Overlay welding is a technique that uses welding to clad filler metal onto the surface of a metal material or component. It can achieve specific surface properties and surface dimensions through overlay welding. Overlay welding is widely use in the manufacturing and repair of parts with wear resistance, corrosion resistance or special performance requirements. In a few cases, overlay welding is also used purely for the purpose of repairing part dimensions.

Overlay welding has the following functions: improving wear resistance and corrosion resistance, thereby extending the service life of parts. It facilitates the production of a hard metal surface on a tough base material, thereby achieving the best performance combination. It can economically utilize precious alloy elements, thereby reducing manufacturing costs. It can save the cost of maintenance and replacement parts for enterprises. It can improve the efficiency of equipment and reduce power consumption.

Nowadays, overlay welding has been widely used in the manufacturing of special equipment such as petroleum, chemical equipment, and nuclear equipment, especially corrosion-resistant overlay welding has been widely used in the manufacturing of composite plate pressure vessels. Among them, overlay welding tube sheet and flange greatly save material costs, and overlay welding of corrosion-resistant layer on the inner wall of the connecting pipe also solves the problem of small diameter connecting pipes not being able to use composite plate coil welding.

To apply welding technology to production, two issues must be addressed: first, selecting the welding material, which includes the composition and shape of the welding alloy, and the composition of the welding alloy often depends on the requirements for the performance of the welding alloy; The second is to choose appropriate welding methods and develop corresponding welding processes.