5 Welding of Dissimilar Metals—Challenges and a Way Forward …
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of welding two metals having different coefficients of thermal expansions, and also
restricts the detrimental elements moving to the weld pool at higher temperature [7].
5.3.5 Thermal Conductivity
A proper heat balance is required to be maintained while joining the dissimilar
metalshaving significant dissimilarity in thermal conductivities. Thus, directional
heat flow occurs towards the metal with higher thermal conductivitydue to the rapid
conduction of heat. Often, preheating of the metal with greater thermal conductivity
is performed to control the loss of heat and also to reduce the cooling rate [7].
5.3.6 Thermal Expansion
Large dissimilarity in thermal expansion coefficients of the two metals induces
tensile and compressive stresses during solidification. This, in turn, leads to hot/cold
cracking. This becomes critical for the weld joints deployed at high-temperature
applications and in cyclic mode i.e. in expansion and contraction [7].
5.3.7 Corrosion
The base materials and the weld joint produced have different corrosion behavior
which is another concern for welding of dissimilar metals. Galvanic corrosion is the
most usual problem. To deal with this problem, cathodic protection is enabled on the
base metals by varying the composition of the weld metal [8].
5.4 Welding Methods—Difficulties and Opportunities
for Dissimilar Metals
The use of welding as a manufacturing process is believed to have been initiated in
Egypt, somewhere around 4000 B.C. Since then, there have been various developments in this technology, which has brought several different techniques for welding
of materials. At present, with the emergence of robots, welding is getting more
popularity as it uses computer-controlled programs to weld metal more quickly and
accurately.
The available welding techniques for joining dissimilar materials have been categorized in Fig. 5.1. Amongst these techniques, laser beam welding (LBW), electron
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of welding two metals having different coefficients of thermal expansions, and also
restricts the detrimental elements moving to the weld pool at higher temperature [7].
5.3.5 Thermal Conductivity
A proper heat balance is required to be maintained while joining the dissimilar
metalshaving significant dissimilarity in thermal conductivities. Thus, directional
heat flow occurs towards the metal with higher thermal conductivitydue to the rapid
conduction of heat. Often, preheating of the metal with greater thermal conductivity
is performed to control the loss of heat and also to reduce the cooling rate [7].
5.3.6 Thermal Expansion
Large dissimilarity in thermal expansion coefficients of the two metals induces
tensile and compressive stresses during solidification. This, in turn, leads to hot/cold
cracking. This becomes critical for the weld joints deployed at high-temperature
applications and in cyclic mode i.e. in expansion and contraction [7].
5.3.7 Corrosion
The base materials and the weld joint produced have different corrosion behavior
which is another concern for welding of dissimilar metals. Galvanic corrosion is the
most usual problem. To deal with this problem, cathodic protection is enabled on the
base metals by varying the composition of the weld metal [8].
5.4 Welding Methods—Difficulties and Opportunities
for Dissimilar Metals
The use of welding as a manufacturing process is believed to have been initiated in
Egypt, somewhere around 4000 B.C. Since then, there have been various developments in this technology, which has brought several different techniques for welding
of materials. At present, with the emergence of robots, welding is getting more
popularity as it uses computer-controlled programs to weld metal more quickly and
accurately.
The available welding techniques for joining dissimilar materials have been categorized in Fig. 5.1. Amongst these techniques, laser beam welding (LBW), electron