Joining of dissimilar materials

TLDR: Current and emerging joining technologies are reviewed according to the mechanisms of joint formation, i.e.; mechanical, chemical, thermal, or hybrid processes.

Abstract: Emerging trends in manufacturing such as light weighting, increased performance and functionality increases the use of multi-material, hybrid structures and thus the need for joining of dissimilar materials. The properties of the different materials are jointly utilised to achieve product performance. The joining processes can, on the other hand be challenging due to the same different properties. This paper reviews and summarizes state of the art research in joining dissimilar materials. Current and emerging joining technologies are reviewed according to the mechanisms of joint formation, i.e.; mechanical, chemical, thermal, or hybrid processes. Methods for process selection are described and future challenges for research on joining dissimilar materials are summarized.

Figures

Fig. 5. Process of clinching [259].

Fig. 28. Alternative hybrid structures [112].

Fig. 23. Rivet-weld hybrid joining.

Fig. 2. Example of threaded fasteners [71].

Fig. 20. Material being extruded out of the area of contact during dissimilar metal friction joining.

Fig. 12. Laser weldability of dissimilar metals [233].

Full text

Joining
of
dissimilar
materials
K.
Martinsen
(3)
a,b,
*
,
S.J.
Hu
(1)
c
,
B.E.
Carlson
d
a
Sintef
Raufoss
Manufacturing,
Raufoss,
Norway
b
Gjøvik
University
College,
Gjøvik,
Norway
c
Department
of
Mechanical
Engineering,
The
University
of
Michigan,
Ann
Arbor,
MI,
USA
d
General
Motors
R&D,
Detroit,
MI,
USA
1.
Introduction
Among
the
many
manufacturing
technologies,
joining
has
been
identified
as
a
key
enabling
technology
to
innovative
and
sustainable
manufacturing
[6].
Due
to
functional
needs
and
technological
limitations,
it
is
usually
not
possible
to
manufacture
a
product
without
joining
of
some
sort.
Products
are
typically
assembled
using
multiple
components
[100]
and
joining
processes
are
essential
in
manufacturing
to
provide
product
function
and
increase
manufacturing
process
efficiency.
Improvements
of
material
properties
and
traditional
processes
for
monolithic
structures
as
well
as
extended
use
of
additive
manufacturing
processes
can
reduce
the
need
for
joining
and
the
number
of
joints
in
a
product
[294].
Nevertheless,
the
production
processes
and
the
required
functions
of
the
products
make
a
‘‘joint-free’’
concept
unrealistic
in
most
cases.
Moreover,
the
search
for
increased
product
features
and
performance
from
hybrid
structures
with
different
classes
of
materials
requires
the
presence
of
joints.
Understanding
of
joining
technologies
is
therefore
a
key
issue
in
manufacturing,
and
there
is
a
continuous
development
of
novel
processes
as
well
as
improvements
of
existing
processes.
Joining
can
be
complex
and
spans
a
wide
range
of
approaches,
materials
and
techniques.
Messler
[149]
defines
joining
to
be:
‘‘The
process
used
to
bring
separate
parts
of
components
together
to
produce
a
unified
whole
assembly
or
structural
entity’’.
Campbell
[44]
considers
joining
as:
‘‘a
large
number
of
processes
used
to
assemble
individual
parts
into
a
larger,
more
complex
component
or
assembly’’.
In
[15,211]
two
definitions
of
joining
are
presented,
where
the
first
definition
is:
‘‘.
.
.joining
is
the
act
or
process
of
putting
or
bringing
things
together
to
make
them
continuous
or
to
form
a
unit’’.
The
second
definition
explained
in
[15,211]
is:
‘‘joining
is
the
process
of
attaching
one
component
or
structural
element
to
another
to
create
an
assembly’’.
The
Sub-Platform
on
Joining
[6]
of
the
EU
Manufuture
Technology
platform
defines
joining
as:
‘‘Creating
a
bond
of
some
description
between
materials
or
components
to
achieve
a
specific
physical
performance’’.
This
bond
can
take
many
forms,
and
can
be
described
as
being
generated
by
one
or
a
combination
of
several
of
the
following
processes:
Mechanical—a
joint
formed
through
a
mechanical
mechanism,
Chemical—a
bond
formed
through
chemical
reaction,
Thermal—a
bond
formed
through
applying
thermal
energy.
In
this
paper
we
will
follow
this
definition,
but
add
hybrid
processes
as
a
4th
class
and
divide
thermal
processes
into
fusion
and
solid-state
processes.
1.1.
Joining
of
dissimilar
materials
The
drive
for
more
optimal,
lightweight
and
high
performance
structures,
and
the
trend
of
integrating
an
increased
number
of
functions
in
each
part
[26]
can
be
met
by
combining
various
materials
into
a
multi-material
hybrid
structure.
The
different
properties
of
the
different
materials
are
jointly
utilised
to
achieve
the
product
performance
needed.
This
trend
is
reported
for
several
industries
such
as:
Automotive
[176],
Aeronautics
[209,276],
Clothing
[289],
Tooling
[186],
Implants
[217],
Power
generation
[131],
and
Marine
application
[22].
The
mix
of
new
materials
will
require
a
systematic
approach
to
material
selection:
these
materials
will
interact
with
each
other
in
new
ways,
and
new
CIRP
Annals
-
Manufacturing
Technology
xxx
(2015)
xxx–xxx
A
R
T
I
C
L
E
I
N
F
O
Keywords:
Joining
Dissimilar
materials
Modelling
and
testing
A
B
S
T
R
A
C
T
Emerging
trends
in
manufacturing
such
as
light
weighting,
increased
performance
and
functionality
increases
the
use
of
multi-material,
hybrid
structures
and
thus
the
need
for
joining
of
dissimilar
materials.
The
properties
of
the
different
materials
are
jointly
utilised
to
achieve
product
performance.
The
joining
processes
can,
on
the
other
hand
be
challenging
due
to
the
same
different
properties.
This
paper
reviews
and
summarizes
state
of
the
art
research
in
joining
dissimilar
materials.
Current
and
emerging
joining
technologies
are
reviewed
according
to
the
mechanisms
of
joint
formation,
i.e.;
mechanical,
chemical,
thermal,
or
hybrid
processes.
Methods
for
process
selection
are
described
and
future
challenges
for
research
on
joining
dissimilar
materials
are
summarized.
ß
2015
CIRP.
*
Corresponding
author
at:
Gjøvik
University
College,
TØL,
Teknologivn
22,
2815
Gjøvik,
Norway.
Tel.:
+47
99521849.
E-mail
address:
kristian.martinsen@hig.no
(K.
Martinsen).
G
Model
CIRP-1404;
No.
of
Pages
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Please
cite
this
article
in
press
as:
Martinsen
K,
et
al.
Joining
of
dissimilar
materials.
CIRP
Annals
-
Manufacturing
Technology
(2015),
http://dx.doi.org/10.1016/j.cirp.2015.05.006
Contents
lists
available
at
ScienceDirect
CIRP
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homepage:
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0007-8506/ß
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CIRP.

