The difference between hypoxic copper rod and oxygen-free copper rod

Copper rods are the main raw materials in the cable industry. Due to different production processes, the oxygen content and appearance of the copper rods produced are different. Due to the different manufacturing methods, it is divided into low-oxygen copper rods and oxygen-free copper rods, which have their own characteristics. Today, the editor of China Cable Network will introduce the difference between the two~

Low oxygen copper rod: The copper rod produced by the continuous casting and rolling method is hot rolled under protective conditions, and the oxygen content is in the range of 200-500ppm, but sometimes it is as high as 700ppm or more. Bright, called low oxygen copper rod, sometimes called polished rod.

Oxygen-free copper rod: The copper rod produced by the upward continuous casting method, the oxygen content of which is below 10ppm, is called oxygen-free copper rod.

1. About the inhalation and desorption of oxygen and its state of existence

The oxygen content of cathode copper used to produce copper rods is generally 10-50 ppm, and the solid solubility of oxygen in copper at room temperature is about 2 ppm. The oxygen content of the low-oxygen copper rod is generally 200 (175)-400 (450) ppm, so the entry of oxygen is inhaled in the liquid state of copper. From the organizational point of view, oxygen in low-oxygen copper exists near the grain boundary in the state of copper oxide, which is common for low-oxygen copper rods, but rare for oxygen-free copper rods. The presence of copper oxide in the form of inclusions at grain boundaries negatively affects the toughness of the material. The oxygen in oxygen-free copper is very low, so the structure of this copper is a uniform single-phase structure, which is beneficial to toughness.

2. The difference between hot-rolled structure and cast structure

The low-oxygen copper rod is hot-rolled, so its structure is a hot-worked structure. The original cast structure has been broken, and the recrystallization form has appeared when the rod is 8mm, while the oxygen-free copper rod is a cast structure with coarse grains. The successful annealing requirements for oxygen-free copper are: the first annealing when the wire is drawn from the rod but has not yet cast the structure, the annealing power should be 10-15% higher than that of the low-oxygen copper in the same situation. After continuing to draw, the annealing power in the later stage should leave enough margin and perform different annealing processes for low-oxygen copper and oxygen-free copper to ensure the flexibility of the wire in process and the finished product.

3. The difference between the fluctuation of oxygen content and possible hot rolling defects

The drawability of oxygen-free copper rods is superior to that of low-oxygen copper rods in all wire diameters. In addition to the above organizational reasons, oxygen-free copper rods have less inclusions, stable oxygen content, and no defects that may be caused by hot rolling. . In the production process of continuous casting and rolling, if the process is unstable and the oxygen monitoring is not strict, the unstable oxygen content will directly affect the performance of the rod.

4. The difference in toughness between hypoxic copper rods and oxygen-free copper rods

Both can be pulled to 0.015mm, but the low-temperature oxygen-free copper in the low-temperature superconducting wire has only a 0.001mm spacing between the filaments.

5. The economic difference between the raw material of the rod and the wire

Manufacturing oxygen-free copper rods requires high-quality raw materials. In general, when drawing copper wires with a diameter of >1mm, the advantages of low-oxygen copper rods are more obvious, and the oxygen-free copper rods are more superior when drawing copper wires with a diameter of <0.5mm.

6. Differences in the wire making process

The wire-making process of the low-oxygen copper rod cannot be copied to the wire-making process of the oxygen-free copper rod, at least the annealing process of the two is different. Because the softness of the wire is deeply affected by the material composition and rod making, wire making and annealing process, it cannot be simply said that the low-oxygen copper or the oxygen-free copper is soft and hard.