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The effect of electrode extension in Submerged Arc welding


The electrode extension, or 'wire stickout' as it is sometimes called, is the length of unmelted wire that extends beyond the end of the contact tip or jaw. The electrode extension is an important variable as it controls the degree of resistance heating of the electrode wire before it melts in the weld pool. For normal welding, the electrode extension should be 25-30mm for mild steel and rather less, say 20-25mm for stainless steels. (This is because the electrical resistivity of stainless steel is greater than mild steel). If the extension is short, the heating effect is small and penetration is deep. Increasing the extension increases the temperature of the electrode but decreases the penetration although deposition rate is increased. Increased extension is therefore useful in cladding and surfacing applications but steps have to be taken to guide the extended electrode otherwise the arc may wander.

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