The core of preventing overheating cracks and hot cracks lies in temperature control, process optimization, and material selection. Since their causes differ, targeted strategies are needed to effectively mitigate the risks.
1. Preventive Measures for Overheating Cracks
Measures and Specific Implementation
Strictly control heating temperature. Ensure the hot runner operating temperature is ≤600°C, and the heat treatment temperature must not exceed 1150°C (the overheating critical point for H13 steel).
Avoid prolonged high-temperature holding. Reduce the chance of atomic diffusion at grain boundaries, preventing oxidation and void accumulation.
Dual thermocouple monitoring + automatic alarm. Employ a redundant temperature control system to monitor and record temperature curves in real time, automatically cutting off power if the temperature exceeds the limit.
Select anti-overheating materials. Prioritize the use of microalloyed or powder metallurgy steels such as PM-H13 and H13+Ti/V/Nb.
Practical suggestions: Conduct metallographic sampling inspections before new molds arrive at the factory, and regularly check the grain condition every 6–12 months during operation.
2. Hot Cracking Prevention Measures
Measures and Specific Implementation
Optimize Welding Process Parameters: Control heat input, avoiding excessive welding current and slow cooling rates.
Improve Joint Design and Restraint: Reduce structural rigidity, avoid stress concentration, and use preheating (200–300°C) to reduce thermal stress.
Use Low-Hydrogen Welding Concrete: Select welding electrodes with low water content or gas shielded welding (e.g., Ar+CO₂) to reduce the risk of hydrogen-induced cracking.
Crate Filling and Slow Cooling Treatment: Fill the crater at the end of welding and take measures to maintain heat and slow cooling to reduce solidification shrinkage stress.
Data Support: Preheating + low-hydrogen welding concrete can reduce the incidence of hot cracking by more than 70%.
3. Joint Prevention Mechanism (Systematic Protection)
Establish incoming material inspection standards: Conduct metallographic, chemical composition, and purity analysis on newly purchased materials to ensure the absence of original defects;
Implement a pre-welding inspection system: Before any welding operation, the material condition, temperature control records, and process compliance must be confirmed;
Conduct regular metallographic sampling inspections: Every 3–6 months under high-load conditions to promptly detect grain coarsening or early damage;
Training and standardizing operating procedures: Strengthen operators' ability to identify overheating and hot cracks, and eliminate violations of operating procedures.
Safety Principle: Prevention is better than cure. Through integrated management of "materials + process + monitoring," the risk of cracking can be significantly reduced.
