Inspection of metal materials

Metal materials are metallurgical products, and the production, ordering, transportation, use, storage and inspection of metal materials must be based on a unified technical standard-metallurgical product standards. The staff engaged in metal materials must master the relevant content of the standard.
The standards used in my country’s metallurgical products are national standards (code-named “GB”), Ministry standards (Metallurgical Industry Ministry standard “YB”, First Machinery Ministry standard “JB”, etc.) Enterprise Standard Level III.

(1) Packaging inspection

It depends on the type, shape, size, precision and anti-corrosion of metal materials.

1. Bulk: that is, no packaging, ingots, blocks (not afraid of corrosion, not expensive), large steel (large steel, thick steel plate, rail), pig iron, etc.

2. Bundles: refers to small size, corrosion has little effect on use, such as small and medium steel, pipe steel, wire, thin plate, etc.

3. Box (barrel): refers to anti-corrosion, small and thin products, such as tinplate, silicon steel sheet, magnesium ingot, etc.

4. Shaft: refers to wire, steel wire rope, steel strand, etc.

For bundled boxes and shaft-packed products, first check whether the packaging is complete.

(2) Mark inspection

The mark is a mark that distinguishes the material and specification of the material, and mainly describes the supplier’s name, brand, inspection lot number, specification, size, grade, net weight, etc. Signs have;

5. Coloring: paint the end surface and the end of metal materials with various colors, mainly used for steel, pig iron, non-ferrous materials, etc.

6. Printing: The method of stamping or spraying paint on the specified parts of the metal material (end face, end), indicating the brand, specification, standard number, etc. of the material. Mainly used for medium and heavy plates, profiles, non-ferrous materials, etc.

7. Listing: Bundles, boxes, shafts and other metal materials are listed outside to indicate their brand, size, weight, standard number, supplier, etc.

The signs of metal materials must be carefully identified during inspection and properly protected during transportation and storage.

(3) Inspection of specifications

Specification size refers to the nominal size of the main parts of the metal material (length, width, thickness, diameter, etc.).

8. Nominal size (nominal size): It is the ideal size that people want in production, but there is a certain gap between it and the actual size.

9. Size deviation: The difference between the actual size and the nominal size is called size deviation. Greater than the nominal size is called positive deviation, and less than the nominal size is called negative deviation. It is called the allowable deviation within the specified range of the standard, and the size exceeding the range is called the size tolerance, and the tolerance is a non-conforming product.

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10. Accuracy grade: There are several ranges for the allowable deviation of metal materials, and are divided into several grades called accuracy grades according to the size of the allowable deviation. The accuracy grades are divided into ordinary, higher, advanced, etc.

11. Delivery length (width): is the main delivery size of metal materials, and refers to the length (width) specifications that metal materials should have when they are delivered.

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12. Normal length (indefinite length): The length is not specified, but it must be within a specified length range (different types, different lengths, depending on the department and factory).

13. Short ruler (narrow ruler): The length is less than the lower limit of the prescribed general length dimension, but not less than the prescribed minimum allowable length. For some metal materials, part of the “short ruler” can be handed in as required.

14. Cut-to-length length: The length of the metal material must have the length specified by the purchaser in the order contract (generally positive deviation).

15. Length of multiple ruler: The length of the metal material must be an integer multiple of the length specified by the purchaser in the order contract (plus saw cut, positive deviation).