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1. Prepared by:
Mohamed ali mohamed naga
Mohamed mahmoud hassan el moqattaf
Mahmoud ezzat ali amer
Supervised by
DR/Mohamed A.Daha

2. •Use of bolted flanged pipe joints is very common in
petrochemical and nuclear industry.
•Engineering are increasingly faced with the need to
join dissimilar materials and Improving the ability to
join dissimilar materials with engineered properties
are enabling new approaches to light-weighting
automotive structures.

3. Residual stresses
 Heat from welding may cause localized expansion, which is taken up
during welding by either the molten metal or the placement of parts
being welded. When the finished weldment cools, some areas cool and
contract more than others, leaving residual stresses.
 Residual tensile stresses exist in the weld metal and the adjacent base
metal, while residual compressive stresses exist the areas farther away
from the weld metal.

5. Why FEM ??
 During welding a very complex thermal cycle is applied to the
weldment which in-turn causes irreversible elasto-plastic
deformations and consequently gives rise to the residual stresses
in and around fusion zone and heat affected zone (HAZ).
 The stress/strain development during the welding is complex to
visualize, since it is a three dimensional time and temperature
dependent problem.
 Although, the experimental investigations provide valuable
insights into the process of arc welding, many experimental
techniques are complex and expensive and some quantities, such
as the transient stress/strain development during welding,
cannot be measured at all.
 Furthermore, traditional trial and error approach based on costly
and time consuming welding experiments encounters hindrance
to sound welds due to welding process parameters optimization.

6. Pipe-Flange
 Pipe-flanges are protruding rims, edges, ribs, or collars
used to make a connection between two pipes or between a
pipe and any type of fitting or equipment component.
 Flanges are relatively simple mechanical connectors that
have been used successfully for high-pressure piping
applications. They are well understood, reliable, cost-
effective, and readily available. In addition, the moment-
carrying capacity of flanges is significant compared to
other mechanical connectors.

7. 

8. Pipe Flange Material
• Carbon steel: is steel alloyed primarily with carbon. It
has a high hardness and strength which increases with
carbon content, but lowers ductility and melting point.
• Stainless steel: is steel alloyed with chromium in
amounts above 10%. Chromium enables stainless steel to
have a much higher corrosion resistance than carbon steel,
which rusts readily from air and moisture exposure. This
makes stainless steel better suited for corrosive
applications that also require high strength.

9. • Aluminum: is a malleable, ductile, low density metal
with medium strength. It has better corrosion resistance
than typical carbon and alloy steels. It is most useful in
constructing flanges requiring both strength and low
weight.
• Brass: is an alloy of copper and zinc, often with
additional elements such as lead or tin. It is
characterized by good strength, excellent high
temperature ductility, reasonable cold ductility, good
conductivity, excellent corrosion resistance, and good
bearing properties.

10. Dissimilar Metal Joining
 Dissimilar metal welding has become a critical
technology in many areas, to utilize hybrid structures
and reduce the cost and weight of components. There
are many applications in which weldments are made
from metals of different compositions. The same is
true of a mechanical wear problem, a high-
temperature situation, or other conditions in which
different properties are required from different parts of
the same weldment.

11. Dissimilar materials classification
 Slightly dissimilar
• Essentially the same material but with slightly different
composition
• Often different steels to each other or different series Al alloy
(EX. Stainless steel 304l to stainless steel 316)
• Dissimilar
•Same type of material to each other (e.g. metal to meta)
(EX. Aluminium to steel OR copper to steel)
• Highly dissimilar
different material types (EX. metal to ceramic or metal to organic)

12. Issues:
 Welding dissimilar metals often introduces new difficulties
to welding as Wide different physical characteristics of :
• Melting temperature.
• Vapourisation temperature.
• Coefficient of thermal expansion.
• Thermal diffusivity.

