Thermal dilatometer is an important measuring tool for thermal expansion of physical properties of materials.Understanding and studying the thermal expansion properties of materials play an important role in engineering design,material research and application development.Thermal expansion not only exists in metal materials,but also widely exists in steel,glass and other materials.

At present,thermal expansion apparatus is widely used in many fields such as metal,refractory,glass and ceramics.The thermal expansion of a substance is based on the fact that the average distance between particles of a constituent substance increases with increasing temperature.

Iron and steel have many types of phase transition properties,and their high-temperature structures and their transition products have different volume densities.Therefore,when the steel sample is heated or cooled,the phase change leads to the volume effect,and the superposition appears on the expansion curve,so that the linear relation between the expansion and the temperature is destroyed.Through thermal expansion measurement,to determine the critical solid steel transition point mendelevium.

The instrument in iron and steel material thermal expansion coefficient were measured,using step temperature or slow speed constant temperature,temperature control,the expansion rod of fused quartz or high alumina solid sample detector relative to the length change of the carrier,through thermal expansion coefficient definition,calculation of instantaneous and average heat coefficient of expansion.