Hastelloy C276 (UNS N10276)
Comprehensive technical specification for Hastelloy C276 (UNS N10276) covering Canadian stock sizing, machinability, tooling, common defects, and storage guidelines for industrial fabrication and machining operations.
Material Overview & Common Uses
Hastelloy C276 (UNS N10276) is a wrought nickel-chromium-molybdenum alloy with outstanding corrosion resistance in reducing and oxidizing environments. It is widely used in chemical processing, pollution control, pulp and paper, pharmaceutical, and oil & gas industries. In Canadian fabrication shops, it is commonly specified for reactors, heat exchangers, piping systems, and scrubbers where resistance to pitting, stress-corrosion cracking, and oxidizing acids is critical. The alloy is non-magnetic and retains high strength at elevated temperatures up to 1900°F (1038°C).
Core Technical Properties & Sizing
| Property | Value |
|---|---|
| Chemical Composition | Ni (balance), Cr (14.5–16.5), Mo (15.0–17.0), Fe (4.0–7.0), W (3.0–4.5), Co (≤2.5), Mn (≤1.0), V (≤0.35), Si (≤0.08), C (≤0.01), P (≤0.025), S (≤0.010) |
| Density | 0.321 lb/in³ (8.89 g/cm³) |
| Melting Range | 2415–2500°F (1325–1370°C) |
| Tensile Strength (annealed) | min 110 ksi (760 MPa) |
| Yield Strength (0.2% offset, annealed) | min 51 ksi (350 MPa) |
| Elongation (annealed) | min 30% |
| Hardness (annealed) | Rockwell B 90 max |
| Sizing & Tolerance Parameter | Value |
|---|---|
| Standard Canadian Sheet/Plate Sizing | 48″ x 120″ (4×10 ft) and 60″ x 144″ (5×12 ft); thicknesses 0.028″ (22 ga) up to 0.500″ (1/2″). Plate up to 2″ in 96″ x 240″ (8×20 ft). |
| Thickness Tolerances (ASTM B575) — Sheet 0.028–0.049″ | ±0.004″ |
| Thickness Tolerances (ASTM B575) — 0.050–0.109″ | ±0.005″ |
| Thickness Tolerances (ASTM B575) — 0.110–0.187″ | ±0.006″ |
| Thickness Tolerances (ASTM B575) — Plate 0.188–0.250″ | ±0.010″ |
| Thickness Tolerances (ASTM B575) — Over 0.250″ | ±0.015″ |
| Flatness Tolerances — Sheet (up to 0.187″) | 1/8″ in any 36″ width |
| Flatness Tolerances — Plate | 1/4″ in any 72″ length |
Machinability, Tooling & Feeds
| Parameter | Recommendation |
|---|---|
| Machinability Rating | 20–30% of free-machining steel |
| Recommended Tooling | Carbide inserts (C2 or C3 grade) with sharp edges and positive rake angles |
| Cutting Speed — Rough Turning | 100–200 SFM |
| Feed — Rough Turning | 0.005–0.015 in/rev |
| Depth of Cut — Rough Turning | 0.050–0.150 in |
| Cutting Speed — Finishing | 150–250 SFM |
| Feed — Finishing | 0.003–0.008 in/rev |
| Coolant | Water-soluble, 10–15% concentration, generous volume |
| Drilling | Cobalt HSS or carbide drills with heavy-duty point geometry; peck cycles |
| Threading | Single-point or thread milling; avoid taps |
| Sawing | Bimetal blades, 4–6 TPI, 60–100 SFM, with coolant |
Common Defects & Quality Control
| Defect | Quality Control Check |
|---|---|
| Surface scale & oxide discoloration | Visual inspection; verify mill test reports (MTR) per ASTM B575 |
| Lamination or delamination in plate edges | Visual inspection; reject material if present |
| Micro-cracking near sheared edges | Dye penetrant inspection |
| Pitting or crevice corrosion | Visual inspection; PMI (Positive Material Identification) using XRF to confirm chemistry |
| Weld porosity or hot cracking | Verify filler metal and shielding gas compliance |
| Dimensional distortion from residual stress relief | Measure flatness on granite table; check thickness with micrometer at multiple points |
Reject material with visible laminations, cracks, or thickness out of tolerance.
Storage, Handling & Racking Guidelines
Store Hastelloy C276 indoors in a dry, climate-controlled environment (40–60% RH) to prevent surface oxidation. Keep away from carbon steel to avoid iron contamination which can cause localized corrosion. Use dedicated racks with plastic or rubber-lined supports to prevent scratching. For sheet and plate, store flat on pallets with protective paper or plastic interleaving. Do not stack heavy plates on thin sheets. Use lifting straps or suction cups for handling; avoid chains or steel hooks that can mar the surface. For long-term storage, apply a light oil or protective coating. Rotate stock FIFO to avoid age-related surface degradation. In racking, ensure even weight distribution and secure straps to prevent sliding.