EN 10253-2 Type B buttweld pipe fittings in 2.4610 — Hastelloy C-4 (NiCr16Mo16Ti, N06455). A Ni-Cr-Mo alloy without tungsten. The absence of W makes C-4 more thermally stable than C-276 in the 650–1040°C range — less prone to grain boundary precipitation. This thermal stability is the key selection criterion. Corrosion performance similar to C-276 in reducing environments; matched by Ti addition for stabilisation.
| Grade | W.Nr. | Cr % | Mo % | W | Key Advantage |
|---|---|---|---|---|---|
| C-276 | 2.4819 | 15–17% | 15–17% | 3–4.5% | Best all-round; reducing acids, highest PRE |
| C-4 (this grade) | 2.4610 | 14–18% | 14–17% | None | Superior thermal stability — no W precipitation |
| C-22 | 2.4602 | 20–22.5% | 12.5–14.5% | 2.5–3.5% | High Cr for oxidising + reducing media |
Specify C-4 (2.4610) when the component will be exposed to sustained temperatures in the 650–1040°C range in service or during fabrication (stress relief, PWHT, or process excursions). The W in C-276 promotes μ-phase and P-phase precipitation at these temperatures, reducing corrosion resistance. C-4 with Ti stabilisation avoids this. For purely ambient-temperature service with no thermal excursion risk, C-276 provides equivalent or slightly higher corrosion resistance and is typically the first-choice grade.
| W.Nr. | 2.4610 |
| EN Name | NiCr16Mo16Ti |
| ASTM UNS | N06455 |
| Trade Name | Hastelloy C-4 |
Filler: ERNiCrMo-7 (C-4 matching). No PWHT. Excellent thermal stability post-weld — a primary advantage over C-276.
