Welding Distortion and Warpage

Warpage in welding and residual stresses occurring in welds are a nuisance for any welding engineer. The distortion spoils the aesthetic appeal of the product, and affects its usability for the intended purpose. Residual stresses can give rise to initiation of fracture in the metal, which can result in catastrophic failure. Therefore, it is important … Read more

Multipass Welding: All You Need To Know

Multipass welding is typically required when thick sections are required to be welded.  This technique is used in the industry for joining of thick sections, carrying out repairs, build ups, surface hard-facing and so on. As the name suggests, multipass welds consist of multiple passes of welding in a joint.  One pass of the weld … Read more

Electric Welding Circuits

a. A shock hazard is associated with all electrical equipment, including extension lights, electric hand tools, and all types of electrically powered machinery. Ordinary household voltage (115 V) is higher than the output voltage of a conventional arc welding machine. b. Although the ac and dc open-circuit voltages are low compared to voltages used for … Read more

Multilayer Welding

Multilayer Welding or Multiple layer welding is used when maximum ductility of a steel weld is desired or several layers are required in welding thick metal. Multilayer welding is accomplished by depositing filler metal in successive passes along the joint until it is filled (fig. 10-20). Since the area covered with each pass is small, the weld … Read more

Trial Weld

As in all welding, good root penetration and avoidance of defects are important. In some cases, a trial weld will be required on-site. This should be done at the working depth and in the most difficult position required, usually overhead. The specimen weld should be brought to the surface and inspected before the actual welding commences. A … Read more

Expansion And Contraction In Welding Operations

Most welding processes involve heat. High-temperature heat is responsible for much of the expansion and contraction in welding operations because warpage and stress occur. When metal is heated, it expands in all directions. When the metal cools, it contracts in all directions. Some distortions caused by weld shrinkage are shown in the figure above. There … Read more

Arc Welding

The term arc welding applies to a large and varied group of processes that use an electric arc as the source of heat to melt and join metals. In arc welding processes, the joining of metals, or weld, is produced by the extreme heat of an electric arc drawn between an electrode and the workpiece, or between … Read more

Other Arc Welding Equipment

Arc Welding Equipment: Cables Two welding cables of sufficient current-carrying capacity with heavy, tough, resilient rubber jackets are required. One of the cables should be composed of fine copper strands to permit as much flexibility as the size of the cable will allow. One end of the less flexible cable is attached to the ground lug … Read more

AC Welding

The number of times this cycle is repeated in one second is called the frequency, measured in hertz. Alternating current for arc welding normally has the same frequency as the line current. The voltage and current in the ac welding arc follow the sine wave and return to zero twice each cycle. The frequency is so … Read more