Weld Cladding

Weld cladding techniques were first developed at Strachan & Henshaw, Bristol, United Kingdom, for use on defence equipment, especially, for various parts of submarines. Through weld cladding, the composite structure is developed by the fusion welding process. All metals used as fillers may be used for weld cladding. Materials such as nickel and cobalt alloys, copper alloys, manganese alloys, alloy steels, and few composites are commonly used for weld cladding. Weld clad materials are widely used in various industries such as chemical, fertilizer, nuclear and steam power plants, food processing and petrochemical industries. Various industrial components whose base metals are weld-clad are steel pressure vessels, paper digesters, urea reactors, tube sheets and nuclear reactor containment vessels. Cladding using gas tungsten arc welding is widely used in aircraft engine components to maintain high quality. Weld cladding can be done by using various processes such as Submerged arc welding (SAW), Gas metal arc welding (GMAW), Gas tungsten arc welding (GTAW), Flux-cored arc welding (FCAW), Submerged arc strip cladding (SASC), Electro slag strip cladding (ESSC), Plasma arc welding (PAW), Explosive welding, etc. GTAW and PAW are widely used for the cladding operations, and they produce superior quality cladding because they generate high stable arc and spatter free metal transfer. Welding variables and inert gas shielding can be precisely controlled in both GTAW and PAW. Though GTAW and PAW cladding can produce excellent overlay with a variety of alloy materials, deposition rate is low compared to other processes which limit its application in industries. Submerged arc strip cladding (SASC) and Electro slag strip cladding (ESSC) is extensively used for cladding large surfaces of the heavy–wall pressure vessels. Three most important characteristics of SASC and ESSC are high deposition rate, low dilution and high deposition quality. Deposition rate in ESSC is much more than in SASC because of the absence of arc, whereas, dilution in ESSC is less compared to SASC because of the same reason. Weld cladding is widely done using flux-cored arc welding (FCAW) process due to various advantages. With properly established process parameters automation and robotization can be done easily in FCAW. Wear, corrosion and heat resistance of material surface is enhanced by plasma transferred arc (PTA) surfacing. PTA process is also considered as an advanced GTAW process used largely for overlay applications. Various advantages of PTA surfacing are very high deposition quality, high-energy concentration, narrow heat-affected zone, less weld distortion, etc. On the other side, demerits of PTA surfacing are low deposition rates, overspray, and very high equipment costs Cladding with the use of submerged arc welding (SAW) is applied for large areas, and its fusion efficiency is quite high. SAW can be easily automated and employed especially for heavy section work.