Page 38 - SSAB Welding Handbook Edition 2

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5.0 Properties of the heat-affected zone Welding handbook

5.4 Measures for additional Two different alternatives are:
improvements of the mechanical 1) Applying temper beads at the end of a welding
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properties in the HAZ performance. The microstructure at the location
with the peak hardness in the HAZ has a content
Welding with heat inputs that have more restrictions of martensite and /or bainite. A temper bead can
than the normal recommendations supports even anneal these microstructures and decrease the peak
higher toughness values in the HAZ. By adopting hardness. When applying this technique, the weld
an optimized heat input, with corresponding t sequences in the joint are arranged so that the
8/5
values in table 5.2, the typical minimum toughness temperbead is placed a short distance from the
in the HAZ can fulfill requirements of at least 40 J HAZ according to fig. 5.9. Pay attention to the
at -40ºC. Applying these values can further increase location of the temper bead. A temper bead placed
the static strength in the joint. too far from or too close to the HAZ might not
give the desired effect.
Steel grade Optimized t values**
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Strenx 700 5-10 s
Strenx 900 5-15 s
Strenx 960 5-15 s Hardness
Hardness
Strenx 1100 5-10 s Temper
Strenx 1300 5-10 s bead
L ≈L/4
** Valid for a typical min. impact toughness of 40 J at -40°C.

Table 5.2: Optimized t values.
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Hardness requirements for the HAZ are relatively
unusual for the Strenx grades. When they do
occur, it is usually for the Strenx 700 and Strenx Fig. 5.9: The application of a temper bead technique.
900 grades and they are normally related to the
maximum allowed hardness values in the HAZ.
This is usually done to minimize the risk of stress 2) A post-weld heat treatment in accordance with
corrosion cracking in the HAZ, which may be chapter 16 can reduce the maximum hardness
relevant to structures exposed to corrosive values in the joint.
environments. The requirements regarding
maximum hardness values in the HAZ can be
fulfilled in the vast majority of cases by following
the recommendations for suitable heat inputs for
the Hardox and Strenx grades.

There are additional techniques that can reduce the
peak hardness in the HAZ, if needed.

38 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.