ASTM TM18 Thermal bimetal strip
overview
Thermal bimetal strip is by the different expansion coefficient of
two or more than two layers of metal or metal solid combination,
and along the entire interface varies with temperature and the
thermal function of shape changes in composite materials.One of
high expansion coefficient become active layer, low expansion
coefficient becomes passive.When requirements with high
resistivity, but heat sensitive resistance performance is
essentially the same type of thermal bimetal series, can be added
between the two layers of different thickness of middle layer as a
shunt layer, is to achieve the purpose of control different
resistivity.
The basic characteristic of the thermal bimetal is changing with
temperature and temperature deformation, resulting in a certain
moment.Many devices use this feature to convert heat energy into
mechanical work to achieve automatic control.Thermal bimetal used
for control system and temperature sensor in the measuring
instrument.
Main features: Linear temperature range is higher, low thermal
performance, can be used at high temperature.
| shop sign | ASTM TM18 |
| With brand | |
Composite layer
alloybrand | High expansion layer | Ni19Cr2 |
| middle layer | -------- |
| Low expansion layer | Ni42 |
Chemical composition
| shop sign | Ni | Cr | Fe | Co | Cu | Zn | Mn | Si | C | S | P |
| ≤ |
| Ni42 | 41.0~43.0 | - | allowance | - | - | - | ≤0.6 | ≤0.3 | 0.05 | 0.02 | 0.02 |
| Ni19Cr3 | 18.0~20.0 | 2.0~4.0 | allowance | - | - | - | 0.3~0.6 | 0.15~0.30 | 0.25~0.35 | 0.02 | 0.02 |
performance
| Than bending K(20~135ºC) | Temperature curvature
F/(greenhouse ~ 130 ºC) | resistivity | Linear temperature
/ ºC | Allows the use of temperature / ºC | Density (g/cm after) |
| Nominal value | Allowable deviation | Standard values | Allowable deviation |
| Level 1 | Level 2 |
| 11.7 | ±8% | ±10% | 25.7%±10% | 0.7 | ±5% | +90~320 | -70~430 | 8.0 |
