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Influence of Welding Current, Voltage and Welding Speed on Welding Seam in Welded Pipe
1. Welding current
When the welding current increases, the penetration depth and residual height increase, and the fusion width changes little, because:
(1) With the increase of current, the heat input and arc force increase, the position of heat source moves down, the penetration increases, and the welding current is directly proportional to the penetration
(2) With the increase of current, the melting amount of welding wire increases. Because the melting width remains unchanged, the residual height increases
(3) With the increase of current, the diameter of arc column increases, the arc depth increases, the range of arc spot is limited, and the melting width remains unchanged
2. Arc voltage
With the increase of arc voltage, arc power, heat input and distribution radius increase, penetration decreases, fusion width increases and reinforcement decreases, which is due to the increase of fusion width and the decrease of welding wire melting amount.
3. Welding speed
When the welding speed increases, the energy, weld width and penetration decrease, the reinforcement decreases, and the deposited amount of welding wire metal is inversely proportional to the welding speed.
The voltage affects the melting width, and the current affects the melting depth. The voltage should be the minimum splash, and the current should be burn through without burn through. If one parameter is fixed, the welding current has a great impact on the welding quality and welding productivity by adjusting the other parameter.
The welding current affects the penetration depth. If the current is too large, there will be undercut, burn through and other defects. If the current is too small, the arc is unstable, and the penetration depth is small, there will be defects such as incomplete penetration. The welding current can be selected according to the electrode diameter, and then adjusted appropriately according to the joint form, weld position, weldment thickness, welding level, etc
The arc length determines the arc voltage, the arc length, the arc voltage is high, the arc length, and the arc voltage is low. The arc voltage will affect the weld width.
During welding, the arc shall not be too long, which will make the arc combustion unstable, lead to metal splash, and cause air holes in the weld due to air invasion. Therefore, short arc shall be used during welding, and the arc length is generally required not to exceed the electrode diameter.
The welding speed is directly related to the welding productivity. On the premise of ensuring the quality, the maximum welding speed can be obtained by using larger electrode diameter and welding current. At the same time, the welding speed should be adjusted according to the specific situation to ensure the consistency of weld height and width.