A Comprehensive Analysis of the Principle, Application and Operation Techniques of Arc Welding

 

As an efficient and flexible fusion welding technology, arc welding uses the high temperature generated by the electric arc to melt metal materials and form strong welded joints. Its core lies in achieving local melting of the welding rod and the workpiece through a stable electric arc (with a temperature reaching over 5000K) between the electrode and the workpiece, and then completing the connection. The following provides a detailed introduction from aspects such as the principle, equipment, operation characteristics and application fields.

 

I. The Basic Principle of Arc Welding

The welding process of arc welding is divided into three stages: arc ignition, molten pool formation and weld solidification. During arc ignition, the electrode briefly contacts the workpiece to form a short - circuit, and then separates to generate an electric arc. The high temperature of the arc locally melts the welding rod and the workpiece, forming a liquid metal molten pool. As the arc moves, the molten pool gradually cools and crystallizes, finally forming a dense weld. The melting of the electrode coating produces gas and slag, which isolate the air to protect the molten pool. At the same time, the weld composition is optimized through metallurgical reactions to improve the welding quality.

 

II. Classification of Arc Welding Equipment and Power Sources

Arc welding equipment is mainly composed of arc welding machines, welding torches, welding rods and cables. According to the power source type, arc welding machines can be divided into the following two categories:

1. AC arc welding machines: They have low cost and are easy to maintain, suitable for welding ordinary steel.

2. DC arc welding machines: They have higher stability and are divided into DC straight polarity (the workpiece is connected to the anode, suitable for thick - plate welding) and DC reverse polarity (the workpiece is connected to the cathode, suitable for thin - plate welding). In addition, pulse and inverter power supply technologies are gradually becoming mainstream due to their high - efficiency and energy - saving characteristics.

 

III. Technical Characteristics and Operation Advantages

1. Flexible operation: Arc welding equipment is portable and can adapt to various spatial positions such as flat welding, vertical welding, horizontal welding and overhead welding, as well as different joint forms such as butt joints, lap joints and corner joints.

2. Strong material adaptability: It is suitable for various metals such as low - carbon steel, low - alloy steel, stainless steel and heat - resistant steel. Dissimilar metals can also be welded by matching welding rods.

3. Low assembly requirements: During the welding process, the arc position and parameters can be adjusted in real - time to make up for the workpiece assembly errors and ensure uniform penetration of the weld.

4. Limitations: The welding efficiency is relatively low, requiring frequent replacement of welding rods and cleaning of slag. The weld quality highly depends on the operator's skill level, such as current control and electrode movement speed.

 

IV. Operation Techniques and Precautions

1. Arc ignition and arc termination control: Use the contact arc ignition method. After a short contact, quickly lift the welding rod to avoid sticking. When terminating the arc, fill the crater to prevent cracks.

2. Electrode movement techniques: Select straight - line electrode movement, zig - zag or crescent - shaped trajectories according to the weld type, and keep the arc length stable (usually 2 - 4mm).

3. Parameter matching: The electrode diameter and current magnitude need to be matched with the workpiece thickness. For example, for a 3.2mm electrode, the recommended current is 90 - 130A. Multi - layer and multi - pass welding can be used for thick - plate welding, and inter - layer cleaning should be noted.

 

V. Application Fields and Industry Value

Arc welding is widely used in fields such as machinery manufacturing, construction engineering, pipeline installation and equipment maintenance. Typical scenarios include:

- Steel structure welding: Such as the connection of beams and columns in bridges and factories.

- Pipeline systems: Sealing welding of oil and chemical pipelines.

- Dissimilar metal connection: Reliable bonding between stainless steel and carbon steel can be achieved through special welding rods.