How does tempering temperature affect the toughness of H13 material?

Tempering temperature has a major impact on the toughness of H13 material. At very low temperatures (<550°C), toughness is low and brittleness is high; the ideal range for overall toughness is between 550 and 600°C, which efficiently releases tension and improves impact resistance.

 

1. The connection between toughness and tempering temperature

Range of Temperatures

Performance of Toughness

Analysis of Causes

<550°C

High brittleness and poor toughness

Unreleased residual stress, unstable martensitic structure, and microcrack susceptibility

The ideal range is 550–600°C.

Ideal toughness

Stress is completely discharged, the structure changes into uniform tempered martensite plus scattered carbides, and it has the best impact resistance over 600°C.

Reduced resilience

Although flexibility somewhat rises, the matrix softens, the carbides coarsen, strength and wear resistance are seriously compromised, and overall service performance declines.

Practical Application: In Wuhan's mold factories, 580℃×2h×2 tempering is a common procedure. Impact toughness ratings that fulfill the demands of high-load circumstances can reach 15–20 J/cm².

 

2. Temperature Control's Effect on Service Efficiency

Repercussions of Not Enough Toughness:

During high-pressure injection molding or stamping, molds are vulnerable to abrupt breakage;

The service life is shortened by the faster propagation of thermal fatigue cracks (crazing);

Early failure is caused by localized stress concentration.

Case Study: After just three days of operation, a company's H13 hot runner nozzles fractured brittlely due to a low tempering temperature (only 530°C). As a result, the entire batch of products was scrapped.

 

3. Crucial Steps to Boost Toughness

Conduct Double Tempering: To totally eradicate stress rebound, cool to ambient temperature after the initial tempering;

Precise Temperature Control: To prevent localized overheating or underheating, use a PID temperature-controlled furnace to guaranty a temperature differential of ≤ ±5°C;

Multi-Point Temperature Measurement Verification: To ensure temperature uniformity, set up temperature measurement points at various points across the furnace;

Maintain Furnace Temperature Curves: To accomplish process traceability, maintain thorough heating and cooling data for every furnace.

"Precise temperature control, sufficient number of tests, and data archiving" are safety concepts that guaranty each batch of H13 workpieces has good toughness and high strength.