Nowadays, laser welding machines have been widely used in welding fields, such as: jewelry welding, stainless steel welding, welding of other materials, etc. In laser welding, shielding gas will affect weld formation, weld quality, weld penetration depth and penetration width. In most cases, blowing shielding gas will have a positive effect on the weld, but it may also cause damage. Come unfavorable effect. Below, Leapion Laser will share with you the types and functions of shielding gas during laser welding.
First of all, the commonly used laser welding shielding gases in the laser welding process are mainly N2, Ar, He, and their physical and chemical properties are different, and therefore the effect on the weld is also different.
The ionization energy of N2 is moderate, higher than that of Ar, and lower than that of He. Under the action of laser, the ionization degree is average, which can reduce the formation of plasma cloud better, thereby increasing the effective utilization rate of laser. Nitrogen can chemically react with aluminum alloy and carbon steel at a certain temperature to produce nitrides, which will increase the brittleness of the weld, reduce the toughness, and have a greater adverse effect on the mechanical properties of the weld joint. Therefore, it is not recommended to use nitrogen. Aluminum alloy and carbon steel welds are protected.
The nitride produced by the chemical reaction between nitrogen and stainless steel can increase the strength of the weld joint, which will help improve the mechanical properties of the weld. Therefore, nitrogen can be used as a shielding gas when welding stainless steel.
The ionization energy of Ar is relatively low, and the ionization degree is high under the action of laser, which is not conducive to controlling the formation of plasma cloud and will have a certain impact on the effective utilization of laser. However, the activity of Ar is very low and it is difficult to chemically interact with common metals. The cost of Ar is not high. In addition, the density of Ar is higher, which is beneficial to sink to the top of the weld pool, and can better protect the weld pool, so it can be used as a conventional shielding gas.
The ionization energy of He is high, and the ionization degree is very low under the action of laser, which can well control the formation of plasma cloud. The laser can act on metal well, and the activity of He is very low, and it basically does not chemically react with metal. It is a good shielding gas for welding seams, but the cost of He is too high. Generally, mass production products will not use this gas. He is generally used for scientific research or products with very high added value.
1. The correct blowing of shielding gas will effectively protect the weld pool to reduce or even avoid oxidation;
2. The correct blowing of shielding gas can effectively reduce the splash produced during the welding process;
3. The correct blowing of shielding gas can promote the uniform spread of the weld pool during solidification, so that the weld is formed uniformly and beautifully;
4. The correct blowing of shielding gas can effectively reduce the shielding effect of the metal vapor plume or plasma cloud on the laser, and increase the effective utilization rate of the laser;
5. The correct blowing of shielding gas can effectively reduce the welding seam porosity.
Under normal circumstances, as long as the gas type, gas flow rate, and blowing method are selected correctly, the desired effect can be obtained. However, incorrect use of shielding gas will also have an adverse effect on welding.
1. Incorrect blowing of shielding gas may cause the weld to deteriorate;
2. Selecting the wrong gas type may cause cracks in the weld, and may also reduce the mechanical properties of the weld;
3. Choosing the wrong gas flow rate may cause more serious oxidation of the weld (whether the flow is too large or too small), and may also cause the weld pool metal to be seriously interfered by external forces and cause the weld to collapse or unevenly form;
4. Choosing the wrong gas blowing method will cause the welding seam to fail to achieve the protective effect or even basically no protective effect or have a negative impact on the welding seam formation;
5. Blowing in shielding gas will have a certain impact on the weld penetration, especially when welding thin plates, it will reduce the weld penetration.
For more professional questions about laser welding machines, please contact Leapion Laser.