The quality of the mold steel directly affects the quality of the mold, and the quality of the mold directly affects the quality of the pressure processing technology, the precision of the product and the production cost. Therefore, it’s important to select the good quality mold steel.
1. The surface of the fake steel is prone to scarring. The reasons are: (1) the material of the fake and inferior steel is uneven, and there are many impurities; (2) The guide equipment of the fake inferior material manufacturer is simple and easy to stick steel, and these impurities are easy to cause crusting after biting the roller.
2. The surface of the fake inferior material is prone to cracks. The reason is that the billet is an adobe, and the adobe has many pores. The adobe is cracked by the action of thermal stress during the cooling process, and cracks occur after rolling.
3. The appearance of fake steel is often pockmarked. The pockmark is a defect caused by the irregularity of the surface of the steel due to the serious wear of the groove. Due to the pursuit of profit by shoddy steel manufacturers, the most frequent rolling mill rolling is exceeded.
4. The inner diameter of the counterfeit steel has large fluctuations. The reasons are: (1) the temperature of the steel is unstable and there are yin and yang; (2) the composition of the steel is not uniform; (3) due to the poor equipment, the strength of the foundation is low, and the rolling of the rolling mill is large. There will be a large change in the inner diameter in the same week, and such a steel bar is unevenly stressed and easily broken.
5. The fake steel material contains more impurities, the density of steel is too small, and the size is too bad, so in the absence of vernier calipers, it can be weighed and checked. For example, for rebar 20, the national standard specifies a maximum negative tolerance of 5%. At a fixed length of 9 M, its single theoretical weight is 120 kg. Its minimum weight should be: 120X (l-5%) = 114 kg. The actual weight of a single root is less than 114 kg, which is a fake steel because its negative tolerance exceeds 5%. In general, the effect of the phasing weighing will be better, mainly considering the problem of cumulative error and probability theory.
