Description and Translation of GB/T 70.1 Fasteners
GB/T 70.1 fasteners, a key Chinese standard for mechanical components, function as hexagon socket head cap screws widely used in precision machinery, automotive assemblies, and electrical equipment. Their primary role is to provide high-strength detachable connections, transmitting axial clamping forces while enabling installation in confined spaces due to their recessed drive design. These screws ensure precise component positioning and reliable performance in applications requiring secure fastening with minimal head protrusion.
In terms of materials, GB/T 70.1 fasteners are predominantly manufactured from alloy steel (e.g., 8.8, 10.9, and 12.9 grades per GB/T 3098.1) and high-quality carbon steel, offering excellent tensile strength and mechanical durability. For corrosion-resistant requirements, stainless steel variants (e.g., 304, 316) compliant with relevant standards are specified to ensure performance in humid or chemically exposed environments.
Surface treatments include zinc plating with passivation for enhanced rust resistance, black oxide coating for increased wear resistance and aesthetic appeal, and phosphating to improve lubrication during installation. These treatments effectively extend service life and optimize compatibility with various operating conditions.
Key characteristics of GB/T 70.1 fasteners include fine metric threads, cylindrical heads with hexagonal sockets, and precise dimensional tolerances ensuring interchangeability. Their mechanical attributes feature specified tensile strengths (minimum 800 MPa for 8.8 grade, up to 1220 MPa for 12.9 grade), appropriate hardness values, and excellent torque transmission. Additionally, they exhibit consistent clamping performance and high precision, making them indispensable in precision engineering and high-load mechanical assemblies.
| Thread Size d | M1.6 | M2 | M2.5 | M3 | M4 | M5 | M6 | M8 | M10 | M12 | ||||
| P | Pitch | 0.35 | 0.4 | 0.45 | 0.5 | 0.7 | 0.8 | 1 | 1.25 | 1.5 | 1.75 | |||
| dk | max | For plain head | 3 | 3.8 | 4.5 | 5.5 | 7 | 8.5 | 10 | 13 | 16 | 18 | ||
| For knurled heads | 3.14 | 3.98 | 4.68 | 5.68 | 7.22 | 8.72 | 10.22 | 13.27 | 16.27 | 18.27 | ||||
| min | 2.86 | 3.62 | 4.32 | 5.32 | 6.78 | 8.28 | 9.78 | 12.73 | 15.73 | 17.73 | ||||
| ds | max | 1.6 | 2 | 2.5 | 3 | 4 | 5 | 6 | 8 | 10 | 12 | |||
| min | 1.46 | 1.86 | 2.36 | 2.86 | 3.82 | 4.82 | 5.82 | 7.78 | 9.78 | 11.73 | ||||
| k | max | 1.6 | 2 | 2.5 | 3 | 4 | 5 | 6 | 8 | 10 | 12 | |||
| min | 1.46 | 1.86 | 2.36 | 2.86 | 3.82 | 4.82 | 5.7 | 7.64 | 9.64 | 11.57 | ||||
| s | Nominal Size | 1.5 | 1.5 | 2 | 2.5 | 3 | 4 | 5 | 6 | 8 | 10 | |||
| max | Gread 12.9 | 1.545 | 1.545 | 2.045 | 2.56 | 3.071 | 4.084 | 5.084 | 6.095 | 8.115 | 10.115 | |||
| other performance levels | 1.56 | 1.56 | 2.06 | 2.58 | 3.08 | 4.095 | 5.14 | 6.14 | 8.175 | 10.175 | ||||
| min | 1.52 | 1.52 | 2.02 | 2.52 | 3.02 | 4.02 | 5.02 | 6.02 | 8.025 | 10.025 | ||||
| t | min | 0.7 | 1 | 1.1 | 1.3 | 2 | 2.5 | 3 | 4 | 5 | 6 | |||
| Weight of per 1000 steel products(≈kg) | - | |||||||||||||
| Length of Thread b | Ref. | |||||||||||||
Description and Translation of GB/T 70.1 Fasteners
GB/T 70.1 fasteners, a key Chinese standard for mechanical components, function as hexagon socket head cap screws widely used in precision machinery, automotive assemblies, and electrical equipment. Their primary role is to provide high-strength detachable connections, transmitting axial clamping forces while enabling installation in confined spaces due to their recessed drive design. These screws ensure precise component positioning and reliable performance in applications requiring secure fastening with minimal head protrusion.
