First, from the appearance
On the surface of the steel, if the surface of the steel has pitting, scarring, cracks, etc., it can be judged that it is a fake and inferior product.
Judging from the metallic luster, the fake and inferior products have no metallic luster and are light red or similar to pig iron.
The horizontal bars of inferior steel often appear unsatisfactory. The reason is that in order to achieve a large negative tolerance, the reduction amount of the first few passes of the product is too large, the iron shape is too small, and the hole shape is not full.
The cross section of inferior steel is oval, the inner diameter fluctuates greatly, and the longitudinal bars of rebar are often wavy.
Second, the selection criteria
Standards are uniform rules for repetitive things and concepts. It is based on the comprehensive results of science, technology and practical experience. It is agreed upon by relevant parties, approved by the competent body, and issued in a specific form as a guideline and basis for common compliance.
The standards implemented by my country’s steel products include national standards (GB, GB/T), industry standards (YB), local standards and enterprise standards.
Therefore, buyers must look for steel with these standards.
Third, the guarantee conditions
According to the provisions of the technical conditions of metal materials, the manufacturer should carry out inspection and ensure that the inspection results meet the required performance, chemical composition, internal organization and other quality indicators, which are called guarantee conditions.
Fourth, the quality certificate
The production of metal materials is the same as the production of other industrial products. It is carried out according to unified standards, and the product factory inspection system is implemented. Unqualified metal materials are not allowed to be delivered.
For delivered metal materials, the manufacturer provides a quality certificate to ensure its quality.
The quality certificate for metal materials not only states the name, specification, number of delivered pieces, weight, etc. of the material, but also provides all the inspection results of the specified guarantee items.
Fifth, technical conditions
The various performance indicators and quality requirements that the product should meet in the standard are called technical conditions, such as chemical composition, external dimensions, surface quality, physical properties, mechanical properties, process properties, internal organization, delivery status, etc.
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