Laser surface strengthening and heat treatment can be divided into three categories: firstly, the metal does not melt when the laser is irradiated, but the tissue changes, and the process is mainly laser phase hardening (laser quenching). The second is that the metal melts when the laser is irradiated, and the tissue changes after cooling, or adds other elements to improve the surface properties, including laser melting, laser alloying, laser amorphous and crystallization. In the case of laser irradiation, the metal surface of the metal is vaporized, which can change the tissue. This kind of process is mainly for the laser impact hardening. The theoretical basis of the above various laser heat treatment techniques is the interaction of laser and matter and its metallic behavior.
Laser heat treatment is the development and supplement of traditional heat treatment technology. It can solve the problem of material reinforcement that other surface treatment methods cannot solve or cannot solve. After laser treatment, casting layer surface strength can reach more than HRC60, carbon, high carbon steel and alloy steel in the surface layer of hardness can reach more than HRC70, thus improve its wear resistance, fatigue resistance, corrosion resistance and anti oxidation performance and prolong its service life.
Laser heat treatment is widely used in automotive industry and is used in many key parts (such as cylinder block). The cylinder liner, crankshaft, camshaft, exhaust valve, seat or piston ring can all be used for HJ laser heat treatment. Similarly, agricultural locomotives should be widely used. In agricultural production, the machine's working condition is varied, some machines (plough, cultivator, planter, harvester) directly to work in the abrasive medium, make many parts wear quickly. On the other hand, in order to obtain sufficient strength, the machine has a large amount of material, which is not only wasteful of materials, but also bulky. For such parts, after the laser hardening treatment the hardness is higher than conventional quenching hardness of 5% one 20%, laser alloying can choose according to requirements to join the new material, new alloy layer formed on the basis of the base material, in order to obtain satisfactory performance. In addition, because of the improved performance, the low-performance substrate can be used to reduce the quality of the substrate.