The welding parameters of carbon dioxide gas shielded welding are: wire diameter, welding current, arc voltage, welding speed, gas flow, dry extension length, power polarity, loop inductance, welding gun inclination.

1. Wire diameter, wire diameter affects weld penetration

This article discusses the most commonly used wire diameter 1.2mm solid wire. Brand: H08MnSiA. When the welding current is 150~300, the weld penetration is 6~7mm.

2. Welding current, select the size of welding current according to the thickness of the weldment, material, welding position and the required transition form

The welding current of short-circuit transition is between 110~230A (40~230A in the welder's manual); the welding current of fine particle transition is between 250~300A. The welding current determines the wire feeding speed.

The change of welding current has a decisive influence on the depth of the molten pool. With the increase of welding current, the depth of molten pool increases significantly and the width of molten pool increases slightly.

3. Arc voltage, arc voltage is not welding voltage

Arc voltage is the voltage measured between the conductive nozzle and the weldment, while welding voltage is the voltage displayed by the voltmeter on the welding machine. Welding voltage is the sum of arc voltage and voltage drop on the cable connecting the welding machine and the weldment. Usually, arc voltage is between 17~24V. Voltage determines weld width.

4. Welding speed. Welding speed determines weld formation.

If the welding speed is too fast, the penetration depth and width will be reduced, and welding defects such as undercut, lack of fusion, and pores will easily appear; if the welding speed is too slow, welding defects such as collapse and increased welding deformation will appear. Under normal circumstances, the welding speed is more appropriate at 80mm/min.

5. Gas flow rate, CO2 gas has cooling characteristics

Therefore, the amount of gas flow rate determines the protection effect. Normally, the gas flow rate is 15L/min; when working in a windy environment, the flow rate is above 20L/min (the mixed gas should also be heated).

6.Dry extension length. Dry extension length refers to the distance from the conductive nozzle to the weldment.

Ensuring that the dry extension length remains unchanged is an important factor in ensuring the stability of the welding process. The dry extension length determines the preheating effect of the welding wire and directly affects the welding quality.

When the welding current and voltage remain unchanged, the welding wire extends too long, the welding wire melts quickly, the arc voltage increases, the welding current becomes smaller, and the temperature of the molten droplet and the molten pool decreases, which will cause welding defects such as incomplete penetration and incomplete fusion;

If it is too short, the temperature of the molten droplet and the molten pool is too high, which will cause molten iron to be lost during full-position welding, and welding defects such as biting and depression will occur. According to welding requirements, the dry extension length is between 8 and 20 mm.

In addition, if the dry extension length is too short, the welding line cannot be seen clearly, and the conductive nozzle will clamp the welding wire or even burn the conductive nozzle due to overheating.

7. Power supply polarity, usually adopt DC reverse connection (reverse polarity)

The workpiece is connected to the cathode, the welding wire is connected to the anode, the welding process is stable, the spatter is small, and the penetration depth is large.

If the DC is connected positively, under the same conditions, the welding wire melts quickly (about 1.6 times that of reverse connection), the penetration depth is shallow, the pile height is large, the dilution rate is small, and the spatter is large.

8. Loop inductance. Loop inductance determines the arc burning time, which in turn affects the penetration depth of the base material.

The appropriate loop inductance can be obtained by adjusting the size of the welding current. A large current should be selected as much as possible.

Under normal circumstances, the welding current is 150A and the arc voltage is 19V; the welding current is 280A and the arc voltage is 22~24V, which is more suitable and can meet most welding requirements.

9. Welding gun inclination angle

When the inclination angle is greater than 25°, the spatter increases significantly, the weld width increases, and the weld depth decreases. Therefore, the welding gun inclination angle should be controlled between 10 and 25°. Try to weld from right to left to form a good weld.

If the push technique is used, the welding gun inclination angle can reach 60 degrees, and a very flat, smooth and beautiful weld can be obtained. The welding current controls the wire feeding speed, and the arc voltage controls the melting speed of the welding wire. Increasing the current speeds up the wire feeding, and increasing the voltage speeds up the welding wire melting.

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