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.
