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模具硬度不足、硬度不均，咋办

Die hardness is not enough, hardness is uneven.

模具热处理硬度是非常重要的力学性能指标，硬度不合格是十分严重的缺陷。模具热处理后硬度不足或硬度不均将使模具耐磨性及疲劳强度等性能降低，导致模具早起失效，严重降低模具的使用寿命。

Hardness of mold heat treatment is a very important mechanical property index, and unqualified hardness is a very serious defect. Insufficient hardness or uneven hardness after heat treatment will reduce the wear resistance and fatigue strength of the die, resulting in early failure of the die, seriously reducing the life of the die.

1.产生原因

1. causes

1）模具截面大，钢材淬透性差，如大型模具选用了淬透性低的钢种。

1) the die cross section is large and the hardenability of the steel is poor, for example, the steel with low hardenability is used in the large mould.

2）模具钢原始组织中碳化物偏析严重或组织粗大，钢中存在石墨碳和碳化物偏析、聚集。

2) Carbide segregation is serious or coarse in the original structure of die steel. Graphite carbon and carbide segregation and aggregation exist in the steel.

3）模具锻造工艺不正确，锻造后未进行很好的球化退火，使模具钢球化组织不良。

3) The die forging process is incorrect, and the die steel is not well spheroidized annealed after forging, resulting in poor spheroidizing structure.

4）模具表面未除净退火或淬火加热时产生的脱碳层。

4) the decarburization layer produced on the die surface without heating or quenching.

5）模具淬火温度过高，淬火后残留奥氏体量过多；或淬火温度过低，加热保温时间不足，使模具钢的相变不完全。

5) If the quenching temperature is too high, too much retained austenite will be retained after quenching, or if the quenching temperature is too low and the heat preservation time is insufficient, the phase transformation of the die steel will be incomplete.

6）模具淬火加热后冷却速度过慢，分级与等温温度过高或时间过长，淬火冷却介质选择不当。

6) The cooling rate of the mold after quenching and heating is too slow, the classification and isothermal temperature are too high or the time is too long, and the quenching cooling medium is improper.

7）碱浴水分过少，或淬火冷却介质中含杂质过多，或淬火冷却介质老化。

7) alkali bath water is too small, or quenching cooling medium contains too much impurities, or quenching cooling medium aging.

8）模具淬火冷却后出淬火冷却介质时温度过高，冷却不足。

8) after quenching, the quenching temperature is too high and the cooling is not enough.

9）回火不充分及回火温度过高等。

9) insufficient tempering and high tempering temperature.

2.对策

2. Countermeasures

1）正确选用模具钢种，大型模具应选用淬透性高的高合金模具钢。

1) choose the type of die steel correctly. Large mould should use high alloy die steel with high hardenability.

2）加强原材料检查，确保原材料符合标准。对不良原材料钢材进行合理的锻造并进行球化退火处理，确保获得良好的组织。碳素工具钢不易多次退火，以防石墨化。

2) strengthen the inspection of raw materials to ensure that the raw materials meet the standards. The bad raw material steel is forged reasonably and spheroidized annealing is carried out to ensure good microstructure. Carbon tool steel is not easy to be annealed repeatedly to prevent graphitization.

3）严格执行锻造工艺和球化退火工艺，保证有良好的预备热处理组织。

3) strictly enforce forging process and spheroidizing annealing process to ensure good preparation heat treatment organization.

4）热处理前应彻底清除模具表面的锈斑和氧化皮，并注意加热时的保护，尽量采用真空加热淬火或保护气氛加热淬火，盐浴加热时应进行良好的脱氧处理。

4) Before heat treatment, the rust spots and oxide scales on the die surface should be thoroughly removed, and the protection during heating should be paid attention to. Vacuum heating and quenching or protective atmosphere should be used as far as possible for heating and quenching. Good deoxidization treatment should be carried out when heating in salt bath.

5）正确制订模具淬火加热工艺参数，确保相变充分，以大于临界冷却速度的冷却速度进行快速冷却，以获得合格的金相组织。

5) Correctly formulate the quenching and heating process parameters to ensure adequate phase transformation and rapid cooling at a cooling rate greater than the critical cooling rate in order to obtain qualified metallographic structure.

6）正确选用淬火冷却介质和冷却方式，严格控制分级与等温温度和时间。

6) properly choose quenching cooling medium and cooling method, strictly control the classification and isothermal temperature and time.

7）要严格控制碱浴水分含量，对长期使用的淬火冷却介质要经常进行过滤及定期更换，并保持清洁，定期检测其淬火冷却特性曲线。

7) The water content in alkali bath should be strictly controlled, the quenching medium used for a long time should be filtered and replaced regularly, and kept clean, and the quenching cooling characteristic curve should be detected regularly.

8）对尺寸大的模具，适当延长浸入淬火冷却介质的时间，防止模具出淬火冷却介质的温度过高。

8) For large size dies, the time of immersion in quenching medium should be prolonged to prevent the temperature of dies out of quenching medium from being too high.

9）模具淬火后应及时、充分回火，并防止回火温度过高。

9) after quenching, the mould should be timely and fully tempered, and prevent the tempering temperature from being too high.

10）对硬度要求高的模具可采用深冷处理（如-110～-196℃）。

10) mold with high hardness can be treated by cryogenic treatment, such as -110 to -196 C.

11）进行表面强化处理。

11) surface strengthening.