Welding Method for Aluminized Steel Plates

Introduction

Aluminized steel plates are made by applying an aluminum-silicon alloy coating to a cold-rolled steel base. These plates are as easy to weld as traditional coated steel, although the welding conditions differ.

Properties of Aluminized Steel Plates

Aluminized steel plates are easy to weld due to the softness of aluminum and its high conductivity. This results in better thermal conductivity at the weld than with cold-rolled steel plates. The aluminum coating has a higher melting point than galvanized steel, is less prone to flow, and creates a small melting area. Therefore, a lower current is needed compared to welding galvanized steel. Additionally, the welding process produces minimal harmful smoke, benefiting the environment.

Welding Techniques

Metal Inert Gas (MIG) Welding

MIG welding, including MIG “short arc” welding, uses argon-containing gas for protection. This improves arc stability, reduces welding spatter, and results in neat, attractive welds. MIG welding typically requires a low voltage (about 15-24V), and titanium electrodes are used for conventional welding.

High-Frequency or Low-Frequency Welding

When using these methods to make products like pipes, the edges of aluminized steel plates should be cleaned before welding.

	Electrode shape		Add pressure（KN）	Time (week)	Current(KA)	Reduction strength(KN)
	D	R
0.6	16	25	1.770	9	8.70	1.86
0.8	16	25	1.960	10	9.50	2.45
1.0	16	50	2.450	11	10.50	4.12
1.2	16	50	3.140	12	12.00	5.86
1.4	16	50	3.920	14	13.00	7.85
2.0	16	50	5.390	16	14.00	12.70

Spot Welding

Spot welding aluminized steel plates requires higher currents and closer process monitoring than cold-rolled steel plates. Electrode maintenance is crucial to prevent deformation of the contact surface. Regular adjustments and effective water cooling of the welding nozzle extend electrode life. A minimum of 7 liters/minute of cooling water is needed, with a water temperature not exceeding 25 degrees Celsius.

Due to the good electrical and thermal conductivity of the coating, a larger welding current is necessary. A spherical electrode made of hard copper alloy should be used.

Conclusion

The following table shows the welding conditions for spot welding aluminized steel plates (general commercial grade, with a coating amount of 40g/m² on both sides) for reference. Users should adjust these conditions based on actual working conditions.