G-TECH 630

SMAW
  • FERRITIC - MARTENSITIC STAINLESS STEEL
630 (17-4-PH)

Description

Rutile-basic coated electrode for welding precipitation hardening stainless steels.
This electrode is used for hardfacing and for welding precipitation hardening stainless steels base metal of similar composition such as 17- 4 and 17-7. It can be used in the as weld condition as well as heat treated to improve mechanical properties. Typical applications include Hydraulic components, pump shaft and impellers. Excellent weldability with a spatter free arc, self-releasing slag producing a very smooth bead appearance.
Specifications
EN ISO 3581-B
E 630-16
AWS A5.4
E630-16
Werkstoff Number
1.4034
Shielding
-
Positions
PA, PB, PC, PD, PE, PF
Current
DC+, AC
Packaging Type
Carton box
Asme qualifications
F-No (QW432)
4
A-No (QW442)
-

Pren

17.16
Chem. Comp. %
DEFAULT
C
0.02
Mn
0.6
Ni
4
Cr
16.5
P
0.01
S
0.01
Mo
0.2
Si
0.3
Cu
2.3
Mechanical Properties
min
variant
Tensile strength Rm MPa
930
950
Yield strength Rp0.2 MPa
0
600
Elongation A (L0=5d0) %
6
7
Impact Charpy ISO-V
-
-
Impact Charpy ISO-V
-
-
Welding Parameters
2.5 mm
3.2 mm
4.0 mm
Ampere
50A - 80A
80A - 110A
110A - 150A
Voltage
-
-
-
Packaging
53 pcs/kg
27 pcs/kg
19 pcs/kg
Packaging Type
Carton box
Carton box
Carton box
Description

Application

The 630, also known as 17-4-PH, is used for welding high-strength martensitic stainless steels hardened by precipitation with the addition of copper. This material offers strength up to three times greater than standard austenitic stainless steels of the 300 series. Alloys, such as the FV520/450 type, offer corrosion resistance similar to 304 stainless steel. However, the 630/17-4PH types, lacking molybdenum and with high carbon content, display weaknesses in resistance to intergranular and pitting corrosion, unlike the FV520/450 types. Typical applications include pump shafts, impellers, and hydraulic equipment used in the petrochemical, marine engineering, and nuclear sectors.

Alloy Type

High strength martensitic precipitation hardening stainless steels.

Microstructure

In the PWHT condition the microstructure consists of precipitation hardened tempered martensite with some retained austenite.

Materials

  • EN W.Nr.: 1.4542 (X5CrNiCuNb 16-4), 1.4548 (X5CrNiCuNb17-4-4), 1.4549 (GX5CrNiCuNb1)
  • ASTM: A564, A693, A705, gr. XM-25, A564, gr. 630, A747, CB7Cu-1 (cast)
  • UNS: S45000, S17400
  • PROPRIETARY: FV520B (Firth Vickers), Custom 450, 630 (Carpenter), 17-4PH (AK Steel Steel)

Welding & PWHT

For welding thicknesses up to 15 mm, preheat is generally not required. For thicker sections, a preheat and interpass temperature range of 100-200 °C is recommended. Temperatures exceeding 200 °C may inhibit martensitic transformation, causing a coarse microstructure. When using matching composition consumables, it is essential to perform Post-Weld Heat Treatment (PWHT). Normally, materials are employed in an over-aged condition. The PWHT for over-aging involves: at 750 °C for 2 hours, with air cooling to 15 °C; followed by a second stage at 550 °C for 2 hours, with further air cooling. During the cooling of the weld metal, austenite transforms into martensite (Ms) at temperatures below approximately 250 °C, maintaining a significant fraction of austenite at room temperature. Since sub-zero cooling is impractical, this austenite is destabilized through annealing at 750-850 °C. The precipitation of carbide in austenite raises the Ms temperature, allowing complete transformation during cooling, ensuring more effective tempering and aging in the second PWHT cycle. Skipping the first PWHT cycle can lead to properties with greater variability between batches.

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