Low heat input, less spatter and low deformation after welding are some of the
advantages of joining titanium alloys using CMT welding. However, few systematic
studies about the effects of welding parameters on joint formation and microstructure
characteristics have been conducted. In this paper, a numerical model for CMT based
on time interval loading and double ellipsoid volume heat flow distribution
is established by using APDL language in ANSYS software. The effects
of wire feed speed and welding speed on the temperature field, stress field
and deformation cloud distribution characteristics of CMT welding for TC4
titanium alloy are studied. The numerical simulation results in a high degree of
coincidence with the experimental weld, with an average error of no more than
7%. At the same time, the influence of wire feed speed and welding speed
on the surface formation and microstructure of the weld is experimentally
studied in this paper. The results of numerical simulation show that with the
increase of wire feed speed, the area of high temperature zone of the joint
enlarges. The peak temperature at the arc closing position changes from
2858
C to
4182
C.
As the welding speed increases, the area of high temperature zone of the joint
shrinks. The peak temperature at the arc closing position decreases from
4722
C to
2133
C.
When the wire feed speed is 5.5 m/min and the welding speed is 0.45 m/min, the
maximum von Mises residual stress on the upper surface is relatively small, 730 MPa,
and the maximum deformation is relatively small, 0.869 mm. The experiment results
show that with the increase of the wire feed speed, the melt width on the front side
gradually increases and the formation of the back side gradually changes from
discontinuous to continuous and uniform. The average grain size in the weld increases from
10.0
m
to 16.7
m.
With the increase of welding speed, the melt width on the front side gradually
decreases and the formation of the back side gradually changes from continuous and
uniform to discontinuous. The average grain size in the weld decreases from
14.3
m to
9.1
m.
Keywords
TC4 titanium alloy, CMT welding, finite element simulation,
microstructure