Types of Electrodes Used in Welding

A welding electrode is a piece of wire or rod used in the welding process for joining the metals. The welding electrode is connected to the welding machine, carrying welding current, and establishes an electric arc to fuse the metals for joining. Also in some cases, the electrode used itself acts as the filler material while joining the metals.

Types of Electrodes Used for Welding

There are different types of electrodes used for welding. While selecting an electrode for welding it is important to consider some factors like tensile strength, the composition of metals to be welded, welding position, joint design, etc. Let us see the various types of electrodes used for welding purposes.


Types of Welding Electrodes :

The welding electrodes are divided into two types, consumable electrodes, and non-consumable electrodes. The below shows the classification of electrodes used for arc welding.

Types of Electrodes Used for Welding

Non-Consumable Electrodes :

The electrodes which do not consume during the welding process i.e., which do not melt away by arc heat and fuse on the weld bead, are called non-consumable electrodes. The electrodes of this type have high melting points and their job is to establish an electric arc. Since the electrode doesn't form the part of the weld bead, it can be used for a longer time.


The choice of electrode material used for welding doesn't depend upon base metals to be welded, whereas it is considered in the case of consumable electrodes. Most of the non-consumable electrodes are made up of carbon, graphite, or tungsten and some of the welding methods which use non-consumable electrodes are tungsten inert gas welding, atomic hydrogen welding, carbon arc welding, etc.

Consumable Electrodes :

The electrodes which melt due to heat developed by the arc and become part of the weld bond are called consumable electrodes. In other words, these electrodes are consumed during the welding process and subsequently deposit on the weld bead. The main characteristic of consumable electrodes is that they have a low melting point so that the arc will melts metal pieces as well as the tip of the electrode which acts as the filler material in the gap.


Depending upon the composition of metals to be welded, consumable electrodes made up of different types of materials are used. Usually, most of the consumable electrodes are made up of low alloy steel or nickel steel with a diameter of 2-8mm and a length of 200-500mm. Again these electrodes are distinguished by the type of flux coating present on them.


The consumable electrodes are further classified into the following types,
  1. Bare Electrodes.
  2. Coated Electrodes,
    • Lightly Coated Electrodes.
    • Heavily Coated Electrodes.

Bare Electrodes :

These electrodes do not have a coating of flux on them. These electrodes are often used in automatic and semiautomatic welding. As these electrodes are plain, the globules of the metal get transferred from the electrode to the work, and they get exposed to the oxygen and nitrogen in the surrounding air.


Due to this, some nonmetallic constituents are formed and they are trapped in the solidifying weld metal. As a result, the strength and ductility of the material are decreased. Bare electrodes are used for lower welding voltages.


The currents ranging from 160 to 310 amperes are used with these electrodes according to their size. The weld can be done satisfactorily by bare electrodes with a dc supply when the electrode is connected to the negative terminal.

Lightly Coated Electrodes :

Lightly coated electrodes are an improved version of bare electrodes which contain a layer of coating that is several tenths of a millimeter thick. This coating is made up of lime mixed with soluble glass that acts as a binder. The main purpose of the light coating is to improve the stability of the arc. Hence, this coating is also called stabilized coating.


This type of electrode provides better protection against oxidation of the weld. They are more advantageous compared to bare electrodes. They require higher welding voltage and lower current when compared to bare electrodes. These are used for welding nonessential jobs.


Heavily Coated Electrodes :

Heavily coated electrodes contain a heavy layer of coating. The commonly used materials for coating are titanium oxide, ferromanganese, silica, flour, asbestos clay, calcium carbonate, etc. These electrodes are mainly used to obtain a weld metal of high quality by eliminating the formation of oxides and nitrides.


The advantages of coated electrodes in the welding process are,
  • The arc produced by the electrodes is stabilized, since the coated electrodes contain the arc stabilizing materials like Na, CaCo3, Ti, and K compounds.
  • By using these electrodes the melting rate is increased, which makes the welding work faster.
  • The tendency of deionizing the arc at zero current instant with ac supply can be overcome by the coated electrode by creating covering gases around the arc thereby keeping arc spacing ionized.
  • When a coating is provided on the electrodes, they become insulated from the outer region. Thus these electrodes can be used at high currents.
  • Using these electrodes spattering of metal is avoided while welding.
  • The impurities present on the metal surface being welded are removed while welding.
  • Using these electrodes overhead and vertical welding can be done very easily.
  • The coating present over the electrode protects the metal from contamination due to atmospheric conditions.

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