Laser techniques are born in the early 1960s, and has grown rapidly in a high-tech. Its development and penetration, led to the development of other disciplines and technologies, laser technology has become the one of the main pillars of century high-tech industry. Laser processing technology is mainly used in industrial laser technology in laser processing technology to accelerate the transformation of the traditional processing industry, providing a new means of modern industrial processing technology, a significant influence. Laser machining refers to a high-power laser beam for cutting industrial parts, heat treatment, welding, drilling, etc., as compared with the conventional processing methods, the laser processing characteristics are: high concentration of laser beam energy, small processing areas, and thus thermal deformation, high processing quality, high precision, machining parts from the size, shape restrictions, without cooling medium, and non-polluting, low noise, low labor intensity, high efficiency. Industrial laser processing technology is emerging in China. First, the characteristics of laser heat treatment technology of laser surface heat treatment method is the use of high power density of the laser beam on the metal surface treatment, it can achieve a phase change material hardening (or called surface hardening, surface amorphous, surface remelting pure fire), surface alloying surface modification, generated with additional surface hardening reach the surface composition, organization, change properties. Monochrome laser with coherence, direction and four characteristics of high energy density, and therefore its penetration ability. Penetration of the laser power is its high energy density filial strength, duration and decision. When the power density of 103W / cm2 ~ 107W / cm2, with 103 ℃ / s ~ 107 ℃ / s heating rate of the metal surface is heated to just below the melting point of critical transition temperature, its surface quickly austenitizing, then rapidly since Cold quenching, cooling speeds of up to 1.7 × 104 ℃ / s, the metal surface was quickly strengthened, which is laser transformation hardening. Significant features laser heat treatment is: a high-speed heating, high-speed cooling, the organization received a fine, high hardness, good wear resistance; hardening parts is greater than the residual compressive stress obtained 400kgf / mm2 to help improve fatigue performance; can also be the local Selective quenching, through multi-spot size control, more suitable for other thermal methods incompetence hardened holes, deep trenches, micro, angle and tool edge and other local areas; laser can be long-distance transmission can be realized A multi-stage lasers simultaneously, using computer programming for laser heat treatment process control and management, automation of production processes. Second, application and development of laser heat treatment in industry due to the laser annealing quite obvious advantages, to solve the traditional metal heat treatment can not be solved or not easy to solve technical problems at home and abroad by the attention, the laser heat treatment has been rapid development . High-power CO2 lasers developed rapidly since the 1970s, the advanced industrial countries have been the product of high-power CO2 lasers, serialization. China from the "Plan" after successfully developed a kilowatt to megawatt-class high-power multimode CO2 laser. With the development of high-power lasers, the laser can be achieved by various forms of surface treatment. It is caused by changes in the material structure of the metallurgical process, the heating time is in the range of 10-3s ~ 10-7s, the power density per square millimeter of greater than 0.1 kW. Its wide range of applications, almost all metal surface heat treatment can be applied. Currently apply more cars, metallurgy, petroleum, heavy machinery, agricultural machinery and other serious wear and tear of machinery industry, as well as aerospace, aviation and other high-tech products. Laser heat treatment is extensively used in the automotive industry, in many key auto parts, such as: cylinder, cylinder, crankshaft, camshaft, exhaust valve, seat, rocker, aluminum piston ring grooves, etc. can almost laser heat treatment . For example, General Motors Corporation with more than a dozen kilowatt CO2 laser, partial hardening of the commutator shell wall, Nissan 30,000 sets, increase efficiency fourfold. Our high-power CO2 lasers automobile engine cylinder hole wall hardening, extended engine overhaul mileage to 150,000 km or more, a cylinder equal to three cylinders without treatment. Laser heat-treated wear cylinder, cylinder liner hardened with the substantial increase, not hardened belt can increase the storage, faster performance to improve the lubrication of tractor development, has introduced a new brand, but the tractor with an internal combustion engine cylinder block, cylinder sets short life, serious damage to a large amount of maintenance, engine parts plant in Xi'an Science and Technology Commission to help countries, first built a diesel engine cylinder liner laser heat treatment production line, with an annual output 600,000, 10,000 hours life expectancy. Cylinder similar laser heat treatment equipment and production lines Laser Coating with laser alloying process, but the difference is not additional alloying, melting the metal surface then cooled and solidified to obtain a nearly uniform fine surface structure, for some eutectic alloy , but also to give an amorphous surface layer having excellent corrosion resistance, for example, on a diesel engine iron chromium-based valve seat surface coating, the surface of the stainless steel obtained good. Laser heat treatment has been used in a large locomotive manufacturing, greatly improving the life of the locomotive, primarily laser heat treatment laser annealing of large crankshafts locomotives and locomotive diesel cylinder and locomotive reed. Mold manufacturing process complexity, high precision, shapes, widely used, but often because of short lifetime of the mold and increase the cost of repair is very difficult. Mold surface with a laser to heat treatment, has gradually been adopted is limited awareness and can exponentially increase die life, but also from the shape and size. Laser heat treated crankshaft the laser heat treatment has increasingly shown its advantages, various high-power CO2 laser heat treatment machines continue to come out. Some large companies at the expense of the introduction of foreign advanced equipment, such as the introduction of Germany DLoco 6000W CO2 laser for large crankshafts heat treatment production lines. At the same time, the domestic high-power CO2 laser heat treatment equipment sales doubled every year, laser heat treatment production line in the country have been developed. There are currently more successful examples DLoco for locomotive crankshafts, cylinder, vertical reed laser heat treatment production line; diesel engine cylinder combustion engine plant in Xi'an laser heat treatment production line; the internal combustion engine and the capital Beijing car company car engine cylinder liner laser heat treatment production line ; Changchun First Automobile Works laser heat treatment production line. At the same time the country has also established a different scale laser machining center for laser annealing machine parts for various industries. Third, the development of new applications of laser heat treatment, promote the industrialization of laser processing laser is a high-tech, very broad applications. The key technology of laser heat treatment are threefold: high-power lasers; more freedom processing equipment and computer support; laser heat treatment process for different applications. After China's laser science and technology personnel efforts more than a decade, these three aspects of the fast development and create conditions for the promotion of laser heat treatment technology. In recent years, laser industry with double-digit growth rate, higher than the rate international laser industry development, but also higher than the national industrial growth rate, showing that the prospects are ambitious. Laser heat treatment technology is not yet widespread in the country, mainly people on laser technology, there are varying degrees of mystification and prejudice. Technique, laser heat treatment application promotion, lack of practice. Therefore, as soon as possible to scientific research in laser technology, in particular laser heat treatment technology for economic, market-oriented, the whole of society, mainly for industrial enterprises and services, continue to promote and expand its applications. To achieve this purpose, the establishment of a dedicated laser heat treatment production line is important, but the establishment of multi-purpose laser processing center for more SMEs and more essential. In the United States, Europe and Japan have this machining center more than 800, many of the city in recent years has also established a similar laser machining centers, services to all industries, it has played a good role model, but also created considerable economic and social benefits. It is no exaggeration to say that the laser heat treatment can solve almost all the problems of metal surface heat treatment, but the process must constantly explore, explore, experiment. Laser heat treatment center can do the job, and the fastest development of its applications. For example, in the growing automobile and tractor repair industry, laser heat treatment has made a very good application effect. It can be predicted, laser processing technology, especially the development and application of laser heat treatment technology will accelerate the process of China's laser industry. 

keywords: Laser Heat Treatment , , ,