Fifth ,signs & inspection of steel for steel structure hangar
Logo is the difference between the steel material, the specification of the mark, the main description of the steel supplier for steel structure hangar, grade, inspection lot number, size, size, level, net weight and so on. Logo has;
1.color: the end of the metal material, the end coated with a variety of colors of paint, mainly for steel, pig iron, colored materials and so on.
2.print: metal materials in the provisions of the site (end, end) to play stamps or painting methods, indicating the material grades, specifications, standard number and so on. Mainly used for plate, profiles, colored materials and so on.
3. listed: into a bundle, into a box, into a shaft and other metal materials listed on the outside of its brand name, size, weight, standard number, such as suppliers.
Marking of metal materials should be carefully identified in the transport, storage and other processes to be properly protected.
(B) the size of the test
Size refers to the nominal size of the main part of the metal material (length, width, thickness, diameter, etc.).
1.nominal size (nominal size): people want to produce in the ideal size, but it has a certain gap with the actual size.
2. size deviation: the difference between the actual size and nominal size is called size deviation. Greater than the nominal size is called positive deviation, less than the nominal size called negative deviation. Within the provisions of the standard within the scope of the allowable deviation, over the range called size tolerance, tolerance is not qualified products.
3. the accuracy of the size of the metal material to allow the deviation of the provisions of several ranges, according to the size of the allowable deviation of different sizes designated as a number of grades called precision grade, precision grade points ordinary, higher, advanced and so on.
4. delivery length (width): is the main size of metal material delivery, refers to the delivery of metal materials should have a long (wide) degree specifications.
5. the length of the length (not the length of length): the length does not make certain provisions, but must be within a specified length range (by different varieties, the length is not the same, according to the Ministry, plant set).
6. short foot (narrow): the length is less than the specified normal length of the lower limit, but not less than the specified minimum allowable length. For some metal materials, according to the provisions of some of the "short foot".
7. length of length: the length of the metal material must be provided in the order contract specified in the length (usually positive deviation).
8. the length of the length of the material: the length of the metal material must be required in the order contract specified length of the integer multiple (plus saw the mouth, positive deviation).
The size of the inspection should pay attention to measuring the material parts and the selection of appropriate measurement tools.
(C) the number of tests
The number of metal materials, generally refers to the weight (except for individual cases of plate, fish plate to the number of pieces), the number of test methods are:
1. according to the actual weight measurement: the actual weight of the metal material should generally be measured all pounds. There are solid packaging (such as boxes, together, barrels, etc.), in the packaging are marked gross weight, net weight and tare. Such as thin steel, silicon steel, ferroalloy can be sampled not less than 5% of the number of batches, such as sampling weight and mark the weight of access to a large, you must all out of the box weighing.
2.according to the theoretical conversion measurement: the nominal size of the material (the actual size) and the proportion of the weight calculated for those length of the plate and other materials can be calculated according to the theory, but in the conversion should pay attention to the formula and the actual material proportion.
(D) Surface quality inspection
Surface quality inspection is mainly on the material, appearance, shape, surface defects of the test, are:
1. oval: round section of the metal material, in the same section on the direction of the diameter of the phenomenon. The ellipticity is expressed by the difference between the maximum and minimum diameters in the same section, and is different for different purposes.
2. bending, bending: bending is rolling material. In the length or width direction is not straight, the shape of the curve of the general term. If they are represented by numbers in degrees, it is called curvature.
3. reverse: strip rolling material along the longitudinal axis twisted into a spiral.
4. sickle bend (side bend): refers to the metal plate, belt and close to the rectangular section of the shape along the length (narrow side of the side) of the bend, one side was concave curve, the other side of the convex curve, known as the "sickle Bend ". Expressed in concave height.
5. scoop curvature: refers to the length of the board or the width of the direction of the same time the ups and downs of the wave phenomenon, the formation of scoop, called scoop curvature. The value of the degree of scoop is called the curl.
6. surface cracks: refers to the metal surface cracks.
7.ear: due to improper roll and other reasons, there are along the rolling direction of the protrusion, called the ear.
8. including injury: refers to the surface of the material was straight or curved groove marks can usually see the ditch at the end.
9. scarring: refers to the uneven distribution in the metal surface was tongue-shaped, nail-shaped or fish-like flakes.
10. bonding: metal plate, foil, with the roll in the sheet when the layer produced by the layer, the line, the surface of the mutual adhesion, after opening the surface leaving a bond trace, called bonding.
11. iron oxide skin: iron oxide skin refers to the material in the heating, rolling and cooling process, the metal oxide generated on the surface.
12. folding: metal in the hot rolling process (or forging) the formation of a surface defects, the surface of each other equivalent to the bimetallic layer, a straight line or curve-like coincidence.
13. pitting point: refers to the surface of the metal material rough rough surface.
14. subcutaneous bubbles: the surface of the metal material showed irregular distribution of different sizes, different shapes, surrounded by smooth small bumps, rupture of the convex paw was claw-shaped claw or tongue-shaped scar, called the bubble.
Surface defects are mainly due to the production, transportation, handling, storage and other improper operation. Depending on the impact on the use of different, some defects are simply not allowed to exceed the limit. Some defects do not exist, but do not allow more than the limit; whether the surface defects are allowed to exist, or allow the existence of the relevant standards are clearly defined.
(E) Guarantees of internal quality inspection
The quality of the internal testing of metal materials is based on the material to adapt to different requirements, to ensure that the conditions are different in the factory and acceptance must be carried out under the conditions of inspection, and meet the requirements, to ensure that the conditions
1. the basic guarantee conditions: the minimum requirements of the material quality, whether or not proposed, have to ensure that, such as chemical composition, basic mechanical properties.
2. additional guarantee conditions: refers to the demand side in the order contract specified requirements, only to test, and to ensure that the test results meet the requirements of the project.
3. the agreement to ensure that the conditions: both supply and demand negotiations and orders in the contract to ensure that the project.
4 Senate conditions: the two sides to negotiate the inspection project, but only for reference conditions, not for assessment.
Internal inspection of metal materials mainly mechanical properties, physical properties, chemical properties, process performance, chemical composition and internal organization inspection, these tests are generally carried out in a professional inspection agency.