Which key point is most sensitive in the tempering curve of H13 material?

The tempering temperature is the most sensitive critical point in the H13 material's tempering curve. The equilibrium between the mold's toughness and wear resistance can be directly impacted by a temperature deviation of more than ±5°C, which can result in a hardness shift of 1~2 HRC.

1. Why is the most sensitive factor the tempering temperature? Factors & Reasons:

Hardness Response: A change of ±10°C can result in a hardness shift of 1~2 HRC within the 550~600°C range. The risk zone is reached when the recommended range is exceeded.

Critical Microstructure Transformation: Low temperatures (<550°C) result in inadequate tempering, which leaves behind high brittleness and residual high-carbon martensite. Overheating (>600°C) results in over-tempering, carbide coarsening, and diminished strength.

Significant Actual Impact: A temperature control problem caused a corporation to set the temperature to 530°C, resulting in a recorded hardness of 53.5 HRC. After just three days online, a brittle fracture happened.

In order to guaranty a furnace temperature differential of ≤±5°C, the recommended control window is 580℃±5°C, together with multi-point temperature measurement and PID temperature control.

PID temperature control and multi-point temperature measurement are used to ensure a furnace temperature differential of ≤±5°C. The recommended control window is 580°C.

2. Other Important Points' Relative Stability

Crucial Point

Level of Sensitivity

An explanation

Tempering Periods

Elevated

It is a discrete variable (one vs. two times), non-continuous fluctuation, and must be done twice.

Keeping Time

Moderate

The impact is less severe than temperature; thick portions only require an extension of +30 minutes for every 25 mm.

Cooling Technique

Moderate

Air cooling is the norm; water cooling or air cooling only becomes problematic if it is used too quickly.

Core Conclusion: The only continuous and extremely sensitive process parameter is temperature; even a slight variation might result in an abrupt shift in performance.

3. How Can Temperature-Sensitive Points Be Accurately Controlled?

When using a PID temperature control system, make sure the difference between the actual and set values is less than or equal to ±5°C.

Multi-point temperature measurement verification: Set up at least three temperature measurement points in the furnace's upper, middle, lower, and corner sections;

Frequent calibration of equipment: Check temperature controls and thermocouples every three months;

Maintain furnace temperature curves: To ensure traceability, keep thorough heating and cooling records for every furnace.