Standard: GB /T 4388 - 2008
Available sizes: (6) to 8 (8 sizes)
| Size | P | k_max | s_max | s_min | k_nominal |
|---|---|---|---|---|---|
| (6) | 10 | 135 | 11 | 6 | 120 |
| (8) | 12 | 151 | 13 | 7 | 134 |
| 3.2 | 4 | 87 | 5 | 3.5 | 78 |
| 4 | 5.5 | 99 | 7 | 4.5 | 89 |
| 5 | 7 | 111 | 8 | 4.5 | 99 |
Standard corrosion protection for indoor and mild outdoor environments.
Salt spray: 96–200 hours | RoHS compliant (trivalent chromium)
High-performance coating for automotive, marine, and harsh environments.
Salt spray: 720–1500 hours | Recommended for grade 8.8+
Heavy-duty protection for structural and outdoor applications.
Salt spray: 500–1000 hours | Thread tolerance adjustment required
Note for high-strength fasteners (Grade 10.9, 12.9): Electroplating processes require hydrogen embrittlement relief baking (minimum 4 hours at 200°C within 4 hours of plating). Contact our engineering team for grade-specific plating recommendations.
Request detailed technical specifications, material certifications, and availability information for your application requirements. Our engineering team can provide product recommendations, custom specifications, and technical documentation.
| 5.5 |
| 8 |
| 119 |
| 10 |
| 5.5 |
| 106 |
| 7 | 10 | 135 | 13 | 7 | 120 |
| 8 | 12 | 159 | 14 | 7 | 134 |
© 2026 Ningbo Ruixi Metal Surface Technology Co., Ltd.. All rights reserved.