The specific hardness data for H13 material after tempering is typically stable within the range of 48~52 HRC. Through a standardized two-tempering process (e.g., 580℃×2h×2 times), the measured hardness can be precisely controlled within 49~51 HRC, with a single-piece range of ≤2 HRC, demonstrating high batch consistency.
1. Measured Hardness Data under Typical Processes
|
Tempering Temperature |
Holding Time |
Tempering Times |
Measured Hardness (HRC) |
Application Scenarios |
|
550℃ |
2 hours |
2 times |
50.5~52.0 |
High wear resistance requirements, brittleness needs monitoring |
|
580℃ |
2 hours |
2 times |
49.0~51.0 |
Optimal overall performance, mainstream process |
|
600℃ |
2 hours |
2 times |
48.0~50.0 |
High toughness conditions, accepts slight softening |
Case Study from a Mold Factory in Wuhan: After tempering a hot runner nozzle at 580℃ for 2 hours and 2 times, the hardness at 5 measuring points was 49.8, 50.1, 50.3, 49.9, and 50.0 HRC, with an average of 49.9 HRC and a range of only 0.5 HRC. The service life exceeds 500,000 cycles.
2. Key Factors Affecting Hardness Data Consistency
Temperature Control Accuracy: A temperature difference > ±5℃ can cause hardness fluctuations of 1~2 HRC;
Insufficient Tempering Cycles: Hardness often exceeds 52 HRC with only one tempering cycle, resulting in unstable microstructure;
Workpiece Thickness and Holding Time: An additional 30 minutes is required for every 25mm of thickness to ensure sufficient tempering of the core;
Raw Material Composition: Cr, Mo, and V contents must meet standards (Cr: 5.0%~5.5%, Mo: 1.1%~1.75%, V: 0.8%~1.2%).
Abnormal Case: A batch with a tempering temperature lower than 530℃ achieved a measured hardness of 53.5 HRC, and experienced brittle fracture after only 3 days on the production line.
3. Data Verification and Quality Assurance
Multi-point testing: 3-5 points are tested per piece (center, edge, thickness boundary) to ensure a range ≤ 2 HRC;
Metallographic evidence: The microstructure is uniform tempered martensite + dispersed carbides;
Process documentation: Furnace temperature curves and test records are preserved for traceability.
Safety principles: "Data speaks for itself, process is controllable, and microstructure is reliable." The combination of these three principles ensures the authenticity and reliability of hardness data.
