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You can also observe visual-optically such artificially formed relief
elements and defects, as:
Incomplete fusion (pos. 1) at joint edges;
curved scratches pos . 2 of 100-200 µm width well-
discernible with the naked eye;
However, visual-optical data do not help to establish the belonging
of the scratches pos. 2 to the paint film or the metal of the sample
surface .
In the results of magnetogram visualization of the given object
(Fig . 10 b) incomplete fusion (pos . 1) is observed at joint edges,
and their detailing degree is higher, than that of the optical image .
Obviously the curved scratches (pos. 2) belong to the paint film, so
long as they are absent in the results of the visualization of the object
magnetogram .
Moreover, visualization enabled to detect the overlap of electrode
metal pos . 3 and machining process paths pos . 4 not observed visual-
optically through the paint film layer.
The possibility to observe the structure and defects of joint welds
in the objects of aluminum alloys is an important control feature, as
it enables to examine e.g. the ways of VIN data alterations based on
welding technologies .
The following example (Fig 11) shows the probabilities of sensitivity
increase of magnetographing when investigating weak signals of
residual stress in ferromagnetic materials when applying different
power levels of the Fe-scanner (see paragraph 2 .3 for the power
levels) .
The manufacturing techniques of the test-object with
the examination results shown in Fig . 11 do not differ from those of
test-object №2 (Fe). The only difference is the material used. I.e.
the surface photo image of this test-object being similar to those
shown in Fig. 7a – is a polished surface with a completely removed
relief of the initial marking (cut with the superficial layer of the metal).
It should be noted that
high sensitivity level of magnetographing
enables to control efficiently metal internal tension only on flat
and smooth surfaces
. Otherwise, if the object surface is covered
with deep scratches, in consequence of this high sensitivity level of
magnetographing, the signal of these scratches will be amplified
manyfold in the record and as a result it will “camouflage” a useful
signal from internal stress .