manufacturing
systems
might
be
needed
[49].
This
requires
the
ability
to
simultaneously
optimize
material
choice
and
geometry.
Recent
developments
include
proposals
for
multi-material
design
procedures
[276],
and
optimal
material
selection
with
respect
to
light
weight
and
recyclability
[209].
A
commonly
known
example
is
the
Boeing
787
Dreamliner
which
uses
composite
materials
as
the
primary
material
in
the
airframe
structure,
although
also
includes
20%
aluminium,
15%
titanium,
10%
steel,
and
5%
other
[279].
In
modern
car
body
structures
high
strength
steels
can
be
used
in
the
longitudinal
beams
for
strength,
aluminium
alloys
in
bumper
beams
for
lightweight
and
crashworthiness
and
composite
sheets
in
panels
for
lightweight
and
high
stiffness.
The
EU
FP6–project
Super-
lightCar
[223]
showed
how
mass
can
be
reduced
by
combining
aluminium,
steel,
magnesium
and
glass
fibre
reinforced
thermo-
plastics
(see
Fig.
1).
Dissimilar
materials
can
be
described
as:
‘‘materials
or
material
combinations
that
are
difficult
to
join,
either
because
of
their
individual
chemical
compositions
or
because
of
large
differences
in
physical
properties
between
the
two
materials
being
joined’’
[44].
Hybrid
structures
can
be
defined
as
[12,221]:
‘‘A
combination
of
two
or
more
materials
in
a
pre-determined
configuration
and
scale,
optimally
serving
a
specific
engineering
purpose’’.
In
this
paper
we
will
use
the
following
definition
for
a
hybrid
structure:
A
hybrid
structure
consisting
of
two
or
more
components
of
dissimilar
materials
joined
together
to
achieve
a
specific
physical
perfor-
mance.
These
components
of
dissimilar
materials
are
to
be
joined
together,
and
different
joining
processes
have
unique
strengths
and
limitations
for
the
joining
of
dissimilar
materials.
There
are,
however,
significant
challenges
when
materials
of
different
chemical,
mechanical,
thermal,
or
electrical
properties
are
to
be
joined
together.
The
incompatibility
on
chemical,
thermal
and
physical
levels
(thermal
expansion,
ductility,
fatigue/fracture
mechanics,
elastic
modulus
etc.)
can
create
problems
both
for
the
joining
process
itself,
but
also
for
the
structural
integrity
of
the
joints
during
the
use
phase
of
the
product.
Galvanic
corrosion,
different
thermal
expansion
and
other
effects
of
bringing
two
different
materials
closely
together
must
be
addressed.
To
be
able
to
join
dissimilar
materials,
the
product
design
and
the
joining
process
design
must
equalize
these
challenges.
As
Messler
[149]
describes
it:
‘‘differences
must
be
minimized,
inherently
through
the
choice
of
material
or
through
some
other
means.
This
becomes
increasingly
difficult
as
the
basic
nature
–
atomic
level
structure,
microstructure,
and
(macrostructure)
–
of
the
various
materials
involved
becomes
more
different.’’
The
field
of
joining
is
very
large
and
there
are
a
large
number
of
different
joining
methods.
This
paper
gives
an
overview
of
the
state-of-the-art
on
a
selection
of
processes.
Many
methods
are
not
mentioned
though,
and
joining
of
wood,
glass
and
concrete/
cement
is
not
covered.
The
authors
have
a
strong
foothold
in
automotive
industry,
which
to
some
extent
explain
the
choice
of
methods
described.
The
joining
methods
and
the
knowledge
are
still
applicable
for
several
industry
sectors.
2.
Review
of
joining
methods
for
dissimilar
materials
In
this
section,
we
review
the
joining
process
by
the
mechanisms
of
joint
formation,
e.g.,
mechanical,
chemical
and
thermal
processes.
Hybrid
processes
that
combine
one
or
two
of
the
above
methods
are
also
reviewed.
2.1.
Mechanical
joining
processes
2.1.1.
Threaded
fasteners
Joining
using
threaded
fasteners
or
screws
has
been
in
practice
for
a
long
time.
Screws
of
various
forms
can
be
applied
in
one-sided
joining
when
access
from
the
other
side
of
the
components
is
limited.
Bolt
and
nut
combinations
are
commonly
used
when
access
is
available
from
both
sides
of
the
components
to
be
joined.
Fig.
2
shows
some
examples
of
threaded
fasteners.
When
disassembly
is
required,
threaded
fasteners
are
usually
the
preferred
method
since
unscrewing
does
not
lead
to
destruction
of
the
components.
Screw
joints
for
thin
gauge
sheet
metals
do
not
provide
sufficient
load
bearing
length
of
the
screw,
so
other
joining
methods
or
additional
elements,
such
as
flow
drill
screws,
collar
forming,
or
spring
nuts,
are
used
to
increase
the
load
bearing
length
[71].
Bolted
joints
have
been
in
use
for
more
than
500
years
[33].
They
are
simple
to
use
and
virtually
the
only
choice
for
disassembly
and
reassembly
of
a
product,
whether
driven
by
maintenance
or
remanufacturing.
Bolted
joints
can
be
designed
for
tensile
or
shear
loads,
or
a
combination.
If
the
applied
force
is
more
or
less
parallel
to
the
bolt,
then
the
joint
is
called
a
tension
or
tensile
joint
(see
Fig.
3).
If
the
applied
force
is
perpendicular
to
the
bolt
axis,
the
joint
is
a
shear
joint.
For
other
applications,
a
joint
can
be
designed
to
withstand
both
tensile
and
shear
loads.
Bickford
[33]
provides
an
excellent
overview
of
joint
design,
materials
consideration,
loading
and
strength
analysis.
2.1.2.
Flow
drill
screws
Flow
Drill
Screws,
FDS,
fill
the
void
of
a
single-sided
mechanical
fastening
method
for
structural
automotive
joints
and
at
this
point
is
a
commercial
off
the
shelf
technology
capable
of
both
manual
and
fully
automated
assembly.
The
North
American
automotive
industry
is
now
following
the
trend
set
by
European
counterparts
who
have
been
using
FDS
since
1996
[43].
Traditional
automotive
steel-intensive
Body
In
White
(BIW)
single-sided
joining
has
been
via
gas
metal
arc
welding.
This
fusion
method
implies
however,
Fig.
1.
Material
distribution
in
a
superlight
car
body
[30].
Fig.
2.
Example
of
threaded
fasteners
[71].
Fig.
3.
Bolted
joints
in
tension
and
shear.
K.
Martinsen
et
al.
/
CIRP
Annals
-
Manufacturing
Technology
xxx
(2015)
xxx–xxx
2
G
Model
CIRP-1404;
No.
of
Pages
21
Please
cite
this
article
in
press
as:
Martinsen
K,
et
al.
Joining
of
dissimilar
materials.
CIRP
Annals
-
Manufacturing
Technology
(2015),
http://dx.doi.org/10.1016/j.cirp.2015.05.006

