Metal material testing project

What are the metal material testing items? According to the editor's understanding, the testing items can be divided into two main parts, one isProduction score is an internal quality inspectionMainly testing the mechanical properties, chemical composition, metallography, anti-corrosion, non-destructive, dimensional, welding and other aspects of the product. The main testing standards can be based on North America ISO、 China, Europe, Germany, Japan, and other standards,The other part is used for production, ordering, transportation, use, storage, and inspectionThis part must be based on unified technical standards (GB, YB, JB). Below is a detailed introduction to the content.

The main internal testing items for metal materials are as follows:

1. Mechanical properties:Mainly including tensile test, high and low temperature tensile test, compression test, shear test, torsion test, bending test, impact test, Rockwell hardness test, Brinell hardness test, Vickers hardness test, and flattening test;

2. Chemical composition analysis:Mainly analyze the content of various chemical components in metal materials (carbon, silicon, manganese, phosphorus, sulfur, nickel, chromium, molybdenum, copper, vanadium, titanium, tungsten, lead, niobium, mercury, tin, cadmium, antimony, aluminum, magnesium, iron, zinc, nitrogen, hydrogen, oxygen);

3. Metallographic testing:Mainly including non-metallic inclusions, macrostructure, grain size, fracture inspection, coating thickness, hardening layer depth, decarburization layer, gray cast iron metallography, ductile iron metallography, and metallographic section analysis;

4. Coating testing:The commonly used methods include coating thickness measurement Coulomb method, coating thickness measurement metallographic method, coating thickness measurement eddy current method, coating thickness measurement X-ray fluorescence method, coating composition analysis, and surface stain analysis;

5. Corrosion testing:Including neutral salt spray test, acidic salt spray test, copper ion accelerated salt spray, sulfur dioxide corrosion test, hydrogen sulfide corrosion test, mixed gas corrosion test, stainless steel 10% oxalic acid corrosion test, stainless steel sulfuric acid iron sulfate corrosion test, stainless steel 65% nitric acid corrosion test, stainless steel nitric acid corrosion test, stainless steel sulfuric acid copper sulfate corrosion test, stainless steel 5% sulfuric acid corrosion test;

6. Non destructive testing:Including ultrasonic testing, radiographic testing, magnetic particle testing, and penetrant testing;

7. Dimensional testing:Including dimension measurement, symmetry, perpendicularity, flatness, circular runout, coaxiality, parallelism, roundness, and roughness;

8. Welding Procedure Qualification:Including tensile testing, bending testing (face bending, back bending, and side bending), ultrasonic testing, radiographic testing, magnetic particle testing, penetrant testing, surface visual inspection, macroscopic organization testing, weld hardness testing, and impact testing.

9. Failure analysis includes:The procedures and steps of failure analysis, investigation of failure events, determination of the cause or first failure component, careful collection and proper storage of the wreckage of the failure component, collection of background information on the failure component, determination of the failure analysis plan and development of implementation details, inspection, testing, and analysis.

In addition to the above, there are also the following testing items, mainly used for the production, ordering, transportation, use, and storage of metal materials.

（1） The packaging inspection is determined based on the type, shape, size, accuracy, and corrosion resistance of the metal material.

1. Bulk:That is, without packaging, wiping ingots, blocks (not afraid of corrosion, not expensive), large steel (large steel, thick steel plates, steel rails), pig iron, etc.

2. Bundling:Refers to small size and minimal impact of corrosion on usage, such as small and medium-sized steel, pipe steel, wire rod, thin plate, etc.

3. Boxes (barrels):Refers to corrosion-resistant, small, and thin products such as tinplate, silicon steel sheets, magnesium ingots, etc.

4. Axial formation:Finger wires, steel wire ropes, steel strands, etc. The packaging of bundled boxes and shaft packaging products should be checked for completeness first.

（2） The inspection mark is a mark that distinguishes the material and specifications of the material, mainly indicating the supplier's name, brand, inspection batch number, specifications, size, grade, net weight, etc. The signs include:

5. Coloring:Apply various colored paints on the end faces and parts of metal materials, mainly used for steel, pig iron, non-ferrous materials, etc.

6. Printing:The method of stamping or painting on designated areas (end faces, ends) of metal materials, indicating the material's grade, specifications, standard number, etc. Mainly used for medium thick plates, profiles, non-ferrous materials, etc.

7. Listing:Metal materials such as bundles, boxes, and shafts should be labeled outside to indicate their brand, size, weight, standard number, supplier, etc. When inspecting the markings of metal materials, they should be carefully identified and properly protected during transportation, storage, and other processes.