In terms of materials, GB/T 70.1 fasteners are predominantly manufactured from alloy steel (e.g., 8.8, 10.9, and 12.9 grades per GB/T 3098.1) and high-quality carbon steel, offering excellent tensile strength and mechanical durability. For corrosion-resistant requirements, stainless steel variants (e.g., 304, 316) compliant with relevant standards are specified to ensure performance in humid or chemically exposed environments.
Surface treatments include zinc plating with passivation for enhanced rust resistance, black oxide coating for increased wear resistance and aesthetic appeal, and phosphating to improve lubrication during installation. These treatments effectively extend service life and optimize compatibility with various operating conditions.
Key characteristics of GB/T 70.1 fasteners include fine metric threads, cylindrical heads with hexagonal sockets, and precise dimensional tolerances ensuring interchangeability. Their mechanical attributes feature specified tensile strengths (minimum 800 MPa for 8.8 grade, up to 1220 MPa for 12.9 grade), appropriate hardness values, and excellent torque transmission. Additionally, they exhibit consistent clamping performance and high precision, making them indispensable in precision engineering and high-load mechanical assemblies.
| Thread Size d | M1.6 | M2 | M2.5 | M3 | M4 | M5 | M6 | M8 | M10 | M12 | ||||
| P | Pitch | 0.35 | 0.4 | 0.45 | 0.5 | 0.7 | 0.8 | 1 | 1.25 | 1.5 | 1.75 | |||
| dk | max | For plain head | 3 | 3.8 | 4.5 | 5.5 | 7 | 8.5 | 10 | 13 | 16 | 18 | ||
| For knurled heads | 3.14 | 3.98 | 4.68 | 5.68 | 7.22 | 8.72 | 10.22 | 13.27 | 16.27 | 18.27 | ||||
| min | 2.86 | 3.62 | 4.32 | 5.32 | 6.78 | 8.28 | 9.78 | 12.73 | 15.73 | 17.73 | ||||
| ds | max | 1.6 | 2 | 2.5 | 3 | 4 | 5 | 6 | 8 | 10 | 12 | |||
| min | 1.46 | 1.86 | 2.36 | 2.86 | 3.82 | 4.82 | 5.82 | 7.78 | 9.78 | 11.73 | ||||
| k | max | 1.6 | 2 | 2.5 | 3 | 4 | 5 | 6 | 8 | 10 | 12 | |||
| min | 1.46 | 1.86 | 2.36 | 2.86 | 3.82 | 4.82 | 5.7 | 7.64 | 9.64 | 11.57 | ||||
| s | Nominal Size | 1.5 | 1.5 | 2 | 2.5 | 3 | 4 | 5 | 6 | 8 | 10 | |||
| max | Gread 12.9 | 1.545 | 1.545 | 2.045 | 2.56 | 3.071 | 4.084 | 5.084 | 6.095 | 8.115 | 10.115 | |||
| other performance levels | 1.56 | 1.56 | 2.06 | 2.58 | 3.08 | 4.095 | 5.14 | 6.14 | 8.175 | 10.175 | ||||
| min | 1.52 | 1.52 | 2.02 | 2.52 | 3.02 | 4.02 | 5.02 | 6.02 | 8.025 | 10.025 | ||||
| t | min | 0.7 | 1 | 1.1 | 1.3 | 2 | 2.5 | 3 | 4 | 5 | 6 | |||
| Weight of per 1000 steel products(≈kg) | - | |||||||||||||
| Length of Thread b | Ref. | |||||||||||||
