Page 116 - SSAB Welding Handbook Edition 2

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19.0 Stud arc welding Welding handbook

19.9 Post-weld heat treatments
If hydrogen cracks still occur after the post-weld
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Post-weld heat treatment is an alternative to heat treatment, new studs are welded and kept for
preheating procedures to minimize the risk for gradually longer periods of time at the maximum
hydrogen cracks. The main advantage of a post-weld temperature until no cracks occur.
heat treatment is that, in many cases, it facilitates
higher productivity compared to preheating.
19.10 Evaluation of properties in
If post-weld heat treatment is carried out, a
feasible procedure is to: stud welds
4 Heat the stud directly after welding It is good practice to evaluate the properties in stud
4 When heating, make sure that the stud is heated welds prior to manufacturing to find a procedure
almost completely to an orange color, see fig. 19.7. that fulfils the criteria for the joint.
The stud is kept at the maximum temperature of
approximately 15-20 s. When assessments are made for stud welds, the
evaluation methods are mostly associated with
4 Make sure that the temperature in the parent metal
does not exceed the stated temperatures in table visual examination of the weld quality, resistance to
19.2 during welding. hydrogen cracks and measurements of the mechanical
properties in the joint.

A geometrically sound weldment and examples of
different discontinuities that can be observed
visually are shown in fig. 19.8.

It is feasible to evaluate the static strength,
bendability, torque resistance, hardness of stud
welds and resistance to hydrogen cracks. During
production, a suitable measure is to check the
properties in the stud welds continuously. Visual
control, for example, can be made of all
stud welds.

Fig. 19.7: Post-weld heat treatment.

A B C D E
Fig. 19.8: Joints with and without visual discontinuities. A) A correct joint B) Insufficient lift at arc striking or insufficient grounding conditions
C) Unsuitable torch angle D) Heat effect too low during welding E) Heat effect too high during welding

116 This handbook contains general suggestions and information without any expressed or implied warranty of any kind. SSAB hereby expressly disclaims
all liability of any kind, including any damages, in connection with the use of the information and for their suitability for individual applications.
It is the responsibility of the user of this brochure to adapt the recommendations contained therein to the requirements of individual applications.