Laser welding machine has cracks in welding

‌The main reasons for laser welding machine cracks include too fast cooling speed, differences in material properties, improper welding parameter settings, and poor weld design and welding surface preparation. ‌

1. First of all, too fast cooling speed is a major cause of cracks. During the laser welding process, the welding area is quickly heated and then quickly cooled. This rapid cooling and heating will cause large thermal stress inside the metal, which will then form cracks. ‌

2. In addition, different metal materials have different thermal expansion coefficients. When welding two different materials, cracks may occur due to differences in thermal expansion. ‌

3. Improper settings of welding parameters such as power, speed, and focal length will also lead to uneven heat distribution during welding, affecting welding quality and even causing cracks. ‌

4. The welding surface area is too small: The size of the laser welding spot is affected by the laser energy density. If the welding spot is too small, excessive stress will be generated in the local area, leading to cracks. ‌

5. Poor weld design and welding surface preparation are also important factors that cause cracks. Improper weld geometry and size design may lead to welding stress concentration, and improper cleaning and pretreatment of the welding surface will affect the quality and strength of the weld and easily lead to cracks

For these problems, the following solutions can be taken:

1. Control the cooling rate, slow down the cooling rate by preheating or using retarder, etc. to reduce the accumulation of thermal stress;

2. Select matching materials, try to choose materials with similar thermal expansion coefficients for welding, or add a layer of transition material between two different materials;

3. Optimize welding parameters, adjust appropriate welding parameters according to the characteristics of the welded materials, such as appropriately reducing power, adjusting welding speed, etc.;

4. Increase welding surface area: Appropriately increasing the welding surface area can alleviate the stress and crack problems caused by small local welds.

5. Carry out material pretreatment and post-weld treatment, remove impurities such as oil, scale, etc. from the welding part, and use heat treatment methods such as annealing and tempering to eliminate welding residual stress and improve the toughness of the welded joint.

6. Perform subsequent heat treatment: For some materials that are difficult to avoid cracks, appropriate heat treatment can be performed after welding to eliminate the stress generated after welding and avoid the occurrence of cracks.