Ten Common Defects And Solutions of Laser Welding

Ten Common Defects and Solutions of Laser Welding

Laser welding is an efficient and precise welding method that uses a high-energy-density laser beam as a heat source. It has the advantages of high efficiency, precision, and ease of use. Today, laser welding has been widely used in various industries, such as electronic parts, automobile manufacturing, aerospace and other industrial manufacturing fields.

However, laser welding is not omnipotent. Sometimes, processing errors may occur due to operation or parameter setting. Only by fully understanding these defects and learning how to avoid them can the value of laser welding be better realized.

Ten Common Defects and Solutions

Welding Splash 

The splash produced by laser welding seriously affects the surface quality of the weld and will contaminate and damage the lens. Generally, it manifests as: after laser welding is completed, many metal particles appear on the surface of the material or workpiece and adhere to the surface of the material or workpiece.

Cause of splash: The surface of the processed material or workpiece is not cleaned, there are oil stains or pollutants, and it may also be caused by the volatilization of the galvanized layer.

Solution: A. Pay attention to cleaning the material or workpiece before laser welding; B. Splash is directly related to power density. Appropriately reducing the welding energy can reduce splash

Crack

The cracks caused by continuous laser welding are mainly thermal cracks, such as crystal cracks, liquefaction cracks, etc.

Causes of cracks: Mainly due to excessive shrinkage force before the weld is completely solidified.

Solution: Filling wire, preheating and other measures can reduce or eliminate cracks.

Porosity

Porosity on the weld surface is a defect that is more likely to occur in laser welding.

Causes of pores: A. The laser welding molten pool is deep and narrow, and the cooling speed is very fast. The gas generated in the liquid molten pool has no time to overflow, which easily leads to the formation of pores. B. The weld surface is not cleaned, or the zinc vapor of the galvanized sheet evaporates.

Solution: Clean the workpiece surface and the weld surface before welding to improve the volatilization of zinc when heated. In addition, the blowing direction will also affect the formation of pores.

Undercut

Undercut means: the weld is not well combined with the parent material, a groove appears, the depth is greater than 0.5mm, the total length is greater than 10% of the weld length, or greater than the length required by the acceptance standard.

Reasons for undercut: A. The welding speed is too fast, the liquid metal in the weld will not be redistributed on the back of the small hole, and undercuts will form on both sides of the weld. B. The joint assembly gap is too large, and the molten metal in the joint filling is reduced, which is also prone to undercut. C. At the end of laser welding, if the energy decreases too quickly, the small hole is prone to collapse, which will also cause local undercuts.

Solution: A. Control the processing power and speed of the laser welding machine to avoid undercuts. B. The weld undercuts found during inspection can be polished, cleaned and repaired to meet the requirements of the acceptance standard.

Weld accumulation

The weld is obviously overfilled, and the weld is too high when filling.

Causes of weld accumulation: wire feeding speed is too fast or welding speed is too slow during welding.

Solution: increase welding speed or reduce wire feeding speed, or reduce laser power.

Welding deviation

The weld metal will not solidify in the center of the joint structure.

Causes of deviation: inaccurate positioning during welding, or inaccurate filling welding time and welding wire alignment.

Solution: adjust the welding position, or adjust the welding time and welding wire position, as well as the position of the lamp, welding wire and weld.

Weld depression

Weld depression refers to the phenomenon of depression on the surface of the weld metal.

Cause of depression: During brazing, the center of the weld is poor. The center of the light spot is close to the lower plate and deviates from the center of the weld, causing part of the parent material to melt.

Solution: Adjust the light wire matching.

Poor weld formation

Poor weld formation includes: poor weld ripples, uneven and irregular welds, uneven transition between welds and parent materials, poor welds, and uneven welds.

Causes of this situation: unstable wire feeding or discontinuous light during weld brazing.

Solution: Adjust the stability of the equipment.

Weld bead

When the weld track changes greatly, weld bead or uneven forming is easy to appear at the corner.

Cause: The weld track changes greatly and the teaching is uneven.

Solution: Weld under the optimal parameters and adjust the viewing angle to make the corner coherent.

Surface slag inclusion

Surface slag inclusion refers to: during the welding process, the surface slag that can be seen from the outside mainly appears between layers.

Analysis of the cause of surface slag inclusion: A. When welding multiple layers and multiple passes, the interlayer coating is not clean; or the surface of the previous layer of weld is uneven or the surface of the weldment does not meet the requirements. B. Improper welding operation techniques such as low welding input energy and too fast welding speed.

Solution: A. Select a reasonable welding current and welding speed. The interlayer coating must be cleaned when welding multiple layers and multiple passes. B. Grind the weld to remove the surface slag inclusion and repair it when necessary.