Types of Welds
The type of weld used depends on various factors, including:
- Where you’re welding
- The industry you’re working in
- The types of metal you’re using
Here’s a guide to the four main types of welding techniques.
Metal Inert Gas (MIG) Welding
MIG welding uses an electric current to fuse metal and is one of the most common methods. Welders form an electric arc between a consumable wire and metals, then guide the wire using a contact tip. Shielding gas is fed through the welding gun to protect the weld from contaminants, while the consistent wire feeding melts workpiece metals and joins them inside the weld pool radius. MIG welding is commonly used in the automotive, construction, and manufacturing industries.
Tungsten Inert Gas (TIG) Welding
TIG welding fuses metal by creating an electrical current with a non-consumable tungsten electrode stick. This method requires an inert shielding gas, typically helium and argon, to protect the weld area and electrode from atmospheric contamination. The TIG process involves electrical energy produced from a constant-current welding power source; the energy is conducted across the arc through a plasma column.
TIG welding is perfect when working with thin sections of stainless steel, aluminum, copper alloys, or magnesium. Technicians use TIG welding if they want greater control over the weld, delivering stronger and higher-quality welds. TIG welding is primarily used in the aerospace and energy industries.
Stick welding fuses metal using a flux-coated electrode to produce an electrical current. Welders use carbon steel and other filler metal to weld joints between base metals. Technicians prefer stick welding because it’s portable, doesn’t require a shielding gas, and creates effective bonds on unclean surfaces. Some of the industries that use stick welding include construction, metal fabrication, and shipbuilding.
Flux-Cored Arc Welding
Flux-cored arc welding is similar to MIG welding because it requires a continuous wire and power supply. However, the difference lies in the electrode. Flux-cored arc welding uses a hollow tube electrode filled with flux and fed into the weld pool with a weld gun. This welding method is ideal for outdoor use because it offers protection against the elements. Flux-cored arc welding is used in the shipbuilding and construction industries because it’s effective at welding thicker metals.
Types of Joints
Weld joint design refers to how pieces of metal are fused. Each joint’s design impacts the quality, and making the proper selection requires careful attention. Here are the five basic types of welding joints:
A butt joint is the most common type used in welding. The process involves placing two metal pieces on the same plane and fusing the sides together. The melted surface is known as the paying surface and can be shaped before welding to increase strength. Common defects of butt joints include burn-through, incomplete penetration, and porosity.
Tee joints are formed by intersecting two metals at a 90-degree angle so the edges fuse in the center and create a T shape. The joint may be two plates, a tube onto a plate, or a pipe onto a cylindrical metal. Welding metals into a tee joint requires effective penetration into the weld’s roof. A common defect with tee joint welding is lamellar tearing, which happens when the joints are restricted.
Corner joints are similar to tee joints but differ in metal positioning. While metals in tee joint welding meet in the middle, corner joints join and form an L shape. Corner joint welding is common in the sheet metal industry, specifically in the construction of frames and boxes. Common defects in corner joint welding include weld surface irregularities and imperfections.
Lap joints are created by placing two metal pieces in an overlapping pattern. These joints are typically used to fuse metals with different thicknesses together. The amount of overlap is determined by the metal’s consistency, and eliminating gaps is critical to maintaining the joint’s strength. Lap joints are used in the automotive industry, and common defects include lamellar tearing and corrosion.
An edge joint fuses metals on an even edge. The purpose of welding edge joints is to bind pieces together and evenly distribute stress. Welders must be careful to avoid corrosion, slag inclusion, and porosity when creating an edge joint.