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80
3. The maximum temperature reached during FSW is above the melting
temperature.
4. The characteristics of the material being joined affect the microstructure of
a friction-stir weld.
5. FSW is the only method for welding austenitic stainless steels.
6. Pipes can be welded using FSW.
Reading and speaking
7 In small groups read the characteristics of FSW given below and
distribute them into two categories in the table. Compare with other groups.
Then speak about advantages and disadvantages of FSW.
Advantages Disadvantages
Ø The method requires a stable welding machine with a powerful fixture.
Ø Material from 15-30 mm can be welded on both sides.
Ø No joint preparation, only degreasing.
Ø The method can only be used on straight, flat workpieces or hollow
profiles with an abutment or backing.
Ø High, consistent quality.
Ø No grinding or brushing.
Ø No consumables.
Ø No shielding gas.
Ø This welding method leaves an end hole when the tool is pulled away
from workpiece. In many cases, this hole can be cut off, but, in other
cases, it has to be sealed using another method.
Ø Flat surface without weld reinforcement or splatter.
Ø No magnetic blowing as the welding is done without an arc.
Ø Environmentally-compatible method without flash, fumes or ozone
formation. Less risk of pores and cracking as the temperature never
reaches the melting point of aluminium.
Ø No burning off of alloy substance as the temperature never reaches
melting point.
Ø Alloys which are difficult to weld can be welded as there is only a
small risk of hot cracking. High productivity.
Ø Material thickness from 1.6-15 mm can be welded as single-pass
procedures.
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