Bar and Rod
Plate and Sheet
Strip
Pipe and Tube
Wire
Welding
Powder Material
Cast Products
Forged Products
Fittings
Fastening
Round Bar:
φ2–500 mm, 1–6 m length
Flat/Square Bar:
4–100 mm thickness/width
Hex Bar:
A/F 3–100 mm
Hollow Bar:
OD 20–300 mm
Sheet:
0.3–6 mm thickness
Medium Plate:
6–25 mm thickness
Heavy Plate:
25–100 mm thickness
Standard Strip:
0.05–3 mm thick,
10–600 mm wide
Precision strip:
0.01–0.5 mm thick,
tight tolerance ±0.005 mm
Foil:
0.005–0.1 mm thick
Seamless Tube:
OD 6–450 mm,
WT 1–50 mm,
1–12 m length
Welded Tube:
OD 10–600 mm,
WT 1–20 mm
Capillary Tube:
OD 1–10 mm,
WT 0.1–2 mm
Wire Form:
Cold Drawn Wire,
Bright Wire,
Spring Wire,
Fine Wire,
Ultra-fine Wire
General Diameter:
φ0.1–10 mm
Coil Weight:
50–500 kg,
customizable tolerance
Solid Wire:
φ0.8–4.0 mm
Flux-cored Wire:
φ1.2–4.0 mm
Welding Rod:
φ2.0–5.0 mm
Powder Form:
AM 3D Printing Powder,
Spherical Powder,
Gas-atomized Powder,
Water-atomized Powder
Particle Size:
10–150 μm
Sphericity:
≥90% for AM grade
Cast Ingot:
φ200–800 mm
Precision Casting:
min wall 0.5 mm
Cast Pipe:
OD 100–600 mm,
WT 10–50 mm
Forged Bar:
Φ35–500 mm
Forged Ring:
OD 200–2000 mm
Forging Weight:
1–5000 kg
Fittings Form:
Elbow, Tee, Reducer, Flange, Cap, Outlet, Lap Joint
Size range:
1/2''–24'' (DN15–DN600)
Wall thickness:
Sch10–Sch160, STD, XS, XXS
Pressure Class:
150–2500 LB
Fastening Form:
Bolt, Nut, Screw, Stud, Washer, Pin, Rivet
Metric: M3–M64
Imperial: #4–2.5''
Length: 6–500 mm
Alloy C-4 is a low-carbon austenitic nickel–chromium–molybdenum alloy — the most microstructurally stable of the widely used Ni-Cr-Mo materials. This datasheet presents the material within the American (ASTM / ASME / SAE-AMS / UNS) standard system.
Its defining attribute is exceptional thermal/structural stability: controlled low carbon, silicon and iron, the absence of tungsten, and a small titanium addition together suppress the nucleation and growth of deleterious second-phase precipitates (such as M₆C carbides and sigma/mu phases) in the grain boundaries of the weld heat-affected zone. As a result the alloy can be welded without fear of sensitisation, and it retains structural stability and ductility even after prolonged exposure in the 650–1040 °C range.
With its high chromium and molybdenum contents it withstands both oxidising and non-oxidising acids — in particular hydrochloric, sulphuric, formic and acetic acids and acid blends — and resists pitting and crevice attack in chloride and other halide media. Like other nickel alloys it is ductile, easy to form and weld, and possesses outstanding resistance to chloride stress-corrosion cracking. It is used widely in chemical-process equipment, and is listed in NACE MR0175 / ISO 15156 for sour service.
Values per manufacturer (VDM / Haynes) data, solution-annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 8.64 | g/cm³ |
| Melting range | 1350–1380 | °C |
| Young's modulus (20 °C) | 211 | GPa |
| Thermal conductivity (20 °C) | 10.1 | W/m·K |
| Specific heat capacity (20 °C) | 406 | J/kg·K |
| Electrical resistivity (20 °C) | 1.25 | µΩ·m |
| Coefficient of thermal expansion (20–100 °C) | 10.8 | µm/m·°C |
| Maximum structural-stability temperature | ~1040 | °C |
| Structure | Austenitic (FCC) | — |
Limiting composition per ASTM B574 (UNS N06455).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Nickel | Ni | Balance | — | Base element; corrosion resistance |
| Chromium | Cr | 14.5 | 17.5 | Oxidising-media resistance; passive film |
| Molybdenum | Mo | 14.0 | 17.0 | Pitting/crevice + reducing-acid resistance |
| Iron | Fe | — | 3.0 | Controlled low (aids stability) |
| Titanium | Ti | — | 0.70 | Stabiliser; suppresses HAZ carbide precipitation |
| Cobalt | Co | — | 2.0 | Residual |
| Manganese | Mn | — | 1.0 | Deoxidiser |
| Carbon | C | — | 0.01 | Ultra-low; thermal stability |
| Silicon | Si | — | 0.10 | Controlled low (aids stability) |
| Phosphorus | P | — | 0.020 | Residual impurity |
| Sulphur | S | — | 0.010 | Residual impurity |
Key feature: no tungsten, low Fe/Si/C + Ti — the basis of C-4's outstanding thermal stability vs C-276.
