This low carbon cobalt base type combines good high
temperature strength with high ductility. The improved
ductility provides better resistance to weld cracking than
the high carbon types. It has high resistance to corrosion,
oxidation and sulphidation; good resistance to cavitation erosion
and resists thermal shock better than high carbon
types. Galling resistance is inferior to high carbon types
but bed-in properties are better.
It is used to surface valves and valve seats, hot shear
blades, hot work dies, ingot tong ends and equipment for
handling hot steel. Used for cat cracker slide valves in
petrochemical industry. Also finds applications in a very
wide range of industries including steel, cement, marine
and power generation. Preheat not required, but advisable for first layer when
deposited on hardenable alloy steels. Interpass control
to ~200°C maximum is advisable to minimize possible
hot cracking in heavy multipass deposits.
Deposits are machinable with carbide tools and may be
finished by grinding where necessary.
CoCrMo alloy matrix containing dispersed hard carbides.
In the as-welded condition the microstructure consists of
a cobalt based austenite with a number of carbides and
other complex phases.
Materials to be welded
Used for surfacing mild, low alloy and stainless steels and also for nickel base alloys.
Can also be used for the repair of similar base materials
(UNS R30021, Stellite 21 - Deloro Stellite) although it is optimized for surfacing not