140
P. Sarkar et al.
generation and softens the material for proper mixing. The F z must be so selected
that the stress caused by it becomes higher than the flow stress of the base material
for a satisfactory joint.
Along with the above-mentioned process parameters, two other process parameters namely, α and PD are also important in producing a good weld. α is used to
increase the forging force further and also to decrease the amount of flash formation.
For better mixing, α must be inclined towards the trailing edge of the pin. PD helps
to increase the heat input by providing more contact surface, and also by increasing
the downward F z .
4.1.5.3 Influence of Material Properties
The properties of tool, workpiece, and anvil materials also play essential roles in the
process. As the tool touches the workpiece material, it generates frictional and deformational heating that consequently softens the materials and aids in better mixing
and joining. The tool further increases the deformational volume by dwelling in one
place and creating more heat to soften the material. During welding, the material
offers resistance to tool movement. This causes the tool to experience F z and transverse load. Depending on the type of material to be welded and to ensure a long life of
the FSW tool, the tool material must possess properties like strength and stability at
high temperatures. Less reactivity to the environment, high fracture toughness, wear
resistance are some of the other vital criteria the tool material must fulfil. It should
have good machinability to be easily manufactured, and last but not the least, they
must be of low cost and readily available. The most frequently used FSW tool to weld
Al and other softer materials are AISI H13 hot-working, air-hardened Cr-Mo tool.
Table 4.1 describes some of the most used FSW tool materials for welding different
workpiece materials.
Again, the properties of the workpiece material like strength, melting point, recrystallization temperature, thermal conductivity, compatibility to join with other materials also influence the process. The thermal conductivity of the anvil material also is
a secondary factor for distributing the heat generated to the parts to be welded during
the FSW process.
4.1.6 Advantages of FSW Process
Being a solid-state joining process, FSW has many advantages over other traditional
welding processes that made it acceptable over the globe.
The absence of melting in FSW, unlike other fusion welding processes, makes the
weld-free from defects like porosity, blowholes, cracking, distortion, etc. In addition,
it eliminates the use of any protective gas (for Al grades, steel). Further, no fume
is generated during the process, thus making it an environment-friendly and green
process.
P. Sarkar et al.
generation and softens the material for proper mixing. The F z must be so selected
that the stress caused by it becomes higher than the flow stress of the base material
for a satisfactory joint.
Along with the above-mentioned process parameters, two other process parameters namely, α and PD are also important in producing a good weld. α is used to
increase the forging force further and also to decrease the amount of flash formation.
For better mixing, α must be inclined towards the trailing edge of the pin. PD helps
to increase the heat input by providing more contact surface, and also by increasing
the downward F z .
4.1.5.3 Influence of Material Properties
The properties of tool, workpiece, and anvil materials also play essential roles in the
process. As the tool touches the workpiece material, it generates frictional and deformational heating that consequently softens the materials and aids in better mixing
and joining. The tool further increases the deformational volume by dwelling in one
place and creating more heat to soften the material. During welding, the material
offers resistance to tool movement. This causes the tool to experience F z and transverse load. Depending on the type of material to be welded and to ensure a long life of
the FSW tool, the tool material must possess properties like strength and stability at
high temperatures. Less reactivity to the environment, high fracture toughness, wear
resistance are some of the other vital criteria the tool material must fulfil. It should
have good machinability to be easily manufactured, and last but not the least, they
must be of low cost and readily available. The most frequently used FSW tool to weld
Al and other softer materials are AISI H13 hot-working, air-hardened Cr-Mo tool.
Table 4.1 describes some of the most used FSW tool materials for welding different
workpiece materials.
Again, the properties of the workpiece material like strength, melting point, recrystallization temperature, thermal conductivity, compatibility to join with other materials also influence the process. The thermal conductivity of the anvil material also is
a secondary factor for distributing the heat generated to the parts to be welded during
the FSW process.
4.1.6 Advantages of FSW Process
Being a solid-state joining process, FSW has many advantages over other traditional
welding processes that made it acceptable over the globe.
The absence of melting in FSW, unlike other fusion welding processes, makes the
weld-free from defects like porosity, blowholes, cracking, distortion, etc. In addition,
it eliminates the use of any protective gas (for Al grades, steel). Further, no fume
is generated during the process, thus making it an environment-friendly and green
process.