In daily steel procurement, the most irritating thing is nothing more than the purchase of defective seamless steel pipes, which affects product quality. How to identify defective seamless steel pipes? Learn about it with seamless steel pipe manufacturers.
For customers who don’t understand, first of all, we can identify it most intuitively from the surface of the steel pipe.
1. The trademark and printing of high-quality tubes are relatively standardized.
2. Fake and inferior steel pipes have no metallic luster and are light red or similar to pig iron for two reasons. 2. Its billet is adobe. 2. The rolling temperature of fake and inferior materials is not standard. Their steel temperature is measured visually, so it cannot be rolled according to the regular austenite region, and the performance of the steel will naturally fail.
3. Fake and inferior steel pipes are easy to scratch. The reason is that the manufacturers of fake and inferior steel pipes have poor equipment, which is prone to burrs and scratches on the surface of the steel. Deep scratches reduce the strength of the steel.
4. Manufacturers of fake and inferior steel pipes pack loosely because they don’t have driving cars. The sides are oval.
5. The cross-section of fake and inferior steel pipes is elliptical. The reason is that in order to save materials, the reduction in the first two passes of the finished roll is too large. The strength of this kind of rebar is greatly reduced, and it does not meet the standard of rebar shape.
6. The surface of fake and inferior steel pipes is prone to scarring.
There are two reasons: (1) The raw materials of fake and inferior steel pipes are uneven and have many impurities. (2) The guides and guards of fake and inferior material manufacturers are poorly equipped and easy to stick to steel. These impurities are prone to scarring after biting the roll.
7. The appearance of fake and inferior materials is prone to cracks. The reason is that its billet is adobe, and the adobe has many pores.
During the process, due to the effect of thermal stress, cracks occur, and there are cracks after rolling.
8. Fake and inferior steel pipes are prone to folding.
Folding is a variety of fold lines formed on the surface of the steel pipe, and this defect often runs through the entire longitudinal direction of the product. The reason for the folding is that the counterfeit and inferior manufacturers seek high efficiency, the reduction is too large, the ear will occur, and the folding will occur in the next rolling process. The folded product will crack after bending, and the strength of the steel will drop greatly.
9. The appearance of fake and inferior steel pipes often has pockmarks.
The pockmarked surface is due to the serious wear and tear of the rolling groove, which causes the irregular unevenness of the steel surface. Because manufacturers of fake and inferior steel pipes want to seek profits, there are often overruns in grooving and rolling.
The next step is to have a few requirements for the ability to identify customers. The following points can also help you identify them.
1. The horizontal ribs of fake and inferior steel pipes are thin and low, and the phenomenon of insufficient filling often occurs. The reason is that in order to achieve a large negative tolerance, the reduction of the first few passes of the finished product is too large, the iron shape is too small, and the passing shape is not full.
2. The composition of high-quality steel is uniform, the tonnage of the cold shear is high, and the end face of the cutting head is smooth and regular. However, due to poor raw materials, the end face of the cutting head often has meat loss, that is, unevenness and no metallic luster. And because the products of fake and inferior material manufacturers have fewer heads, big ears will appear at the head and tail.
3. The raw materials of fake and inferior steel pipes contain many impurities, the density of the steel is relatively small, and the scale is seriously out of tolerance, so it can be weighed and checked without a vernier caliper. For example, regarding rebar 20, the national standard stipulates that the maximum negative tolerance is 5%, and its single theoretical weight is 120 kg when the length is 9M, and its minimum weight should be: 120 X(l-5%)=114 kg , The actual weight of a single piece weighed out is less than 114 kg, which is a fake and inferior steel because its negative tolerance exceeds 5%. Generally speaking, the whole phase weighing effect will be better, mainly considering the problem of cumulative error and probability theory.
4. The inner diameter of fake and inferior steel pipes fluctuates greatly, the reason is; 1. The steel temperature is unstable and has negative and positive sides. 2. The composition of steel is uneven. 3. Due to poor equipment and low foundation strength, the rolling mill has a large bounce. There will be large changes in the same week, and such steel bars are prone to fracture due to uneven stress.
The above is the content about identifying the quality of seamless steel pipes compiled by the editor for you. I hope it will be helpful to our customers. Of course, when we purchase, we still need to look for big brands and companies to guarantee the quality.