Views: 0 Author: XDLASER Publish Time: 2021-09-14 Origin: XDLASER
Laser welding is mainly aimed at the welding of thin-walled materials and precision parts, which can realize spot welding, butt welding, overlap welding, seal welding, etc. with high depth width ratio, small weld width, small heat affected zone, small deformation, fast welding speed, flat and beautiful weld, no treatment or simple treatment after welding, high weld quality, no pores, accurate control, small focus light spots and high positioning accuracy, Easy automation. Then, how to use the protective gas correctly in laser welding?
In laser welding, shielding gas will affect weld formation, weld quality, weld penetration and weld width. In most cases, blowing shielding gas will have a positive impact on the weld, but it may also bring adverse effects.
Positive functions:
1. correct blowing of shielding gas will effectively protect the weld pool and reduce or even avoid oxidation;
2. correct blowing of shielding gas can effectively reduce the spatter generated during welding;
3. The correct blowing of shielding gas can promote the uniform spreading of weld pool during solidification, making the weld formation uniform and beautiful;
4. Correct blowing of shielding gas can effectively reduce the shielding effect of metal vapor plume or plasma cloud on laser and increase the effective utilization rate of laser;
5. Correct blowing of shielding gas can effectively reduce weld porosity.
As long as the gas type, gas flow and blowing mode are selected correctly, the ideal effect can be obtained. However, incorrect use of shielding gas will also have an adverse impact on welding.
Negative functions:
Incorrect blowing of shielding gas may cause weld deterioration;
1. Selecting the wrong gas type may cause cracks in the weld and reduce the mechanical properties of the weld;
2. Selecting the wrong gas blowing flow may lead to more serious oxidation of the weld (whether the flow is too large or too small), or serious interference of the weld pool metal by external forces, resulting in weld collapse or uneven forming;
3. Selecting the wrong gas blowing method will lead to the weld not reaching the protection effect or even basically no protection effect, or have a negative impact on the weld formation;
4. Blowing shielding gas will have a certain impact on the weld penetration, especially when welding thin plates, it will reduce the weld penetration.
The commonly used shielding gases for laser welding mainly include N2, AR and he, and their physicochemical properties are different, so their effect on the weld is also different.
The Principles of choosing shielding gas:
First of all, it should be clear that the so-called "oxidation" of the weld is only a common name. In theory, it refers to the chemical reaction between the weld and harmful components in the air, resulting in the deterioration of the weld. It is common that the weld metal reacts with oxygen, nitrogen and hydrogen in the air at a certain temperature.
Preventing the weld from being "oxidized" is to reduce or avoid the contact between such harmful components and the weld metal under high temperature. This high temperature state is not only the molten pool metal, but the whole time period from the time when the weld metal is melted to the time when the pool metal solidifies and its temperature is reduced below a certain temperature.
The selection of shielding gas directly affects the quality, efficiency and cost of welding production. However, due to the diversity of welding materials, the selection of welding gas is also complex in the actual welding process. It is necessary to comprehensively consider the welding material, welding method, welding position and required welding effect, and select more suitable welding gas through welding test, Achieve better welding results.
For details, welcome to contact XDLASER.
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