Inspection of metal materials

In the inspection of specifications and dimensions, attention should be paid to the measurement of material parts and the selection of appropriate measuring tools.
(4) Quantity inspection

The quantity of metal materials generally refers to the weight (except for a few cases of backing plates and fishplates, which are counted in pieces). The quantity inspection methods are as follows:

This article is provided by Machinery Knowledge Network, please pay attention to the content provided by Machinery Knowledge Network

17. Measured by actual weight: Metal materials measured by actual weight should generally be weighed and inspected. For strong packaging (such as boxes, boxes, barrels, etc.), the gross weight, net weight and tare weight should be indicated on the package. Such as thin steel plates, silicon steel sheets, and ferroalloys can be sampled at least 5% of the batch. If the sampled weight and the marked weight are very different, all must be weighed out of the box.

18. Conversion and measurement according to theory: The weight calculated by the nominal size (actual size) and specific gravity of the material can be converted theoretically for those fixed-length profiles, but pay attention to the conversion formula and the actual material when converting. proportion.

(5) Surface quality inspection

Surface quality inspection mainly refers to the inspection of materials, appearance, shape, and surface defects, including:

19. Ovality: Metal materials with circular cross-sections have different diameters in all directions on the same cross-section. Ovality is expressed by the difference between the largest and smallest diameters on the same section, and the standards for different materials are different.

20. Bending and bending: bending is the rolled material. A general term that is not straight or curved in the length or width direction. If the degree of their unevenness is expressed in numbers, it is called curvature.

21. Torsion: The strip-shaped rolled material is twisted into a spiral along the longitudinal axis.

22. Sickle curve (side curve): refers to the bending along the length (narrow side) of metal plates, strips and shapes close to the rectangular section, one side is concave and the other is convex, called “sickle” bend”. Expressed in recessed height.

23. Scooping curvature: refers to the simultaneous appearance of high and low undulating waves in the length and width of the plate or belt, forming a scooping curvature, which is called scooping curvature. The value indicating the degree of buckling is called buckling.

24. Surface crack: refers to the crack on the surface of a metal object.

25. Ears: due to improper roll fit and other reasons, the protrusions that extend along the rolling direction are called ears.

26. Including wounds: refers to the straight or curved grooves on the surface of the material, the bottom of the groove can usually be seen.

27. Scarring: refers to the tongue-like, nail-like or fish-scale flakes that are unevenly distributed on the surface of the metal material.

28. Adhesion: The mutual adhesion of points, lines and surfaces between layers and layers of metal plates, foils, and strips during rolling and annealing. After being opened, there are adhesion marks on the surface, which is called adhesion.

29. Iron oxide scale: Iron oxide scale refers to the metal oxide formed on the surface of the material during heating, rolling and cooling.

30. Folding: It is a kind of surface defect formed in the process of hot rolling (or forging) of metal. The bimetallic layers folded on each other on the surface are overlapped in a straight line or a curve.

31. Pockmark: Refers to the rough surface of metal material with uneven surface.

32. Subcutaneous bubbles: The surface of metal materials presents irregular distribution of different sizes, different shapes, small round bumps around, and ruptured bumps that are chicken-foot-shaped cracks or tongue-shaped scars, which are called bubbles.

Surface defects are mainly caused by improper operations such as production, transportation, loading and unloading, and storage. Depending on the impact on the use, some defects are not allowed to exceed the limit at all. Somewhat lacking

Although the sink does not exist, it is not allowed to exceed the limit; whether various surface defects are allowed to exist, or the extent to which they are allowed, are clearly stipulated in the relevant standards.

(6) Guarantee conditions for internal quality inspection

The basis for the inspection of the internal quality of metal materials is to adapt to different requirements according to the material, and the guarantee conditions are also different. The inspection must be carried out according to the guarantee conditions during the factory and acceptance, and meet the requirements, the guarantee conditions are divided; 33. Basic guarantee conditions: the lowest material quality Requirements, whether proposed or not, must be guaranteed, such as chemical composition, basic mechanical properties, etc.