The following are some common testing standards and aspects involved for threaded steel:
National Standards (The current main one is GB/T 1499.2 – 2024 “Steel for Reinforced Concrete – Part 2: Hot-Rolled Ribbed Bars”)
1. Chemical composition:◦ The content ranges of elements such as carbon (C), silicon (Si), manganese (Mn), phosphorus (P), and sulfur (S) in the chemical composition of each grade of reinforcing bars are stipulated.

2. Mechanical properties:◦ Indexes such as yield strength, tensile strength, elongation after fracture, and total elongation at maximum force are specified. For seismic-resistant reinforcing bars with the letter “E”, there are also special requirements such as the ratio of yield strength to tensile strength and the ratio of ultimate strength to yield strength.◦ Test methods include tensile tests, etc.

3. Dimensions and tolerances:◦ Include requirements for dimensions such as inner diameter, height of transverse ribs, height of longitudinal ribs, and spacing. The length deviation of reinforcing bars delivered at fixed lengths is stipulated (not exceeding 0 – 50mm, etc.), and the weight deviation (the negative tolerance is tightened by reducing 0.5%, and the measurement accuracy for weight deviation should be accurate to 1g).

4. Technological properties:◦ Reverse bending properties (for reinforcing bars with the letter “E” in the grade, etc.), bending tests.

5. Metallographic structure:◦ Mainly ferrite and pearlite, and no other structures that affect performance are allowed. Tempered martensite structure is not allowed at the base circle.

6. Surface quality:◦ The surface of the reinforcing bars shall be free of cracks, scabs and folds; raised blocks are allowed on the surface, but shall not exceed the height of the transverse ribs.

7. Product marking:◦ The grade mark, the serial number of the production enterprise (the last three digits of the license), and the nominal diameter in millimeters should be rolled on the surface. Additionally, a registered factory name or trademark can also be rolled.
Other Relevant Standards
1. “GB/T 20065 – 2016 Threaded Bars for Prestressed Concrete”: Applicable to threaded bars for prestressed concrete (finish-rolled threaded bars)◦ The strength grade, size, shape, weight, technical requirements, test methods, and inspection rules of prestressed threaded bars are stipulated.

2. “GB/T 2101 – 2008 (General Requirements for Acceptance, Packaging, Marking and Quality Certification of Section Steel)”: Some contents can be used for the acceptance, packaging and marking of threaded steel.

3. “GB/T 33953 – 2017 Corrosion-Resistant Reinforcing Bars for Reinforced Concrete”: Referenced when threaded steel has special requirements such as corrosion resistance.

4. Some industry standards and local standards may also stipulate the testing of threaded steel for specific uses or regions (such as threaded steel used in some special environments).
Testing Method Standards (Partially)
1. Tensile test: In accordance with GB/T 228.1 – 2021 “Metallic Materials – Tensile Testing – Part 1: Method of Test at Room Temperature”, etc.

2. Chemical analysis methods (for determining chemical composition): GB/T 223 series, etc.

3. Metallographic inspection: Relevant metallographic inspection method standards can be referred to.

4. Fatigue test (when there are special requirements): GB/T 3075 – 2021 “Metallic Materials – Fatigue Testing – Axial Force Controlled Method”, etc.

5. Bending test: According to relevant bending test standards.