RA333 Forgings (UNS N06333)

RA333 at a glance

What RA333 is, and when to specify it

Most high-temperature alloys are selected on creep-rupture strength, which sets how much load a part carries for a given service life. RA333 is not competitive on that measure. Inconel 617 and Haynes 230 are considerably stronger above 900 °C. RA333 is selected instead for resistance to atmosphere attack: carburising gases, molten salt, repeated water or oil quenching, and acid condensation on shutdown.

The 44–47% nickel keeps the structure austenitic and slows carbon diffusion. The 24–27% chromium forms the primary protective oxide. The 0.75–1.50% silicon develops a silica-rich sub-scale that restricts carbon ingress and resists metal dusting, the form of catastrophic carburisation found in reformer and syngas equipment. Molybdenum, cobalt and tungsten at 2.5–4% each provide solid-solution strengthening. There is no precipitation-hardening system in the alloy.

Specify RA333 when

• The part is cycled into and out of a carburising or nitriding furnace atmosphere.
• The part is quenched in oil or water from red heat on a repeated cycle.
• Metal dusting has already caused failure of an iron-based grade in the same position.
• The equipment sees sulfuric or polythionic acid condensation on shutdown.
• Service is above 1100 °C and the applied load is low.

Specify another grade when

• The part is a code-stamped pressure component. RA333 is not an ASME BPVC material. Use Alloy 800H/800HT or Inconel 617.
• Creep-rupture strength governs the design. Use Haynes 230 or Inconel 617.
• Service stays below 900 °C in clean air. Alloy 330 or 800H costs less per kilogram.
• Room-temperature strength governs. RA333 yields at about 324 MPa.

Open-die forged product forms in RA333

Chemical composition of RA333 (UNS N06333)

Composition limits below are the UNS N06333 ranges used by ASTM B718 and B719 and by AMS 5717, in weight percent. The highlighted row is the silicon range that separates RA333 from other 25% chromium nickel alloys.

Phosphorus and sulfur are held to the residual limits of the governing specification. Every heat is supplied with a ladle analysis on the mill certificate; product analysis on the finished forging can be added on request. Source: Jiangyin Jiangnan Metal Co., Ltd., RA333 forging specification.

Mechanical properties of RA333 forgings

Typical room-temperature properties, solution annealed

RA333 is supplied in the solution-annealed condition. The values below are representative of annealed forgings and vary with section size and cooling rate. They are typical values for design screening, not guaranteed minimums.

Acceptance minimums for a given order are set by ASTM B719 or AMS 5717, or agreed on the purchase order where a customer specification governs. State the required minimums on your enquiry and they will be confirmed with the quotation. The mill test certificate issued with each forging governs acceptance.

Behaviour at temperature

Strength falls with temperature, as it does for any solid-solution alloy. Above about 800 °C the design is governed by creep and stress rupture rather than by short-term tensile strength, and RA333 sits below Inconel 617 and Haynes 230 on that measure. For load-bearing high-temperature parts, request creep and stress-rupture data for the specific temperature and design life with the enquiry.

Physical properties of RA333

Nominal values compiled from published alloy literature for guidance in design screening. Where a physical property is used in a design calculation, request the figure in writing against the specific temperature.

RA333 vs Alloy 330, 800H, Inconel 617 and Haynes 230

These five grades compete for the same high-temperature positions and are routinely substituted for one another on drawings. They differ mainly in nickel content, in silicon, and in whether the design is governed by creep strength or by atmosphere attack.

Where atmosphere attack governs the design, specify RA333. Where applied load governs, specify Inconel 617 or Haynes 230. Where neither governs, Alloy 330 or 800H is the lower-cost option. Comparison compiled by Jiangyin Jiangnan Metal Co., Ltd. from published alloy literature. Verify against the current producer data sheet before finalising a design.

RA333 equivalent designations and standards

There is no ASTM specification written specifically for N06333 forgings. Open-die forgings are ordered to ASTM B719 or AMS 5717 chemistry, with mechanical acceptance values and NDT class stated on the purchase order. RA333 does not carry maximum allowable stresses in the ASME Boiler and Pressure Vessel Code and must not be specified for code-stamped pressure-retaining components. For those duties use Alloy 800H/800HT or Inconel 617.

