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How to identify 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 in pursuit of high efficiency, the amount of pressure is too large, produce handle, a rolling produce folding, folding products after bending cracks, the strength of steel big drop.

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 and shoddy rectangular pipe material is not uniform, more impurities.

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

Shoddy material surface is easy to crack, the reason is that it is entirely adobe, adobe air, Adobe during cooling due to the action of thermal stress, cracks 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. Shoddy material rolling temperature is not standard, their steel temperature is through the visual, so according to the provisions of the austenite region of steel rolling, the performance of 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

Cross section and rectangular pipe oval, the reason is that manufacturers in order to save materials, and finished the first two reduction is too large, the strength of the rebar is greatly decreased, but also does not conform to the dimensions of the steel standard.

High quality steel components uniform, cold shearing machine tonnage is high, the cutting head face is smooth and neat, and the inferior material because of poor material, cutting head face often have the meat off phenomenon, which is uneven, and no metallic luster. And because the manufacturers cut less head, head and tail will appear big ears.


The material containing impurities and steel rectangular tube, the density of small, and the size difference in no vernier caliper, can weigh check on it. For example, 20 steel, the national standard stipulated in the maximum negative tolerances of 5%, fixed length 9M single theory its weight is 120 kilograms, the minimum weight should be: 120 X (l-5%) =114 kg, the actual weighing 114 kg more than single out small, 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.

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