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P. Sarkar et al.
stress corrosion cracking in Al alloys are reduced due to the low residual stress,
and the peak temperature associated with the process.
iv. Since the tool never penetrates through the workpiece completely, FSW
produces a very smooth root appearance that hardly requires further machining.
v. This solid-state welding permits the dynamic recrystallization of the grains
producing a fine-grained nugget zone that enhances the hardness and strength
of the joint up to 97% of the base material [24].
vi. Another benefit of the process is its potential to create a very narrow HAZ. A
wide HAZ that is generally observed in other low heat density fusion welding
processes can be eliminated in FSW.
vii. The mechanization of the process further eradicates the need for a high skilled
worker. Lower automation cost of the machines and operating costs, less
employee training, and no need for consumables in this process result in cost
savings.
viii. The simplicity of the process and availability of the tool materials (especially
for Al material) increase its production rate that makes it easily acceptable for
the industries.
4.1.7 Disadvantages of FSW Process
FSW has very few disadvantages, unlike the other fusion welding techniques. They
are described below.
i. FSW being a fully mechanized process, increases the capital cost, thus offering
a barrier to use this process for small industries. Moreover, the capital cost is
justified only if continuous production is done using the process.
ii. Due to the generation of high force and torque during the process, the workpiece must be held very rigidly to avoid any defective welding or accidents. It
thus necessitates the highly rigid fixtures that can sustain the load and torque.
Moreover, for different jobs, the fixtures must be designed separately.
iii. The absence of the use of filler material in FSW restricts its application to
produce fillet shape welding. The autogenous process restricts its ability to join
at certain welding positions only.
iv. The existence of keyhole at the end of the joint line is another critical limitation
of the process. Some applications like the marine tank joining etc. cannot allow
any keyhole at the end of the joint.
The advancements made by various researchers in the FSW process address the
above-mentioned issues and are mentioned in the following section.
P. Sarkar et al.
stress corrosion cracking in Al alloys are reduced due to the low residual stress,
and the peak temperature associated with the process.
iv. Since the tool never penetrates through the workpiece completely, FSW
produces a very smooth root appearance that hardly requires further machining.
v. This solid-state welding permits the dynamic recrystallization of the grains
producing a fine-grained nugget zone that enhances the hardness and strength
of the joint up to 97% of the base material [24].
vi. Another benefit of the process is its potential to create a very narrow HAZ. A
wide HAZ that is generally observed in other low heat density fusion welding
processes can be eliminated in FSW.
vii. The mechanization of the process further eradicates the need for a high skilled
worker. Lower automation cost of the machines and operating costs, less
employee training, and no need for consumables in this process result in cost
savings.
viii. The simplicity of the process and availability of the tool materials (especially
for Al material) increase its production rate that makes it easily acceptable for
the industries.
4.1.7 Disadvantages of FSW Process
FSW has very few disadvantages, unlike the other fusion welding techniques. They
are described below.
i. FSW being a fully mechanized process, increases the capital cost, thus offering
a barrier to use this process for small industries. Moreover, the capital cost is
justified only if continuous production is done using the process.
ii. Due to the generation of high force and torque during the process, the workpiece must be held very rigidly to avoid any defective welding or accidents. It
thus necessitates the highly rigid fixtures that can sustain the load and torque.
Moreover, for different jobs, the fixtures must be designed separately.
iii. The absence of the use of filler material in FSW restricts its application to
produce fillet shape welding. The autogenous process restricts its ability to join
at certain welding positions only.
iv. The existence of keyhole at the end of the joint line is another critical limitation
of the process. Some applications like the marine tank joining etc. cannot allow
any keyhole at the end of the joint.
The advancements made by various researchers in the FSW process address the
above-mentioned issues and are mentioned in the following section.