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Welding handbook 18.0 Non destructive evaluations

18.0 Non-destructive evaluations
©SSAB

A non-destructive evaluation (NDE) of the joint By employing an ultrasonic examination of the
and its surroundings is a way to find potential welded joint, an inspection of potential embedded
discontinuities that have occurred due to welding. discontinuities can be performed for fully
Several types of methods for non-destructive penetrated joints. Linear, rounded and elongated
evaluations exist and this chapter focuses on discontinuities can be detected with this method.
describing those most relevant to the Strenx and
Hardox grades. These methods are visual testing, Very small discontinuities can be detected with
magnetic particle testing, penetrant testing and non-destructive evaluations. However, the
ultrasonic testing. A basis for their application is minimum size of a detectable discontinuity
that the properties of the welded structure are not depends on factors such as:
impaired by the examination. 4 The shape of the discontinuity
4 Characteristics of the individual NDE method
It is recommended to conduct a non-destructive
evaluation of the joint with more than one 4 How carefully the evaluation is carried out
method since each method is suitable for detection 4 The surface conditions of the inspected area
of certain types of discontinuities. A basic 4 The thickness of the plates that are included in
recommendation is always to at least carry out the joint during ultrasonic testing
visual testing.
Therefore, it is essential that the NDE testing is
Either magnetic particle testing or penetrant carried out in a manner, normally performed
testing can be applied to find discontinuities that according to specified regulations, that facilitates
are surface breaking. These methods can detect the detection of discontinuities that cannot be
discontinuities of various shapes, especially linear accepted in the structure. For proper testing, it is
discontinuities such as cracks and lack of fusion. essential that each NDE method is performed using
However, shallow discontinuities covering a trained personnel.
relatively large area, such as undercuts and spatter,
can be more difficult to identify. During magnetic In the following context, the capabilities for the
particle testing, the joint is magnetized. This test mentioned NDE methods are further described.
can be performed on joints welded with unalloyed
and low-alloyed consumables but it is not appropriate
for joints welded with stainless austenitic consumables
since they produce a weld metal that may not be
ferromagnetic. Penetrant testing does not have any
formal restrictions regarding the type of joint or the
welding conditions.

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all liability of any kind, including any damages, in connection with the use of the information and for their suitability for individual applications. 103
It is the responsibility of the user of this brochure to adapt the recommendations contained therein to the requirements of individual applications.