Hastelloy C-2000 / Alloy C-2000 Forgings UNS N06200 · W.Nr. 2.4675 · NiCr23Mo16Cu · NS3405

Hastelloy C-2000 and Alloy C-2000: one alloy, two names

HASTELLOY® C-2000® is the Haynes International trade name for this alloy. Alloy C-2000 is the generic designation used by every other producer. Both refer to the same nickel-chromium-molybdenum-copper chemistry, specified internationally as UNS N06200 and W.Nr. 2.4675. Drawings and enquiries use the two names interchangeably, and both are frequently written without the hyphen, as Hastelloy C2000 or Alloy C2000.

One distinction worth knowing before you order

UNS N06200 defines a composition range. Haynes holds its branded Hastelloy C-2000 to a tighter internal window inside that range. Material from any other mill, including this one, is supplied to the full UNS N06200 and ASTM B564 limits, which is what the great majority of project specifications call for.

If your specification names Haynes-produced material specifically rather than the UNS number, say so at enquiry stage. We will tell you plainly whether we can meet it rather than ship against a specification we cannot satisfy.

Key data at a glance

Chemical composition

Composition limits below follow ASTM B564 for UNS N06200. Every heat is analyzed by optical emission spectrometry and the certified analysis is supplied with the forging.

Carbon is held to 0.010% maximum and silicon to 0.08% maximum. Both limits exist to suppress grain-boundary precipitation during welding and slow cooling, which is why C-2000 holds its corrosion resistance in the as-welded condition. It is also why melt practice matters more for this grade than for a general-purpose stainless.

Melting practice

Material is supplied from double-melted stock. The usual route is electric arc furnace with argon-oxygen or vacuum-oxygen decarburization, followed by electroslag remelting (EAF + AOD/VOD to ESR). Vacuum induction melting followed by ESR is used where a customer specifies it. Double melting controls sulfur, oxygen and inclusion content, and gives the ingot soundness that a forging of this section thickness needs.

Mechanical properties

Values are room-temperature minimums per ASTM B564 for solution-annealed forgings. Typical mill results run 10 to 15% above these figures.

Strength falls as temperature rises. Hastelloy C-2000 retains useful strength to roughly 649 °C, but it is a wet-corrosion alloy rather than a high-temperature structural alloy. See the note on service temperature in the FAQ before specifying it for hot duty.

Forging and heat treatment

Hastelloy C-2000 has a narrow hot-working window and work hardens faster than austenitic stainless steel. Most of the difficulty in forging it comes down to holding temperature.

Why the finishing temperature matters

The window between 1232 °C and 954 °C is about 280 °C wide, roughly half what carbon steel allows. A heavy ring rolled in a single heat will drop below 954 °C before the section is reduced, so the piece goes back into the furnace between passes. Forging on below the finish temperature does more than harden the part. It tears the grain structure, and the resulting defects show up on ultrasonic inspection after annealing, by which point the material has already been paid for.

The anneal after forging

Every forging is re-annealed after the last hot working operation, and after any cold work producing 7% or more outer-fiber elongation. Solution annealing dissolves the secondary phases that form on slow cooling from forging heat. A part that skips it can still pass its tensile test and then fail in service, because the mechanical properties are unaffected while the corrosion resistance is not. Rapid water quench from annealing temperature is required. Air cooling is acceptable only on sections under 10 mm.

Forged product forms and sizes

All parts are made to drawing. Send the drawing or the finished dimensions with the machining allowance you want, plus the specification, test requirements and certificate level. Quotation follows within one working day.

Hastelloy C-2000 compared with C-276, C-22 and Alloy 59

The four alloys below are the usual shortlist for aggressive acid service. They are not interchangeable. The choice normally comes down to whether the process stream is oxidizing, reducing, or swings between the two.

*PREN calculated as Cr + 3.3 × (Mo + 0.5W) from the nominal composition, rounded to the nearest whole number. PREN ranks pitting resistance in chloride media only. It says nothing about behavior in sulfuric or hydrofluoric acid, where the copper in C-2000 is the deciding factor. Confirm any selection against corrosion data for your actual medium, concentration and temperature.

C-276 and C-22 were each developed toward one end of the oxidizing-reducing scale. C-2000 was developed to hold both ends at once. That matters on plants running mixed acid, and where feedstock changes move the stream composition around. It also matters where standardizing on one alloy across a unit is worth more than a small gain on any single line.

Applications for Hastelloy C-2000 forgings

Chemical and petrochemical processing

Reactor closures, forged nozzles, tube sheets and shell-and-tube heat exchanger components in sulfuric acid, hydrochloric acid and mixed-acid service. Rolled rings and forged flanges for columns, towers, tanks, silos and preheaters.

Pumps, valves and rotating equipment

Pump shafts, agitator and mixer shafts, plunger pump components, valve bodies, valve stems, seat rings and blocks for ball, check, globe, gate and plug valves handling corrosive media.

Flue gas desulfurization and pollution control

Forged rings and discs for scrubber internals, absorber components and duct hardware, where chloride concentration and pH swing over the operating cycle.

Pharmaceutical and fine chemicals

Forged components for crystallizers, reaction vessels and process modules where product purity rules out iron contamination from the vessel wall.

Oil, gas and offshore

Forged bushings, sleeves, discs and manifold components for subsea and deepwater production systems, wellhead and Christmas tree hardware, and sour-service equipment carrying both H₂S and chlorides.

Testing, inspection and certification

• Chemical analysis. Optical emission spectrometry on every heat, certified analysis supplied with the forging.
• Mechanical testing. Tensile and hardness per ASTM B564 and ASTM A370, from test coupons heat treated with the production parts.
• Ultrasonic testing. To ASTM A388, EN 10228-3 or SEP 1921, acceptance class as specified on the order.
• Liquid penetrant testing. To ASTM E165 on machined surfaces where required.
• Positive material identification. Handheld XRF confirmation before dispatch.
• Intergranular corrosion testing. ASTM G28 Method A on request, to verify the solution anneal.
• Dimensional inspection. Full dimensional report against the customer drawing.
• Material certificate. EN 10204 3.1 as standard. EN 10204 3.2 counter-signed by TÜV, SGS, BV or Lloyd's Register on request.

Third-party inspection, witness testing and customer source inspection are welcome at the plant. Certificate numbers and scope are available on request.

Welding and machining

Hastelloy C-2000 welds readily by GTAW, GMAW and SMAW. Use matching filler: AWS A5.14 ERNiCrMo-17 wire, or AWS A5.11 ENiCrMo-17 covered electrodes. ERNiCrMo-10, the Alloy C-22 grade, is an accepted substitute where matching filler is unavailable.

No preheat is required and post-weld heat treatment is not normally applied. Keep interpass temperature low and heat input moderate. The low carbon and silicon limits are what allow the alloy to hold its corrosion resistance as welded. For machining, the alloy work hardens quickly, so use positive rake, rigid setups, slow speeds with heavy feeds, and never dwell in the cut.

Related nickel alloy forgings

• Hastelloy C-276UNS N10276
• Hastelloy C-22UNS N06022
• Alloy 59UNS N06059
• Hastelloy C-4UNS N06455
• Hastelloy B-3UNS N10675
• Hastelloy G-3UNS N06985
• Inconel 625UNS N06625
• Incoloy 825UNS N08825
• Alloy 602UNS N06025
• Inconel 617UNS N06617