During the upset, the coarse-grain area is pressed out into preexternal
reinforcement and flash and the welded joint is formed
at the expense of the fine-grain area.
4.2. Results of radiography test
The quality of the MIAB welded specimen (20th trial of Table 4)
is assessed using non-destructive testing. Radiography using X-ray
is employed to identify and analyze the defects at the MIAB welded
joint. Initially the test is carried out on the MIAB welded specimen
in the presence of the reinforcement. From the test results it is
observed that there are several pores at the weld joint as shown in
Fig. 6.
Fig. 6. X-ray film indicating the presence of pores at the joint (with reinforcement).
Subsequently, the MIAB welded specimen 3 (parameters as per
trial 20 of Table 4) is subjected to radiography test. However, for
this test, the reinforcement is removed by grinding. Further, the
grinded weld area is cleaned before the radigraphy test. The result
from this test showed that considerable number of pores still exist
as shown in Fig. 7. However, there is a reduction in the number of
pores in the weld region. This indicates that the pores are highly
concentrated mainly on the reinforcement of the weld region and
not much concentarted in actual weld line along the thickness of
butt surfaces.
Secondly, the SA213A T11 tubes are grinded, then buffing is performed
and the butt surfaces are cleaned to remove the impurities.