G-TECH 1021

SMAW
  • COBALT ALLOYS
Gr. 21

Description

Hardfacing electrode with rutile-basic coating
Rutile-basic coated electrode with good weldability, easy to remove slag. It is used for surfacings subjected to light to medium abrasion, violent mechanical shocks, severe thermal shocks, severe erosion and corrosion, cavitation, high temperatures up to 1000°C, metallic friction, compression. The deposit has the property of hardening in operation. It is widely used in hot stamping and forging, for reloading forging dies and all types of tools that work at high temperatures and subject to shocks and pressures.
Specifications
AWS A5.13
ECoCr-E
DIN 8555
E 20-UM-300-CTZ
Shielding
-
Positions
PA, PB, PC, PD, PF
Current
DC+
Packaging Type
Carton box
Asme qualifications
F-No (QW432)
71
A-No (QW442)
-

Hardness

28HRC - 32HRC
Chem. Comp. %
DEFAULT
C
0.25
Mn
0.8
Ni
2.8
Cr
28
Mo
5.5
Si
0.8
Fe
2.5
W
0.05
Welding Parameters
2.5 mm
3.2 mm
4 mm
Ampere
80A - 120A
100A - 140A
150A - 200A
Voltage
-
-
-
Packaging
pcs/kg
pcs/kg
pcs/kg
Packaging Type
Carton box
Carton box
Carton box
Anti-wear Characteristics
Adhesive wear
Abrasive wear
Impact
Corrosion
Heat
Description

Application

This low-carbon cobalt-based alloy type seamlessly blends commendable high-temperature strength with heightened ductility. The enhanced ductility contributes to superior resistance to weld cracking compared to its high-carbon counterparts. It exhibits notable resistance to corrosion, oxidation, and sulfidation, displaying robust resistance to cavitation erosion and better resistance to thermal shock than high-carbon types. While its galling resistance is somewhat lower than high-carbon types, it compensates with superior bed-in properties. This alloy is widely employed for surfacing valves, valve seats, hot shear blades, hot work dies, ingot tong ends, and equipment designed for handling hot steel. It serves as a preferred material for cat cracker slide valves in the petrochemical industry and finds diverse applications across a broad spectrum of industries, including steel, cement, marine, and power generation. While preheating is generally not mandatory, it is advisable for the first layer when deposited on hardenable alloy steels. Interpass control to approximately 200°C maximum is recommended to minimize potential hot cracking in heavy multipass deposits. The deposits exhibit machinability with carbide tools and can be refined through grinding as necessary.

Alloy Type

CoCrMo alloy matrix containing dispersed hard carbides.

Microstructure

In the as-welded condition the microstructure consists of a cobalt based austenite with a number of carbides and other complex phases.

Materials

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 joining.

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