15 tricks to identify the advantages and disadvantages of mold steel
1. Fake and inferior steel is easy to fold. Folding is the formation of various folded lines on the surface of steel, and this defect often runs through the longitudinal direction of the entire product. The reason for folding is that the reason for the shoddy manufacturers to pursue efficiency, the amount of pressure is large, the ear is produced, the next rolling will produce folding, the folded product will crack after bending, and the strength of the steel will decrease.
2. The appearance of fake and shoddy steel often has hemp surface phenomenon. The hemp surface is a defect of irregular unevenness on the surface of the steel caused by the serious wear of the rolling groove. Due to the pursuit of profits by shoddy steel manufacturers, there are often grooved rolling that exceed the standard.
3. The surface of fake and inferior steel is easy to produce scarring. There are two reasons: 1) The material of fake and inferior steel is uneven and has many impurities. 2) The guidance equipment of fake and inferior material manufacturers is simple, easy to stick steel, and these impurities are easy to produce scarring after biting the roll.
4. The surface of fake and inferior materials is easy to produce cracks, because its blank is adobe, adobe has many pores, adobe in the process of cooling due to the action of thermal stress, cracks, after rolling there are cracks.
5. Fake and shoddy steel is easy to scratch, because the equipment of fake and inferior material manufacturers is simple, easy to produce burrs, and scratch the surface of steel. Deep scratches reduce the strength of the steel.
6. Shoddy steel has no metallic luster and is light red or pig-like color for two reasons: 1) Its blank is adobe. 2) The temperature of counterfeit and inferior material rolling is not standard, and their steel temperature is visually measured, so that it cannot be rolled according to the specified austenitic area, and the performance of steel naturally cannot meet the standard.
7. The cross ribs of fake and inferior steel are thin and low, and the phenomenon of filling is often dissatisfied, because in order to achieve a large negative tolerance, the first few layers of the finished product are too large to press down, the iron type is too small, and the hole type is not satisfied.
8. The cross-section of fake and inferior steel is oval, because in order to save materials, the manufacturer has a large amount of pressure in front of the finished roll, and the strength of this rebar is greatly reduced, and it does not meet the standard of rebar dimensions.
9. The composition of high-quality steel is uniform, the tonnage of the cold shearing machine is high, and the end face of the cutting head is smooth and neat, while the fake and inferior wood often has the phenomenon of falling meat due to poor material, that is, uneven, and no metallic luster. And because the products of fake and inferior material manufacturers have fewer heads, large ears will appear at the head and tail.
10. The material of fake and inferior steel contains many impurities, the density of steel is small, and the size is out of tolerance, so in the absence of vernier calipers, it can be weighed and checked. For example, for rebar 20, the standard stipulates that the larger negative tolerance is 5%, and its single theoretical weight is 120 kg when the length is 9M, and its minimum weight should be: 120X (L-5%) = 114 kg, and the actual weight of the weighed single stick is smaller than 114 kg, which is shoddy steel because it has a negative tolerance of more than 5%. In general, the effect of integral weighing will be better, mainly considering the problem of cumulative error and probability theory.
11. The inner diameter size of fake and shoddy steel fluctuates greatly, because; 1) The steel temperature is unstable and has a yin and yang side. 2) The composition of the steel is uneven. 3) Due to the rudimentary equipment, the foundation strength is low. Source: Mold technology The bounce of the whole screen rolling mill is large. There will be a large change in the inner diameter in the same week, so that the steel bar is unevenly stressed and easy to break.
12. The trademark and printing of high-quality materials are relatively standardized.
13. Three large threads with a diameter of 16 or more, the spacing between the two trademarks is above IM.
14. The longitudinal bars of shoddy steel rebar are often wavy.
15. Fake and shoddy steel manufacturers are relatively loosely packaged because they do not drive. The sides are oval in shape.