92
N. Bhardwaj et al.
Friction stir welding involves combination of several physical phenomena like
frictional heat due to tool-work surface interaction, heat due to large plastic deformation, dynamic microstructural evolution and material stirring [40]. Multiple process
parameters influence the quality of weld produced. The fine-tuning of these parameters helps in producing defect-free welds by controlling the heat input during welding.
Modeling and simulation of the FSW process help to choose the best process parameters without undergoing extensive experimental trials, making the FSW process
economical and less time-consuming. Moreover, modeling of the process using
various numerical methods and computational tools helps in understanding the
process and improving it. Analysis and visualization of material flow, stress and
strain evolution, residual stresses after welding and temperature field in the crosssection during welding can be obtained easily by modeling [2]. Modeling does not
have the physical limitations of experimental observation,thus, it can be effective in
the understanding of the effect of process parameters during welding. There has been
a drastic improvement in the modeling of multiphysics problems, including FSW, in
recent years. However, the studies are limited, and there is a requirement of further
studies in the modeling of FSW process, especially for reducing simulation time.
The present article presents a survey on different approaches taken for modeling of
FSW and its future scope. A case study of a finite element (FE) simulation of two
AA6061 sheets welded using FSW is also presented as an example.
3.2 Friction Stir Welding Process
In 1891, Bevington patented friction welding where frictional heat produced by
relative spinning of two axisymmetric parts is utilized to form the joint between the
two parts [11]. The modifications over a period of time, led to development of a
variant of friction welding, are known as the friction stir welding, which removed
the limitation of welding only axisymmetric parts. Thomas [82] patented the FSW
process first in 1991. It was mainly developed for butt welding of aluminum alloys
that are usually hard to join using conventional welding. The process expanded to
other joint configurations (lap joints and T-joints) and also to different materials
like magnesium alloys, copper as well as steel and titanium [45]. The commercial
applications of FSW in industries have increased in the last two decades owing to
its economic and environmental advantages over conventional fusion welding. FSW
welds showed higher strength in both bending and tensile tests as compared to MIG
and TIG welds of AA5086-H32 [81]. A higher fatigue strength was also observed
in FSW joints [28]. A brief overview of the FSW process is presented in the next
section to pave the way for discussion on its modeling in detail.
N. Bhardwaj et al.
Friction stir welding involves combination of several physical phenomena like
frictional heat due to tool-work surface interaction, heat due to large plastic deformation, dynamic microstructural evolution and material stirring [40]. Multiple process
parameters influence the quality of weld produced. The fine-tuning of these parameters helps in producing defect-free welds by controlling the heat input during welding.
Modeling and simulation of the FSW process help to choose the best process parameters without undergoing extensive experimental trials, making the FSW process
economical and less time-consuming. Moreover, modeling of the process using
various numerical methods and computational tools helps in understanding the
process and improving it. Analysis and visualization of material flow, stress and
strain evolution, residual stresses after welding and temperature field in the crosssection during welding can be obtained easily by modeling [2]. Modeling does not
have the physical limitations of experimental observation,thus, it can be effective in
the understanding of the effect of process parameters during welding. There has been
a drastic improvement in the modeling of multiphysics problems, including FSW, in
recent years. However, the studies are limited, and there is a requirement of further
studies in the modeling of FSW process, especially for reducing simulation time.
The present article presents a survey on different approaches taken for modeling of
FSW and its future scope. A case study of a finite element (FE) simulation of two
AA6061 sheets welded using FSW is also presented as an example.
3.2 Friction Stir Welding Process
In 1891, Bevington patented friction welding where frictional heat produced by
relative spinning of two axisymmetric parts is utilized to form the joint between the
two parts [11]. The modifications over a period of time, led to development of a
variant of friction welding, are known as the friction stir welding, which removed
the limitation of welding only axisymmetric parts. Thomas [82] patented the FSW
process first in 1991. It was mainly developed for butt welding of aluminum alloys
that are usually hard to join using conventional welding. The process expanded to
other joint configurations (lap joints and T-joints) and also to different materials
like magnesium alloys, copper as well as steel and titanium [45]. The commercial
applications of FSW in industries have increased in the last two decades owing to
its economic and environmental advantages over conventional fusion welding. FSW
welds showed higher strength in both bending and tensile tests as compared to MIG
and TIG welds of AA5086-H32 [81]. A higher fatigue strength was also observed
in FSW joints [28]. A brief overview of the FSW process is presented in the next
section to pave the way for discussion on its modeling in detail.