Heat-treated salt bath salts include heated base salts and salt bath correctors.
The salt for heat-treatment salt bath should have suitable melting point and boiling point, low volatility, good fluidity and conductivity, sufficient thermal stability, and should not have chemical reactions with workpieces, electrodes, crucibles, furnace linings, etc. The working temperature of the salt bath should be 100 ~ 200 ℃ higher than the melting point.
Correction agent is used for deoxidation of salt bath, it should have good deoxidation effect, not explode, not easy to crust, clear molten salt, good fluidity, easy to remove slag, non-corrosion and non-adhesion to the workpiece, and easy residue salt Cleaning and other features.
I. Basic salts: Commonly used basic salts are barium chloride, sodium chloride, potassium chloride,
Potassium nitrate and sodium nitrite. The physical properties of the base salt are shown in Table 1, the technical requirements are shown in Table 2, and the heating performance requirements are shown in Table 3.
Second, salt for high temperature salt bath
High temperature salt bath salt land refers to single or multiple base salts used at a temperature above 950 ° C.
Add the mixed salt of the calibrator.
This type of salt is suitable for quenching heating of alloy steel and high speed tool steel. New salts of barium chloride, sodium chloride and potassium chloride must be dehydrated before use. Barium chloride should be kept at 500 ° C for 3-4 hours. Sodium chloride and potassium chloride should be kept at 400 ° C. , Keep warm for 2-4 hours. Barium chloride is a highly toxic drug, and relevant regulations should be controlled to store and store the barium salt residue without chemical treatment before it can be discharged.
Table 4 Compositions of commonly used high and medium temperature salt bath salts
3. Medium temperature bath bath
The salt for medium temperature salt bath refers to a mixed salt in which base salts of various base types are mixed with a corrector at a temperature of 650-950 ° C.