Seamless rolled rings
Ring-rolled with no weld seam. Rectangular or profiled section, for furnace retorts, muffle end rings and casing joints.
UNS N06025 at a glance
Reference values for design screening. The mill test certificate issued with each forging governs acceptance.
- Grade
- UNS N06025, also written Alloy 602 CA, Nicrofer® 6025 HT
- UNS number
- N06025
- Werkstoff / DIN
- 2.4633 / NiCr25FeAlY
- Alloy family
- Nickel-chromium-iron, austenitic, carbide strengthened, not age hardened
- Forging standard
- ASTM B564 / ASME SB-564
- Delivery condition
- Solution annealed approx. 1220 °C, rapid cooled
- Required grain size
- ≥ 70 µm for published creep values
- Max service, air
- 1200 °C (2192 °F), non-pressure parts
- Max pressure service
- 899 °C ASME I · 982 °C ASME VIII-1 · 1150 °C VdTÜV 540
- Density
- 7.93 g/cm³ (0.287 lb/in³)
- Melting range
- 1340–1400 °C (2444–2552 °F)
- Room-temp minima
- Rm ≥ 675 MPa · Rp0.2 ≥ 270 MPa · A ≥ 30%
- Matching filler
- FM 602 CA, 2.4649, S Ni 6025, AWS ERNiCrFe-12
- Certification
- EN 10204 3.1 standard, 3.2 third-party witnessed on request
- Forged by
- Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China
- Lead time
- Typically 25–45 days depending on size and melt availability
What UNS N06025 is, and when to specify it
UNS N06025 (Alloy 602 CA) is specified when a part must carry load at metal temperatures above roughly 1000 °C, or when the oxide scale must not spall off into the process, or when the atmosphere is carburising.
Three things in the chemistry account for how the alloy behaves. All three are visible in the composition table below.
Aluminium at 1.8–2.4%. This is roughly double the aluminium in Alloy 601 and it changes the nature of the protective scale. Under the outer chromia layer a continuous, tightly bonded alumina layer forms. Alumina grows slowly and, unlike a thick chromia scale, it stays attached through repeated heating and cooling. That is why UNS N06025 is chosen for cyclic furnace duty and for processes where flaking oxide would contaminate the product.
Carbon at 0.15–0.25%. This is very high for a corrosion-resistant nickel alloy and it is intentional. Primary M23C6 and M7C3 carbides precipitate on solidification and remain stable at temperature, pinning the structure and carrying creep load above 1000 °C where solid-solution alloys have very little strength left. The trade-off is that the alloy is not intended for aqueous corrosion service.
Yttrium 0.05–0.12% and zirconium 0.01–0.10%. Yttrium is a reactive-element addition that improves adhesion of the oxide scale to the metal. Zirconium restrains grain coarsening, which is what lets the alloy be used above 982 °C without losing its structure.
Choose UNS N06025 over Alloy 601 when the duty is cyclic. Choose it over Alloy 800HT when metal temperature exceeds about 982 °C. Choose it over both when the atmosphere is carburising or when metal dusting is the failure mode.
The face-centred cubic matrix means the alloy has no ductile-to-brittle transition and stays tough at sub-zero temperature. Below about 800 °C some γ′ precipitation can occur, and between 600 and 750 °C the material is susceptible to stress-relaxation cracking, This is handled by a stabilisation anneal. See forging, heat treatment and welding.
Chemical composition of UNS N06025
Composition limits in weight percent for UNS N06025 / W.Nr. 2.4633. The three highlighted rows are the additions that distinguish this alloy from ordinary nickel-chromium heat-resisting grades.
