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co2 welding
CO2 welding-Carbon dioxide gas shielded welding process 3/3
2021-12-30
The relationship between arc voltage and welding current during short circuit transition
Welding process parameters of CO2 gas shielded welding 2/3
2022-01-07

Welding process parameters of CO2 gas shielded welding 1/3

In CO2 gas shielded welding, reasonable selection of welding process parameters is an important condition to ensure weld quality and improve production efficiency.  The main parameters of CO2 gas shielded welding include welding wire diameter, welding current, arc voltage, welding speed, welding wire extension length, power supply polarity, gas flow, welding gun Angle, arc alignment position, nozzle height, etc.

Welding process parameters of wire diameter

The larger the diameter of the wire, the greater the welding current allowed, usually according to the thickness of the welding part, welding position and efficiency requirements to choose.  When welding vertical, horizontal and inverted welds of thin plates or medium thick plates, welding wires with diameters less than 1.6mm are mostly used.  In the specific welding process .The choice of wire diameter can be referred to right pic. Figure Choice of wire diameter shows the influence of the diameter of the welding wire on the penetration depth  

Influence of wire diameter on penetration depth
Influence of wire diameter on penetration depth
Wire diameter
(mm)
The thickness of the weldment (mm) Welding position Globular transfer
0.8 1~3 A variety of locations short circuiting transfer
1 1.5~6 A variety of locations short circuiting transfer
1.2 2~12 Medium thickness A variety of locations short circuiting transfer
downward welding/flat fillet weld Fine particle transition
1.6 6~25 Medium thickness A variety of locations short circuiting transfer
downward welding/flat fillet weld Fine particle transition
2 Medium thickness downward welding/flat fillet weld Fine particle transition

When the welding current is the same, the welding depth increases with the decrease of wire diameter.  The diameter of welding wire also has obvious influence on the melting rate of welding wire.  When the current is the same, the thinner the wire, the higher the deposition speed.  At present, the diameter of welding wire commonly used is 0.8mm, 1.0mm, 1.2mm and 1.6mm.  Thick wires with diameters of 34.5mm are also currently in use at some weld locations.  

Welding process parameters of welding current

Welding process parameters welding current is one of the important welding parameters of CO2 gas shielded welding. The welding current should be selected according to the thickness of welding parts, material, welding wire diameter, welding position and required droplet transition form. The relationship between welding wire diameter and welding current is shown in Table 4-8.  Each wire diameter has a suitable current range, only within this range can the welding process remain stable.  Usually 0.8~1.6mm diameter welding wire, short circuit transition welding current is 40~230A;  Fine particle transition welding current 250-500A .
The relation between wire diameter and welding current
Wire diameter(mm) welding current(A)
0.6 40~100
0.8 50~160
0.9 70~210
1 80~250
1.2 110~350
1.6 >=300
When the external characteristics of the power supply is unchanged, change the wire feeding speed, at this time the arc voltage is almost unchanged, the welding current changes, the faster the wire feeding speed, the greater the welding current at the same wire feeding speed, with the increase of the diameter of the welding wire, the welding current also increases.  The change of welding current has a decisive influence on the depth of the molten pool. With the increase of welding current, the molten depth increases significantly and the molten width increases slightly, as shown in Figure Influence of welding current on weld forming.Figure 4-19 and Figure 4-20 show the influence of welding current on deposition speed and depth.
Influence of welding current on weld forming
Influence of welding current on weld forming
Influence of welding current on deposition speed
Influence of welding current on deposition speed
Influence of welding current on penetration
Influence of welding current on penetration

As can be seen from the figure, with the increase of welding current, both the deposition speed and the fusion depth increase.  However, it should be noted that when the welding current is too large, it is easy to cause burning through, welding leakage and cracks and other defects, and the deformation of the welding parts is large, and the splash is very big in the welding process;  When the welding current is too small, it is easy to produce defects such as incomplete welding, incomplete fusion, slag inclusion and poor weld forming.  In order to improve the production efficiency, a large welding current is usually used under the condition of guaranteeing the welding penetration and forming well. Welding process parameters is so important.