68
A. K. Choudhary and R. Jain
2.8.1.2 Cu Welding
Pure copper or copper-based alloy is the third most widely used material after
iron/steel and aluminum alloys. It has excellent electrical conductivity and good
corrosion resistance. In addition to this, it has good ductility, toughness, non-magnetic
behavior, and catalytic properties that have attracted considerable interest in various
industries. It has wide applications in the field of space, defense, electronics, and
military. Also, copper alloy welded with FSW has shown excellent formability and
good resistance to oxidation [122].
Jha et al. [47] investigated the microstructural investigation for Cu0.8Cr0.1Zr
alloy. Welding speed of 100 mm/min showed a fine grain size in the weld nugget
zone. At lower travel velocity, larger grains were observed, the reason could be a long
time offered for the recrystallization process. Defect-free weld was produced between
800 to 1200 rpm and welding speed from 40 to 100 mm/min. The thermocouple is
fixed at a distance of 2 mm and 12 mm from the shoulder in the transverse direction.
In both cases, a temperature difference of around 250 °C is observed. Also, the
temperature difference of 2–3 °C is reported between AS and RS it is due to the
difference in relative velocity components between AS and RS. The weld efficiency
was reported to be 60%.
Guan et al. [123] investigated the FSW of Cu alloy with a thickness of 20 and
50-micron thickness. The peak temperature attained is 256 °C which enables the
recrystallization temperature of copper. Moving from 800 to 900 rotational speed
resulted in enhanced interface bonding. The EDS analysis indicated no impurities
were present in the weld. For 50 μm thickness foil, process parameters of 800 rpm
and 25 mm/min resulted in a 56 N fracture capacity.
Lee and Jung [124] studied FSW of copper at 1250 rpm and 61 mm/min and it
resulted in the defect-free weld. They used tool steel material with a 3° tilt angle.
The average grain size of base metal was 210 μm, while HAZ and SZ have 230 μm
and 100 μm, respectively. Weld zone hardness was lower as compared to the base
metal. The result shows the hardness distribution near the weld zone was independent
of grain size. The base metal hardness was around 110 HV, but hardness near the
weld region has reduced significantly and varied from 60 to 90 HV. The tensile test
result showed that fracture happened around the HAZ due to lower hardness. A joint
efficiency of 87% is reported for the weld.
Hwang et al. [125] investigated FSW in butt configuration for joining of C11000
with 3.1 mm thickness. The K-type thermocouple was employed for temperature
measurements at different locations. Also, a 1° tilt was provided for better forging.
Successful FSW weld was formed between the temperature of 460 and 530 °C. Also,
the temperature towards AS is a little higher than the RS. Tensile strength and the
hardness variation (near TMAZ) were reduced to about 60% as compared to the
original sample.
Khodaverdizadeh et al. [15] investigated the influence of tool pin shape on grain
size and mechanical properties for FSW of copper. Threaded cylindrical and square
pin were used at 600 rpm and 75 mm/min. Temperature history was measured using
a K-type thermocouple. Square pin profile resulted in a fine recrystallized grain
A. K. Choudhary and R. Jain
2.8.1.2 Cu Welding
Pure copper or copper-based alloy is the third most widely used material after
iron/steel and aluminum alloys. It has excellent electrical conductivity and good
corrosion resistance. In addition to this, it has good ductility, toughness, non-magnetic
behavior, and catalytic properties that have attracted considerable interest in various
industries. It has wide applications in the field of space, defense, electronics, and
military. Also, copper alloy welded with FSW has shown excellent formability and
good resistance to oxidation [122].
Jha et al. [47] investigated the microstructural investigation for Cu0.8Cr0.1Zr
alloy. Welding speed of 100 mm/min showed a fine grain size in the weld nugget
zone. At lower travel velocity, larger grains were observed, the reason could be a long
time offered for the recrystallization process. Defect-free weld was produced between
800 to 1200 rpm and welding speed from 40 to 100 mm/min. The thermocouple is
fixed at a distance of 2 mm and 12 mm from the shoulder in the transverse direction.
In both cases, a temperature difference of around 250 °C is observed. Also, the
temperature difference of 2–3 °C is reported between AS and RS it is due to the
difference in relative velocity components between AS and RS. The weld efficiency
was reported to be 60%.
Guan et al. [123] investigated the FSW of Cu alloy with a thickness of 20 and
50-micron thickness. The peak temperature attained is 256 °C which enables the
recrystallization temperature of copper. Moving from 800 to 900 rotational speed
resulted in enhanced interface bonding. The EDS analysis indicated no impurities
were present in the weld. For 50 μm thickness foil, process parameters of 800 rpm
and 25 mm/min resulted in a 56 N fracture capacity.
Lee and Jung [124] studied FSW of copper at 1250 rpm and 61 mm/min and it
resulted in the defect-free weld. They used tool steel material with a 3° tilt angle.
The average grain size of base metal was 210 μm, while HAZ and SZ have 230 μm
and 100 μm, respectively. Weld zone hardness was lower as compared to the base
metal. The result shows the hardness distribution near the weld zone was independent
of grain size. The base metal hardness was around 110 HV, but hardness near the
weld region has reduced significantly and varied from 60 to 90 HV. The tensile test
result showed that fracture happened around the HAZ due to lower hardness. A joint
efficiency of 87% is reported for the weld.
Hwang et al. [125] investigated FSW in butt configuration for joining of C11000
with 3.1 mm thickness. The K-type thermocouple was employed for temperature
measurements at different locations. Also, a 1° tilt was provided for better forging.
Successful FSW weld was formed between the temperature of 460 and 530 °C. Also,
the temperature towards AS is a little higher than the RS. Tensile strength and the
hardness variation (near TMAZ) were reduced to about 60% as compared to the
original sample.
Khodaverdizadeh et al. [15] investigated the influence of tool pin shape on grain
size and mechanical properties for FSW of copper. Threaded cylindrical and square
pin were used at 600 rpm and 75 mm/min. Temperature history was measured using
a K-type thermocouple. Square pin profile resulted in a fine recrystallized grain