13. Joining processes of Dissimilar
materials
 Fusion arc welding processes: gas tungsten arc
welding (GTAW or TIG), gas metal arc welding
(GMAW).
 Other fusion welding processes: laser welding,
resistance spot and projection welding.
 Solid-state joining processes: friction stir welding,
friction and inertia welding.
 Brazing: is a metal-joining process in which two or
more metal items are joined together by melting and
flowing a filler metal into the joint, the filler metal
having a lower melting point than the adjoining metal.

14. GMAW
 In the GMAW process, an arc is established between a
continuous wire electrode (which is always being
consumed) and the base metal. Under the correct
conditions, the wire is fed at a constant rate to the arc,
matching the rate at which the arc melts it.

15. Joint Design

16. Study objective
 Develop a 3D finite element model (FEM) to estimate the
weld pool geometry and to analyze the temperature field in
GMAW process of a dissimilar metals pipe-flange joint.
 Investigate the effect of welding heat input on the weld
pool geometry and size of a dissimilar metals pipe-flange
joint.
 Investigate the suitable welding parameters for each two
dissimilar metals.
 Determine which two metals are the most preferred to be
welded together.

17. Proposed finite element modeling
 The 3D FE model of pipe flange.

18. •joint contains a total of 50105 nodes. element
type DC3D8.

19. •Higher temperature and flux gradients are
expected in and around the FZ and HAZ
therefore, a relatively fine mesh is used within
a distance of 10 mm on both sides of the weld
centre line .

20. Material Modeling
 The temperature dependent thermo properties such as
conductivity, specific heat and density are used for
thermal analysis.
 And other required properties such as liquidus
temperature, solidus temperature and latent heat.
 Materials used :
 low carbon steel.
304l Stainless steel.
316 Stainless steel.
Duplex steel.

21. Low Carbon Steel
•The latent heat is 247000 K. the solidus
and liquidus temperature (1738 & 1817 K)
respectively.

22. Heat source modeling
• Goldak et al. proposed a model with a double ellipsoidal
moving heat source configuration to incorporate this
volume heating and the size and shape of the heat source
can be easily changed to model both the shallow and deep
penetrating welding processes. In addition, it has the
versatility and flexibility to handle dissimilar metal
joining. The power density distribution of the front and
rear half is

23. Goldak equation parameteters

24. Heat source moving
 To apply the load expressed in the Equation, the FEM
package ABAQUS requires a user subroutine to program.
The user subroutine DFLUX helps define a non-uniform
distributed heat flux as a function of position, time,
temperature, element number, integration point number,
etc.
 During the heat transfer or mass diffusion analysis, DFLUX
will be called at each flux element-based or surface-based
(heat transfer only) integration point to create a non-
uniform heat flux distribution.

25. User subrotine
SUBROUTINE DFLUX(FLUX,SOL,KSTEP,KINC,TIME,NOEL,NPT,COORDS,JLTYP,
1TEMP,PRESS,SNAME)
!
INCLUDE 'ABA_PARAM.INC'
!
DIMENSION FLUX(2), TIME(2), COORDS(3)
CHARACTER*80 SNAME
!-----------------------------------------------------------------------------
FLUX1=FLUX(1)
IF (KSTEP.GT.11) GO TO 10
!-----------------------------------------------------------------------------
q= 0.85*225*22
V= 0.00625
c1= 0.0103
c2= 0.0129
a= 0.01
b= 0.003
pi= 3.14159
f1= 0.6
f2= 1.4
OMEGA= 0.107
rc= 0.0584
angle= OMEGA*time(2)

