How to identify fake and shoddy steel in appearance

1. Fake and shoddy steel are prone to folding. Folds are various fold lines formed on the surface of steel, and this defect often runs throughout the length of the product. The reason for folding is that shoddy manufacturers pursue high efficiency and the reduction is too large, resulting in ears. Folding will occur during the next rolling process. The folded product will crack after bending, and the strength of the steel will be greatly reduced.

2 The appearance of fake and inferior steel products is often pitted. Pockmarking is an irregular uneven defect on the steel surface caused by severe wear of the rolling groove. Due to the pursuit of profits by manufacturers of shoddy and inferior steel products, groove rolling often exceeds the standard.

3 The surface of fake and inferior steel is prone to scarring. There are two reasons:

(1) The material of fake and inferior steel is uneven and contains many impurities.

(2) The guide equipment of the fake and inferior steel manufacturers is simple and easy to stick to the steel. These impurities can easily cause scarring after biting the rollers.

4 The surface of fake and inferior materials is prone to cracks because its raw material is adobe, which has many pores. The adobe is subject to thermal stress during the cooling process, causing cracks, and cracks appear after rolling. .

5 Fake and shoddy steel is easy to scratch. The reason is that the equipment of the fake and shoddy steel manufacturers is simple and easy to produce burrs and scratch the surface of the steel. Deep scratches reduce the strength of steel.

6 Fake and inferior steel has no metallic luster and is light red or similar in color to pig iron. There are two reasons:

(1) Its blank is adobe.

(2) The rolling temperature of fake and inferior steel products is not standard. Their steel temperature is measured by visual inspection. In this way, rolling cannot be carried out in the specified austenite area, and the performance of the steel products will naturally not meet the standards.

7 The transverse ribs of fake and inferior steel materials are thin and low, and often are not fully filled. The reason is that in order to achieve a large negative tolerance, the reduction amount of the first few passes of the finished product is too large, the iron shape is too small, and the holes are too small. The model is not fully charged.

8 The cross-section of fake and inferior steel is oval. The reason is that in order to save materials, the manufacturer has a larger reduction amount in the first two passes of the finished roller. The strength of this kind of rebar is greatly reduced, and it does not meet the requirements. Standard for external dimensions of rebar.

9 The composition of high-quality steel is uniform, the tonnage of the cold shear machine is high, and the end face of the cutting head is smooth and neat. However, due to the poor material quality of fake and inferior steel, the end face of the cutting head often has meat loss, that is, it is uneven. And no metallic luster. And because the products produced by fake and inferior material manufacturers have fewer heads, big ears will appear at the head and tail.

10 Fake and inferior steel materials contain many impurities, the density of the steel is low, and the dimensions are seriously out of tolerance, so it can be weighed and checked without a vernier caliper. For example, for rebar 20, the national standard stipulates that the maximum negative tolerance is 5. When the fixed length is 9M, its theoretical weight of a single rod is 120 kg. Its minimum weight should be: 120 X (l-5) = 114 kg, weighing If the actual weight of a single piece is less than 114 kilograms, it is fake steel because its negative tolerance exceeds 5. Generally speaking, the effect of phase-integrated weighing will be better, mainly considering the issues of cumulative error and probability theory.

11 The inner diameter size of fake and inferior steel fluctuates greatly because of:

(l) The unstable steel temperature has a yin and yang side.

(2) The composition of steel is uneven.

(3) Due to the crude equipment and low foundation strength, the rolling mill has a large bounce. There will be large changes in the inner diameter within the same week. Such uneven stress on the steel bars will easily lead to breakage.

12 The trademarks and printing of high-quality materials are relatively standardized.

13 For large threads with a diameter of 16 or more steel materials, the distance between the two trademarks is above IM.

14 The longitudinal bars of shoddy steel rebar are often wavy.

15 The fake and shoddy steel manufacturers have no operation, so the packaging is relatively loose. The sides are oval.

16 rebar and wire rod packaging are generally 1.5t/piece of rebar and 1.3t/piece of wire.

The steel plates produced by 17 inferior steel mills have obvious wavy surfaces due to poor rolling and cooling techniques, which do not meet the national standards