Stainless steel Electrode

Why SS electrode have less length as compared to alloy steel or carbon steel Electrodes?

Simply because of their chemical composition.
As we all know carbon will give strength to any compound. By the addition of carbon we can increase the strength of a material.
In case of stainless steels they are almost free from carbon (0.04 to .08% carbon) due to lack of carbon they suffer in strength. But while considering other properties like impact strength and corrosion resistance they are superior than carbon steels .

*There is a point at which the carbon can increase the strength after that it will decrease the strength of the material and makes it brittle.

Sir i asking about the length of electrode not strength.

Sorry I thought it was strength.
They are shorter in length because they have a higher coefficient of thermal expansion and lower thermal conductivity .
That simply means they retain heat for a longer period of time and there is a greater chance to overheat the electrode prior to actual welding take place which will affect the alloying elements adversily.
Since the electrode hold the heat it becomes red hot during the time of welding which results in globular type deposition of weld metal over parent metal which is not desirable.

I think it is related to resistivity.

R=A const*l/A and the constant is called resistivity.
All electrodes are conductors and they have resistance and hence resistivity. But SS is not like the rest due to their low thermal conductivity they didn’t dissipate the heat energy like the rest of electrodes do. That simply leads into overheating of electrode .When the electrode overheat it’s temp rises and results into undesirable metal transfer of weld metal more like a globular transfer .

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