This article reviews the classical models for the pseudo-steady-state temperature distribution of the thermal field around moving point and line sources. These include thick- and thin-plate models and the medium-thick-plate model. The analytical solutions to the differential heat flow equation under conditions applicable to fusion welding are provided. The article also provides an overview of the factors affecting heat flow in a real welding situation using the analytical modeling approach because this makes it possible to derive relatively simple equations that provide the required background for an understanding of the temperature-time pattern.

This article provides information on the various types of welds and joints. It reviews the weld joint design considerations: the ability to transfer load and the cost. The article explains the throat size and weld size requirements of fillet welds, and presents a comparison of fillet and groove welds. It details the various design considerations for groove-weld selection, including the groove angle, root opening, and depth of the groove. The article also describes the methods of edge preparation and concludes with an illustration of the recommended proportions of grooves for arc welding.

The melting temperature necessary to weld materials in the gas-tungsten arc welding (GTAW) process is obtained by maintaining an arc between a tungsten alloy electrode and a workpiece. This article discusses the advantages and limitations and applications of the GTAW process. It schematically illustrates the key components of a GTAW manual torch. The article describes the process parameters, such as welding current, shielding gases, and filler metal. It discusses the GTAW process variations in terms of manual welding, mechanized welding, narrow groove welding, and automatic welding.