Identification of steel tubes
1., shoddy steel folding prone.
Folding is a series of broken lines formed on the surface of steel tubes, which often run through the longitudinal direction of the whole 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.
2 and the pipe surface often pitted phenomenon.
Ma is due to a defect of groove wear caused by irregular rugged steel surface. Due to the pursuit of profits of inferior steel pipe manufacturers, rolling groove is often the most standard.
3., inferior steel pipe surface prone to scarring.
There are two reasons: (1) the quality of stainless steel pipes is uneven, and the impurities are many. (2). Inferior goods manufacturers guide and defend equipment simple, easy to stick steel, these impurities bite, roll prone to scarring.
4., fake wood surface easy to produce cracks, because its billet is adobe, Adobe pores more, Adobe in cooling
During the process, cracks are produced due to thermal stress, and cracks occur after rolling.
5., inferior steel pipe is easy to scratch, because the inferior steel pipe factory equipment is simple, easy to produce burr, scratches the steel surface. Deep scratches reduce the strength of the steel.
6., stainless steel pipe metal luster, pale red or similar to the color of pig iron, for two point two reasons, its blank is adobe. 2, the quality of stainless steel rolling temperature is not standard, their steel temperature is through visual inspection, this can not be rolled according to the provisions of the austenitic region, the performance of steel can not meet the standard.
7., inferior steel pipe of thin and thin tendons, often filled with dissatisfaction phenomenon, because manufacturers in order to achieve large negative tolerance, finished a few days down the amount of pressure is too large, iron type is small, filled with dissatisfaction.
Section 8 of the fake steel 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.
9 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 product shoddy material manufacturers cut head, head and tail will appear Erzi big.
10., inferior steel pipe material contains more impurities, steel density is too small, and the size is too bad, so in the absence of vernier caliper, it can be weighed and checked. 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%) weighing =114 kg, the actual weight of 114 kg than single out small, is inferior steel, reason it is more than 5% negative tolerance. Generally speaking, the whole phase weighing effect will be better, mainly taking into account the cumulative error and probability theory.
11., the quality of the internal diameter of the inferior steel pipe fluctuates greatly because of the instability of L and steel. 2, the composition of steel is uneven. 3, because the equipment is simple, the foundation strength is low, the mill spring is big. There will be a larger change in the same week, such steel bars uneven force, prone to fracture.
12., quality pipe trademarks and lettering are more standardized.
13., three steel pipe diameter greater than 16 of the big thread, the distance between two trademarks are above IM.
14., shoddy steel, longitudinal steel rebar is often wavy.
15., shoddy steel pipe manufacturers because there is no driving, so relatively loose packaging. Oval in profile.