Correlation between physical properties and temperature
(1) Specific heat capacity
With the change of temperature, the specific heat capacity will change, but in the process of temperature change, once phase transformation or precipitation occurs in the metal structure, the specific heat capacity will change significantly< br>
(2) Thermal conductivity
Below 600 ℃, the thermal conductivity of various stainless steels is basically in the range of 10~30w/ (m ·℃). With the increase of temperature, the thermal conductivity tends to increase. At 100 ℃, the order of thermal conductivity of stainless steel is 1Cr17, 00Cr12, 2 Cr 25N, 0 Cr 18ni11ti, 0 CR 18 Ni 9, 0 CR 17 Ni 12m ο 2、2 Cr 25Ni20。 The order of thermal conductivity at 500 ℃ is 1 CR 13, 1 CR 17, 2 Cr 25N, 0 Cr 17ni12m ο 2. 0 Cr 18Ni9Ti and 2 Cr 25ni20. The thermal conductivity of austenitic stainless steel is slightly lower than that of other stainless steels. Compared with ordinary carbon steel, the thermal conductivity of austenitic stainless steel is about 1/4 at 100 ℃< br>
(3) Linear expansion coefficient
In the range of 100-900 ℃, the linear expansion coefficient of main grades of various stainless steels is basically 10 ˉ 6~130*10 ˉ 6℃ ˉ 1, and showed an increasing trend with the increase of temperature. For precipitation hardening stainless steel, the linear expansion coefficient is determined by aging treatment temperature< br>
(4) Resistivity
At 0~900 ℃, the specific resistance of main grades of various stainless steels is basically 70*10 ˉ 6~130*10 ˉ 6 Ω· m, and it tends to increase with the increase of temperature. When used as heating materials, materials with low resistivity shall be selected< br>
(5) Permeability
Austenitic stainless steel has very low permeability, so it is also called non-magnetic material. Steels with stable austenite structure, such as 0 CR 20 Ni 10 and 0 CR 25 Ni 20, will not be magnetic even if they are processed with large deformation greater than 80%. In addition, high carbon, high nitrogen and high manganese austenitic stainless steels, such as 1cr17mn6nisn, 1Cr18Mn8Ni5N series and high manganese austenitic stainless steels, will occur under the condition of large reduction processing ε Phase transition, so it remains non-magnetic. At high temperatures above the Curie point, even strong magnetic materials will lose their magnetism. However, some austenitic stainless steels, such as 1cr17ni7 and 0Cr18Ni9, have a metastable austenite structure. Therefore, martensitic transformation will occur during large reduction cold working or low-temperature processing. They will be magnetic and their permeability will be improved< br>
(6) Elastic modulus
At room temperature, the longitudinal elastic modulus of ferritic stainless steel is 200kn/mm2, and that of austenitic stainless steel is 193kn/mm2, slightly lower than that of carbon structural steel. With the increase of temperature, the longitudinal elastic modulus decreases, Poisson's ratio increases, and the transverse elastic modulus (stiffness) decreases significantly. The longitudinal elastic modulus will have an effect on work hardening and microstructure aggregation< br>
(7) Density
Ferritic stainless steel with high chromium content has low density, while austenitic stainless steel with high nickel content and high manganese content has high density. At high temperature, the density becomes smaller due to the increase of character spacing< br>