(1) Cracking

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

2. Coarse original tissue: Improve the tissue through appropriate pre-heat treatment.

3. The quenching temperature is too high or the holding time is too long: correctly grasp the heating treatment to improve the organization.

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

5. Low tempering temperature or insufficient tempering time: select the appropriate tempering process.

(2) Cracks

1. Raw materials have microscopic cracks: strictly control the internal quality of raw materials.

2. Improper heat treatment operation (heating speed is too fast, improper coolant selection, and cooling time is too long) : Pay attention to preheating and select the appropriate coolant.

3. The mold shape is special, the thickness is not uniform, with sharp corners and threaded holes, etc. : plugging thread holes, filling sharp corners, wrapping dangerous sections and thin walls, and taking graded quenching.

4. Re-quenching without intermediate annealing surface: When repairing or refurbishing the mold, annealing or high temperature tempering must be carried out.

5. Not tempering in time after quenching: tempering in time.

6. Insufficient tempering: To ensure the tempering time, the alloy steel should be tempered according to the required number of times.

7. Improper grinding operation: Select the correct grinding process.

8. During EDM, there are high tensile stress and microscopic cracks in the hardened layer: improve the EDM process; Stress relief tempering; The hardened layer is removed by electrolysis or corrosion or other means.

(3) Deformation

1. There is carbide segregation and accumulation in steel: choose the right forging process.

2. Large forging die is selected with low hardenability of steel: the right choice of forged steel.

3. Surface decarburization or machining did not remove the surface decarburization layer: pay attention to heating protection, salt bath deoxygenation.

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

5. Too little alkali bath moisture: strictly control alkali bath moisture.

6. Insufficient residence time in coolant: Increase residence time.

7. The tempering temperature is too high: Select an appropriate tempering temperature.