Page 118 - SSAB Welding Handbook Edition 2

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20.0 Hardfacing Welding handbook

4 Erosion wear appears when smaller particles, like Hardfacing Buffer layer
sand, hit a surface at high velocity. Erosion wear
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can be considered as a type of impact wear.
4 Abrasive wear involves abrasive sliding wear,
which is characterized by a free flow of material
that grinds the wear surface, according to fig. 20.3.

Steel substrate

Fig. 20.4: A plate subjected to hardfacing.

20.1 Surface appearance of the steel

The steel surface should be cleaned before welding
the buffer layer. Contaminants on the surface such
as oil, grease, rust and water should be removed
Fig. 20.3: Abrasive wear.
with appropriate measures prior to welding.

4 There are also combinations of abrasion wear,
impact wear and erosion wear. Impact wear and 20.2 Characteristics of the
erosion wear are, in general terms, more buffer layer
aggressive compared to abrasive wear. The buffer layer provides a ductile weld metal
between the base metal and the hardfacing layer.
After the wear type is clarified, the hardfacing A ductile stainless austenitic consumable of type
procedure can be performed. A complete AWS 307 or AWS 309 is suitable. The buffer layer
hardfacing performance involves the following
steps: is normally welded with a thickness of one to two
passes.
4 Ensure that the steel surface being hardfaced
has been properly cleaned. The essential benefits of applying a buffer layer
4 Weld the buffer layer, apply preheating if required. are to:
4 Weld the hardfacing layer, apply preheating if 4 Achieve a more secure attachment between the steel
required. substrate and the hardfacing layer. This is especially
important when the structure is subjected to impact
The different weld layers of a hardfacing performance wear. Without the buffer layer, there is a greater risk
are illustrated in fig. 20.4. for spalling of the hardfacing layers from the steel
surface, according to fig. 20.5.
All types of conventional welding processes can be
used for both the buffer layer and the hardfacing
layer. The normal welding processes for both are
MMA welding, MAG welding and SAW.

Fig. 20.5: Spalling effect of a hardfacing layer.

118 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.