In laser welding, shielding gas will affect the weld shape, weld quality, weld penetration and penetration width. In most cases, blowing shielding gas will have a positive effect on the weld, but it may also bring come to an adverse effect.
Positive effect of shielding gas
1. The correct blowing of shielding gas will effectively protect the weld pool to reduce or even avoid oxidation.
2. Correct blowing of shielding gas can effectively reduce spatter during welding.
3. The correct blowing of protective gas can promote the uniform spreading of the weld pool when it solidifies, making the weld shape uniform and beautiful.
4. Correct blowing of protective 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 rate, and insufflation method are selected correctly, the ideal effect can be obtained. However, incorrect use of shielding gas can also have adverse effects on welding.
Adverse Effects of Shielding Gas
1. Improper insufflation of shielding gas may result in poor weld seam.
2. Choosing the wrong type of gas may cause cracks in the weld, and may also lead to a decrease in the mechanical properties of the weld.
3. Choosing the wrong gas blowing flow rate may lead to more severe weld oxidation (whether the flow rate is too large or too small), and may also cause the weld pool metal to be seriously disturbed by external forces, resulting in weld collapse or uneven formation.
4. Choosing the wrong gas injection method will result in no protective effect or even no protective effect on the weld seam, or have a negative impact on the weld seam formation.
5. Insufflation of shielding gas will have a certain impact on the penetration depth of the weld, especially when welding thin plates, it will reduce the penetration depth of the weld.
Therefore, it is very important to choose the correct shielding gas during laser welding. The commonly used laser welding shielding gas is argon or nitrogen, which can effectively protect the metal welding surface from oxidation, so as to achieve the best welding quality.