significant
dimensional
distortion
and
is
less
applicable
to
dissimilar
material
combinations.
FDS
can
be
used
with
or
without
a
pre-drilled
hole
(depending
on
the
screw).
The
rotating
screw
first
heats
up
the
material
to
facilitate
penetration.
As
the
screw
tip
penetrates
the
material,
it
also
acts
to
extrude
the
material
into
a
funnel
shape.
Once
the
tip
has
pierced
the
material,
threads
are
formed
and
the
screw
is
then
driven
downward
until
final
tightening.
The
strength
of
the
joint
comes
from
extrusion
and
flow
that
creates
greater
interlock
depth
(see
Fig.
4).
This
process
is
not
without
limitations
such
as
thin
gauge
materials
and
the
perpendicularity
of
the
screw
to
avoid
skidding.
FDS
is
often
used
in
conjunction
with
adhesives.
Furthermore,
there
are
some
concerns
for
galvanic
corrosion
so
the
head
of
the
screw
is
often
covered
with
a
sealer
as
in
the
Mercedes
SL
[18].
Audi
was
an
early
FDS
user
for
Al
joints
and
implemented
it
with
pre-drilled
holes
on
the
TT
and
without
predrilled
holes
on
the
R8
[123].
They
also
used
this
for
a
steel–Al
joint
on
Audi
TT
production
[81].
The
method
has
been
shown
appropriate
for
various
combinations
of
steel,
aluminium,
magnesium
and
carbon
fibre
reinforced
polymers
(CFRP).
Szlosarek
et
al.
[236]
analysed
the
damage
and
fracture
mechanisms
for
joints
between
fibre–
reinforced
composites,
CFRP,
and
metals.
They
found
that
the
peak
loads
were
independent
of
loading
angles
albeit
they
used
a
predrilled
hole
in
the
CFRP.
Under
pure
cross
tension
load,
shear
punching
caused
the
characteristic
failure
mode.
Under
shear
load
the
CFRP
laminate
becomes
damaged
under
bearing
stress
leading
to
fibre
kinking
damage.
This
is
just
one
example
of
an
overall
need
for
additional
work
to
characterize
the
failure
loads
and
damage
mechanisms
of
various
dissimilar
material
joints
under
static,
dynamic,
and
fatigue
loading
conditions.
2.1.3.
Clinching
Clinching
is
a
mechanical
joining
process
where
the
sheet
metal
parts
are
joined
together
by
an
interlock
formed
through
local
plastic
deformation
without
cutting
or
the
use
of
any
external
elements
such
as
a
fastener
or
rivet,
see
Fig.
5.
Varis
[259]
provides
a
nice
description
of
the
tools
and
process
of
clinching
as
well
as
the
modes
of
failure
of
the
clinched
joints.
Mucha
[169]
investigated
the
locking
mechanism
in
clinching
using
finite
element
analysis.
To
form
a
clinched
joint,
the
materials
to
be
joined
need
to
have
high
ductility.
Two
overlapping
sheets
are
deformed
together
under
the
action
of
a
punch
and
a
die
in
a
press
machine.
The
process
is
relatively
simple
and
it
does
not
produce
any
heat,
splashes,
or
emissions.
‘‘A
clinched
joint
is
characterized
by
a
pit
on
the
punch
side,
and
a
rise
on
the
die
side’’
[164,259].
Since
the
joint
is
formed
by
the
mechanical
deformation
of
the
overlapping
sheets,
clinching
can
be
used
to
join
dissimilar
materials,
or
difficult
to
weld
materials.
Varis
[260]
studies
the
suitability
of
clinching
in
joining
high
strength
steels
in
construc-
tion.
Abe
et
al.
[1]
studied
the
clinch
joining
of
high
strength
steel
and
aluminium
alloy
sheets.
It
was
found
that
the
relatively
low
ductility
of
the
high
strength
steel
may
lead
to
fracture
of
the
steel
sheet.
As
such,
proper
die
design
is
necessary
to
enhance
control
of
the
metal
flow.
Neugebauer
et
al.
[177]
introduced
a
die-less
clinching
method
for
joining
magnesium
sheets.
There
can
be
two
failure
modes
for
a
clinch
joint
under
load:
(i)
A
joint
may
fail
around
the
neck
due
to
excess
thinning
and
deformation
of
the
sheet
metal
around
the
die
corner.
This
happens
often
if
the
die
corner
radius
is
small.
(ii)
If
the
deformation
is
insufficient
and
the
mechanical
interlocking
is
weak
under
load,
the
sheet
may
separate.
The
relative
strength
of
this
joint
is
low
as
compared
to
the
more
common
self-piercing
rivet
favoured
in
the
automotive
industry
for
dissimilar
material
joints.
Mori
et
al.
[164]
gives
an
extensive
overview
of
clinching.
2.1.4.
Friction
stir
blind
riveting
Friction
stir
blind
riveting
(FSBR)
is
another
process
for
mechanical
joining
in
situations
with
only
single
sided
accessibili-
ty.
FSBR
was
originally
proposed
by
Gao
et
al.
[79].
Unlike
conventional
blind
riveting,
no
pre-drilled
hole
is
necessary.
In
this
process
a
blind
rivet
is
rotated
at
high
speeds
(6–12,000
rpm),
and
is
then
lowered
onto
the
upper
surface
of
the
top
workpiece.
This
generates
frictional
heat
thereby
softening
the
workpiece
material
and
enabling
the
rivet
to
be
driven
through
the
stack-up
under
reduced
force.
Once
the
rivet
is
driven
into
place,
the
blind
rivet
is
upset
as
in
conventional
blind
riveting,
to
join
the
workpieces
together
(see
Fig.
6
and
Fig.
7).
Gao’s
work
was
targeted
at
Al–Al
joining
and
showed
that
both
lap-shear
and
fatigue
strength
were
significantly
better
than
comparable
resistance
spot
welds.
Additional
work
[154]
highlighted
the
fracture
mode
(shearing
of
the
workpieces
by
the
rivet
followed
by
a
tearing
mode)
which
was
the
same
as
conventional
rivets,
though
in
FSBR
there
is
a
thermo-mechanical
zone
created
by
material
flow
resulting
from
the
rivet
insertion
which
increased
the
hardness
adjacent
to
the
rivet.
This
effect
is
enhanced
with
increased
rivet
feed
rates
resulting
in
slight
increases
of
peak
strength.
Lathabai
et
al.
[124]
extended
the
application
to
include
combinations
of
wrought
and
cast
Al
alloys
as
well
as
Mg–Al
joints.
They
found
that
the
process
is
sensitive
to
stack-up
order
since
the
top
workpiece
impacts
insertion
force
and
the
bottom
workpiece
directly
affects
the
failure
load
since
the
rivet
head
on
the
top
workpiece
distributes
the
load
over
a
greater
area.
Furthermore,
they
investigated
both
solid
and
hollow
rivet
designs
[125]
as
well
as
the
effect
of
process
parameters.
Their
major
finding
was
that
rivets
Fig.
4.
Flow
drill
screw
steel–Al
joint.
Fig.
5.
Process
of
clinching
[259].
Fig.
6.
Friction
stir
blind
riveting
Gao
et
al.
[79].
Fig.
7.
Friction
stir
blind
rivet
in
a
CFRP–Al
joint.
K.
Martinsen
et
al.
/
CIRP
Annals
-
Manufacturing
Technology
xxx
(2015)
xxx–xxx
3
G
Model
CIRP-1404;
No.
of
Pages
21
Please
cite
this
article
in
press
as:
Martinsen
K,
et
al.
Joining
of
dissimilar
materials.
CIRP
Annals
-
Manufacturing
Technology
(2015),
http://dx.doi.org/10.1016/j.cirp.2015.05.006

