Cost reduction and efficiency is the ultimate goal pursued by enterprises, looking at the history of steel industry technology, many major technological breakthroughs, such as converter steelmaking, continuous casting, continuous rolling, etc., the primary motivation is to reduce costs. In today's metallurgical technology has been quite mature, with the help of remanufacturing technology to extend the service life of the core components of metallurgical production line, not only to enhance the performance of new products, but also to repair the old products, extend product life, while effectively reducing the equipment maintenance and downtime, improve production efficiency.
Principle of laser hardening
Laser quenching technology is a heat treatment that utilizes a focused laser beam as a heat source to irradiate the surface of the workpiece to be treated, so that the temperature of the part to be hardened rises sharply in an instant, forming austenite, and then obtains a hardened layer of martensite or other fine-grained structure through rapid cooling.
Technical characteristics of laser surface hardening
1. High power density, fast heating speed, small deformation of parts.
The heat treatment process can control the deformation, the workpiece does not need to be ground after treatment, and it can be used as a post-process of parts finishing.
2. Can be used for parts with complex shapes.
Such as blind holes, internal holes, small grooves, thin-walled parts. Can be or part, can also be different in different parts of the same part as needed. It can overcome the high-frequency quenching due to the limitations of the inductor, it is difficult to surface quenching of parts with complex shapes, the heating area is difficult to control, and thin-walled parts are easy to crack when quenching. Processing of large parts, in the carburizing, quenching and other chemical heat treatment process, do not need to be limited by the size of the furnace.
3. It is universal.
Due to the deeper laser focus, there are no strict limitations on the size, dimensions and surface of the parts when quenching. However, the existing medium and high frequency quenching must be for a variety of parts to make a suitable inductor.
4. Unrestricted for some quenching temperature higher stainless steel parts, quenching temperature and melting point temperature is very close to the use of inductors for local surface quenching of the product is easy to burn the edges or irregular parts, resulting in parts scrapped, while the laser surface quenching is not subject to this limitation.
5. No Cooling Required
Laser quenching is a clean, efficient, environmentally friendly quenching process, fast cooling, without the need for water, oil and other cooling media.
6. Meet the hardening requirements
The surface hardening layer has fine organization, high hardness and good wear resistance, which can meet the requirements of surface hardening products with shallow hardening layer depth (generally 0.3~2.0mm).
Some application examples in the steel industry
Roll laser alloying
Rolls are the main working parts and tools for continuous plastic deformation of metal in rolling mills, and the long-term harsh working environment leads to surface spalling, cracks and even fracture. Alloying the rolls by laser can effectively extend the service life of the rolls. The figure below shows the alloying treatment of bar rolls by laser, with no deformation, high temperature resistance, corrosion resistance, and significant increase in the amount of oversteel.
Furnace bottom roll laser melting
Furnace bottom roll as a high-temperature slab transmission medium, long-term work in a high-temperature environment filled with corrosive gases, and high-temperature slabs in direct contact with the roll ring, the surface is prone to sticking to the surface of the steel, tuberculosis, oxidation, corrosion, wear and tear, high-temperature creep and other phenomena, in particular by the sticking to the steel and tuberculosis caused by the lower surface of the slab pits, scratches, heavy skin and other types of quality defects, especially in the silicon-steel, cold-rolled raw materials, such as soft steel on the performance of the most prominent. Through the laser in the roll ring surface coating a layer of high temperature, oxidation, wear-resistant new materials, to avoid the use of the bottom of the furnace roll cycle roll ring surface of the phenomenon of sticking steel, tuberculosis, or loose peeling of the oxide skin and other phenomena, affecting the quality of the slab subsequent rolling, and can effectively improve the economic efficiency of the production line.
Laser quenching technology can be a variety of guide rails, large gears, journals, cylinder walls, molds, vibration dampers, friction wheels, rolls, roller parts for surface strengthening. Applicable materials are medium and high carbon steel, cast iron.
