The effect of laser welding on the surface treatment of titanium alloy rods

The process parameters of laser welding are difficult to master because the thermal efficiency fluctuates greatly during the welding process. The surface condition of the titanium alloy rod being welded has a significant impact on the thermal efficiency: the surface brightness has a considerable influence. The brighter the surface, the greater the light emission to the laser, and most of the laser energy is reflected to other objects and transferred to the surrounding substances or media in the form of "heat". However, the thermal efficiency can suddenly change. Before the titanium alloy rod melts, only about 10% - 20% of the light energy is absorbed by the titanium alloy rod and heats it up. When the temperature rises to the melting point of the weld metal and begins to melt, the absorption rate of the titanium alloy rod for light energy increases sharply. At this time, about 60% - 80% of the light energy is absorbed by the metal, and the sudden change in the thermal effect can easily cause the weld to be burned through.

To avoid or reduce this adverse effect, some corresponding measures can be taken, such as roughening the surface of the welded titanium alloy rod; using pulsed laser beams; adjusting the input energy; adjusting the size of the light spot; changing the pulse width and the steepness of the attenuation wave, etc.

Using a natural ruby crystal containing aluminum oxide and dissolved in a low concentration of chromium atoms as the working substance of the laser generator is called a solid-state laser generator. Using CO2, etc. as the working substance of the laser generator is called a gas laser generator.

At present, the power of laser welding machines is only at the kilowatt level, and the price is expensive, the welding cost is high, and the application range is not yet widespread. It is only used for some micro-component welding points in the production and manufacturing of certain instruments and equipment, especially for some welding points that are relatively concealed, and cannot be welded by general welding methods. Laser beams can be used to achieve multi-station welding with the help of optical fibers and deflection prisms.