Laser welding of silicon steel sheets and welding effects

Laser welding of silicon steel sheets involves using a high-energy laser beam to melt and join the materials. The process requires precise control of parameters such as laser power, welding speed, and protective gas flow. For thin silicon steel sheets (0.05–0.5 mm), lower power and higher speed are typically used to avoid excessive melting and deformation. Thicker sheets need higher power for sufficient penetration. Multi-layer welding demands accurate alignment and gap control to ensure quality. Pre-treatment, such as cleaning and grinding, is essential to remove surface contaminants. Protective gases like helium or argon are used to shield the weld from oxidation. Proper equipment calibration and parameter optimization are crucial for achieving high-quality welds with minimal deformation and good mechanical and electromagnetic properties.

Detailed Explanation of Laser Welding of Silicon Steel Sheets and Welding Effects

I. Laser Welding of Silicon Steel Sheets

Laser welding is a method that uses a high-energy laser beam as the heat source. The laser beam is focused on the surface of the workpiece through a focusing lens, causing the material to melt rapidly and form a welded joint. Here is a detailed introduction to laser welding of silicon steel sheets:

• Welding Equipment: This mainly includes a laser welding machine, gas protection device, beam guide, and cooling system. The performance of the laser welding machine directly affects the welding quality and efficiency.
• Welding Process:
  • Workpiece Clamping: Place the silicon steel sheets to be welded on the lower plate of the welding fixture, with the welding seam positioned in the groove of the lower plate. Then, screw the upper pressing plate onto the lower plate. The gap between the silicon steel sheets should be 0.03 to 0.1 times the plate thickness, and the misalignment should be less than 0.05 times the plate thickness.
  • Welding Operation: Use a machine tool or robotic arm to hold the laser welding head for welding, ensuring that the center of the laser spot is on the centerline of the welding seam of the silicon steel sheets, and the edge of the laser spot overlaps with the welding surface of the silicon steel sheets. The distance between the protective gas nozzle and the surface of the silicon steel sheets should be 20 to 30 mm, and the protective gas nozzle should be located in front of the direction of movement of the laser head.
• Welding Parameters: Adjust the laser power, welding speed, protective gas flow, defocusing amount, and other parameters according to the thickness of the silicon steel sheets and the welding requirements. For example, when using a 1000W single-mode continuous fiber laser, the welding power is 650W, the welding speed is 6m/min, helium gas is used as the protective gas, and the defocusing amount is -12mm.

II. Welding Effects

• Weld Appearance: The weld is bright and free of pores, with uniform width and a smooth, aesthetically pleasing surface. For example, after welding silicon steel sheets with a thickness of 0.3mm, the weld width is 0.5mm.
• Deformation: The deformation after welding is minimal, with the excess height not exceeding 10% of the plate thickness. For example, when bending on a roll with a diameter of 150mm, the weld does not crack.
• Performance: The weld and heat-affected zone are extremely narrow, with high hardness but relatively low plasticity. The weld formed by laser welding has good mechanical and electromagnetic properties.

III. Relationship between Silicon Steel Sheet Thickness and Laser

• Thin Silicon Steel Sheets: For silicon steel sheets with a thickness of 0.05 to 0.5mm, laser welding can achieve high-quality butt welding. When welding thin silicon steel sheets, the laser power and welding speed need to be adjusted according to the specific thickness.
• Thick Silicon Steel Sheets: As the thickness of the silicon steel sheets increases, higher laser power and more appropriate welding parameters are required to ensure the penetration depth and quality of the weld.

IV. Relationship between Multi-layer Silicon Steel Sheets and Laser

• Multi-layer Welding: When welding multi-layer silicon steel sheets, the alignment and gap control between each layer need to be considered. Laser welding can achieve precise welding of multi-layer silicon steel sheets, but the precision and stability of the welding equipment are more demanding.
• Heat-Affected Zone: The control of the heat-affected zone is particularly important during multi-layer welding to avoid adverse effects on the electromagnetic properties of the silicon steel sheets.

V. Precautions

• Pre-treatment: Before welding, the silicon steel sheets need to be pre-treated, including grinding and cleaning, to remove surface contaminants such as oil and oxides.
• Protective Gas: Use helium or argon as the protective gas, with the gas flow controlled at 15 to 30L/min.
• Defocusing Amount: Choose the appropriate defocusing amount according to the welding requirements. Negative defocusing can achieve greater penetration depth, while positive defocusing is suitable for thin materials.
• Equipment Check: Before welding, carefully inspect and adjust the laser welding equipment to ensure it is in optimal working condition.

Laser Welding Parameters for Silicon Steel Sheets