with
a
hollow
mandrel
head
accommodated
the
workpiece
material
that
was
displaced
by
the
rivet.
This
resulted
in
lower
insertion
forces
as
well
as
eliminated
flash
formation
at
the
rivet
exit
hole.
Min
et
al.
[155]
investigated
quality
issues
related
to
stack-up
order
in
Mg–Al
joints.
For
example
placing
the
relatively
brittle
AM60
cast
Mg
alloy
on
the
bottom
resulted
in
semi-brittle
fracture
on
the
backside
whereas
the
FSBR
exhibited
better
strength
versus
conventional
blind
riveting
only
when
the
more
ductile
Al
was
the
bottom
workpiece.
Zhang
et
al.
[292]
investigated
the
feasibility
of
FSBR
Mg–Steel
joints.
They
found
that
with
sufficiently
high
feeding
rates
even
the
DP600
material
could
be
pierced
at
2200
rpm,
though
their
process
development
was
focused
on
Mg
as
the
top
workpiece.
However,
in
subsequent
work
[291]
they
show
that
having
the
Mg
as
the
top
workpiece
resulted
in
the
softer
magnesium
being
extruded
downward
as
the
rivet
is
inserted.
This
then
pushes
against
the
steel
bottom
workpiece
resulting
in
a
considerable
gap
at
the
faying
interface.
With
the
steel
as
the
top
workpiece,
it
is
much
stiffer
and
does
not
extrude
downward
resulting
in
a
tighter
joint.
Lastly,
Min
et
al.
[156]
investigated
CFRP-Al
FSBR
joints
and
because
of
the
significant
differences
in
the
thermal-mechanical
properties
both
the
FSBR
process
and
lap-shear
strengths
of
the
CFRP–Al
joints
were
sensitive
to
stack-up
order.
The
relative
brittleness
of
the
CFRP
material
was
found
to
be
limiting
the
process
window
robustness.
2.1.5.
Self-piercing
riveting
(SPR)
Self-piercing
riveting
is
extensively
described
by
Mori
et
al.
[164],
and
is
not
covered
in
detail
in
this
paper.
In
a
SPR
process,
a
hollow
rivet
is
pierced
through
the
top
sheet
and
through
the
influence
of
a
counter
acting
die,
deformed
and
inserted
into
the
lower
sheet
(see
Fig.
8)
[93].
He
et
al.
[92]
provide
a
review
of
SPR
research.
Compared
to
the
more
traditional
methods
of
sheet
material
joining,
the
advantages
offered
by
SPR
include
the
ability
of
joining
dissimilar
materials
[25,34].
There
is
no
need
for
pre-
drilling
as
in
blind
riveting,
fast
cycle
time
and
ease
of
incorporating
SPR
within
the
predominant
Resistance
Spot
Welding
(RSW)
based
assembly
line
infrastructure.
SPR
joints
are
also
believed
to
have
good
mechanical
strength,
in
particular,
fatigue
strength
[108].
However,
SPR
also
has
several
limitations.
A
given
rivet
can
only
manage
a
limited
sheet
thickness
range,
and
it
requires
a
die
and
access
in
order
to
deform
the
rivet;
it
is
difficult
for
the
rivet
to
flare
inside
high
strength
materials.
Mori
et
al.
[165]
describes
a
case
of
plastic
joining
of
ultra
high
strength
steel
and
aluminium
alloy
sheets
using
SPR
[165].
The
rivet
is
specially
designed
for
the
task
using
FEM
modelling
to
overcome
the
potential
problems
from
the
differences
in
material
properties.
2.1.6.
Sewing
and
filament
winding
Joining
of
dissimilar
materials
by
applying
threads
or
fibres
in
processes
such
as
stitching,
sewing
and
winding
are
ancient
crafts
processes.
Sewing
is
still
the
main
way
to
join
fabrics,
leather
and
other
materials
for
clothing,
furniture,
bags
etc.
There
are
however
few
industrial
cases
of
automated
sewing,
typically
aided
by
special
purpose
customized
fixtures.
Automation
of
sewing
processes
has
been
investigated
by
some
authors:
Seliger
and
Stephan
[215],
Kudo
et
al.
[120],
Wittig
and
Rattay
[281],
Wittig
[280]
and
Kawauchi
[113].
The
problem
is
not
only
the
sewing
itself,
but
also
the
handling
of
materiel
into
and
out
of
the
sewing
process.
Wetterwald
et
al.
[278]
shows
an
example
of
flexible,
automated
sewing
of
leather
and
fibre
foam
with
automated
handling
without