| Element | Min % | Max % | Role in the alloy |
|---|---|---|---|
| Nickel (Ni) | balance | – | Austenitic matrix; carries the alloy’s high-temperature stability |
| Chromium (Cr) | 24.0 | 26.0 | Forms the outer chromia scale; resists oxidation and sulfidation |
| Iron (Fe) | 8.0 | 11.0 | Cost balance; kept low enough not to harm oxidation resistance |
| Carbon (C) | 0.15 | 0.25 | Deliberately high. Forms M23C6 / M7C3 carbides that carry creep load |
| Aluminium (Al) | 1.8 | 2.4 | Builds the adherent alumina sub-layer that survives thermal cycling |
| Titanium (Ti) | 0.10 | 0.20 | Ties up nitrogen; assists structural stability |
| Yttrium (Y) | 0.05 | 0.12 | Reactive element; anchors the oxide scale to the substrate |
| Zirconium (Zr) | 0.01 | 0.10 | Restrains grain coarsening above 982 °C |
| Manganese (Mn) | – | 0.15 | Residual limit under the UNS listing |
| Silicon (Si) | – | 0.50 | Deoxidiser |
| Copper (Cu) | – | 0.10 | Residual limit |
| Phosphorus (P) | – | 0.020 | Kept low for hot workability |
| Sulfur (S) | – | 0.010 | Kept low for hot workability and scale adhesion |
Source: Jiangyin Jiangnan Metal Co., Ltd., UNS N06025 forging specification, compiled from ASTM B564 / ASME SB-564 and DIN EN 10302 for material 2.4633. Manganese is listed at 0.50% maximum in some European specifications and 0.15% maximum under the UNS listing; we forge to the tighter 0.15% limit unless the order states otherwise. Every heat is supplied with a ladle analysis on the mill certificate, and product analysis on the finished forging can be added on request.
Mechanical properties of UNS N06025 forgings
Minimum short-term properties, solution annealed
These are minima, not typical values, for material solution annealed at approximately 1220 °C with a grain size of 70 µm or coarser. They apply to bar and forgings up to 100 mm section; properties for heavier sections are agreed at order.
| Temperature °C | Temperature °F | Rp0.2 MPa | Rp0.2 ksi | Rm MPa | Rm ksi | Elongation A % |
|---|---|---|---|---|---|---|
| 20 | 68 | 270 | 39.2 | 675 | 97.9 | 30 |
| 100 | 212 | 240 | 34.8 | 650 | 94.3 | 30 |
| 200 | 392 | 220 | 31.9 | 625 | 90.6 | 30 |
| 300 | 572 | 200 | 29.0 | 600 | 87.0 | 30 |
| 400 | 752 | 190 | 27.6 | 580 | 84.1 | 30 |
| 500 | 932 | 180 | 26.1 | 560 | 81.2 | 30 |
| 600 | 1112 | 175 | 25.4 | 520 | 75.4 | 30 |
| 700 | 1292 | 170 | 24.7 | 420 | 60.9 | 30 |
Source: Jiangyin Jiangnan Metal Co., Ltd., compiled from VdTÜV material data sheet 540 for 2.4633 / NiCr25FeAlY, solution-annealed condition, grain size ≥ 70 µm.
Impact toughness
ISO V-notch impact values at 20 °C in the solution-annealed condition, grain size ≥ 70 µm:
- Longitudinal: greater than 69 J/cm²
- Transverse: greater than 56 J/cm²
Because the matrix is face-centred cubic, UNS N06025 has no ductile-to-brittle transition and stays tough down to cryogenic temperature. Long exposure in the 600–750 °C range reduces room-temperature toughness through carbide and γ′ precipitation; specify a stabilisation anneal if the part will be re-tested after service.
Creep and stress-rupture data
Above about 625 °C the design of a UNS N06025 part is set by creep, not by tensile strength. Below that temperature the short-term values in Table 2 govern.
The table below gives the 1% creep limit and the creep rupture strength for 10,000-hour and 100,000-hour lives. A safety factor of S = 1.5 is normally applied to the Rp1.0 creep limit for component design.
| Temp. °C | Temp. °F | Rp1.0 / 104 h | Rp1.0 / 105 h | Rm / 104 h | Rm / 105 h |
|---|---|---|---|---|---|
| 650 | 1202 | 185 | 120 | 215 | 140 |
| 700 | 1292 | 132 | 85 | 155 | 100 |
| 750 | 1382 | 75 | 45 | 90 | 48 |
| 800 | 1472 | 32 | 16.5 | 42 | 20 |
| 850 | 1562 | 19 | 9.7 | 26 | 14 |
| 900 | 1652 | 13 | 7.5 | 18 | 9.7 |
| 950 | 1742 | 8.8 | 5.4 | 12.8 | 6.7 |
| 1000 | 1832 | 5.8 | 3.4 | 9.0 | 4.5 |
| 1050 | 1922 | 3.6 | 1.9 | 6.2 | 3.1 |
| 1100 | 2012 | 2.2 | 1.0 | 4.4 | 2.1 |
| 1150 | 2102 | 1.0 | 0.4 | 3.0 | 1.4 |
| 1200 | 2192 | – | – | 2.2 | 0.8 |
Source: Jiangyin Jiangnan Metal Co., Ltd., compiled from VdTÜV material data sheet 540 for 2.4633, base material solution annealed at approximately 1220 °C with grain size ≥ 70 µm. Values are typical, not guaranteed minima, and assume the grain size requirement is met. Weld metal and heat-affected zones must be assessed separately.
