Inspection II of the hottest metal materials

2022-08-09
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Inspection of metal materials (II)

(IV) inspection of quantity

the quantity of metal materials generally refers to the weight (except for individual cases of baseplates and fishplates, which are calculated in pieces). The quantity inspection methods are:

17 Measured by actual weight: metal materials measured by actual weight should generally be weighed and inspected. For solid packages (such as boxes, containers, barrels, etc.), the gross weight, net weight and tare weight shall be indicated on the package. For example, the number of steel sheets, silicon steel sheets and ferroalloys that can be sampled for inspection shall not be less than 5% of a batch. If there is a big difference between the sampling weight and the marked weight, all must be unpacked and weighed

18. Calculation by theoretical conversion: the weight calculated by the nominal size (actual size) and specific gravity of the material can be converted theoretically for those shaped plates and other materials with fixed size, but attention should be paid to the conversion formula and the actual specific gravity of the material when converting

(V) surface quality inspection

surface quality inspection is mainly the inspection of materials, appearance, shape and surface defects, mainly including:

19 Ovality: the phenomenon that the diameter of metal materials with circular section is different in all directions on the same section to meet the requirements of automobile manufacturing industry for lightweight, high-strength and easy processing materials. Ovality is expressed by the maximum and minimum diameter difference on the same section, and the standards for different materials are different

20. Bending, bending degree: bending is rolling material. It is a general term that is not straight in the direction of length or width and in the shape of a curve. If their unevenness is expressed in numbers, it is called curvature

21. Torsion: the strip rolling material is twisted into a spiral shape along the longitudinal axis

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

23. Scoop curvature: refers to the wave phenomenon of ups and downs in the length and width direction of the plate or belt at the same time, forming a scoop shape, which is called scoop curvature. The value indicating the degree of curvature is called the degree of curvature

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

25. Ears: the protrusions extending along the rolling direction due to improper roll matching and other reasons are called ears

26. Inclusion: it refers to that the material surface is in a straight line or arc groove, and the groove bottom can usually be seen

27. Scab: refers to the tongue shaped, nail shaped or fish scale shaped thin slices unevenly distributed on the surface of metal materials

28. Bonding: the mutual adhesion of points, lines, and surfaces between layers of metal plates, foils, and strips produced during overlapping rolling and annealing. After being lifted, there are bonding traces on the surface, which is called bonding

29. Iron oxide scale: iron oxide scale refers to the metal oxide generated on the surface of the material during the heating, rolling and cooling process (the sound of specimen damage may also be heard)

30. Folding: it is a kind of surface defect formed by metal in the hot rolling process (or forging). The bimetallic layers whose surfaces are folded mutually coincide in a straight line or curve shape

31. Pitting: refers to the uneven rough surface of metal materials

32. Subcutaneous bubbles: irregular distribution of small bumps with different sizes and shapes on the surface of metal materials. The raw materials of ABS are light yellow or milky white pellets. The broken bumps are chicken claw shaped cracks or tongue like scars, which are called bubbles

surface defects are mainly caused by improper operations such as production, transportation, loading and unloading, and storage. According to the different impact on the use, some defects are not allowed to exceed the limit at all. Although some defects do not exist, they are not allowed to exceed the limit; Whether or not various surface defects are allowed to exist, or to what extent, are clearly specified in the relevant standards

(VI) guarantee conditions for internal quality inspection

the inspection basis for 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 at the time of delivery and acceptance, and meet the requirements. The guarantee conditions are divided into points

33. Basic guarantee conditions: the minimum requirements for material quality, whether or not HBS is only applicable to metal materials below 450n/mm2 (MPA), must be guaranteed, such as chemical composition, basic mechanical properties, etc

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