Characteristics of Laser Quenching Technology and Its Application in Steel Heat Treatment

Reducing costs and increasing efficiency is the ultimate goal pursued by enterprises. Throughout the history of steel industry technology, many major technological breakthroughs, such as converter steelmaking, continuous casting, and rolling, have been driven primarily by the desire to reduce costs. In today's highly mature metallurgical technology, utilizing remanufacturing technology to extend the service life of core components in metallurgical production lines can not only improve the performance of new products, but also repair waste products, extend product life, and effectively reduce equipment maintenance and downtime, improving production capacity.

The basic principle of laser quenching
Laser quenching technology is a heat treatment technique that uses a focused laser beam as a heat source to irradiate the surface of the processed workpiece, causing the temperature of the hardened part to rapidly increase, forming austenite, and then rapidly cooling to obtain a hardened layer of martensite or other fine-grained structures.

Technical characteristics of laser surface quenching
1. High power density, fast heating speed, and small part deformation
The heat treatment process can control deformation, and the processed workpiece does not need to be ground, which can be used as the last step of precision machining of parts.
2. Can be used for complex shaped spare parts
Such as blind holes, inner holes, small grooves, thin-walled parts, etc. It can be done or partially done, or different treatments can be done in different parts of the same section as needed. It can overcome the limitations of high-frequency quenching due to sensors, making it difficult to surface quench complex shaped parts, controlling the heating area, and making thin-walled parts prone to cracking during quenching. In chemical heat treatment processes such as carburization and quenching, the processing of large parts does not need to be limited by the size of the furnace.
3. Universality
The deep focus of laser does not have strict limitations on the size, size, and surface of parts during the quenching process. But the existing medium and high frequency quenching must produce sensors suitable for various parts.
4. Unrestricted
For certain stainless steel parts with high quenching temperatures, their quenching temperature is very close to the melting point temperature. When using sensors to locally quench the surface of a product, it is easy to burn corners or irregular parts, resulting in part scrapping. However, laser surface quenching is not limited by this.
5. No cooling required
Laser quenching is a clean, efficient, and environmentally friendly quenching process with fast cooling speed and no need for cooling media such as water or oil.
6. Meet hardening requirements
The surface hardening layer has a fine structure, high hardness, and good wear resistance, which can meet the requirements of products with shallow surface hardening layer depth (generally 0.3-2.0mm).

 Application examples of laser quenching technology in the steel industry
1. Laser alloying of rolling rolls
Roll is the main working component and tool in the steel rolling mill that produces continuous plastic deformation of metals. Long term harsh working conditions can lead to surface peeling, cracking, and even fracture. Alloying the rolling mill with laser can effectively prolong the service life of the rolling mill. Through laser alloying treatment of rod rollers, the steel's passing ability is significantly improved due to its non deformation, high temperature resistance, and corrosion resistance.

2. Roller bottom laser quenching
As a medium for transporting high-temperature slab, the furnace bottom roller works in a high-temperature environment filled with corrosive gases for a long time. The roller ring in direct contact with the high-temperature slab is prone to phenomena such as steel sticking, nodulation, oxidation, corrosion, wear, and high-temperature creep on the surface. Especially, various quality defects such as pits, scratches, and heavy skin on the lower surface of the slab caused by steel sticking and nodulation are particularly prominent on soft steel such as silicon steel and cold rolled raw materials. Laser quenching a layer of new material on the surface of the roller ring that is resistant to high temperature, oxidation, and wear. During the service life of the furnace bottom roller, surface nodules or loose or peeling oxide scales may affect the subsequent rolling quality of steel plates and billets, which can effectively improve the economic benefits of the production line. Laser quenching technology can strengthen the surfaces of various guides, large gears, journals, cylinder walls, molds, shock absorbers, friction wheels, rollers, and roller parts. Applicable materials include medium and high carbon steel, cast iron, etc.

Source: Electronics World