G-TECH 20.18.9CuR

SMAW
  • HIGH TEMPERATURE ALLOYS
254 SMO

Description

6%Mo superaustenitic coated electrode
The weld metal closely matches the composition of equivalent 6%Mo superaustenitic parent material, usually castings, and is used only when post weld solution annealing is applied. Heat-input of <1.5 kJ/mm and interpass temperature of <100°C are recommended as high dilution by the base metal may cause weld cracking. It has a very low carbon content ensuring little risk of carbide precipitation during welding. Main applications include equipment for handling of seawater, cooling water pipes, components in pulp bleaching plants and pipelines for chemicals with high halide contents.
Specifications
Shielding
-
Positions
PA, PB, PC, PD, PE, PF
Current
DC+;
Packaging Type
Carton box

Pren

42.94
Chem. Comp. %
DEFAULT
C
0.03
Mn
0.8
Ni
18.5
Cr
20.5
Mo
6.8
Si
0.8
Cu
0.7
Mechanical Properties
min
variant
Tensile strength Rm MPa
-
550
Yield strength Rp0.2 MPa
-
300
Elongation A (L0=5d0) %
-
36
Impact Charpy ISO-V
-
-
Impact Charpy ISO-V
-
-
Welding Parameters
2.5 mm
3.2 mm
4 mm
Ampere
60A - 90A
80A - 110A
100A - 150A
Voltage
-
-
-
Packaging
55 pcs/kg
30 pcs/kg
19 pcs/kg
Packaging Type
Carton box
Carton box
Carton box
Description

Application

The weld metal corresponds to 6%Mo superaustenitic parent material, typically castings, and is exclusively employed when applying post-weld solution annealing. With an extremely low C content, there is minimal risk of carbide precipitation during heating, such as in the welding process. It exhibits a PRE number exceeding 40. The base metal, with its stable austenitic structure, can be prone to hot cracking during welding, necessitating the use of low heat input. Solidification following partial remelting, as in welding, results in the redistribution of elements like Mo, Cr, and Ni. These segregations persist in the cast structure of the weld and can compromise the material's corrosion resistance in specific environments. Engineered specifically for use in oil and gas offshore platforms and the pulp and paper industry, this material finds common applications in equipment handling seawater, including seawater cooling, cooling water pipes, ballast water systems, firefighting systems, equipment in pulp bleaching plants, as well as tanks and pipelines for chemicals with high halide contents. It is advisable to maintain a heat input of <1.5 kJ/mm and an interpass temperature of <100°C.

Alloy Type

6% molybdenum and nitrogen-alloyed austenitic stainless steel.

Microstructure

Austenite.

Materials


EN W.Nr.: 1.4547 (X1CrNiMoCuN20-18-7).
UNS: S31254.
PROPRIETARY: 254 SMO (Outokumpu).

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