1. Inferior steel material containing impurities, the density of steel is too small, and size tolerance serious, so there is no caliper of the case, you can check it by weight. For example, rebar 20#, the national standard set forth in the most negative tolerance of 5%, cut-9M single theory when it weighs 120 kilograms, its minimum weight is: 120X (l-5%) = 114 kg, Weighing out. The actual weight of a single smaller than 114 kg, it is inferior steel, because it is more than 5% negative tolerance. Generally speaking, commensurate with the amount of whole would be better, mainly taking into account the accumulated error and probability theory this problem.
2. Inferior inner diameter steel fluctuations due:
l, steel surface temperature instability of yin and yang. 2, the steel composition uneven. 3, due to poorly equipped, low intensity ground, rolling the big bounce. There will be changes in the same week a larger diameter, this discontinuity is easy to produce steel fracture.
3. Trademarks and printing high-quality materials are relatively standardized.
4. Three large steel screw diameter of 16 or more, the spacing between the two trademarks in more than IM.
5. Inferior longitudinal reinforcement steel rebar are often wavy.
6. Inferior steel manufacturers, no traffic, so the packaged loose. Side of the oval.
7. Inferior steel prone to folding. Fold is formed on the surface of steel line, this defect often throughout the product vertical. Have folded due to shoddy manufacturers for high efficiency. Rolling reduction is too large, resulting in the ears, under the fold to produce a rolling, folding of the product after bending will crack, steel strength decreased.
8. Ma shoddy steel exterior surface phenomena often. Pock is due to severe wear and tear caused by steel rolling groove irregular uneven surface defects. As the inferior steel manufacturers to the pursuit of profit, most often excessive rolling rolling groove.
9. Inferior steel surface is easy to produce scarring. There are two reasons: 1. Inferior steel material is uneven, impurities. 2. Shoddy materials manufacturers guide and guard equipment simple, easy to stick steel, these impurities after the roll bite is easy to produce scarring.
10. Shoddy material surface easy to crack, because it is blank adobe, adobe pores more adobe in the cooling process due to thermal stresses, cracks, after rolling through the cracks there.
11. Inferior steel is easy to scratch, because the shoddy materials manufacturers poorly equipped, easy to produce glitch, scratch the surface of steel. Deep scratches reduce the strength of steel.
12. Inferior steel no metallic luster, pale red or similar color of pig iron, for two reasons Second, it is adobe blank. 2, inferior wood rolling temperature non-standard, their steel temperature is visual, so the region can not be required for rolling of austenitic stainless steel performance standards can not be natural.
13. Inferior steel cross bars thin and low, often dissatisfied with the phenomenon of charge, because the manufacturers to achieve large negative tolerance, finished a few of pressure before the volume is too large, iron-type small, hole fully satisfied.
14. Inferior steel oval-shaped cross section appear before, because the manufacturers in order to save materials and finished products before the two rollers of rolling reduction is too large, this greatly decrease the strength of steel, but steel does not conform to the standard dimensions.
15. Homogeneous high-quality steel, cold shear tonnage of high-cut head and face smooth and neat, and inferior material because the material is poor, cut the meat off the head and face often have the phenomenon that is uneven, and no metallic luster. And because of shoddy materials manufacturers products less cutting head, big ears will be sub-head and tail.
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