The national standard for rebar is GB1499-1998. If it meets this standard, it is a national standard. If it does not meet this standard, it is a non-standard. You can use a vernier card measuring tool to simply measure whether the actual size is about one specification or more smaller than the stated size (generally, the rebar is rolled with a specification mark) (for example, the standard inner diameter of 12 rebar is 11.5±0.4mm, while the standard inner diameter of fake rebar is 11.5±0.4mm. The inner diameter is mostly around 10mm).
my country’s standards recommend rebar series with nominal diameters of 6, 8, 10, 12, 16, 20, 25, 32, 40, and 50mm. The length of supply is divided into two types: fixed length and double length. Since non-standard rebar is rolled from adobe, its surface quality is poor, often with defects such as scarring, and has an overall rough feel.
At the same time, some small rolling mills have a reddish surface color due to insufficient heating temperature and rolling speed. The non-standard rebar is flattened and has an oblate oval shape when viewed from the end face of the steel bar, while the end face of the regular steel bar should be basically round.
Extended information:
The quality of finished products of threaded steel bars changes with the process conditions of metallurgical smelting heats and hot rolling batches. The heat number and batch number are the basis for sampling inspection. Therefore, the import receiving and warehousing departments must pay attention to retaining the marks on the goods, and the export enterprises and foreign trade departments must also distinguish the batches and heat numbers and provide quality certificates in accordance with standard requirements.
Rebar is generally delivered naked and bundled. Pay attention to moisture-proofing during storage. Rust will have a negative impact on the performance of rebar. Rebar is a steel bar with ribs on the surface, also called ribbed steel bar. It usually has two longitudinal ribs and transverse ribs evenly distributed along the length.
The transverse ribs have three shapes: spiral, herringbone, and crescent. Expressed in millimeters of nominal diameter. The nominal diameter of ribbed steel bars is equivalent to the nominal diameter of plain round steel bars of equal cross-section.
Baidu Encyclopedia-Rebar