1 Fake steel breaks easily. Folding is a variety of broken lines formed on the surface of steel, which often runs through the longitudinal direction of the whole product. The reason for folding is that fake and shoddy manufacturers pursue high efficiency, and the reduction is too large, resulting in ears, which will fold in the next rolling, and the folded products will crack after bending, and the strength of steel will be greatly reduced.
The appearance of fake and shoddy steel often has pits. Pockmarked surface is an irregular and uneven defect of steel surface caused by serious groove wear. Due to the pursuit of profits by fake and shoddy steel manufacturers, the rolling groove often exceeds the standard.
3. The surface of fake and inferior steel is easy to scar. There are two reasons:
(1) The quality of fake and inferior steel products is uneven and there are many impurities.
(2) The guide equipment of fake and inferior steel manufacturers is simple and easy to stick to steel, and these impurities are easy to scar after biting the roll.
The surface of fake and inferior wood is easy to crack, because its body is adobe with many pores. Because of the thermal stress in the cooling process, the brick cracked and cracked after rolling.
5. Fake and inferior steel products are easy to be scratched, because the equipment of fake and inferior manufacturers is simple, and it is easy to produce burrs and scratch the steel surface. Deep scratches will reduce the strength of steel.
6 Fake and inferior steel has no metallic luster and is reddish or similar to pig iron for two reasons:
(1) Its blank is adobe.
(2) The rolling temperature of fake and inferior steel is not standard. Their steel temperature is all measured visually, so it is impossible to roll in the specified austenite zone, and the properties of steel will naturally fail to meet the standard.
7 The horizontal stripes of fake and shoddy steel are thin and low, which often leads to the phenomenon of insufficient filling. The reason is that in order to achieve greater negative tolerance, the reduction in the first few passes of the finished product is too large, the iron shape is too small, and the hole shape is not satisfied.
The section of fake and inferior steel bar is oval, because in order to save materials, the reduction of the first two rolls of finished products is too large, and the strength of this steel bar is greatly reduced, which does not meet the standard of steel bar shape and size.
High-quality steel has uniform composition, high cold shear tonnage, smooth and tidy end face of cutting head, but the end face of cutting head often loses meat because of poor material, that is, it is uneven and has no metallic luster. Moreover, because the products of fake and inferior wood manufacturers are cut less, there will be big ears at the head and tail.
10 There are many impurities in fake and inferior steel, the steel density is too small, and the size is out of tolerance, so it can be weighed and checked without vernier caliper. For example, the national standard stipulates that the maximum negative tolerance of rebar 20 is 5%, and its theoretical weight is 120kg when the length is 9M, and its minimum weight should be:120x (L-5%) = 14kg, and the actual weight ratio of a single thread is1. Generally speaking, the effect of integer proportional quantity will be better, mainly considering cumulative error and probability theory.
1 1 The inner diameter of fake and inferior steel fluctuates greatly because:
(l) The temperature of steel is unstable and has two sides.
(2) The composition of steel is uneven.
(3) Due to poor equipment and low foundation strength, the rolling mill bounces greatly. The inner diameter will change greatly in the same week, and such steel bars will be easily broken due to uneven stress.
12 trademark and printing comparison specification for high-quality materials.
13 diameter 16 or more, and the distance between two trademarks is above IM.
14 longitudinal bars of fake and inferior rebar are often wavy.
15 The fake and inferior steel products are loosely packed because there is no train. The side is oval.
16 rebar, wire packing rebar 1.5t/ piece, wire 1.3t/ piece.
17 steel plates produced by inferior steel mills have obvious waves on the surface due to poor rolling and cooling processes, which are not in line with China.