1. Optimizing Design and Material Selection
Material Selection: Choose corrosion-resistant materials (such as stainless steel or galvanized bolts) or high-strength alloy steel based on the operating environment (e.g., corrosion and high temperatures). For example, grade 8.8 and grade 10.9 bolts must be designed to match the load requirements.
Structural Design: Avoid stress concentration, standardize the arc transition under the head (e.g., increase the R value), and ensure thread integrity. For large-diameter bolts (e.g., M56 and above), pay special attention to stress concentration at the washer edge.
2. Strict Manufacturing and Quality Control
Raw Material Inspection: Eliminate surface defects such as cracks and folds through magnetic or fluorescent testing. Internal microscopic defects should be detected using metallography.
Heat Treatment: Control the quenching temperature and time to prevent decarburization and inadequate microstructural transformation. High-strength bolts require vacuum heat treatment or shielding gas treatment. Anti-Hydrogen Embrittlement Treatment: Dehydrogenate promptly after electroplating (recommended: 180°C for 4-8 hours). Avoid galvanizing bolts with a tensile strength greater than 1000 MPa.
3. Standardized Installation and Tightening Procedures
Tightening Method: Preferably use the torque-angle-of-action (TAE/TAY) method or the yield point method to ensure accurate preload. For example, the torque for an M10 bolt should be calculated based on the grade (e.g., 39 N·m for grade 8.8, 58 N·m for grade 10.9).
Anti-Loosening Measures: Use lock washers, lock nuts, or high-performance anti-loosening technology (such as improved solutions for hydraulic hammer side plate bolts). Loosening is the primary cause of fracture and requires regular inspection and retightening.
4. Regular Maintenance and Inspection
Non-Destructive Testing: Regularly perform magnetic particle inspection or ultrasonic testing on critical bolts to detect cracks.
Environmental Management: Keep joints clean and dry to reduce corrosion; strengthen vibration monitoring in dynamic load environments.
