Group Standards of the People's Republic of China CN / TUANTI
Latest
T/SZJGJ 001-2024
Scope
4.4 Mechanical and Physical Properties
4.4.1 Yield Strength, Tensile Strength, Hardness, Breaking Torque
Machine screws should comply with GB/T 3098.1 or GB/T 3098.6. Self-tapping screws should conform to GB/T 3098.5 or GB/T 3098.21.
4.4.2 Thread Precision
The thread precision of machine screws should meet the requirements specified in GB/T 197. The thread accuracy for self-tapping screws should comply with the requirements in GB/T 5280.
4.5 Surface Defects
Should conform to the requirements of GB/T 5779.1.
4.6 Corrosion Resistance
The product shall exhibit no corrosion after a neutral salt spray test for parts ≥2 hours.
5 Test Methods
5.1 Appearance Quality
5.2 Tolerance
Inspection according to the methods specified in JB/T 9151.1.
5.3 Mechanical Properties
5.3.1 Yield Strength
Testing should be conducted as per the methods specified in GB/T 3098.1 or GB/T 3098.6 for machine screws.
5.3.2 Tensile Strength
Tensile strength (Rm) testing should be carried out on fasteners with a length of L ≥ 2.5d, as specified in GB/T 228.1 and GB/T 3098.1. The length of the unthreaded portion must be greater than or equal to 2.5d.
5.3.3 Hardness
Testing should follow the provisions in GB/T 230.1.
5.3.4 Breaking Torque
The test should be conducted as per the methods specified in GB/T 3098.13.