Typical room-temperature properties, solution-annealed condition.
| Property | Value | Source |
|---|---|---|
| Ultimate tensile strength | ≥690 MPa (100 ksi); typ. up to ~795 MPa | ASTM B574 min / typical |
| 0.2% proof strength (yield) | ≥275 MPa (40 ksi) | ASTM B574 minimum |
| Elongation at break | ≥40 % | ASTM B574 minimum |
| Hardness | ~90 HRB | Typical |
The alloy is solid-solution-strengthened (not age-hardenable) and can be strengthened by cold work. Its outstanding thermal stability means properties and corrosion resistance are retained after high-temperature exposure and welding. Values are typical or specified minima; confirm against the mill test certificate.
| Environment | Performance | Notes |
|---|---|---|
| Hydrochloric acid | Excellent | High Mo content |
| Sulphuric acid | Excellent | Both oxidising + reducing conditions |
| Formic / acetic acid | Excellent | Organic-acid resistance |
| Acid blends (e.g. HCl + HNO₃) | Outstanding | Balanced Cr/Mo; resists contaminated mineral acids |
| Pitting / crevice (halides) | Excellent | High Mo; chloride/halide media |
| Chloride SCC | Outstanding | Routinely specified where stainless steels fail |
| Weld HAZ / sensitisation | Outstanding | Most stable Ni-Cr-Mo; no σ/μ/M₆C in HAZ |
| Thermal stability (650–1040 °C) | Outstanding | No detrimental intermetallic phases |
A solid-solution, low-carbon Ni-Cr-Mo alloy; not age-hardenable. Heat treatment is solution annealing only.
Solution Anneal Temperature: ~1065 °C (1950 °F), followed by rapid cooling (water quench) Purpose: dissolves secondary phases, restores maximum corrosion resistance and ductility.
C-4's defining advantage is that, owing to its exceptional microstructural stability, it resists sensitisation even after exposure in the 650–1040 °C range — so welded assemblies generally do not require a post-weld solution anneal for corrosion service.
Outstanding weldability — the key advantage of C-4. Its microstructural stability means it can be welded without fear of HAZ sensitisation (no second-phase grain-boundary precipitation), so it is suitable for as-welded service in aggressive media.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Excellent | AWS A5.14 ERNiCrMo-7 (matching C-4 filler) |
| GMAW / MIG | Excellent | AWS A5.14 ERNiCrMo-7 (matching C-4 filler) |
| SMAW / stick | Good | AWS A5.11 ENiCrMo-7 |
Keep the joint clean and oxide-free. Post-weld heat treatment is generally not required for corrosion service, owing to the alloy's stability.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Work hardening | Moderate-to-high; rigid setup, sharp tooling, positive rake |
| Cutting | Low speed, sufficient feed/depth to cut below work-hardened layer |
| Coolant | Ample flood coolant |
| Preferred condition | Solution-annealed |
Forming Processes
| Process | Notes |
|---|---|
| Hot forming | ~954–1107 °C; solution-anneal after hot forming |
| Cold forming | Readily cold-formed; solution-anneal after heavy reductions |
| All standard techniques | Cold and hot formable |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Chemical processing | Reactors, heat exchangers, columns, piping | Mixed-acid + thermal stability + as-welded service |
| Hydrochloric / sulphuric acid | Process vessels and piping | Strong-acid resistance |
| Halide / chloride media | Equipment exposed to chlorides | Pitting/crevice + SCC resistance |
| Welded fabrications | Structures needing as-welded corrosion resistance | No HAZ sensitisation |
| High-temperature corrosion | Components in 650–1040 °C corrosive service | Thermal stability |
| Product Form | ASTM Standard | ASME Code | AMS |
|---|---|---|---|
| Rod and bar | ASTM B574 | ASME SB-574 | AMS 5772 |
| Plate, sheet and strip | ASTM B575 | ASME SB-575 | AMS 5608 |
| Seamless pipe and tube | ASTM B622 | ASME SB-622 | — |
| Welded pipe | ASTM B619 | ASME SB-619 | — |
| Welded tube | ASTM B626 | ASME SB-626 | — |
| Fittings | ASTM B366 | ASME SB-366 | — |
| Castings | ASTM A494 Grade CW-2M | ASME SB-494 | — |
| Welding consumables | AWS A5.14 ERNiCrMo-7 | — | AMS 5801 |
Listed in NACE MR0175 / ISO 15156 and MR0103 / ISO 17945. UNS N06455.
| Alloy | Ni % | Cr % | Mo % | Other | Best Used For |
|---|---|---|---|---|---|
| Alloy C-4 | bal | 14.5–17.5 | 14–17 | Ti, no W | Most thermally stable; as-welded service |
| Alloy C-276 | bal | 14.5–16.5 | 15–17 | W 3–4.5 | Broad corrosion workhorse; as-welded |
| Alloy C-22 | bal | 20–22.5 | 12.5–14.5 | W 2.5–3.5 | Best pitting/crevice; oxidising media |
| Alloy C-2000 | bal | 22–24 | 15–17 | Cu 1.6 | Most versatile; Cu for reducing acids |
| Alloy B-3 | bal | 1–3 | 27–32 | C ≤0.01 | Reducing acids only (Ni-Mo, near-zero Cr) |
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