The main features of laser heat treatment

With the continuous development of society and economy, science and technology change with each passing day. Laser heat treatment is more and more widely use in our daily life. But many people do not know much about laser heat treatment. In fact, laser heat treatment is a surface heat treatment technology.  A high-energy laser beam use to quickly scan the workpiece. So that the surface temperature of the irradiated metal or alloy rises above the phase transition point at an extremely rapid rate. When the laser beam leaves the irradiated site, Heat conduction effect. The matrix in the cold state allows it to cool quickly and perform self-cooling quenching to obtain a finer hardened layer structure. And the hardness is generally higher than the conventional quenching hardness. The following are the main features of laser heat treatment.

(A) directional light

Ordinary light sources emit light in all directions. To make the emitted light propagate in one direction. A certain light-condensing device needs to installe on the light source. For example, the headlights and searchlights of a car are both equippe with a light-concentrating reflector, so that the radiated light is collecte and emitte in one direction. The laser light emitted by the laser is naturally emitted in one direction. The divergence of the beam is extremely small, only about 0.001 radians, which is close to parallel. In 1962, humans used a laser to illuminate the moon for the first time.

The distance between the earth and the moon was about 380,000 kilometers, but the laser spot on the surface of the moon was less than two kilometers. If the focusing effect is very good, the seemingly parallel searchlight beams will hit the moon and cover the entire moon according to its spot diameter.

(Two) extremely high brightness

Before the invention of the laser, the brightness of the high-voltage pulsed xenon lamp in the artificial light source was the highest, which was comparable to the brightness of the sun, and the laser brightness of the ruby laser could exceed the xenon lamp by several tens of billions. Because the laser is extremely bright, it can illuminate distant objects.

The light emitte by a ruby laser on the moon produces an illuminance of about 0.02 lux (a unit of illumination), the color is bright red, and the laser spot clearly visible. If the most powerful searchlight is used to illuminate the moon, the resulting illuminance is only about one trillionth of a lux, which is impossible for human eyes to detect. The main reason for the extremely high laser brightness is directional light emission. A large number of photons are concentrated and emitted in a very small spatial range, and the energy density is naturally extremely high.

(Three) the color is extremely pure

The color of light determine by the wavelength (or frequency) of the light. A certain wavelength corresponds to a certain color. The wavelength range of visible light emitted by the sun is between 0.76 nanometers and 0.4 nanometers. Corresponding colors are 7 colors from red to purple, so the sunlight is not monochromatic. A light source emitting a single color of light is called a monochromatic light source, and the wavelength of the light wave it emits is single. For example, krypton lamps, helium lamps, neon lamps, hydrogen lamps, etc. are all monochromatic light sources and emit only a certain color of light. Although the light wavelength of a monochromatic light source is single, it still has a certain distribution range.

For example, the neon lamp emits only red light, which has good monochromaticity, and know as the crown of monochromaticity. The wavelength distribution range is still 0.00001 nanometers. Therefore, if the red light emitte by the neon lamp carefully identifie, it still contains dozens of red . It can see that the narrower the wavelength distribution interval of light radiation, the better the monochromaticity.

(4) Extreme energy density

The photon energy calculate using E = hv, where h is the Planck constant and v is the frequency. It can see that the higher the frequency, the higher the energy. The laser frequency range is 3.846 × 10 ^ (14) Hz to 7.895 × 10 ^ (14) Hz.

The above points are the main features of laser heat treatment in daily life. I hope it can be helpful to everyone.