| dc.description.abstract | Development of the industrial world are now starting to consider the aluminum
material as the main ingredient in the production process. This is because aluminum
and aluminum alloys including light metals having high strength, corrosion
resistance, good electrical conductors and aluminum is lighter than iron or steel. The
use of aluminum in particular types of AA 1100 in the industrial world are widely
used for heat exchangers, pressure vessels, pipes, etc. However, aluminum and
aluminum alloys have properties that are less well when compared to steel, such as
specific heat and has a high conductivity, easily oxidized and forming an aluminum
oxide Al2O3 having a high melting point, resulting in a fusion between the base
metal and weld metal to be blocked and if in too fast cooling process will form a
smooth cavity ex-pouch of hydrogen. However, the most fundamental difference is
the value of perseverance in the weld metal, where the value of steel weld metal
toughness is always high when compared with the parent metal, while in the weld
metal toughness values of aluminum tend to be smaller than the value of toughness in
the parent metal. Along with these case need to be done research to makes it easy of
aluminum welding and have optimal strength. One of which the welding process of
aluminum alloy can be done by friction stir welding.
FSW (friction stir welding) is a welding method that has been discovered and
developed by Wayne Thomas for the work piece of aluminum and aluminum alloy in
1991 at TWI (The Welding Institute) United States. FSW welding process to occur in
the solid state (solid state joining). FSW welding process to occur at the solvus
temperature, so there is no decrease in strength due to overaging and dissolving of
x
the precipitate coherent. Because the welding temperature is not too high, then the
residual stress and distortion of heat effect is also low. Mechanical characteristics of
the FSW is determined by the parameters: welding speed, tool rotation and tool
pressure.
In this research, the welding of aluminum AA 1100 by friction stir welding
method (FSW) can be done well. Tensile test results obtained that the averages of
ultimate strength for welding with using 780 rpm is 52 222 Mpa, for 980 rpm is 38
472 MPa and 1120 rpm is 56 528 MPa. With these results can be seen that the highest
ultimate strength is use 1120 rpm and ultimate strength at 980 rpm is the lowest.
Wormholes defects in the welding with 980 rpm is the main factor that reduces the
tensile strength in this research. Macro observations are known the largest wormholes
defects in the welding with 980 rpm and also the presence of cracks due to lack of
penetration and cause of stress concentration at the weld, this case also occurs at 780
rpm. From micro observations is known on the grains shape of the stir zone, FeAl3
particles is spread more evenly in matrix of Al due to the stir process during the
welding process. Hardness testing showed that the weld metal is softer than the parent
metal. While the TMAZ region has the lowest hardness. | en_US |