（3） The inspection of specifications and dimensions refers to the nominal dimensions of the main parts (length, width, thickness, diameter, etc.) of metal materials.

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. Dimensional 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 smaller than the nominal size is called negative deviation. Within the standard range, it is called allowable deviation, and exceeding the range is called dimensional deviation, which is considered as non-conforming product.

10. Accuracy level:The allowable size deviation of metal materials specifies several ranges, and is divided into several levels called precision levels according to the different allowable size deviations. Precision levels are divided into ordinary, high, etc.

11. Delivery length (width):The main dimensions for delivering metal materials refer to the length (width) specifications that metal materials should have when delivered.

12. Typical length (variable length):There is no fixed length requirement, but it must be within a specified length range (depending on the variety, the length may vary according to the department or factory).

13. Short ruler (narrow ruler):The length is less than the lower limit of the usual length dimension specified, but not less than the minimum allowable length specified. For some metal materials, according to regulations, a portion of 'short feet' can be paid.

14. Fixed length:The length of the submitted metal material must have the length specified by the purchaser in the purchase contract (generally with a positive deviation).

15. Length per foot:The length of the metal material submitted must be an integer multiple of the length specified by the purchaser in the purchase contract (with saw marks and positive deviation).

16. Specifications and dimensions:Inspection should pay attention to measuring the material location and selecting appropriate measuring tools.

（4） Quantity inspection

The quantity of metal materials generally refers to their weight (except for a few cases where pads and fishplates are measured in pieces), and the methods for quantity inspection include:

17. Measured by actual weight:Metal materials measured by actual weight should generally be fully weighed and inspected. For firmly packaged items such as boxes, closures, drums, etc., the gross weight, net weight, and tare weight should be indicated on the packaging. Thin steel plates, silicon steel sheets, and ferroalloys can be sampled for no less than 5% of a batch. If there is a significant difference between the sampled weight and the marked weight, all samples must be unpacked and weighed.

18. According to theoretical conversion measurement:The weight calculated based on the nominal size (actual size) and specific gravity of the material can be theoretically converted for fixed length templates and other materials, but attention should be paid to the conversion formula and the actual specific gravity of the material when converting.

（5） Surface quality inspection is mainly the inspection of materials, appearance, shape, and surface defects, including:

19. Ellipticity:The phenomenon of unequal diameters in all directions on the same cross-section of a metal material with a circular cross-section. Ellipticity is represented by the difference in diameter between the largest and smallest on the same cross-section, and different standards apply to materials for different purposes.

20. Bending and curvature:Bending is rolling material. The general term for a curved shape that is not straight in length or width direction. If their unevenness is represented by numbers, it is called curvature.

21. Twist:Strip rolled materials are twisted into a spiral shape along the longitudinal axis.

22. Sickle Bend (Side Bend):Refers to the bending of a metal plate with a rectangular cross-section along its length (narrow side), with one side forming a concave curve and the other side forming a convex curve, known as the 'sickle bend'. Represented by concave height.

23. Curvature:The phenomenon of waves appearing high and low in both the length and width directions of a board or strip, forming a scoop shape, called scoop curvature. The numerical value indicating the degree of curvature is called the degree of curvature.

24. Surface cracks:Refers to cracks on the surface of metal objects.

25. Ears:The protrusions that extend along the rolling direction due to improper fit of the rolling mill are called ears.

26. Injury:The straight or curved grooves on the surface of the material usually show the bottom of the groove.

27. Scaring:Refers to thin sheets that are unevenly distributed on the surface of metal materials in a tongue like, nail like, or fish scale shape.

28. Bonding:The mutual adhesion of layers, interlayer points, lines, and surfaces generated during the annealing process of metal plates, foils, and tapes. After being opened, there are adhesive marks left on the surface, which is called adhesion.

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

30. Folding:It is a surface defect formed during the hot rolling process (or forging) of metals, consisting of bimetallic layers that overlap with each other in a straight or curved shape.

31. Matte point:Refers to the rough and uneven surface of metal materials.

32. Subcutaneous air bubbles:The surface of metal materials presents irregular distribution of small protrusions of varying sizes and shapes, with smooth edges around them. The ruptured protrusions form chicken claw shaped cracks or tongue shaped scars, which are called bubbles. The main reason for surface defects is due to improper operations such as production, transportation, loading and unloading, and storage. Depending on the impact on usage, some defects are simply not allowed to exceed the limit. Some defects may not exist, but they are not allowed to exceed the limit; Whether various surface defects are allowed to exist, or to what extent, are clearly specified in the relevant standards.