Principle of vacuum heat treatment process and vacuum heat treatment and heating characteristics

1, the process principle, 1) The phase transition characteristics of metal in the vacuum condition. With atmospheric pressure only 0. 1 mpa, within the scope of the vacuum solid-state phase transformation of thermodynamics, dynamics does not produce any change. In making the vacuum heat treatment process procedures, can completely based on the principle of solid-state phase transformation under ordinary conditions. Can refer to all types of organization transformation of data under normal pressure. ( 2) Vacuum degassing effect, improve the physical properties and mechanical properties of metal materials. ( 3) Vacuum degreasing effect. ( 4) Metal evaporation: under the vacuum heating, surface elements evaporation will happen. Watch a variety of metal vapor pressure ( 5) Surface cleaning effect, achieve less without oxidation and less decarburization heat. Metal oxidation reaction is reversible: Mo ≒ 2 m + 2 o 2 o - O2 write depending on the partial pressure of oxygen in the atmosphere and metal oxide of the size of the partial pressure. When the partial pressure of oxygen partial pressure is greater than the metal oxide reaction to the left, the metal surface oxidation. On the other hand, such as oxide of decompression is greater than that of oxygen partial pressure, reaction to the right, as a result, the oxide decomposition. The theory of oxide and carbon element in the vacuum furnace, the furnace points down on metal oxide partial pressure of oxygen, make the metal oxidation. Table 2 vacuum degree and relative impurities and the relative relationship between dew point 2, vacuum heat treatment heating features: two marked characteristics: one is light the stove heating speed, the second is the workpiece heating speed is slow.