pre-programmed
robot
paths
or
dedicated
fixtures
using
sensor
fusion
feedback
control.
Filament
winding
is
another
process
where
fibre
or
thread
can
be
used
for
joining
of
dissimilar
materials.
Fleischer
and
Schaedel
[75]
show
how
filament
winding
can
be
used
for
joining
CFRP
and
steel
components
for
automotive
space
frame
structures,
see
Fig.
9.
Similar
processes
have
been
patented,
for
example
to
join
composite
tubes
to
metallic
tubes
or
fittings:
US5288109
A
[20],
US
4549919
A
[19].
2.1.7.
Other
mechanical
joining
processes
Mori
et
al.
[164]
give
an
extensive
description
of
joining
by
forming
where
the
joining
workpieces
are
exposed
to
a
forming
process
which
creates
an
interlocking
grip.
Joining
by
forming
can
be
through
hydroforming,
roll
forming,
electromagnetic
forming,
hemming,
seaming
and
staking.
Explosion
joining
can
be
a
low-
cost
simple
solution
for
possible
challenging
tasks
such
as
joining
of
power
lines
in
the
field
far
from
any
other
energy
sources.
Mechanical
joining
by
plastic
deformation
can
provide
stronger
joints
than
attained
by
conventional
mechanical
fastening
processes.
Another
joining
process
described
by
Mori
et
al.
[164]
is
interference
fit
or
friction
fit,
where
joining
forces
are
created
through
two
(or
more)
parts
pressed
together.
These
processes
can
be
used
for
dissimilar
material
joining,
but
problems
such
as
creep
or
galvanic
corrosion
must
be
avoided.
2.2.
Chemical
joining
processes:
Adhesion
The
word
adhesion
is
derived
from
the
Latin
words
for
to
stick
(ad
=
to,
hesion
=
stick)
[263]
and
adhesive
bonding
has
a
strong
position
in
modern
manufacturing
applications
[24].
There
exist
several
theoretical
mechanisms
of
adhesion:
(i)
Adsorption
theory,
(ii)
Chemical
bonding,
(iii)
Diffusion
theory,
(iv)
Electrostatic
attraction,
(v)
Mechanical
interlocking
and
(vi)
Weak
boundary
layer
theory.
None
of
the
theories
are
capable
of
providing
a
comprehensive
explanation
for
all
types
of
adhesive
interaction
and
joints
[23].
Specific
surfaces,
various
mechanisms
and/or
their
combinations
may
be
engaged
in
the
bonding
process.
Bond
formation
results
in
a
contact
zone
(intermediary
zone)
created
between
the
adherent
and
adhesive
[284].
Adhesive
should
completely
wet
the
bonding
area,
but
material
surfaces
will
be
irregular
and
voids
may
occur.
The
adhesive
composition
and
the
contact
zone
determine
the
bond
characteristics,
viscosity
of
adhesive
and
surface
energy
of
the
substrate
[284].
There
are
several
factors
defining
the
adhesive
bond
perfor-
mance
(lifetime,
robustness,
etc.)
[224],
these
factors
are:
(i)
Physical
and
chemical
properties
of
adhesives,
(ii)
nature
of
adherents
(which
materials
are
to
be
joined),
(iii)
type
of
bonding
surface
pre-treatment
(preparation),
(iv)
surface
wettability
and
(v)
joint
design
(appropriate
adhesive
choice).
Joint
design
plays
a
crucial
role
in
adhesive
and
curing
method
choice.
Moreover
the
preparation
of
the
adherent
surface
is
important
to
joint
quality
[261].
Wu
and
Lu
[282]
describe
how
a
low
surface
energy
leads
to
the
appearance
of
weak
adhesion
between
polymers
and
metals.
One
of
the
main
objectives
of
joint
design
is
to
consider
the
stress
distribution(s):
tensile,
compression,
shear,
cleavage,
peel
and
their
combinations
(see
Figs.
10
and
11).
Lap
joint
design
with
Fig.
8.
A
self-piercing
process
[108].
Fig.
9.
Filament
winding
of
automotive
space
frames
[75].
K.
Martinsen
et
al.
/
CIRP
Annals
-
Manufacturing
Technology
xxx
(2015)
xxx–xxx
4
G
Model
CIRP-1404;
No.
of
Pages
21
Please
cite
this
article
in
press
as:
Martinsen
K,
et
al.
Joining
of
dissimilar
materials.
CIRP
Annals
-
Manufacturing
Technology
(2015),
http://dx.doi.org/10.1016/j.cirp.2015.05.006

