Submerged Arc Welding Technical Handbook - Esab

OK Grain 21.85 - Metal powder
addition for high deposition
Typical chemical composition
Grain size: 0.075 - 0.71mm
Density: 3.1 kg/dm 3
C Si Mn P S
0.15% 0.40% 1.70% 0.010% 0.010%
OK Grain 21.85 is a non-alloyed
metal powder which is added to the
SAW process in order to increase
the deposition rate.
The powder is melted by the
heat of the arc. Either the powder
is fed in front of the arc (option a)
or it is transported by magnetic
force, into the arc, along with the
wire(option b).
It is added to various flux -
wire combinations, of which OK
Welding wire
Power
source
Wire feed unit
Flux fill
Base material
Flux hopper
Metal powder
hopper
Metal powder
feeder
Option b
Option a
Welding direction
Flux 10.62/OK Autrod 12.32 is the most
common.
The penetration is reduced, because
part of the heat is utilised to melt
the powder. The process requires all
parameters, including the metal powder
feeding rate on the additional equipment, to
be carefully controlled.
The powder feeding rate is regulated by
the use of a potentiometer which controls
the speed of the bucket wheel and the gap
between the tube and the bucket wheel.
A skilled welding machine operator
is needed who is capable of steering the
additional powder feed unit. Deposition rate
increases up to 100% can be achieved.
Submerged arc welding with metal
powder addition remains a special process,
but with tempting productivity benefits.
62