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Method for the identification of rectangular tubes

Fake rectangular tube prone to collapse. Fold is the rectangular tube surface formed a variety of broken lines, this defect is often run through the entire product. Folding is due to shoddy manufacturers to pursue high efficiency, pressure amount slants big, produce Erzi, a rolling produced folding, folding products after bending will crack and the strength of steel big decline.

Inferior rectangular tube appearance often pitted phenomenon. Ma is due to a defect of groove wear caused by irregular rugged steel surface. As a result of shoddy rectangular tube manufacturers to pursue profit, often the most excessive rolling groove rolling.

The surface is easy to produce scarring and inferior rectangular tube. There are two reasons:

1). Fake rectangular tube material is not uniform, more impurities.

2). Manufacturers guide equipment is simple, easy to stick steel, these impurities

Shoddy material surface is easy to generate crack, the reason is its blank is adobe, adobe air, Adobe cooling off in the process due to thermal stress, crack, after rolling with crack.

The rectangular tube is easy to scratch, the reason is that the factory equipment is simple, easy to produce burr, scratch the surface of steel. Deep scratch to reduce the strength of steel.

No fake rectangular metallic luster, pale red or two point two reasons, it is entirely adobe. False and inferior material rolling temperature is not standard, their steel temperature is through the visual, so can not according to the provisions of the austenite region rolling, the performance of steel natural cannot reach.

Inferior rectangular tubes of thin and low, often appear to be full of dissatisfaction with the phenomenon, the reason is that the manufacturers for the large negative tolerance, finished the first few road pressure

Fake rectangular tube cross section oval. The reason is that manufacturers in order to save materials, finished and before the second pressure amount slants big, this kind of deformed steel bar intensity is greatly decreased and does not conform to the standard screw thread steel dimensions.

Quality steel of uniform composition, cold shearing machine tonnage is high, cutting head face is smooth and neat, and shoddy material because of poor material, cut end often have the meat off phenomenon, namely is uneven, and no metallic luster. And because the manufacturers cut less head, head and tail will appear big ears.

Fake rectangular tube material containing impurities, density of the steel is too small and dimension tolerance in the absence of vernier caliper, the weigh check. For example for threaded steel 20 and national standard provisions of maximum negative tolerance is 5%, the length of 9m its single theoretical weight to 120 kilograms, the minimum weight should be: 120 x (l-5%) in the example kg, weighing out a single actual weight is smaller than 114 kg is inferior steel%. Generally speaking, the whole weighing effect will be better, mainly taking into account the cumulative error and the probability of this problem. 11 the diameter of the inner diameter of the rectangular tube is larger and larger, the reason is that the L, the temperature of the steel is not stable with the Yin and Yang. 2, the composition of the steel is not uniform. 3, because the equipment is simple, the foundation strength is low, the rolling mill's bounce is big. Will appear in the weeks changed greatly, this reinforced the uneven stress prone to fracture.

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