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Y. Shi et al.
(a)
(b)
(c)
(d)
Fig. 10.47 Microstructure. a Transverse cross section b BM, c HAZ, d WM [45]
alloy K-TIG welded joint. Figure 10.47b–d displays the band contrast images of the
TC4 titanium alloy K-TIG welded joint. The microstructure of the BM is consists of
equiaxed primary α grains, α laths and few retained β grains, as shown in Fig. 10.47b.
In Fig. 10.47c, the morphology of α phase in the HAZ has obviously changed. Under
high temperature conditions, the α grains grow significantly. Because the temperature
in the HAZ is higher than the β transus temperature (995 °C), there are a large number
of α laths in the HAZ. The α laths are distributed in parallel and unidirectional form.
The residence time of the WM at high temperature is relatively long, and the grains
of WM grow rapidly. A large number of α laths are formed in the WM. The α laths in
the WM mainly exist in multi-directional form, with scattered distribution, as shown
in Fig. 10.47d.
The EDS spectra show the contents of Al, V and Ti in the BM and WM, as shown
in Fig. 10.48. Compared with the BM, it was found that the elements such as Al,
V and Ti in the WM did not change significantly. The test results proved that the
chemical compositions of the BM and the WM are almost the same.
Y. Shi et al.
(a)
(b)
(c)
(d)
Fig. 10.47 Microstructure. a Transverse cross section b BM, c HAZ, d WM [45]
alloy K-TIG welded joint. Figure 10.47b–d displays the band contrast images of the
TC4 titanium alloy K-TIG welded joint. The microstructure of the BM is consists of
equiaxed primary α grains, α laths and few retained β grains, as shown in Fig. 10.47b.
In Fig. 10.47c, the morphology of α phase in the HAZ has obviously changed. Under
high temperature conditions, the α grains grow significantly. Because the temperature
in the HAZ is higher than the β transus temperature (995 °C), there are a large number
of α laths in the HAZ. The α laths are distributed in parallel and unidirectional form.
The residence time of the WM at high temperature is relatively long, and the grains
of WM grow rapidly. A large number of α laths are formed in the WM. The α laths in
the WM mainly exist in multi-directional form, with scattered distribution, as shown
in Fig. 10.47d.
The EDS spectra show the contents of Al, V and Ti in the BM and WM, as shown
in Fig. 10.48. Compared with the BM, it was found that the elements such as Al,
V and Ti in the WM did not change significantly. The test results proved that the
chemical compositions of the BM and the WM are almost the same.