Trademark notice. RA333® and RA 333® are registered trademarks of Rolled Alloys, Inc. Material made by that company and sold under that brand is theirs. Material produced by Jiangyin Jiangnan Metal Co., Ltd. is correctly described as UNS N06333 / W.Nr. 2.4608 to ASTM B719 or AMS 5717, the same generic chemistry manufactured independently. We are not affiliated with, sponsored by, or endorsed by the trademark holder, and the mark is used here solely to identify the equivalent material specification.

RA333 forgings we produce

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory. Every item below is forged to the customer's drawing or dimensional sketch. There is no fixed catalogue, no tooling charge and no minimum order quantity by piece.

Size and weight capability

Machining allowance is normally 6–20 mm per surface depending on section size, unless your drawing states otherwise. Finish-machined parts to print are also supplied. Plant equipment: 1 t, 3 t, 5 t and 9 t open-die forging hammers, a 5,000 t hydraulic press, and 3 m and 6 m seamless ring rolling mills.

How we make RA333 forgings

1. Melting

   UNS N06333 stock is vacuum induction melted, with ESR remelting added where the customer specification or the service condition calls for improved cleanliness and reduced segregation.

2. Billet verification

   Heat chemistry is confirmed by spectrometer against the N06333 limits, including the 0.75–1.50% silicon range, before any material is heated.

3. Open-die forging

   Forged on hydraulic presses and hammers with a controlled reduction ratio to close porosity and develop a wrought grain flow that follows the part contour. Rings are ring-rolled seamless. The hot-working window for RA333 is narrow and the part is reheated frequently.

4. Solution annealing

   Heated into the solution range and rapidly cooled to return carbides to solution and restore corrosion resistance. RA333 is solid-solution strengthened and is not age hardened. No ageing cycle is applied.

5. Rough or finish machining

   Turned, bored, drilled and faced to your drawing, with agreed machining allowance or to final dimensions.

6. Non-destructive testing

   Ultrasonic examination to EN 10228-3, SEP 1921, ASTM A388 or your nominated class. Liquid penetrant and dimensional inspection as required.

7. Certification and despatch

   EN 10204 3.1 mill certificate as standard; 3.2 with third-party witness (TÜV, BV, LR, SGS, DNV) on request. Marked, preserved and packed for sea or air freight.

Where RA333 forgings are used

These positions are governed by atmosphere and thermal cycling rather than by applied load. RA333 resists carbon pickup, withstands repeated quenching without cracking, and does not suffer polythionic acid stress-corrosion cracking when a plant is shut down and cools through the dew point, which is a common failure mode for austenitic stainless hardware in refinery service.

Welding and machining RA333

Welding

• Weld with matching-composition UNS N06333 bare wire, or matching coated electrodes.
• Do not preheat.
• Hold the interpass temperature below 100 °C (212 °F).
• Use reinforced stringer beads rather than wide weave passes.
• Post-weld heat treatment is not normally required for the alloy itself, although the design code or the customer specification may call for one.

Machining

• Machinability rating is 12–15% of AISI B1112, appreciably harder to cut than austenitic stainless steel.
• Turn at 20–25 sfm (6–8 m/min) with high-speed steel tooling. Carbide allows higher speeds on rigid setups.
• Use positive rake, heavy feeds and continuous cuts. The alloy work hardens rapidly, so dwelling or rubbing glazes the surface and shortens tool life.
• Rigid fixturing and generous coolant flood are essential on thin sections.
• Order forgings close to net shape to reduce machining cost. Rough-machined and finish-machined parts are quoted alongside as-forged.

Testing, inspection and certification

• Chemical analysis. Spectrometric heat analysis and, on request, product analysis on the finished forging.
• Mechanical testing. Room-temperature tensile, yield and elongation as standard; elevated-temperature tensile, stress-rupture and impact testing to your specification.
• Grain size. Determined per ASTM E112 where the order requires it.
• Ultrasonic testing. EN 10228-3, SEP 1921 Class C/D/E, ASTM A388 or customer class.
• Surface NDT. Liquid penetrant examination per ASTM E165 / ASME V Article 6.
• Intergranular corrosion. ASTM A262 practice as agreed.
• Certification. EN 10204 3.1 as standard; EN 10204 3.2 witnessed by TÜV, BV, LR, SGS or DNV on request. Full heat traceability and hard stamping.

Request a quotation for RA333 forgings

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