Principle and characteristic analysis of laser heat treatment
"Heat treatment" is a method of changing the structure or properties of a metal material by heating it in a variety of ways.Although tissue changes in photofocal heat treatment techniques induce surfaces similar to existing high-frequency heat treatment methods, laser heat treatment methods have more advantages. For example, after laser heat treatment, the size change of the base material is almost zero, because the denser tissue becomes a high surface hardness without separate cooling works.Laser heat treatment can also be used for selective heat treatment of required parts, such as three-dimensional shaped mechanical parts and die products, as well as parts of unnecessary blades, direction at the same time, using pyrometer to measure and control real-time surface temperature of substrate, stable heat treatment quality can obtain a large number of small batch production items.
After laser heat treatment, the surface hardness may vary depending on the carbon content of the substrate, and is usually still in & GT;At the horizontal HC in 5365, the effective hardening depth is about 0.8 ^ 1.5 m, and the hardening amplitude is adjusted to a few millimeters to tens of millimeters depending on the laser power.Until the beginning of 2000, mainly used in carbon dioxide laser laser heat treatment project, but the former is a variety of high-power laser development, has a high absorption rate of high-power excitation of metal materials, including semiconductor laser, laser optical disc, optical fiber laser heat treatment and improve the product's hardness and strength field.
Using the basic principle of laser metal heat treatment technology, the temperature of the base material will rise sharply until the base material reaches the temperature in inches, and then the base material will be greatly cooled down again. The laser beam with high energy density is on the surface of the metal material, thus inducing the surface tissue change.The laser irradiation on the substrate is converted into heat energy, the surface of the substrate is heated, and the heat conduction property of the substrate is used to cool the surface of the substrate, and finally the hardness and strength of the substrate are improved.
Characteristics of laser heat treatment are mainly divided into the following five points:
Ordinary light sources emit light in all directions.In order to make the emitted light travel in one direction, it is necessary to install a certain condenser on the light source.For example, car headlights and searchlights are reflectors equipped with a condenser effect, which allows the radiation to be collected and emitted in one direction.The laser beam emitted by the laser beam, naturally, is emitted in one direction, the divergence of the beam is very small, about 0.001 radian, almost parallel
Before the invention of laser, the high-pressure pulsed xenon lamp was the highest artificial light source, about as bright as the sun, while the ruby laser could be billions of times brighter than the xenon lamp.Because of their high brightness, lasers can illuminate distant objects.
Color of pure
Color of light depends on the wavelength (or frequency) of the light.A certain wavelength corresponds to a certain color.The wavelength of visible light emitted by the sun ranges from 0.76 nanometers to 0.4 nanometers, and there are seven corresponding colors ranging from red to purple, so sunlight is not a monochromatic light.A source emitting monochromatic light is called a monochromatic light source, which emits light of a single wavelength.
High energy density
Energy of the photon is calculated by E= HV, where H is Planck's constant and V is the frequency.So the higher the frequency, the higher the energy.The laser frequency range is 3.846×10^(14)Hz to 7.895×10^(14)Hz.