predominately
shear
stress
is
considered
to
have
more
advantages
compared
to
other
designs
[184].
Adhesive
bonding
provides
possibilities
to
join
materials
such
as
plastics,
metals,
rubbers,
and
glass
[288].
Adhesives
have
become
widely
used
in
different
industry
sectors,
especially
in
electronics
[286].
For
example,
adhesive
bonding
is
used
in
the
fibre
to
glass
ferrule
attachment
in
fibre
optics
manufacturing
[284].
Each
type
of
adhesive
provides
a
unique
set
of
performance
and
processing
opportunities
[224].
Adhesives
are
chosen
by
param-
eters
such
as:
Performance,
Processing
conditions,
Materials
to
be
joined,
Curing
type
and
application
type.
Curing
is
the
(adhesive)
transformation
from
liquid
to
solid
state
(polymerization)
which
is
usually
accompanied
by
physical
and
chemical
changes
[2].
Curing
is
typically
induced
by
heat,
electromagnetic
curing
(light,
EM
field
etc.)
and
dual
curing.
Each
adhesive
is
selected
according
to
its
advantages
and
disadvantages
derived
from
mechanical
and
chemical
properties.
Advantages
of
adhesive
bonding
are:
(i)
creation
of
a
continuous
bond,
(ii)
corrosion
prevention
(sealed
joint),
(iii)
stress
distribu-
tion
over
a
joint
area,
(iv)
vibration
reduction,
(v)
invisibility
of
joints
within
assembly,
(vi)
minimization
of
an
assembly
mass,
(vii)
no
substrate
deformation
and
(vii)
minimizations
of
components
in
an
assembly
(Niagu
et
al.
[179];
Small
and
Courtney
[224];
Yacobi
et
al.
[284]).
Limitations
to
the
adhesive
joining
methods
are:
(i)
adhesive
joints
are
difficult
to
disassemble,
(ii)
surface
preparation
requirements
(strength
of
the
bond
requires
special
condition
of
adherent’s
surface),
(iii)
extra
time
needed
for
polymerization,
(iv)
limited
thermal
resistance,
and
(v)
bond
attenuation
from
atmospheric
agents,
degradation
and
chemical
agents.
Typical
causes
of
joint
failures
are
poor
design,
unprepared
surface,
improper
adhesive
selection
for
the
substrate
or
difficult
operating
environment
conditions
[224].
2.3.
Thermal
fusion
joining
processes
2.3.1.
Electric
arc
welding
The
most
common
process
for
fusion
joining
is
electric
arc
welding,
for
example
Gas
Tungsten
Arc
Welding
(GTAW),
Shielded
metal
arc
welding
(SMAW)
and
Gas
metal
arc
welding
(GMAW).
These
methods
can
be
can
be
used
for
‘‘easier’’
dissimilar
metals
joining,
such
as
carbon
steel
to
stainless
steel.
The
challenge
is
the
relative
larger
size
of
the
Heat
Affected
Zone
(HAZ)
and
the
molten
pool
compared
to
the
other
methods
described
in
this
paper,
which
could
lead
to
a
large
zone
of
brittle
Intermetallic
Compounds
(IMC)
when
welding
dissimilar
metals.
The
selection
of
filler
material
is
critical
for
the
quality
of
the
dissimilar
welds.
Mittal
and
Sidhu
[162],
Chen
et
al.
[53],
and
Liu
et
al.
[136]
studied
the
microstructure
of
Ti–Al
GTAW
and
the
formation
of
IMC.
Bahrami
et
al.
[21]
studied
the
mixing
of
two
dissimilar
metals
in
the
GTAW
pool,
both
numerically
and
by
experiments.
Show
how
the
application
of
Activating
Fluxes
can
enhance
the
