G-TECH 320LHR

SMAW
  • SUPERAUSTENITIC STEELS
ALLOY 20

Description

Rutile high recovery coated electrode for Alloy 20
Fully austenitic weld metal with high resistance to corrosion in sulphuric acid, mineral acids and organic acids. Typical applications include tanks and vessels, piping, cast pumps, valves, heat exchanger and other components used in chemical processing, metal cleaning and pickling industries. Excellent weldability with a spatter free arc, self-releasing slag producing a very smooth bead appearance. High recovery coating increases deposition rate but limits welding position to flat.
Specifications
AWS A5.4
E320LR-26
Shielding
-
Positions
PA, PB, PC
Current
DC+, AC
Packaging Type
Carton box
Asme qualifications
F-No (QW432)
5
A-No (QW442)
-

Pren

27.49
Chem. Comp. %
DEFAULT
C
0.02
Mn
1.7
Ni
33.8
Cr
19.9
Nb
0.1
P
0.016
S
0.006
Mo
2.3
Si
0.16
Cu
3.2
Mechanical Properties
min
variant
Tensile strength Rm MPa
520
535
Yield strength Rp0.2 MPa
0
340
Elongation A (L0=5d0) %
28
30
Impact Charpy ISO-V
-
60J @ -196°C
Impact Charpy ISO-V
-
-
Welding Parameters
2.5 mm
3.2 mm
4.0 mm
5.0 mm
Ampere
50A - 80A
80A - 110A
110A - 150A
150A - 200A
Voltage
-
-
-
-
Packaging
30 pcs/kg
18 pcs/kg
12 pcs/kg
8 pcs/kg
Packaging Type
Carton box
Carton box
Carton box
Carton box
ALLOY 20
Description

Application

These consumables provide a fully austenitic weld metal, stabilized with niobium and enriched with molybdenum and copper, ensuring high resistance to corrosion in environments containing sulfuric acid, other mineral acids, organic acids, and their mixtures. Typically, the base material specifications pertain to castings. Typical applications include tanks, process piping, heat exchangers, agitators and rotors, as well as cast pumps and valves, particularly suited for use in chemical processing, metal cleaning and pickling. The 825 consumables are also highly alloyed products characterized by significant corrosion resistance and can be proposed as a technically compatible alternative for certain applications.

Alloy Type

20%Cr-34%Ni-3.5%Cu-2.5%Mo (alloy 20) austenitic corrosion resistant alloy.

Microstructure

In the as-welded condition, the microstructure is fully austenitic.

Materials

  • ASTM: A351, A744 gr. CN-7M
  • PROPRIETARY: Alloy 20, 20Cb, 20Cb-3 (Carpenter), Paramount P20 (Lake, Elliot), Langalloy 20V (Meighs)

Welding & PWHT

No preheat is necessary; however, the interpass temperature must be carefully managed not to exceed 150 °C. Heat input must be strictly controlled, especially when using 4 mm diameter electrodes. Repairing Alloy 20 castings can result in specific issues in the HAZ zones, susceptible to cracking, and in the weld metal, with an increased predisposition to cracking caused by the presence of silicon during reheating. Problematic castings may require a buttering procedure with very low heat input using reduced diameter electrodes and minimal dilution. Welds are generally left in the 'as welded' condition, but castings that meet ASTM specifications may require a solution treatment at 1125 °C after significant repairs.

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