Laser cutting process of common engineering materials
Although almost all metal materials have high reflectivity to infrared energy at room temperature, CO2 lasers emitting 10.6um beams in the far-infrared band are successfully applied to many metal laser cutting practices. The initial absorption rate of 10.6um laser beam by metal is only 0.5%~10%. However, when a focused laser beam with a power density exceeding 106w/cm2 is irradiated on the metal surface, it can be quickly used in microseconds. The surface began to melt. The absorption rate of most metals in the molten state rises sharply, generally by 60% to 80%. (1) Carbon steel. Modern laser cutting system can cut carbon steel plate with a maximum thickness of up to 20mm. The cutting seam of carbon steel can be controlled within a satisfactory width range by the oxidation melting cutting mechanism, and the cutting seam for thin plates can be as narrow as about 0.1mm. (2) Stainless steel. Laser cutting is an effective processing tool for the manufacturing industry that uses stainless steel sheet as the main component. Under strict control of the heat input in the laser cutting process, the heat-affected zone of the trimming can be restricted from becoming very small, thereby effectively maintaining the good corrosion resistance of this type of material. (3) Alloy steel. Most alloy structural steels and alloy tool steels can be laser-cut to obtain good trimming quality. Even for some high-strength materials, as long as the process parameters are properly controlled, straight, non-sticky slag cutting edges can be obtained. However, for tungsten-containing high-speed tool steels and hot mold steels, there will be erosion and slag sticking during laser cutting. (4) Aluminum and alloys. Aluminum cutting is a melting cutting mechanism, the auxiliary gas used is mainly used to blow away the molten product from the cutting area, and usually a better cut surface quality can be obtained. For some aluminum alloys, attention should be paid to prevent the occurrence of intercrystalline micro-cracks on the surface of the slit. (5) Copper and alloys. Pure copper (red copper) basically cannot be cut with CO2 laser beam due to its high reflectivity. Brass (copper alloy) uses a higher laser power, and the auxiliary gas uses air or oxygen, which can cut thinner plates. (6) Titanium and alloys. Pure titanium can well couple the heat energy converted by the focused laser beam. When the auxiliary gas is oxygen, the chemical reaction is fierce and the cutting speed is faster, but it is easy to form an oxide layer on the cutting edge, and it can cause overburn if you are not careful. For the sake of safety, it is better to use air as the auxiliary gas to ensure the cutting quality. The laser cutting quality of titanium alloy commonly used in the aircraft industry is better. Although there will be a little sticky slag at the bottom of the cutting seam, it is easy to remove. (7) Nickel alloy. Nickel-based alloys are also called super alloys, and there are many varieties. Most of them can be oxidized fusion cutting.