At 1000 °C, UNS N06025 still carries about 4.5 MPa for a 100,000-hour rupture life. Buyers specify the alloy for that residual strength at red heat, not for its room-temperature figures.
Physical properties of UNS N06025
Density 7.93 g/cm³ (0.287 lb/in³) at 25 °C. Melting range 1340–1400 °C (2444–2552 °F). Relative magnetic permeability at 20 °C is 1.01 maximum, so the alloy is effectively non-magnetic.
| Temp. °C | Specific heat J/kg·K | Thermal conductivity W/m·K | Electrical resistivity µΩ·cm | Modulus of elasticity GPa | Mean expansion 20–T, 10−6/K |
|---|---|---|---|---|---|
| 20 | 447 | 10.4 | 123 | 215 | – |
| 100 | 465 | 12.3 | 125 | 209 | 14.15 |
| 200 | 488 | 14.0 | 126 | 201 | 14.27 |
| 300 | 501 | 15.5 | 128 | 197 | 14.42 |
| 400 | 514 | 16.9 | 129 | 192 | 14.63 |
| 500 | 516 | 18.4 | 131 | 189 | 14.90 |
| 600 | 517 | 20.1 | 133 | 185 | 15.00 |
| 700 | 550 | 22.0 | 132 | 169 | 15.18 |
| 800 | 583 | 24.1 | 131 | 154 | 16.00 |
| 900 | 603 | 26.2 | 131 | 137 | 16.71 |
| 1000 | 626 | 28.2 | 132 | 118 | 17.31 |
| 1100 | 631 | 29.7 | – | 102 | 17.91 |
| 1200 | 636 | 30.6 | – | – | – |
Source: Jiangyin Jiangnan Metal Co., Ltd., compiled from published physical property data for 2.4633 / N06025. Electrical resistivity is also quoted as 1.15–1.23 µΩ·m depending on source and condition. Values are nominal and are for design screening.
Two numbers matter for detail design. The mean thermal expansion of about 17.3 × 10−6/K at 1000 °C is high. Allow for it in furnace fixture clearances and in bolted or welded joints to lower-expansion materials. Thermal conductivity of 10.4 W/m·K at room temperature is roughly one fifth that of carbon steel, so section heating and welding heat input both behave differently from steel practice.
Oxidation, carburisation and metal dusting behaviour
The defining property of UNS N06025 is that its oxide scale stays attached. A chromia layer forms first, then a continuous alumina layer develops beneath it, anchored by the yttrium addition.
In cyclic oxidation testing, where samples are repeatedly heated and cooled, UNS N06025 shows among the lowest mass losses of the commercial high-temperature alloys, and it outperforms Alloy 601 across the whole application range to 1200 °C. The practical consequences are:
- Scale does not flake into the process. This matters in heat-treatment furnaces, glass and enamel plant, and any operation where exfoliated oxide would mark or contaminate the product.
- Carburisation resistance is high. The chromium and aluminium content gives better carburisation resistance than Alloy 601, so the alloy suits reformers, cracking furnaces and carburising heat-treatment equipment.
- Metal dusting resistance is improved relative to Alloy 601, which matters in syngas, methanol and hydrogen plant operating in the 400–800 °C catastrophic carburisation window.
- Oxidising sulfur-bearing atmospheres are tolerated. Reducing sulfidising atmospheres remain aggressive to all nickel-base alloys and should be assessed separately.
UNS N06025 is a high-temperature alloy, not a wet-corrosion alloy. For aqueous acid or chloride service specify Hastelloy C-276, Inconel 625 or Incoloy 825 instead.
