Some questions about rust of bearing and bearing steel

Question 1: Will bearing steel rust?

Will rust. Bearing steel, including stainless steel, is rusty.

Although stainless steel is said to be stainless, it is actually rusty. In fact, there is no rust-free steel in the world!

Question 2: How does the bearing steel rust?

The so-called stainless steel refers to different degrees of corrosion resistance.

Corrosion rate <0.01mm/y, considered as “complete corrosion resistance”;

If the corrosion rate is less than 0.1mm/y, it is considered “corrosion resistant”;

If the corrosion rate is greater than 0.1mm/y, it is considered “not corrosion resistant”, that is, ordinary steel.

Except for a small part of the bearing steel is stainless steel, most of it is ordinary corrosion-resistant steel, so it is not strange at all to rust, it is normal.

Question 3: Why does the bearing rust?

Bearing rust is related to the material and use environment. Bearing steel itself contains carbon components and will react with water vapor. If you want to prevent the bearing from rusting, you must do a good job of anti-rust treatment. Or choose non-steel bearings.

Metal products are prone to rust after oxidation, and stainless steel bearings are no exception. There are many factors that affect its rust: such as the chemical composition and structure of the metal material itself; the surface finish (corrosion of the battery with poor oxygen concentration); the composition and pH value of the solution in contact with the metal surface; and the environment in which it is located. All are the direct factors that make the bearing rusty.

In addition, when we use the bearing, do not directly touch objects with your hands, because when sweat contacts the bearing, it will form a layer of sweat film on the bearing surface. The sweat film will cause electrochemical effects on the bearing and corrode the bearing. Therefore, we must use special gloves or finger cots and other special tools to pick up the bearing, and don’t touch it directly with your hands.

Question 4: Will bearings made of GCr15 bearing steel rust in an outdoor environment?

Yes, and it will rust very much like ordinary steel. The Cr content of this steel is too small. The value behind the bearing steel is the Cr content, and the unit is one thousandth. The Cr content of GCr15 is only About 1.5%, if the Cr content is close to the 13% boundary, the anti-rust effect will be better. For example, Cr12 (containing about 12% Cr) steel will basically not rust.

Question 5: Can bearing steel be rust-proof?

Although the content of Cr in bearing steel is relatively high and has a certain anti-rust effect, the Cr content of steel is small. The Cr content of GCr15 is only about 1.5%. At this time, the Cr element plays a role in improving the mechanical properties of the steel. The Cr of steel is to improve the hardenability, not to prevent rust. Like ordinary metals, a humid environment can cause corrosion. Therefore, anti-rust measures for bearings and their parts are still very necessary.

Question 6: How to prevent bearing rust?

1. Surface cleaning method

Cleaning must be based on the nature of the surface of the anti-rust material and the prevailing conditions, and an appropriate method must be selected. Commonly used are solvent cleaning method, chemical treatment cleaning method and mechanical cleaning method. When the surface is dry and clean, it can be dried with filtered dry compressed air, or dried with a dryer at 120~170℃, or dried with clean gauze.

2. Method of applying anti-rust oil

(1) Soaking method: Some small bearings are immersed in anti-rust grease to make the surface adhere to a layer of anti-rust grease. The thickness of the oil film can be achieved by controlling the temperature or viscosity of the anti-rust grease.

(2) Brushing method: It is used for large bearings that are not suitable for immersion or spraying. When brushing, it is necessary to pay attention not to accumulate, but also to prevent leakage.

(3) Spray method: Some large bearings cannot be oiled by immersion method. Generally, use filtered compressed air with a pressure of about 0.7Mpa for spraying in a clean air place. The spray method is suitable for solvent-diluted anti-rust oil or thin-layer anti-rust oil, but complete fire protection and labor protection measures must be adopted.