Writer: Eric Bearing Limited
Steel balls are the rolling elements that carry the total load of the ball bearing, and are also one of the important components of the bearing. However, when we use IKO bearings, we often find the phenomenon of cracking of the bearing steel balls, such as: bearing steel ball wear marks, bearing steel The ball has obvious squeeze, the bearing steel ball is partially defective, cracks appear on the bearing steel ball and the surface of the steel ball is peeled off.
So what causes the bearing steel ball to crack? Next, Eric Bearing Limited will share relevant knowledge based on the knowledge of bearing steel balls.
According to the analysis of the cracking fracture of the bearing steel ball, some parts of the IKO bearing steel ball have a linear distribution with bright and uneven edges. These IKO bearing steel balls have obvious signs of extrusion and wear.
After analysis, there may be three possible causes of IKO bearing steel ball cracking:
1. The steel ball is cracked during use after being installed inside the IKO bearing, and the cracking direction is the material rolling direction.
2. There are obvious loose bands in the core of the steel ball, the band-like carbides exceed the standard and the surface contains abnormal elements such as oxygen, calcium, and magnesium. Therefore, it is determined that there is a residual shrinkage cavity in the core of the steel ball, which is a metallurgical defect, which is also the main reason for the cracking of the steel ball during use.
3. The overheating of the quenched and tempered structure of the steel ball increases its brittleness, reduces the compressive strength, and makes the steel ball more prone to cracking.
When the size of the steel ball is small or the fracture is severely squeezed or worn, the rolling direction of the material cannot be determined, and it is difficult to perform conventional fracture analysis. At this time, the crack can be found by observing the relationship between the defect morphology and the metallographic structure by metallographic method. The main reason.
To give another example, a certain IKO bearing steel ball is bright as a whole, and there is no high temperature discoloration, but there is a crack about 10mm, and there is peeling near the crack.
After analysis, the reason for the cracking of this kind of bearing steel ball is mainly due to the excessively high quenching heating temperature and the large amount of carbide dissolution, which significantly increases the carbon content of austenite, and forms network or semi-network carbonization at the grain boundary during cooling. IKO LRXD15 in stock , if you need , contact us .
Observing and analyzing the metallographic structure of the faulty steel ball, it is concluded that the faulty steel ball has overheated during the quenching process. At the same time, there are band-shaped carbides in the steel ball structure, which makes the carbon-poor zone over-mature in the heat treatment process. As a result, the steel ball deforms greatly during quenching, which can easily lead to quenching cracks. That is to say, quenching cracks caused by excessively high quenching temperature.
Quenching cracks refer to the cracks that are generated during the quenching process or during the room temperature placement process after quenching, which are macroscopic cracks and are caused by macroscopic internal stress. After the quenching cracking occurred, in the subsequent work process, the steel ball suffered contact fatigue spalling under the influence of the quenching crack defect and the periodic pulsating contact stress.
Note: During the heat treatment of steel balls, the heat treatment process parameters should be strictly controlled to ensure the stability of the heat treatment temperature and holding time.
Some bearing steel balls are partially convex or elliptical, but the surface of the steel balls after shelling is bright and complete imagination.
The reason for this phenomenon of IKO bearing steel ball may be caused by external factors such as operating conditions, but a considerable part of it is caused by the steel ball itself. Such as raw material defects or manufacturing defects, and the raw material factors are mainly divided into three aspects: surface defects, low magnification structure defects and microstructure defects. The failure of another part of the bearing steel ball may also be caused by fatigue.