GTAW
penetration.
2.3.2.
Plasma
sintering
Sintering
goes
back
to
the
remote
past
and
the
process
for
forming
bricks
[170].
As
a
science
it
appeared
in
the
1920–1930s
[245].
Metallic
powders
were
sintered
(sinter
joining)
in
1933
[241].
In
the
1950s
Lockheed
Missile
Company
developed
‘spark
sintering’
with
the
use
of
electrical
discharge
[170].
This
has
evolved
into
‘Spark
Plasma
Sintering’
process
(SPS)
[230,299].
The
physics
of
the
process
are
not
yet
fully
understood
however,
and
the
existence
of
plasma
in
the
sintering
process
has
been
questioned
[103].
SPS
has
thus
by
some
been
renamed
pulsed
electric
current
sintering
(PECS)
[29].
SPS
is
considered
to
be
an
effective
method
for
consolidating
different
types
of
materials
[65,104].
The
method
provides
rapid
sintering
by
self-heating
[225].
Intermetallic
compounds
(IMC),
metal
and
ceramic
matrix
composites,
nanostructured
materials,
amorphous
materials,
highly
refractory
metals
and
ceramics
can
all
be
processed
using
SPS
(see
Table
1).
This
process
provides
several
advantages
including
sintering
of
materials
like
tungsten
carbide
[183],
high
sintering
speed,
low
power
consumption,
reasonable
performance,
safety
and
reliability
[65,139,158].
SPS
is
a
viable
method
for
joining
dissimilar
materials
in
a
high
temperature
range
and
for
joining
ceramic
matrix
composites
[48,86,143].
Successful
joining
of
silicon
carbide
and
graphite
at
2000
8C
with
a
resulting
tensile
strength
of
18
MPa
has
been
reported
[182].
No
cracks
or
delamination
where
identified
in
the
samples.
Liu
et
al.
shows
how
SPS
can
be
utilized
for
joining
dissimilar
(nanocrystaline)
sintered
materials
such
as
Ni
3
Al
and
TiC/Ni
3
Al
[139].
SPS
has
shown
to
be
an
effective
approach
for
joining
of
CVD–SiC
coated
C/SiC
composites,
directly
and
with
glass–ceramic
(CA),
a
SiC
+
5
wt%
B
4
C
mixture
and
pure
Ti
foils
as
joining
materials
[198].
Furthermore
have
SPS
been
used
for
Ti
to
Steel
joining,
without
the
brittle
Fe–Ti
intermetallic
compounds
(IMC)
and
shape
distortion
of
parent
materials
[157].
A
joint
of
Ti–
6Al–4V
to
low
alloy
steel
made
at
950
8C
was
reported
to
have
a
maximum
tensile
strength
of
250
MPa
[158].
2.3.3.
High
energy
beam
welding
Laser
beam
and
electron
beam
welding
are
high-energy
beam
welding
methods,
where
the
energy
density
is
typically
10
10
to
10
13
W/m
2
.
There
are
generally
two
different
welding
modes:
(i)
melt-in/conduction
mode
or
(ii)
keyhole
mode.
The
conduction
Fig.
10.
Stresses
in
adhesive
joints
[284].
Fig.
11.
Selected
types
of
adhesive
joint
design
[284].
Table
1
Materials
obtained
using
SPS
[57].
Groups
Materials
Metals
Fe,
Cu,
Al,
Au,
Ag,
Ni,
Cr,
Mo,
Sn,
Ti,
W,
Be,
Ir
Alloys
W–Ni–Fe,
W–Cu,
Cu–25Cr,
Ni–49Ti,
Fe–5Mn,
Ti–6Al–4V,
Ti–Al–B,
Al–Si–Cu–Fe
Ceramics
Oxides:
Al
2
O
3
,
Y
2
O
3
,
ZrO
2
,
SiO
2
,
TiO
2
,
HfO
2
,
MgO,
ZnO,
SnO
2
Carbides:
SiC,
B
4
C,
TaC,
TiC,
WC,
ZrC,
VC
Nitrides:
Si
3
N
4
,
TaN,
TiN,
AlN,
ZrN,
VN,
CN
x
Borides:
TiB
2
,
HfB
2
,
LaB
6
,
ZrB
2
,
VB
2
,
MgB
2
Cermets
and
composites
Si
3
N
4

