Laser welding is a precision welding technology that is widely used in various industrial fields. However, during the laser welding process, some common welding defects often occur. The causes, solutions, and preventive measures for each defect are described in detail below:
1.Cracks:
Cause: The thermal stress generated during welding or the shrinkage stress during cooling exceeds the bearing capacity of the material, resulting in the formation of cracks.
Solution: Optimize the welding parameters and process, control the temperature gradient in the welding process, and reduce the stress concentrationStress relief with appropriate preheating and post-heat treatment;Choose the right material with better crack resistance.
Preventive measures: Carry out material inspection and heat treatment before welding to avoid defects and stress concentrations in the welding area.
2.Stomata:
Cause: There are gas residues or gas impurities in the weld area, resulting in the formation of porosity in the weld.
Solution: Clean the welding surface thoroughly to ensure that the welding area is clean;Strengthen the protection of the welding area with appropriate shielding gases and welding parameters;Control the temperature and speed during the welding process to reduce gas dissolution and precipitation.
Preventive measures: Carry out material treatment before welding, including degreasing, rust removal, etc.;For enhanced protection of the welding area, dry shielding gas is used.
3.Shrinkage porosity:
Cause: Rapid or uneven melting and solidification in the weld area, resulting in the formation of craters.
Solution: Adjust the welding parameters and welding speed to make the melting and solidification process uniformIncrease the filler material, increase the volume of the weld, and reduce the occurrence of shrinkage holes.
Preventive measures: control the welding speed and energy density to avoid excessive solidification speed;Use appropriate filler material to increase the amount of filler in the weld.
4.Morphing:
Cause: Thermal deformation or stress imbalance caused by welding, resulting in deformation of welded joints.
Solution: Control the heat input and temperature gradient during the welding process to reduce heat-induced deformationUse appropriate clamps and support structures to reduce the effects of deformation.
Preventive measures: design before welding and reduce the stress concentration of welded jointsStable clamps and support structures are used to provide adequate support.
5.Slag inclusion:
Reason: During the welding process, the oxides, impurities and other substances in the welding area cannot be removed, resulting in slag inclusion.
Solution: Thoroughly clean the welding surface, use appropriate shielding gas and welding parameters to reduce the generation and accumulation of impurities;Use the right filler material and welding technology to reduce the generation of slag inclusions.
Preventive measures: strictly control the surface cleanliness of welding materials and workpieces;High-purity shielding gases and filler materials are used.
6.Discoloration:
Reason: The welding material is subject to high temperature and oxidation, and the surface is oxidized and discolored.
Solution: Control the welding temperature and atmosphere to avoid oxidation reaction and surface discolorationSelect the appropriate shielding gas and welding parameters to reduce the occurrence of oxidation.
Preventive measures: Carry out surface treatment before welding to remove oxide layer and rust;Use appropriate shielding gases and backside reflectors to reduce oxidation.
7.Non-burn-through penetration:
Causes: The welding parameters are not appropriate, and the laser energy is not enough to completely melt and join the welding material.
Solution: Adjust the focus position, power density and welding speed to ensure the complete melting and penetration of the welding materialChoose the right filler material to complement the weld area.
Preventive measures: preheating and parameter adjustment before welding to ensure that the welding parameters match the welding materials;High-power lasers are used to provide sufficient thermal energy.
8.Splash:
Reason: During the welding process, the material is unstable and the spatter phenomenon is generated.
Solution: Clean and treat the welding surface, use appropriate shielding gas and welding parameters to reduce the occurrence of spatter;Adjust the welding speed and focus position to reduce melting and sputtering of the material.
Preventive measures: ensure that the welding area is clean and avoid the presence of impurities;Use appropriate shielding gases to inhibit oxidation and abnormal reactions of the material.
9.Undercut:
Cause: Inappropriate welding parameters, resulting in overheating and melting of the edges during the welding process, resulting in undercuts.
Solution: Adjust the welding power, speed and focus position to make the welding area evenly heated to avoid excessive melting and undercut.
Preventive measures: Adjust the parameters and preheat before welding, control the welding power and speed, and avoid overheating of the welding edge.
By taking appropriate solutions and preventive measures, the common defects in laser welding can be effectively reduced and the quality and reliability of welded joints can be guaranteed. At the same time, welding operators need to have a wealth of experience and skills to identify and properly handle potential welding defects.
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