚ C:

200 ………………………………………………………………… 3

……………………………………………………………… … 700 12

The electrical resistivity, ohm mm2 / m ………………… .0,6-0,7

The temperature coefficient of electrical resistivity at

0-100 ˚ C ………………………………………………………… ..0,00048

Magnetic properties ………………………………………… not is magnetic

Tensile strength δv kgf / mm2:

Soft …………………………………………………………… .60-70

solid (hardening 80%) ………………………………………… …. 110

Elongation δ,%:

Soft …………………………………………………………… .34-45

solid …………… .. ……………………………………………… 3

Hardness HB kgf / mm2:

Soft …………………………………………………………… 150-200

solid …………………………………………………………… .300

Technological properties and modes of processing Chromel T (NH9,5) and K (NH9)

Temperature, ˚ C:

casting ……………………………………………………………… 1550

forging and rolling ……………………………………………… .1180-1220

annealing ………………………………………………………… 800-850 ….

Maximum Operating Temperature, ˚ C ……………………… … 1000

Etchant H2SO4: HNO3 ………………………………………… 1: 1

The temperature of the mold, ˚ C .Before …………………………………… 100

Covering flux ……………………………………………… .steklo

…………………………………………………… Magnesium deoxidizer