Defects in mold heat treatment

There are many reasons for the failure of forging dies. The right to analyze the failure of the die caused by the heat treatment of the material.
(1) Cracking

1. The internal quality of steel causes cracking: strictly control the internal quality of steel.

2. Coarse original structure: improve the structure through proper pre-heat treatment.

3. The quenching temperature is too high or the holding time is too long: Correctly master the heating treatment to improve the structure.

4. Tempering in the tempering brittle zone: try to avoid tempering in the tempering brittle zone.

5. The tempering temperature is low or the tempering time is insufficient: select the appropriate tempering process.

(2) Crack

1. The raw material has microcracks: strictly control the internal quality of the raw material.

2. Improper heat treatment operation (heating speed is too fast, the coolant is selected improperly, and the cooling time is too long): pay attention to preheating and select a suitable coolant.

3. The mold shape is special, the thickness is uneven, with sharp corners and threaded holes, etc.: the threaded holes are blocked, the sharp corners are filled, the dangerous sections and thin walls are wrapped, and graded quenching is adopted.

4. The surface without intermediate annealing is quenched again: when reworking or refurbishing the mold, annealing or high temperature tempering is required.

5. Failure to temper in time after quenching: Temper in time.

6. Insufficient tempering: to ensure the tempering time, alloy steel should be tempered as many times as required.

7. Improper grinding operation: choose the right grinding process.

8. When EDM is used for machining, there are high tensile stress and microcracks in the hardened layer: improve the EDM process; perform stress relief and tempering; remove the hardened layer by electrolysis or corrosion or other methods.

(3) Deformation

1. There is carbide segregation and accumulation in steel: choose a suitable forging process.

2. Large-scale forging dies use steel grades with low hardenability: Correctly select suitable forging steel grades.

3. Surface decarburization or the surface decarburization layer is not removed during machining: pay attention to heating protection, salt bath deoxidation.

4. The quenching temperature is too high and the heating time is insufficient: strictly control the quenching process.

5. Too little moisture in the alkaline bath: strictly control the moisture in the alkaline bath.

6. Insufficient residence time in the coolant: increase the residence time.

7. The tempering temperature is too high: select the appropriate tempering temperature.