SiC,
BN
+
Fe,
Ti
+
TiB
+
TiB
2
,
YSZ,
(Na
1x
K
x
)NbO
3
+
PbTiO
3
,
Al
2
O
3
+
Ni,
Al
2
O
3
+
TiC,
Al
2
O
3
+
SUS,
Al
2
O
3
+
Nd
2
Ti
2
O
7
,
Al
2
O
3
+
SiC,
Al
2
O
3
+
GdAlO3,
Al
2
O
3
+
Ti
3
SiC
2
,
Al
2
O
3
+
C,
ZrO
2
+
Ni,
ZrO
2
+
SUS,
ZrO
2
+
Y
2
O
3
,
ZrO
2
+
Al
2
O
3
+
TiC
0.5
N
0.5
,
WC/Co

VC,
WC/Co
+
Fe
Intermetalids
TiAl,
NiAl,
NbCo,
NbAl,
Sm
2
Co
17
,
Nd–Fe–B,
(Bi,Sb)
2
Te
3
,
Al–Al
3
TiSiC
+
AlN
Other
Organic
materials
(polyimide,
etc.)
K.
Martinsen
et
al.
/
CIRP
Annals
-
Manufacturing
Technology
xxx
(2015)
xxx–xxx
5
G
Model
CIRP-1404;
No.
of
Pages
21
Please
cite
this
article
in
press
as:
Martinsen
K,
et
al.
Joining
of
dissimilar
materials.
CIRP
Annals
-
Manufacturing
Technology
(2015),
http://dx.doi.org/10.1016/j.cirp.2015.05.006

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