welding: joints
Welding pre-heat is commonly used before welding steel or steel alloy materials that are one-inch thick or more. Typically, thicker components require pre-heat, but it depends on the materials and assembly goals.
When do joints need to be pre-heated before welding? Welding is a fabrication process that joins materials — typically metals or thermoplastics — by using high heat to melt the parts together and then allowing them to cool to cause fusion. Welding is distinct from lowertemperature, metal-joining techniques such as brazing and soldering, which do not melt the base metal. Pre-heating components before welding can reduce the rate of cooling and result in stronger and more reliable welds. The process can involve heating the area around the weld joint or the entire part to a specified temperature before welding. When thicker components are preheated, it’s typically possible to achieve
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December 2021
www.fastenerengineering.com
an ideal bond with less heat during the welding process. Thicker material means that more of it, including the surrounding material, will act as a heat sink when welded. This leads the weld to cool more rapidly after the energy source is removed. Although thicker components (usually one inch or thicker) are more likely to require or benefit from preheating, there are several criteria to consider beforehand. To accurately assess if a welding assembly requires pre-heat first consider the type and thickness of the base material. Although it’s difficult to provide simple rules for the material thickness at which pre-heating is ideal, there are rules-of-thumb and different DESIGN WORLD
