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Home Product Center Analysis and Countermeasures of Common Defects in Heat Treatment
Countermeasures of Common Defects in Heat Treatment
| Classification | Analysis | Countermeasures |
| Overheating or Overburning |
1) Thermocouple temperature measurement is not accurate, resulting in high temperature. | 1) Regular inspection. |
| 2) Inappropriate material-feeding method. | 2) Achieve even heating. | |
| 3) Batch mixing of different grades of steels. | 3) Differentiating grades of steels before quenching. | |
| Quenching Distortion |
1) Overhigh quenching temperature. | 1) Referring to the introduction of products to adjust the heating temperature, regularly check the temperature measurement device. |
| 2) Inappropriate hoisting during heating and cooling. | 2) Improve the hoisting device; consider the weight of the work piece. | |
| 3) Methods of heating and cooling | 3) Strengthen the preheating, and controlling the cooling velocity after classification. | |
| Quenching Cracking |
1) Shape defect; radius is too small | 1) Increase radius. |
| 2) Overheating or overburning. | 2) Referring to the introduction of products to decide whether to increase temperature or not; regularly check temperature-measuring device. | |
| 3) The residual decarburized layer leads to the difference of transition, which is between surface and central structure. | 3) Control the machining allowance before quenching. | |
| 4) Poor organization of raw materials (carbide segregation is serious). | 4) Control the sources of raw materials, and strengthen inspection. | |
| 5) Inappropriate cooling conditions. | 5) For the work piece of complex shape and uneven thickness, after classification quenching, cooling velocity of martensite transformation temperature range should be reduced or isothermal quenching should be adopted. | |
| 6) Tempering is not timely or inadequate. | 6) Cool to room temperature and timely tempering, and supplementary tempering is needed. | |
| 7) Stress corrosion cracking. | 7) After quenching, washing for cleaning is necessary. The temperature of the work piece and the temperature of water should be controlled well. | |
| Poor Hardness |
For low hardness： | |
| 1) The chemical composition of the steel is not qualified or materials are mixed. | 1) Strengthening material-feeding management | |
| 2) Quenching temperature is too low. | 2) Referring to the introduction of products to decide whether to increase temperature, and adjust the amount of materials for feeding while heating evenly. | |
| 3) Quenching temperature is too High (Serious overheating or overburning). | 3) Referring to the introduction of products to decide whether to increase temperature or not; regularly check temperature-measuring device. | |
| 4) Quenching cooling velocity is slow. | 4) Accelerate quenching cooling. | |
| 5) Tempering furnace-feeding temperature is too high or not sufficient. | 5) Cool to room temperature and timely tempering, and supplementary tempering is needed. | |
| 6) When decarburization (residual raw material and heat treatment process) | 6) Strictly ensure the minimum machining allowance. Check salt bath deoxidation or the vacuum degree in vacuum furnace. | |
| Is at high hardness. | ||
| 7) Quenching temperature is relatively high. | 7) Reduce the heating temperature properly. | |
| Insufficient Tempering |
1) Inaccurate temperature measurement. | 1) Regularly check the temperature measurement device. |
| 2) The amount of materials for feeding furnace is not proper. | 2) Adjust the amount of materials for feeding while heating evenly. | |
| 3) Carbide pile-up of raw materials. | 3) Control the sources of raw materials, and strengthen inspection. |
