What are the performance indicators of H13 material after tempering?

Hardness, toughness, wear resistance, thermal fatigue life, and residual stress level are the primary performance metrics of H13 material following tempering. Together, these metrics establish the mold's dependability and service performance in high-temperature and high-pressure environments.

 

1. Fundamental Performance Measures and Guidelines

Indicators of Performance

Optimal Range Following Tempering

Test Procedure

An explanation

Hardness

48–52 HRC

Multi-point testing and portable hardness tester.

An excessively high hardness suggests brittleness, while an excessively low hardness indicates quick collapse.

Toughness of Impact

15–20 J/cm²

Charpy impact test.

Fracture resistance is reflected; >18 J/cm² is good.

Resistance to Abrasion

greatly improved.

verification of actual working conditions or a ring-block wear test.

Wear resistance is enhanced by finely distributed carbides.

Life of Thermal Fatigue

more than 30% longer.

modulus statistics or the thermal cycling test.

delayed cracking and high microstructure homogeneity.

Remaining Stress

≤100 MPa

X-ray diffraction (XRD).

Overstress might quickly result in early failure or machining cracking.

Practical Case: An H13 hot runner nozzle with a lifespan surpassing 500,000 cycles and a steady hardness of 49.8 HRC and impact toughness of 17.3 J/cm² was tempered at 580°C for two hours and twice.

 

2. Requirements for Metallographic Structure (Microscopic Verification)

Matrix Structure: Fine carbides dispersed widely and uniform tempered martensite;

Absence of Abnormal Structure: absence of network carbides, untempered martensite, and oxidation of grain boundaries;

Structure Consistency: A "hard surface, soft interior" impression is avoided by having no appreciable structural variances between thick and thin sections.

To ensure a clean and homogeneous structure, it is advised to sample at least 5% of each batch and examine it under a 400× microscope.

 

3. Auxiliary Process Indicators The following process controls can be used to indirectly assess performance compliance even in the absence of destructive testing:

Double Tempering: Prior to the second tempering, the furnace must be let to cool to room temperature.

For precise temperature control, use a PID temperature-controlled furnace with a furnace temperature differential of ≤±5°C and a setting of 580°C±5°C.

Adequate Holding Time: Each holding time should be at least two hours; for thicker pieces, add thirty minutes for every twenty-five millimeters of thickness.

Keeping Furnace Temperature Curves: To guaranty traceability, keep thorough heating and cooling records for every furnace.

Safety Principles: The most dependable strategy combines "data archiving, organizational reliability, and performance compliance".