The difference between low oxygen copper rod and oxygen free copper rod
The difference between low-oxygen copper rods and oxygen-free copper rods Due to the different manufacturing methods, low-oxygen copper rods and oxygen-free copper rods have different characteristics and have their own characteristics.
1) About the inhalation and removal of oxygen and its presence
The cathode copper for producing copper rods generally has an oxygen content of 10 to 50 ppm, and the solid solubility of oxygen in copper is about 2 ppm at normal temperature. The oxygen content of the low-oxygen copper rod is generally 200 (175) - 400 (450) ppm, so the oxygen is inhaled in the liquid state of copper, while the upper oxygen-free copper rod is the opposite, and the oxygen is under the liquid copper. After a certain period of time, it is reduced and removed. Usually, the oxygen content of the rod is below 10-50 ppm, and the lowest is 1-2 ppm. From the tissue point of view, the oxygen in the low-oxygen copper is in the state of copper oxide. It exists near the grain boundaries, which is common for low-oxygen copper rods but rare for oxygen-free copper rods. The appearance of copper oxide in the form of inclusions at the grain boundaries has a negative effect on the toughness of the material. While the oxygen in the oxygen-free copper is very low, the uniformity of the copper structure is advantageous for the toughness of the single-phase structure. Porosity in oxygen-free copper rods is uncommon, and is a common defect in low-oxygen copper rods.
2) Difference between hot rolled structure and foundry structure
Since the low-oxygen copper rod is hot-rolled, its structure is a hot-worked structure, and the original cast structure has been broken. It has been recrystallized in the form of a rod of 8 mm, and the oxygen-free copper rod is a cast structure with coarse grains. This is why, the oxygen-free copper has a higher recrystallization temperature and requires an inherent reason for a higher annealing temperature. This is because recrystallization occurs near the grain boundaries, and the crystals of the oxygen-free copper rods are coarse, and the grain size can reach several millimeters. Therefore, the grain boundaries are small, and the grain boundaries are relatively low even by the drawing deformation. Oxygen copper rods are still less, so higher annealing power is required. The successful annealing requirement for oxygen-free copper is that the first annealing of the rod is drawn, but the line of the structure has not yet been cast, and the annealing power should be 10-15% higher than that of the low-oxygen copper in the same case. After continuous drawing, the annealing power at a later stage should have sufficient margin and a different annealing process for the difference between low-oxygen copper and oxygen-free copper to ensure the softness of the in-process and finished wires.
3) Inclusion, fluctuations in oxygen content, differences in surface oxides and possible hot rolling defects
The pullability of oxygen-free copper rods is superior to that of low-oxygen copper rods in all wire diameters. In addition to the above-mentioned structural reasons, the oxygen-free copper rods are less entrained, the oxygen content is stable, and there are no defects that may occur due to hot rolling. The thickness of the rod oxide can reach ≤15A. If the process is unstable during continuous casting and rolling production, the monitoring of oxygen is not strict, and the instability of oxygen content will directly affect the performance of the rod. If the surface oxide of the rod can be compensated for in the continuous cleaning of the subsequent process, it is more troublesome that a considerable amount of oxide exists in the "subcutaneous", which has a more direct influence on the disconnection of the wire, so that the fine wire is drawn, In the case of ultra-fine lines, in order to reduce the wire breakage, it is sometimes necessary to take a last resort on the copper rod - the reason for peeling or even secondary peeling, in order to remove the subcutaneous oxide.
4) The toughness of low-oxygen copper rods and oxygen-free copper rods are different
Both can be pulled to 0.015mm, but the low temperature grade oxygen-free copper in the low temperature superconducting wire has a spacing of only 0.001mm between the filaments.
5) There is a difference in economics from the raw materials of the rods to the production line
The manufacture of oxygen-free copper rods requires high quality raw materials. Generally, when drawing a copper wire with a diameter of >1 mm, the advantages of the low-oxygen copper rod are obvious, and the oxygen-free copper rod is more advantageous in drawing a copper wire having a diameter of <0.5 mm.
6) The process of making low-oxygen copper rods is different from that of oxygen-free copper rods.
The line-making process of the low-oxygen copper rod cannot be transferred to the line-making process of the oxygen-free copper rod, and at least the annealing process of the two is different. Because the softness of the wire is deeply affected by the material composition and the rod making, the wire making and the annealing process, it cannot be simply said that the low-oxygen copper or oxygen-free copper is soft and hard.
Nowadays, people often hear the confusion of oxygen-free copper and low-oxygen copper. In order to reduce this situation, I feel that it is necessary to help people to judge the product correctly through certain methods based on years of practical experience. species. First of all, oxygen-free copper and low-oxygen copper are definitely not a material, they have very different performances, and if you look carefully at the appearance, you can find some places to distinguish them.
Oxygen-free copper is not the same as the latter's production process. It can be heard by name. The main difference between the two is the difference in oxygen content. Someone said this time, I know that an oxygen, a non-oxygen, although it sounds quite right, is actually wrong. Although called oxygen-free copper, this material is also oxygen-containing, but the content is very small, so small that it is negligible. Such materials are not oxygen-free. The manufacturing process of the two materials is different, so there is a certain difference in their performance. The appearance of oxygen-free copper is more bright, so when two products are encountered at the same time, the general brightness is better than oxygen-free copper. The material is gone.
Due to the different processes for producing copper rods, the oxygen content and appearance of the produced copper rods are different. The copper rod produced by the above process has an oxygen content of less than 10 ppm and is called an oxygen-free copper rod. The copper rod produced by continuous casting and continuous casting is hot rolled under protective conditions, and the oxygen content is in the range of 200-500 ppm, but sometimes Up to 700ppm or more, in general, the copper produced by this method is bright, sometimes called a polished rod.
