G-TECH 312

SMAW
  • AUSTENITIC STAINLESS STEELS
312

Description

Rutile-basic coated electrode for similar steels, medium and high carbon hardenable steels
This alloy gives a two-phase weld deposit with substantial percentages of ferrite in an austenite matrix. Even with considerable dilution the microstructure remains two-phase and thus highly resistant to weld metal cracks and fissures. Weld deposit is work hardenable and gives good wear resistance. Applications include tool steels, shafts, gear teeth, free-cutting steels, unknown specification steels, dissimilar alloy combinations and buffer layers. Excellent weldability with a spatter free arc and self-releasing slag result in a very smooth bead appearance.
Specifications
ISO 3581-A
E 29 9 R 32
AWS A5.4
E312-16
Shielding
-
Positions
PA, PB, PC, PD, PE, PF
Current
DC+, AC
Packaging Type
Carton box
Asme qualifications
F-No (QW432)
5
A-No (QW442)
8

Ferrite

% 40

Pren

29

Hardness

300HV
Chem. Comp. %
DEFAULT
C
0.09
Mn
1
Ni
10
Cr
29
P
0.02
S
0.01
Si
1.15
Cu
0.2
Mechanical Properties
min
variant
Tensile strength Rm MPa
650
700
Yield strength Rp0.2 MPa
450
600
Elongation A (L0=5d0) %
15
22
Impact Charpy ISO-V
-
30J @ 20°C
Impact Charpy ISO-V
-
-
Welding Parameters
2 mm
2.5 mm
3.2 mm
4 mm
Ampere
35A - 50A
50A - 80A
80A - 110A
110A - 150A
Voltage
-
-
-
-
Packaging
88 pcs/kg
56 pcs/kg
28 pcs/kg
18 pcs/kg
Packaging Type
Carton box
Carton box
Carton box
Carton box
312
Description

Application

Suitable for welding medium and high carbon hardenable steels, including those with known or unknown specifications like tool steels, shafts, gear teeth, free-cutting steels, dissimilar alloy combinations, buffer layers, overlays, etc. The welding material, featuring a high alloy and high ferrite content (40-50FN), exhibits exceptional tolerance to dilution on a wide range of hardenable and alloy steels, often requiring minimal or no preheat. It is effective for welding free-cutting steels or those with a low Mn:S ratio, especially below 20, preventing hot cracking due to liquation at the fusion boundary. The resulting weld deposit work-hardens, offering excellent wear and friction resistance. It is useful for corrosion resistance and high-temperature scaling up to about 1000°C. However, it's not recommended for structural applications above 300°C or for welds that undergo post-weld heat treatment due to potential embrittlement. Additionally, it is not suitable for filling up heavy joints, sub-zero applications, or situations requiring high notch toughness.

Alloy Type

Austenite-ferrite weld metal composition of nominally 29%Cr-9%Ni for dissimilar joints and difficult to weld steels.

Microstructure

Duplex austenite-ferrite microstructure with about 40% ferrite.

Materials

Medium and high carbon hardenable steels, tool steels and free-cutting steels.

Welding & PWHT

The procedure is contingent upon the base material. Preheating is generally unnecessary for small components and buffer layers; however, it is advisable for thicker high-carbon steels to prevent potential Heat-Affected Zone (HAZ) quench cracking and regulate peak hardness, typically in the range of 100-250°C. Despite the excellent high-temperature oxidation resistance of 29%Cr-9%Ni alloys, it's crucial to note that duplex high ferrite weld metal may experience 475°C embrittlement above approximately 300°C and sigma embrittlement at elevated temperatures. Consequently, this alloy is not employed in applications involving high-temperature structural service or Post Weld Heat Treatment (PWHT).

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