Arc welding is one of the specific, efficient and economical fusion processes for joining metals. By applying required extreme heat, metal at the joint mostly two or more parts is gonna melted and caused to become parent metal directly, or more commonly, with an intermediate molten filler metal.
- Upon cooling and solidification of metal, a metallurgical bond is created. Since the joining is an intermixture of metals and become parent metal so, the final weldment potentially has the same strength properties as the metal of the parts.
- This is totally different or contrast to non-fusion processes of joining (i.e. soldering, brazing etc.) in which the mechanical and physical properties of the base materials cannot be same as at the joint.
Arc welding uses a welding transformer power supply to generate an electric arc between an electrode and the base material to melt the metals at the welding point of metal.
They can use either
- Direct (DC) or
- Alternating (AC) current, and
consumable or non-consumable electrodes.
Basic Welding Circuit
The basic arc-welding circuit is illustrated here. An AC or DC power source, is connected by a work cable to the work piece and by a cable to an electrode holder of some type, which makes an electrical contact with the welding electrode.
An arc is created across the gap when the energized circuit generated and there is contact between electrode tip and workpiece and is withdrawn, yet still with in close contact.
The arc produces a temperature of about 6500ºF at the tip. This heat melts both the base metal and the electrode, sometimes producing a pool of molten metal called a “crater.”
The crater solidifies behind the electrode as it is moved along the joint. The result is a fusion bond.
