According to the internal and external factors affecting the smelting process, graphite electrode fracture can be summarized into the following two types:

1, internal factors: graphite electrode product quality.

(1) Causes of electrode nipple fracture

The nipple plays a key role in electrode connection in steelmaking. The quality of the graphite electrode nipple is directly related to the use of electrodes in electric furnace steelmaking. In terms of the quality of the nipple itself, there are several main causes of breakage:

a. If the bulk density of the nipple is low, its strength is generally low and it is easy to break when used;

b. The resistivity is too high, and the temperature of the nipple rises quickly, resulting in greater thermal stress at the electrode connection and increased probability of fracture;

c. The bending strength of the nipple is not enough;

d. Internal split graphite electrode nipple mixed with the finished graphite electrode nipple, forming a major hidden danger;

e. The nipple and the machining precision index of the electrode are not matched reasonably, which is easy to break.

(2) Causes of electrode body fracture

Generally speaking, the probability of electrode body fracture is low. The main causes of electrode body fracture are as follows:

a. There are quality defects in the screw hole of the electrode body;

b. Insufficient volume density and strength of electrode body;

c. The electrode body does not match the nipple index and machining accuracy;

d. The deep crack at the end of the electrode body is caused by the poor thermal shock resistance of the electrode;

2. External factors: reasons for the improper operation in the process of installation and use.

(1) The electrode is broken by collapse. If the scrap steel in the furnace has formed a bridge structure in the smelting process, especially when it is close to melting, the long time short-arc operation will produce a large side impact force leading to collapse; An important feature of this kind of accident is that the electrode holding point is subjected to the maximum moment and the probability of fracture near the electrode holding point is the maximum.

(2) Resonance makes the electrode break. When the graphite electrode is subjected to electromagnetic force in the smelting process, it must vibrate. If the mechanical vibration frequency of the electrode column is close to or synchronous with the electromagnetic force vibration frequency, the electrode will have resonance, which is easy to lead to electrode breakage due to fatigue

(3) Non-standard clamping operation leads to electrode fracture. The electrode and the gripper can not maintain vertical, the electrode will produce an additional horizontal component effect; If there is a foreign body on the clamping surface, the clamping point is easy to cause stress concentration; If the electrode is poorly connected, the mechanical strength of the electrode at the connection interface cannot meet the requirements. Force requirement. These bad operations can easily lead to electrode fracture in the smelting process.