Training skills for steel for bearings (1)

**Training Skills for Bearing Steel (1)** Home > Bearing Knowledge > Training Skills for Bearing Steel (1) Source: Bearing Network | Time: 2013-02-11 --- The oxygen content in bearing steel plays a crucial role in determining the number of inclusions, which directly impacts the fatigue life of the bearing. Studies have shown that there is a clear relationship between the oxygen content and the relative life of the steel. The formula is as follows: L10 (relative life) = 372 [O] - 1.6 Where [O] represents the oxygen content in the steel, measured in parts per million (ppm). One of the most significant improvements in bearing steel production has been the reduction in oxygen levels. In the early 1960s, oxygen content was around 30×10⁻⁶, but today it has dropped to between 3–5×10⁻⁶. This improvement has led to an L10 value more than 30 times higher than before vacuum degassing was introduced. ### 1. Vacuum Degassing and Advanced Refining Techniques In 1964, the ladle degassing method was introduced. This involved placing the ladle in a vacuum chamber and using inert gas for stirring, reducing the pressure to 66.5 Pa (0.5 Torr). This process lowered the oxygen content from (25–35)×10⁻⁶ to (15–20)×10⁻⁶. However, this method had a drawback: the alkaline slag was also stirred, limiting the purity of the steel. To address this issue, the RH (Ruhrstahl-Heraeus) method was introduced in 1968. It operated under high vacuum (13.3 Pa or 0.1 Torr), effectively removing hydrogen and oxygen without disturbing the slag. When combined with a 60-ton high-power electric furnace, the oxygen content was further reduced to (8.3–15)×10⁻⁶. In 1974, the LF (Ladle Furnace) method was introduced to complement ultra-high-power electric furnaces. The LF method involves heating, stirring, and vacuum degassing within the ladle, allowing for better control of slag composition, deoxidation, desulfurization, and dehydrogenation. This combination of UHP furnace + LF + RH methods brought the oxygen content down to (5–10)×10⁻⁶, which is essential for consistent casting. Additionally, atomization and circulating vacuum degassing methods, such as the DH method, were developed to further enhance the efficiency of the process. ### 2. Vacuum Treatment in Bearing Steel Production Vacuum treatment not only prevents oxidation of molten steel but also helps in deoxidizing it, achieving higher purity compared to traditional vacuum degassing. Some of the key methods include: #### 2.1 Vacuum Induction Melting (VIM) In the VIM method, high-quality scrap steel and alloy grades are selected and placed into a small induction furnace. The furnace is then placed inside a large vacuum chamber. A sealed hopper is used to add the required alloys. This process ensures minimal contamination and precise control over the chemical composition of the steel. --- **Related Bearing Knowledge** Full-rolling cylindrical roller bearings are essential components in bearing grinding machines, acting as the stepping motor of the system. They ensure smooth operation and help in diagnosing common rolling bearing faults. Understanding their function and maintenance is vital for efficient bearing performance. This article is linked to http:// Please cite China Bearing Network: http:// Previous: Bearings for Diesel Engine Hydraulic Transmission System – Repair Conditions and Methods for Rolling Bearings

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