What is Arc Welding?
The welding process which uses the intense heat of an electric arc to form a weld is known as the arc welding process. All of the arc welding processes employ the same basic circuit.It is basically a fusion welding process. Contact is first made between the electrodes and the work to complete an electric circuit and then by separating the conductors an arc is formed. The electrical energy is converted into intense heat in the arc which attains a temperature ranging from 30000C to 55000C. The heat forms a pool of molten metal by melting the electrode end and edges of the base metal near the arc. This pool of molten metal on solidification becomes the weld. No pressure is generally required to form a weld.
Principle
- Arc welding is a welding process, in which heat is generated by an electric arc struck between an electrode and the workpiece.
- Any arc welding method is based on an electric circuit consisting of the following parts:
- Power supply (AC or DC);
- Welding electrode;
- Workpiece;
- Welding leads (electric cables) connecting the electrode and workpiece to the power supply.
- An electric arc between the electrode and workpiece closes the electric circuit. The arc temperature may reach 5500°C, which is sufficient for fusion the workpiece edges and joining them.
- When a long join is required the arc is moved along the joint line. The front edge of the weld pool melts the welded surfaces when the rear edge of the weld pool solidifies forming the joint.
- When filler metal is required for better bonding, a filling rod (wire) is used either as outside material fed to the arc region or as a consumable welding electrode, which melts and fills the weld pool. Chemical compositions of filler metal are similar to that of workpieces.
- Molten metal in the weld pool is chemically active and reacts with the surrounding atmosphere. As a result, the weld may be contaminated by oxide and nitride inclusions deteriorating its mechanical properties. Neutral shielding gases (argon, helium) and/or shielding fluxes are used for the protection of the weld pool from atmospheric contamination. Shields are supplied to the weld zone in form of a flux coating of the electrode or in other forms.
Types
- Carbon Arc Welding (CAW)
- Shielded Metal Arc Welding (SMAW)
- Submerged Arc Welding (SAW)
- Plasma Arc Welding (PAW)
- Gas Metal Arc Welding (MIG)
- Gas Tungsten Arc Welding (TIG)
