Problem Description: For 316L stainless steel liquid-cooled plate hot forging dies, H13 has a short service life and suffers from rapid die collapse. What die steel should be used?
Frequently Asked Questions: What die steel should be used for liquid-cooled plate hot forging dies? The liquid-cooled plates are made of 316L stainless steel, and the hot forging heating temperature reaches as high as 1100°C, resulting in extremely high operating temperatures for the dies. Currently, many manufacturers use H13 die steel, but they commonly experience short service life and rapid die collapse, making continuous production impossible. Some people are looking for a die steel with “higher hardness” to extend service life—but this is the wrong approach.
Conclusion First: The collapse of the hot-forging die for liquid-cooled plates was not caused by low hardness, but rather by the poor heat resistance of H13, which had been annealed and lost its red hardness. The correct approach is to prioritize the use of 8433, which has excellent heat resistance; for small-sized dies in applications where an outer sleeve is used for clamping, 8566 die steel—which offers both high heat resistance and high hardness—can be selected.
Failure Cause Analysis: The True Mechanism Behind H13 Die Collapse at 1100°C
- H13 die collapse is caused by “annealing,” not “compression”: During the hot forging of 316L liquid-cooled plates, the billet is heated to 1100°C, and the die is exposed to high temperatures for an extended period. H13’s heat resistance is insufficient to withstand tempering softening—resulting in the loss of red hardness and the annealing away of hardness. Consequently, the die loses its load-bearing capacity at high temperatures, leading to collapse and cracking.
- “Increasing hardness” is the wrong approach: The priority order for material selection in hot forging dies is—heat resistance > toughness > hardness. Hardness is the least important factor to prioritize; blindly pursuing high hardness while neglecting heat resistance will not solve the die collapse problem.
Preferred Option: 8433 Heat-Resistant Steel (Large Molds, Deep Cavities)
8433 is a proprietary heat-resistant steel from Yuhui Mold Steel. Key parameters:
| Project | Parameter |
| Heat resistance and stability | 2–3 times that of H13 |
| Hardness | 50-54 HRC |
| Red-hardness characteristics | No annealing is required during its service life; even when the die is worn out, the hardness of its back side does not decrease. |
| Characteristics of the reduced surface | Each time, reducing the surface by 4–5 mm is sufficient to remove the softened layer, while the service life remains unchanged after such reduction. |
Verification Cases:
– Customer producing hot-forged 316L stainless steel swords: After 8,433 cycles of surface reduction (4–5 mm per cycle), service life remained unchanged after removal of the softened layer;
– Customer producing deep-drawn 45 steel products: After 4 cycles of surface reduction, service life remained unchanged, with 10,000 cycles per cycle.
Alternative Option: 8566 Chipping-Resistant Steel (for small dies, round dies, or those secured with an outer sleeve)
If the die is small, secured with an outer sleeve, and requires high heat resistance, high hardness, and high toughness, 8566 Chipping-Resistant Steel is a suitable choice:
| Project | Parameter |
| Resistance to effect of heat | Equivalent to high-speed steel SKH51 |
| Hardness | 58-60 HRC |
| Tenacity | 4 times that of SKH51 |
Customer Feedback: When used in hot-forging dies for stainless steel liquid-cooled plates, the service life was more than three times longer than that of the original dies, while costs were cut in half, demonstrating a clear advantage in terms of cost-effectiveness.
8433 vs 8566:
| Evaluation Dimensions | 8433 | 8566 |
| Mold dimensions | Large-sized mold cavity | Small-sized mold |
| Structure | Deep-cavity integral mold | Circular, with an outer ring tightly fitted |
| Core Requirements | Heat-resistant, resistant to annealing, and long service life | Combines heat resistance, high hardness, and high toughness. |
| Hardness | 50-54 HRC | 58-60 HRC |
| Typical effect | Surface reduction of 4–5 mm without compromising service life | Lifespan increased threefold, while costs were halved. |
All in all, The decision-making sequence for selecting materials for liquid-cooled plate hot-forging dies is as follows: heat resistance is “1,” serving as the foundation for preventing die collapse and cracking; toughness is ‘2’; and high hardness is “3”—small dies capable of withstanding high hardness are generally secured with an outer sleeve. The specific choice between 8433 and 8566 requires a comprehensive assessment based on the product’s shape, die dimensions, and whether an outer sleeve is used.
If you are experiencing issues with die collapse or cracking in your liquid-cooled plate hot forging dies, please provide details about your product, die dimensions, and structure, and we will assist you in selecting the most suitable material.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.