Do You Know What Are The Common Laser Welding Defects? What Are Its Causes And Solutions?

Laser welding uses a high-energy-density laser beam as a heat source. By controlling parameters such as laser pulse width, energy, peak power, and repetition frequency, the workpiece is melted and a specific molten pool is formed. It is an efficient and precise welding method. Since the development of laser welding, it has been widely used in various industries, such as: electronic parts, automobile manufacturing, aerospace and other sky industry manufacturing fields. But even so, the laser welding method will inevitably have some defects, resulting in substandard products. Only by fully understanding the defects caused by laser welding and mastering the solutions can we meet the higher welding process requirements of the product.

So, what are the common laser welding defects? What is the cause and solution?

1. Undercut

Undercut refers to improper selection of welding parameters or incorrect operation methods, resulting in grooves or depressions along the base metal of the weld toe.

Undercut defects can be classified into three qualities:

General: Defect depth is not greater than 1.5mm

Medium: Defect depth is not greater than 1.0mm

Strict: Defect depth is not greater than 0.5mm

Undercut reason:

Improper operation methods, incorrect selection of welding specifications, such as too much welding current, too long arc, improper transport method and angle, too long or too short stay time on both sides of the groove may cause undercut.

Solution:

1. Control the welding current and welding speed of the laser welding machine

2. Moderately master the length of the arc

3. Correctly apply the method of transport and the angle of the electrode

2. Depression of the weld

Weld sag refers to the phenomenon that the metal is heated for too long, the welding current is too high, or other circumstances cause the metal plate to collapse downwards and form a pit.

Causes of weld sinking:

1. The assembly gap is too large, the blunt edge is too small, the volume of the molten pool is large, and the liquid metal falls due to its own weight.

2. The diameter of the electrode or the welding current is too large, slow arc extinguishing or continuous arc welding will increase the temperature of the molten pool and slow cooling, resulting in an increase in the gravity of the metal in the molten pool and a decrease in surface tension.

3. Improper transport angle weakens the pressure of the arc on the molten pool metal or the electrode is not transported to the root of the groove.

Solution:

1. When performing single-sided welding and double-sided forming welding, it is necessary to select the appropriate blunt edge, angle and clearance of the groove. The operation must be skilled and accurate.

2. Strictly control the arc heating time of breakdown and the angle of the strip, the size of the melting hole should be appropriate, and short arc welding should be adopted.

3. Stomata

Pores refer to the cavities formed in the weld when the gas in the molten pool does not escape before the metal solidifies and remains in the weld. The gas may be absorbed by the molten pool from the outside, or it may be generated by the reaction during the welding metallurgy process.

The main reason for the generation of pores is rust, oil stains, etc. on the surface of the base metal or filler metal. If the electrode and flux are not dried, the amount of pores will increase, because the rust, oil stain, electrode coating, and moisture in the flux decompose into gas at high temperature, which increases Gas content in high temperature metals. If the welding line energy is too small, the cooling rate of the molten pool is high, which is not conducive to the escape of gas. Insufficient deoxidation of the weld metal can also increase oxygen pores.

Solution:

1. Remove oil, rust, moisture and sundries from the welding wire, working groove and nearby surfaces.

2. Use basic electrodes, flux, and dry thoroughly

3. Use DC reverse connection and short arc welding

4. Preheat before welding and slow down the cooling rate

5. Use stronger specifications for welding

There is no doubt that laser welding will produce defects, but a good machine will definitely reduce product defects.

Fly Laser Equipment Co., Ltd. is a high-tech enterprise integrating R&D, manufacturing and sales of industrial laser equipment. The company's R&D team is composed of senior professional and cutting-edge talents in the new energy lithium battery equipment industry. Fly Laser's welding equipment has obvious advantages, such as The laser welding spot is fine, the penetration depth is high, the precision is high, the welding surface effect is smooth without bubbles, and the welding quality is good.

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