GH3128 · GB GH3128
GH3128 (-): composition, properties, fittings and flanges
GH3128 (GH3128, GB GH3128) is Tungsten and molybdenum strengthened Ni-Cr-W-Mo high-temperature alloy. GH3128 is specified at Nickel Balance, Chromium 19.0 - 22.0, Tungsten 7.50 - 9.00. GH3128 pairs 8 % tungsten with 8 % molybdenum, giving both high-temperature strength and better resistance to reducing atmospheres than the…
- UNS
- -
- W. Nr.
- -
- Density
- 8.80 g/cm³ (0.318 lb/in³)
- Key strength
- 735 MPa / 107 ksi
Identification and standards
| Short form | GH3128 · GB GH3128 |
|---|---|
| Classification | Tungsten and molybdenum strengthened Ni-Cr-W-Mo high-temperature alloy |
| UNS | - |
| Werkstoff number | - |
| Material family | High-Temperature Alloys / Superalloys |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Nickel (Ni) | Balance | Matrix |
| Chromium (Cr) | 19.0 - 22.0 | Oxidation resistance |
| Tungsten (W) | 7.50 - 9.00 | Solid-solution strengthening |
| Molybdenum (Mo) | 7.50 - 9.00 | Solid-solution strengthening |
| Aluminium (Al) | 0.40 - 0.80 | Scale adherence |
| Titanium (Ti) | 0.40 - 0.80 | Minor hardening |
| Iron (Fe) | 2.00 max | Residual |
| Carbon (C) | 0.05 max | - |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, min | 735 MPa / 107 ksi |
|---|---|
| 0.2 % yield strength, min | 340 MPa / 49 ksi |
| Elongation, min | 40 % |
| Typical hardness | 180 - 220 HB |
| Useful continuous service temperature | About 900 °C |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 8.80 g/cm³ (0.318 lb/in³) |
|---|---|
| Melting range | 1340 - 1390 °C (2445 - 2535 °F) |
| Modulus of elasticity | 207 GPa (30.0 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 11.0 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 12.6 µm/m·°C |
| Specific heat capacity | 445 J/kg·K |
Specifications by product form
| Forgings & flanges | GB/T 14992 / GB/T 14994 (GH3128) |
|---|---|
| Butt weld fittings | To order against GB/T 14992 chemistry |
| Seamless pipe & tube | To order |
| Plate / sheet / strip | GB/T 14995 |
| Bar / rod | GB/T 14994 |
| Welding consumables | Matching GH3128 filler |
| UNS / EN / China | GB GH3128 |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Forged flanges blanks and finished flanges to ASME B16.5, B16.47 Series A/B and B16.36
- Butt weld elbows, tees, reducers, caps and stub ends to ASME B16.9 and MSS SP-43
- Seamless pipe and tube to the applicable ASTM / ASME pipe specification
- Forged rings, discs and hubs machined to your drawing
Typical applications
- Combustion chamber and afterburner sheet structures
- Furnace components exposed to mixed oxidising and reducing atmospheres
- High-temperature bellows, joints and thermal shields
- Radiant tubes and heat treatment baskets
Welding, forming and machining
- Welding
- Weld by GTAW with matching filler and low heat input; the alloy work-hardens and the weld metal should match the tungsten and molybdenum content.
- Heat treatment
- Solution anneal at 1140 - 1180 °C and air cool.
- Hot and cold forming
- Hot work in the range stated by the mill for this grade, then re-solution or re-age before final machining so that the delivered condition matches the certificate.
- Machining
- Machine with sharp carbide or high-speed steel tooling, positive rake, constant feed and ample coolant. Never dwell - the surface work-hardens quickly.
Buy GH3128 from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.