6
S. K. Das et al.
During FSW, the peak temperature remains lower than the melting point temperature
of the workpiece material. Compared to arc welding or any conventional welding,
heat input for FSW is low. Less heat input leads to less residual stress which lead
to reduced distortion. Due to shoulder pressure and low residual stress in FSW, the
joint almost remains smooth eliminating post-weld machining operation.
• Improved energy efficiency
As no melting is involved during FSW, the process consumes less energy with no
harmful emission as there is no use of any filler material.
• Improved joint efficiency
The ratio of strength of the welded joint to that of the base metal defines the efficiency of a welded joint. Joint efficiency of FSW mainly depends on the process
parameters. It is important to select suitable process parameters for achieving 100%
joint efficiency. For some metals, joint efficiency can be achieved beyond 100% by
FSW technique which is impossible to be achieved by other welding techniques.
• Welding in all positions
Due to the absence of weld pool, this welding technology can be employed for joining
along all positions, i.e., vertical, horizontal, etc. Conventional weld joints, viz. butt
joint, lap joint and corner joint, can all be formed using FSW.
• Increased fatigue life
For welding of structural components and in transportation industries, fatigue life
evaluation is most essential. In aerospace sector too, fatigue strength of the weldment
is a major concern. The fatigue life of the welded joint can be improved after FSW
due to the reduction in the residual stress and peak temperature. The fatigue strength
of FSW joint is higher compared to arc welding.
• Improved safety and environmentally friendly
FSW is a fully automatic process. No toxic gas or spatter is produced; due to the
absence of toxic gas, this technique is safe for the welder and reduces the chance of
causing hazard.
• Welding of dissimilar materials
Joining of different metals with different melting temperatures by arc welding
is difficult. This is because lower melting temperature metal will start to melt
before reaching the melting temperature of high-temperature workpiece. For welding
dissimilar material or joining of composite materials with higher strength, this
welding technique is suitable. As this is a solid-state welding technique, there have
no issue of melting problem.
• Non-consumable tool
FSW technique uses a non-consumable tool which is normally made of tool steel,
PCBN or W-base for welding. Hence, continuous requirement of filler material is
S. K. Das et al.
During FSW, the peak temperature remains lower than the melting point temperature
of the workpiece material. Compared to arc welding or any conventional welding,
heat input for FSW is low. Less heat input leads to less residual stress which lead
to reduced distortion. Due to shoulder pressure and low residual stress in FSW, the
joint almost remains smooth eliminating post-weld machining operation.
• Improved energy efficiency
As no melting is involved during FSW, the process consumes less energy with no
harmful emission as there is no use of any filler material.
• Improved joint efficiency
The ratio of strength of the welded joint to that of the base metal defines the efficiency of a welded joint. Joint efficiency of FSW mainly depends on the process
parameters. It is important to select suitable process parameters for achieving 100%
joint efficiency. For some metals, joint efficiency can be achieved beyond 100% by
FSW technique which is impossible to be achieved by other welding techniques.
• Welding in all positions
Due to the absence of weld pool, this welding technology can be employed for joining
along all positions, i.e., vertical, horizontal, etc. Conventional weld joints, viz. butt
joint, lap joint and corner joint, can all be formed using FSW.
• Increased fatigue life
For welding of structural components and in transportation industries, fatigue life
evaluation is most essential. In aerospace sector too, fatigue strength of the weldment
is a major concern. The fatigue life of the welded joint can be improved after FSW
due to the reduction in the residual stress and peak temperature. The fatigue strength
of FSW joint is higher compared to arc welding.
• Improved safety and environmentally friendly
FSW is a fully automatic process. No toxic gas or spatter is produced; due to the
absence of toxic gas, this technique is safe for the welder and reduces the chance of
causing hazard.
• Welding of dissimilar materials
Joining of different metals with different melting temperatures by arc welding
is difficult. This is because lower melting temperature metal will start to melt
before reaching the melting temperature of high-temperature workpiece. For welding
dissimilar material or joining of composite materials with higher strength, this
welding technique is suitable. As this is a solid-state welding technique, there have
no issue of melting problem.
• Non-consumable tool
FSW technique uses a non-consumable tool which is normally made of tool steel,
PCBN or W-base for welding. Hence, continuous requirement of filler material is