26. • C A0 = initial angular position
• C A0 = ATAN2(y,x)
• C OMEGA = Constant angular speed, 0.3433 radian per second
• !-----------------------------------------------------------------------------
• CX= -0.0584+rc*(1-cos(angle))
• CY= 0.028345
• CZ= 0-rc*Sin(angle)
• !-----------------------------------------------------------------------------
• DX = COORDS(1)-CX
• DY = COORDS(2)-CY
• DZ = COORDS(3)-CZ
• !-----------------------------------------------------------------------------
• IF ((COORDS(3).GE. CZ))THEN
• d1=Exp(-3*((DX)**2/(a)**2+(DY)**2/(b)**2+(DZ)**2/(c1)** 2))
• FLUX1=6*1.85*q*d1*f1/(pi*(a*b*c1)*Sqrt(pi))
• ELSE IF ((COORDS(3).LE. CZ)) THEN
• d2=Exp(-3*((DX)**2/(a)**2+(DY)**2/(b)**2+(DZ)**2/(c2)** 2))
• FLUX1=6*1.85*q*d2*f2/(pi*(a*b*c2)*Sqrt(pi))
• ENDIF
• !-----------------------------------------------------------------------------
• IF(FLUX1 .LE. 0.0) THEN
• FLUX1 = 0.0
• ENDIF
• !-----------------------------------------------------------------------------
• 10 FLUX(1)=FLUX1
• FLUX(2)=0.0
• !-----------------------------------------------------------------------------
• RETURN
• END

27. Modeling of heat losses
 During welding, a considerable amount of heat is lost
through the cylinder surfaces by means of convection
(natural) and radiation. To model heat transfer through the
external boundaries of a finite element model, surface or
skin elements are typically used. With these elements, heat
convection and radiation can be modeled.

30. Results of similar metal welding
(low carbon steel)
At V=22 v and I=225 amp At V=18 and I=225 amp
bon steel

31. Results of similar metal welding
(low carbon steel)
At I=225 amp and V=22v At I=200 amp and V=22v

32. Results of dissimilar metal welding
(Pipe ss316-Flange ss304l)
At V=22v , I=225amp and
v=6.25mm/min
At V=25v , I=150amp and
v=6.25mm/min

33. Pipe ss316-Flange ss304l
At V=22v , I=200amp and
v=6.25mm/min
At V=22v , I=225amp and
v=6.05mm/min

34. Pipe ss316-Flange low carbon steel
At V=22v , I=225amp and
v=6.25mm/min
At V=22v , I=225amp and
v=6.05mm/min

35. Pipe ss316-Flange low carbon steel
At V=25v , I=150amp and
v=6.25mm/min
At V=22v , I=200amp and
v=6.25mm/min

36. Pipe low carbon steel-Flange ss304l
At V=22v , I=225amp and
v=6.25mm/min
At V=22v , I=225amp and
v=6.05mm/min

37. Pipe low carbon steel-Flange ss304l
At V=25v , I=150amp and
v=6.25mm/min
At V=22v , I=200amp and
v=6.25mm/min

38. Pipe ss316-Flange Duplex steel
At V=22v , I=225amp and
v=6.25mm/min
At V=22v , I=225amp and
v=6.05mm/min

39. Pipe ss316-Flange Duplex steel
At V=22v , I=200amp and
v=6.25mm/min
At V=25v , I=150amp and
v=6.25mm/min

40. Pipe low carbon steel-Flange duplex
steel
At V=22v , I=225amp and
v=6.25mm/min
At V=25v , I=150amp and
v=6.25mm/min

41. Pipe low carbon steel-Flange duplex
steel
At V=22v , I=200amp and
v=6.25mm/min
At V=22v , I=225amp and
v=6.05mm/min

42. Pipe duplex steel-Flange ss304l
At V=22v , I=225amp and
v=6.25mm/min
At V=22v , I=200amp and
v=6.25mm/min

43. Pipe duplex steel-Flange ss304l
At V=22v , I=225amp and
v=6.05mm/min
At V=25v , I=150amp and
v=6.25mm/min

44. Conclusion
 increasing the heat input provides a wider weld bead
and more fusion of materials in the lateral direction.
 Materials like stainless steel 304l and 316 are slightly
dissimilar and show the same weld bead at different
welding parameters.
 Duplex stainless steel has better weldability than other
materials used in this study as it always show the wider
weld bead and more fusion of material in lateral
direction.
 Decreasing the welding speed cause wider weld bead
and allow more material fusion.