Laser surface strengthening and heat treatment applications

Laser surface strengthening and heat treatment technology is a new material surface treatment technology developed in the past 20 years. The principle of laser surface strengthening technology is to use the characteristics of laser penetration. When the metal surface is heated to a critical transition temperature below the melting point, the surface is rapidly austenitized, then rapidly quenched and quenched, and the metal surface is rapidly Be strengthened. Laser surface strengthening and heat treatment can be divided into three categories: one is that the metal does not melt when the laser is irradiated, but the microstructure changes. This type of process is mainly laser phase transformation hardening (laser quenching); the second is that the metal melts during laser irradiation, and the tissue is cooled. Changes or addition of other elements to improve surface properties, including laser melting, laser alloying, laser amorphization and microcrystallization; third, the metal surface vaporization during laser irradiation, resulting in tissue changes, such processes are mainly laser Impact hardening. The common theoretical basis of the above various laser heat treatment processes is the interaction law of laser and matter and its metallurgical behavior.

Laser heat treatment is the development and supplement of traditional heat treatment technology, which can solve the problem of material strengthening that other surface treatment methods cannot solve or solve. After laser treatment, the surface layer strength of the cast layer can reach above HRC60, and the surface hardness of medium carbon, high carbon steel and alloy steel can reach above HRC70, thereby improving its anti-wear, anti-fatigue, anti-corrosion and anti-oxidation properties and prolonging its performance. Service life.

Laser heat treatment is widely used in the automotive industry. HJ laser heat treatment can be applied to many key parts of the vehicle (such as cylinder block, cylinder liner, crankshaft, camshaft, exhaust valve, valve seat or piston ring). Similarly, agricultural locomotives should also be widely used. In agricultural production, the working conditions of the machine are varied, and some machines (ploughs, cultivators, seeders and harvesters) work directly in the abrasive medium, causing many parts to wear out quickly. On the other hand, in order to obtain sufficient strength, the machine uses a large amount of material, which not only wastes material but also becomes bulky. For such parts, the hardness after laser hardening is 5% to 20% higher than the conventional quenching hardness. Laser alloying can be selected to add new materials according to requirements to form a new substrate-based alloy layer to obtain satisfactory performance. In addition, due to the improved performance after processing, a low-performance substrate can be selected, thereby reducing the quality of the substrate.