The oxygen-free copper rod is also made by imported equipment and domestic equipment, but the difference between the copper rod products is not very big. As long as the copper board is selected well, the production control is relatively stable, and the domestic equipment can also produce a stretchable 0.05. Copper rod. The imported equipment is generally the equipment of Outokumpu in Finland. The original Foshan electrician, after the sale to Yixing Yida is this kind of equipment. In fact, Suzhou Jinhui is the domestic equipment, the quality is OK, but the previous two years The boss did not know if it had any effect.
There are two kinds of international equipment for low-oxygen rods. One is the US Southern Line Equipment, the English is SOUTHWIRE, the domestic manufacturers are Nanjing Huaxin, Jiangxi Copper, and the other is Germany CONTIROD equipment. The domestic manufacturers are Changzhou Jinyuan, Tianjin University. seamless.
The anaerobic and low-oxygen rods are easily distinguished from the oxygen content. The oxygen-free copper is below 10-20 PPM, but some manufacturers can only do 50 PPM or less. The low-oxygen copper rod is at 200- 400 PPM, good rods generally have an oxygen content of about 250 PPM. The anaerobic rods are generally taken by the upper method. The low-oxygen rods are continuous casting and rolling. The two products are relatively low-oxygen rods for enameled wire. More suitable, such as softness, rebound angle, winding performance. But the low oxygen rod is relatively harsh on the drawing conditions, the same stretch of 0.2 filament, if the wire condition is not good, the ordinary anaerobic rod can pull The good low-oxygen rod is broken, but if the rod is placed in a good condition, the same rod, the hypoxic rod may be pulled to double zero five, and the ordinary oxygen-free rod can only be stretched to 0.1. Of course, the finest ones, such as the double zeros, have to rely on imported oxygen-free copper rods. At present, some companies try to use the peeling method to deal with the low-oxygen rods to stretch 0.03 lines. But I am not yet concerned about this aspect. very clear.
The audio line generally prefers to use an anaerobic rod. This is related to the anaerobic rod is single crystal copper, and the low oxygen rod is related to polycrystalline copper. The low oxygen rod and the anaerobic rod are all used by electricians, which are nothing more than wires and cables, enameled wires, Flat wire, copper row. There is no difference in the field of application. The difference between the two is the oxygen content. The national standard specifies a low oxygen oxygen content of less than 450 PPM and an anaerobic rod of less than 20 PPM.
Oxygen-free rods have higher resistivity and processability than low-oxygen rods, so high-demand electrical materials generally use anaerobic rods. For example, the enameled wire, the anaerobic rod must be made of smaller electric resistance. When applied to the motor, the heat is definitely better than the low oxygen rod, so manufacturers who value quality are definitely more willing to use the anaerobic rod as the raw material. Moreover, when the low oxygen rod is drawn, it is difficult to draw a filament lower than 0.5 mm, and the processing performance of the anaerobic rod is much stronger.
Therefore, it is basically a low-oxygen rod for electrical products with large specifications and low resistance requirements; an oxygen-free rod with small specifications and high resistance requirements. Nowadays, more and more cable companies tend to use oxygen-free copper rods as raw materials for cable production. What are the advantages of oxygen-free copper rods compared to ordinary copper rods?
“Compared to ordinary copper rods, oxygen-free copper rods have superior ductility and higher electrical conductivity, making them the most ideal raw materials for wire and cable and electrical and electrical industries,” said a senior oxygen-free copper rod manufacturer.
Only copper rods with an oxygen content below 20 ppm can be called oxygen-free copper rods. Because the resistivity and processing performance of oxygen-free copper rods are stronger than ordinary copper rods, manufacturers who value quality will prefer to use oxygen-free copper rods as raw materials. Compared with oxygen-free copper rods, ordinary copper rods have the disadvantage of being difficult to draw filaments below 0.5 mm, so oxygen-free copper rods are particularly popular with thin wire manufacturers such as enamelled wires.
The characteristics of the copper rod are different depending on the oxygen content of the copper rod. Ordinary copper rods often have a considerable amount of copper oxide impurities, which will have a negative impact on the toughness of the material. The excellent oxygen-free copper rod has almost no impurities and has excellent toughness. Moreover, the excellent oxygen-free copper rod has uniform structure and coarse crystals, which not only overcomes the most common porosity defects in ordinary copper rods, but also has the most superior pullability in all wire diameters.
Compared with ordinary copper rods, oxygen-free copper rods have excellent characteristics such as high purity, low oxygen content, high electrical conductivity and good processing performance, and the appearance is smooth, the surface is round, and there are no burrs, cracks, peeling and inclusion defects. There is no doubt about the advantages.
So, does the oxygen-free copper rod with such excellent performance mean high prices? The industry’s answer is no, on the one hand, the current domestic production of oxygen-free copper rods is mainly based on the upper method, this mainstream process It has the advantages of short process flow, high yield, low cost and low investment. Therefore, the price of oxygen-free copper rod is not much higher than that of ordinary copper rod. On the other hand, the production process of oxygen-free copper is close. 20 years of development, operation methods and processes, etc. have many improvements, such as the addition of refining processes in the production process of the upper indexing method, the use of the waste copper wire generated in the production process of the upper frequency method, eliminating the need for additional processing. Fees and shipping charges. With a complete technical process and production process, a mature oxygen-free copper rod can make the cost of oxygen-free copper rods and ordinary copper rods almost the same.