2 Fundamentals of Friction Stir Welding, Its Application, and Advancements
67
was obtained with a weld efficiency of 93% and 89% for square and cylindrical pin,
respectively. Fine and uniform recrystallized grains were observed in the case of a
square pin due to an increased degree of plastic deformation.
Mohammadi-pour and Khodabandeh [116] FSWed 4 mm thick 7075-T6
aluminum alloy. A comparative study of various tool pin profiles of threaded conical,
conical, and triangular pins made of H13 tool steel was investigated for different input
parameters. Fine equiaxed grains of 2.5 μm, 12.5 μm, and 10 μm were observed at
1600 rpm and 63 mm/min, for respective tool pin profiles. A maximum weld strength
of 370 MPa was obtained for a conical threaded tool profile. Hardness value at SZ
for threaded conical, triangular and conical pins were 180 HV, 175 HV, and 165 HV
respectively.
Jamalian and Farahani [117] joined 6 mm thick 5086-H34 aluminum via FSW.
Tunneling and wormhole defects were obtained at lower rotational speeds due to
insufficient heat generation and lower material flow rates. These defects were also
observed at high rotational speeds because of turbulence in the weld. Weld parameter
of 1250 rpm and 80 mm/min produced sound weld with a weld efficiency of 85%.
Saravanan et al. [118] studied the performance of shoulder to pin diameter (D/d)
ratio (2, 3 and 4) on weld properties for welding of 2xxx series aluminum alloy. The
maximum weld strength of 356 MPa and a hardness value of 151 HV at SZ was
observed at 1200 rpm and 12 mm/min with the D/d ratio of 3.
Tufaro et al. [88] investigated the performance of tool shoulder diameter on heat
distribution during FSW of 3 mm thick AA5052-H32 alloy. Tools of 10, 12, 14,
and 16 mm shoulder diameter were used for joining in butt configuration. Sound
weld was produced at 514 rpm and 98 mm/min. It was reported that increasing
shoulder diameter resulted in a defect-free weld in the SZ with better material flow
characteristics.
Grujicic et al. [119] investigated the FSW of AA5059. AISI H13 tool with conical
threaded was selected as a tool. Material flow behavior was observed towards AS
and RS. The maximum extent of material mixing was investigated by varying input
parameters ie. tool tilt angle and tool pin size. Tool tilt ranges of 3.5°, 2.5°, and
2.0° were investigated and 2.5° was reported as an optimized parameter to produce
a sound weld.
Zhang et al. [120] investigated the heat generation phenomenon during FSW.
Results show that slip rates are lower on the retreating and the front sides as compared
to the advancing and trailing side. This is because of the better material flow in those
regions and this also results in higher heat flux on trailing and advancing sides. A
significant decrease in equivalent plastic strain is observed due to the lowering of
stirring action in the thick plate.
Buffa et al. [121] investigated varying included cone angle with a cylindrical pin
(0°) to conical pin up to 40°. AA7075 was selected as workpiece material. Investigation of the material flow behavior and grain size distribution in the joints were
carried for different cone angles. Results show that the extent of plastic deformation,
strain rate, and size of the weld zone in SZ, and HAZ increases with an increase in
pin angle. A combination of 100 mm/min and pin angle of 40° was reported as an
optimized parameter to get sound weld.
67
was obtained with a weld efficiency of 93% and 89% for square and cylindrical pin,
respectively. Fine and uniform recrystallized grains were observed in the case of a
square pin due to an increased degree of plastic deformation.
Mohammadi-pour and Khodabandeh [116] FSWed 4 mm thick 7075-T6
aluminum alloy. A comparative study of various tool pin profiles of threaded conical,
conical, and triangular pins made of H13 tool steel was investigated for different input
parameters. Fine equiaxed grains of 2.5 μm, 12.5 μm, and 10 μm were observed at
1600 rpm and 63 mm/min, for respective tool pin profiles. A maximum weld strength
of 370 MPa was obtained for a conical threaded tool profile. Hardness value at SZ
for threaded conical, triangular and conical pins were 180 HV, 175 HV, and 165 HV
respectively.
Jamalian and Farahani [117] joined 6 mm thick 5086-H34 aluminum via FSW.
Tunneling and wormhole defects were obtained at lower rotational speeds due to
insufficient heat generation and lower material flow rates. These defects were also
observed at high rotational speeds because of turbulence in the weld. Weld parameter
of 1250 rpm and 80 mm/min produced sound weld with a weld efficiency of 85%.
Saravanan et al. [118] studied the performance of shoulder to pin diameter (D/d)
ratio (2, 3 and 4) on weld properties for welding of 2xxx series aluminum alloy. The
maximum weld strength of 356 MPa and a hardness value of 151 HV at SZ was
observed at 1200 rpm and 12 mm/min with the D/d ratio of 3.
Tufaro et al. [88] investigated the performance of tool shoulder diameter on heat
distribution during FSW of 3 mm thick AA5052-H32 alloy. Tools of 10, 12, 14,
and 16 mm shoulder diameter were used for joining in butt configuration. Sound
weld was produced at 514 rpm and 98 mm/min. It was reported that increasing
shoulder diameter resulted in a defect-free weld in the SZ with better material flow
characteristics.
Grujicic et al. [119] investigated the FSW of AA5059. AISI H13 tool with conical
threaded was selected as a tool. Material flow behavior was observed towards AS
and RS. The maximum extent of material mixing was investigated by varying input
parameters ie. tool tilt angle and tool pin size. Tool tilt ranges of 3.5°, 2.5°, and
2.0° were investigated and 2.5° was reported as an optimized parameter to produce
a sound weld.
Zhang et al. [120] investigated the heat generation phenomenon during FSW.
Results show that slip rates are lower on the retreating and the front sides as compared
to the advancing and trailing side. This is because of the better material flow in those
regions and this also results in higher heat flux on trailing and advancing sides. A
significant decrease in equivalent plastic strain is observed due to the lowering of
stirring action in the thick plate.
Buffa et al. [121] investigated varying included cone angle with a cylindrical pin
(0°) to conical pin up to 40°. AA7075 was selected as workpiece material. Investigation of the material flow behavior and grain size distribution in the joints were
carried for different cone angles. Results show that the extent of plastic deformation,
strain rate, and size of the weld zone in SZ, and HAZ increases with an increase in
pin angle. A combination of 100 mm/min and pin angle of 40° was reported as an
optimized parameter to get sound weld.