Arc Welding Processes
Arc welding is a process for joining pieces of metal. In this process, the high temperature produced by an electric arc near the surface of the metal causes the metal in the pieces to be joined to melt, and upon cooling, to fuse together. This course discusses the most common types of arc welding including shielded metal arc welding, gas metal arc welding, and gas tungsten arc welding. This course also illustrates each type and describes the variables and equipment used in each type.
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Learning Objectives
- Describe the basic components of the arc welding process
- List the three major types of arc welding
- Describe why shielding is important to arc welding
- Describe the electrode in shielded metal arc welding
- Describe the effect of polarity in shielded metal arc welding
- Describe the electrode in gas metal arc welding
- List what gases can be used in gas metal arc welding
- Describe the electrode in gas tungsten arc welding
- Describe the purpose of a high frequency unit in gas tungsten arc welding
Specs
| Course Level | Intermediate |
| Languages | English |
| Compatibility | Audio, Video, MobileReady |
| Based on: | Industry Standards and Best Practices |
Key Questions
What are the three most common types of arc welding?
The three most common types of arc welding are shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), and gas metal arc welding (GMAW).
What happens when the arc and molten metal pools created by arc welding are exposed to open air?
When the metal pools created by arc welding are exposed to the open air, metal oxides and nitrides will form in the weld joint. These compounds lead to porosity, brittleness, and a loss of strength in the joint.
How does one identify the correct metal electrodes to use for the job?
The American Welding Society has developed an identification system for shielded metal arc welding electrodes.
What precautions should be taken when using gas metal arc welding filler wire?
Special care must be given to ensure that the wire is clean. The use of wire that is contaminated by oil, grease, dust, or shop fumes will result in unsound welds.
What are the main gases that are used with gas tungsten arc welding?
Argon and helium are the major gases used for shielding in gas tungsten welding, with argon being the most popular.
Sample Video Transcript
Arc welding is performed by making the workpiece part of an electrical circuit. Electrical power is supplied by a controllable power supply. The supply unit may be a transformer which converts line voltage, or a portable unit with an engine and a generator. The supplied electricity can be direct current (DC) or alternating current (AC). One terminal of the supply unit is connected via a large ground cable and clamp to the workpiece. The other terminal is connected via another cable to a clamp which holds an electrode. When the tip of the electrode is touched to the workpiece and then slightly withdrawn, but kept close, a spark, or arc is created. As long as the electrode tip is kept close to the metal, the arc is sustained. The temperature of the arc, which is 6500 °F or more, creates a pool of molten metal in the workpieces. As the electrode is moved along a joint, the molten metal left behind solidifies to create a fusion bond.
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