Many indications were obtained in places where defects were
not found by means of the RT method. The reasons for this were
partly explained in the introduction to this paper. The indication
in the method of the MMM testing, i.e. the stress concentration
zone, canbearesult ofanon-uniform distribution ofstresses due
to postweld thermal deformations [7,10]. In the search for
volumetric geometrical defects oftheweld seam such indications
are erroneous. But the information is very valuable if an assess-
ment of the quality of postweld thermal treatment of the weld
seam was to be made. A comparison of the magnetic images of
the weld seam before and after thermal treatment can be the
basis for the assessment of its efficiency. Another reason for
obtaining phantom indications is the factthatneither the facenor
the back of the weld seam forms a uniform smooth surface. The
irregularities occurring in them, and affecting the sensor lift-off,