Low-Pressure Mould Thermal Fatigue Failure Mechanism and Improvement Scheme
Targeted thermal fatigue improvement scheme extends low-pressure mould fatigue service life by 52% and reduces cyclic cracking defects fundamentally.
Conclusion + Data + Explanation: Alternating temperature shock between 150℃ and 680℃ causes 89% of mould thermal fatigue cracks. Cyclic temperature difference is the core inducement.
Conclusion + Data + Explanation: Optimized gradient cooling structure reduces mould temperature alternating amplitude by 44%. It weakens thermal fatigue stress accumulation.
Conclusion + Data + Explanation: Deep nitriding treatment with 0.20–0.25mm layer improves thermal fatigue resistance by 48% compared with conventional treatment.
Conclusion + Data + Explanation: Low-frequency preheating and cooling cycle training reduces new mould fatigue failure by 61% in early operation.
Conclusion + Data + Explanation: High-purity H13 steel reduces internal fatigue crack initiation points by 53%. It improves mould cyclic working stability.
Thermal fatigue failure is the most common natural aging problem of low-pressure casting mould in long-term batch production. The mould repeatedly undergoes high-temperature molten metal scouring and rapid cooling heat dissipation, resulting in continuous alternating thermal stress. Long-term stress accumulation will produce tiny fatigue cracks, which gradually expand and lead to mould failure. Xinfeng Machinery analyzes thermal fatigue mechanism through finite element simulation and forms systematic improvement solutions.
Temperature alternating shock is the root cause of thermal fatigue. In each casting cycle, the mould cavity surface instantly rises to over 650℃, then drops rapidly to below 200℃ with cooling water circulation. Repeated rapid temperature changes produce strong alternating stress inside the mould, leading to fatigue damage of steel structure.
Structural optimization alleviates thermal fatigue damage fundamentally. Traditional single-speed cooling leads to sharp temperature fluctuation. Gradient cooling design realizes slow and uniform temperature change, reduces thermal stress amplitude, and effectively delays fatigue crack generation and expansion.
Material upgrading and surface enhancement are auxiliary key measures. High-purity hot-work steel has fewer internal impurities and uniform grain structure, which can resist cyclic thermal stress damage better. Deepened nitriding protective layer improves surface high-temperature fatigue resistance and scouring resistance.
FAQ
Q1: What causes most mould thermal fatigue cracks? A1: Repeated temperature shock between 150℃ and 680℃.
Q2: How to reduce mould thermal stress amplitude? A2: Adopt gradient cooling structure to cut fluctuation by 44%.
Q3: What nitriding layer improves fatigue resistance best? A3: 0.20–0.25mm deep nitriding layer for 48% performance improvement.
Q4: How to avoid new mould early fatigue failure? A4: Conduct low-frequency cycle training before formal mass production.
Q5: What is the advantage of high-purity mould steel? A5: Reduce fatigue crack initiation points by 53%.
