Welding is a machining method that permanently joins two workpieces by localized heating, pressurization, or a combination of both. Compared to other joining methods such as riveting, welding offers advantages such as material savings, reduced structural weight, simplified processes, strong connections, high pressure resistance, ease of mechanization and automation, high production efficiency, and favorable working conditions. What are the different types of welding methods? What are some commonly used welding methods?
I. Classification of Welding Methods
1. Fusion welding
Fusion welding is a method of welding in which workpieces are heated to a molten state and welded without applying pressure. When the material is melted, the heat source rapidly heats the base material joint to be welded to a molten state. Simultaneously, welding material is filled (or not added) into the molten pool, allowing atoms to diffuse into each other. Upon cooling, a weld is formed, joining the two workpieces into one.
2. Pressure welding
Pressure welding is a method of bonding the atoms of two workpieces under pressure (with or without heating). During the process, the contact between the weld metals can be heated to a molten state.
II. Welding Method
1. Shielded metal arc welding
The burning electric arc between the electrode and the workpiece melts the electrode tip and the workpiece joint. The rapidly molten metal at the electrode tip is transferred to the molten metal through small droplets in the arc column, melting together to form a molten pool. The electrode cap continuously decomposes and melts, producing gases and slag that protect the electrode tip, the arc, the molten pool, and their surrounding area from harmful atmospheric contamination of the molten metal. As the arc moves forward, the liquid metal in the molten pool gradually cools and crystallizes, forming a weld. The slag cools and solidifies, forming a slag shell that continues to protect the weld.
2. Argon arc welding
Argon-tungsten inert gas (TIG) welding is a non-consumable electrode, inert gas shielded welding method. It uses argon gas as the shielding gas and an electric arc generated between the tungsten electrode and the workpiece to thermally melt the workpiece and the welding wire (or without a welding wire). TIG welding can be divided into manual TIG welding and automatic TIG welding. During the welding process, argon gas is continuously ejected from the nozzle of the welding torch, forming a protective layer around the arc to isolate it from the air and prevent oxidation of the tungsten electrode, the weld pool, and adjacent heat-affected zones, resulting in a high-quality weld.
3. CO2 gas shielded welding
Carbon dioxide gas shielded welding (CO2) uses CO2 as the shielding gas. The electric arc between the welding wire and the workpiece is used to melt the wire and the workpiece in MIG welding, a process known as CO2 welding. CO2 welding can be categorized into two types based on the welding wire used: fine wire CO2 welding (wire φ=0.5～1.2mm) and coarse wire CO2 welding (wire Φ=1.6～5.0mm). Based on the type of welding wire, it can be divided into solid wire CO2 welding and flux-cored wire CO2 welding. Based on the operating mode, it can be divided into semi-automatic CO2 welding and automatic CO2 welding. The welding torch and the workpiece are connected to the two output terminals of the welding power source, respectively.
What are the different types of welding methods? What are some commonly used welding methods? The welding wire is continuously fed to the arc zone via a wire feed mechanism through a hose and a conductive nozzle, and then transported within the arc zone. An electric arc is generated between the base metal and a carbon dioxide atmosphere. CO and other gases are injected along the welding wire through the welding torch nozzle, forming a localized gas shielding layer around the arc. This mechanically isolates the molten droplets and weld pool from the air, ensuring a stable and continuous welding process and resulting in a high-quality weld.
