Page 120 - SSAB Welding Handbook Edition 2

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20.0 Hardfacing Welding handbook

20.4 Preheat temperatures 20.5 Levels of heat input
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The necessary preheat temperatures of the buffer The recommended heat input for the Hardox and
layer and the hardfacing layer are influenced by Strenx grades when welding the buffer layer and the
the required preheat temperatures of both the base hardfacing layer is the same as for other welding
metal and the consumables. procedures, see chapter 5. If the consumables have
separate recommendations in this respect, this should
Determine the required preheat temperature for be accounted for when determining the applied heat
both the base metal and the consumable for each input. Employ a heat input that fulfils the requirements
welding procedure included in the hardfacing for both the parent metal and the potential requirements
performance. Apply a preheat temperature that for the specific consumable.
fulfils the demands for both. Minimum and
maximum preheat temperatures for Hardox and
Strenx grades are the same as for conventional types 20.6 Recommendations regarding
of welding, see chapter 4. The single plate thickness other welding parameters
in this situation is the plate thickness, Welding parameters related to a specific welding
according to fig. 20.7.
method, shielding gas for example, are selected and
applied in the same manner as for other kinds of
welding operations with the Hardox and Strenx
grades.
A

Steel substrate A = Single plate thickness 20.7 Crack phenomena during
hardfacing
Fig. 20.7: Single plate thickness for hardfacing.
Cracks can form in the area of the hardfacing.
The two most relevant types of cracks related to
This means that preheating is not required before hardfacing of high strength steels are described in
welding the buffer layer for all of the Hardox and this context. The first, and most common, type is a
Strenx grades, except for Hardox 600 and Hardox relief crack, which can occur in the hardfacing layer.
Extreme. These grades require both preheating and The other type is an under-bead crack, that can
stainless consumables of type AWS 307 or AWS 309. form in the parent metal.

120 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.