UNS N06025 equivalent designations and trade names
| System | Designation |
|---|---|
| UNS (USA) | N06025 |
| Werkstoff Nr. (Germany) | 2.4633 |
| EN / DIN name | NiCr25FeAlY (also written NiCr25Fe10AlY) |
| EN standard | DIN EN 10302; DIN 17742 / 17750 / 17752 |
| VdTÜV | Material data sheet 540 |
| Trade names | Alloy 602 CA, Nicrofer® 6025 HT (VDM Metals), RA 602 CA® (Rolled Alloys), Alloy 603 GT |
| Welding filler | 2.4649 · EN ISO 18274 S Ni 6025 · AWS A5.14 ERNiCrFe-12 · FM 602 CA |
| Fittings designation | ASTM B366 WPV602 (wrought) / CRV602 (cast-to-wrought) |
| JIS (Japan) | No direct equivalent registered |
| GB (China) | No direct national equivalent; order to UNS N06025 / 2.4633 |
Nicrofer is a registered trademark of VDM Metals; RA 602 CA is a registered trademark of Rolled Alloys. Jiangyin Jiangnan Metal Co., Ltd. is not affiliated with, sponsored by or endorsed by those trademark holders. Material produced by us is correctly described as UNS N06025 / W.Nr. 2.4633 / NiCr25FeAlY, the same generic specification. Where a code case or design registration is involved, order to the UNS number and confirm equivalence against the mill certificate.
Standards and pressure code approvals
| Product form | ASTM | ASME |
|---|---|---|
| Forgings (our core product) | B564 | SB-564 |
| Rod, bar and wire | B166 | SB-166 |
| Plate, sheet and strip | B168 | SB-168 |
| Seamless pipe and tube | B167, B163 | SB-167, SB-163 |
| Welded tube | B516 | SB-516 |
| Welded pipe | B517 | SB-517 |
| Fittings | B366 (WPV602 / CRV602) | SB-366 |
| Forged flanges, fittings, valves and parts | B462 | SB-462 |
| Billets and bars for reforging | B472 | SB-472 |
Pressure-retaining service limits
UNS N06025 is approved for pressure equipment, and the ceiling depends on which code the design is registered under:
- −10 to 1150 °C (14 to 2102 °F) under VdTÜV material data sheet 540. This is the widest approved range.
- Up to 899 °C (1650 °F) under ASME Boiler and Pressure Vessel Code, Section I.
- Up to 982 °C (1800 °F) under ASME Boiler and Pressure Vessel Code, Section VIII Division 1.
- Up to 1200 °C (2192 °F) for non-pressure parts such as furnace fixtures, radiant tubes and rollers. Here the limit is set by oxidation and applied load, not by code.
Source: Jiangyin Jiangnan Metal Co., Ltd., compiled from ASME BPVC Sections I and VIII Division 1 and VdTÜV material data sheet 540. Confirm the current edition and any code case with your Authorised Inspector before design registration.
Forging, heat treatment, welding and machining
UNS N06025 forges without special difficulty provided the temperature window is respected and the material is kept clean. Sulfur, phosphorus and low-melting-point metals from marking paint, grease or fuel will damage it during heating.
Hot forging
Work between 1200 and 900 °C (2192 and 1652 °F). Charge the billet into a furnace already at working temperature rather than heating it with the furnace. Once the section has equalised, forge within the window and reheat immediately if the workpiece falls below 900 °C. Forging below the lower limit risks cracking. Cool rapidly after hot work, in water or with air nozzles. A heat treatment after forging is required to restore optimum properties.
Directly fired furnaces should burn low-sulfur fuel, natural gas below 0.1% sulfur or heating oil at 0.5% maximum, with a slightly oxidising atmosphere. Reducing or alternating atmospheres should be avoided, and flames must not impinge on the workpiece.
Solution annealing
Solution anneal at approximately 1220 °C (2228 °F). The purpose is to develop a grain size of 70 µm or coarser, which is the condition all published creep values assume. Anneal too low and the grain stays fine, and the part will not reach the creep strength the design relies on. UNS N06025 is not age hardened, so there is no ageing step.
Soak time begins when the section has equalised at temperature:
- Thickness d ≤ 10 mm: t = d × 3 min/mm
- Thickness d = 10–20 mm: t = 30 min + (d − 10) × 2 min/mm
- Thickness d > 20 mm: t = 50 min + (d − 20) × 1 min/mm
Longer soaks are far less damaging than short ones. If further processing follows the anneal, cool quickly in water or forced air. If the anneal is the last operation before service, a slower cool reduces distortion.
Stabilisation annealing
Solution-annealed UNS N06025 is susceptible to stress-relaxation cracking between 600 and 750 °C. If the part will spend more than about 100 hours in that band, stabilise it for at least 3 hours at 950 °C (1742 °F) before service, and again before any repair welding.
Heating and cooling rates for the stabilisation anneal are not critical, but should not be so fast that they distort the part. Stabilisation can be carried out either before or after welding.
Cold forming
Cold work from the solution-annealed condition. UNS N06025 work hardens faster than austenitic stainless steel, so size the forming equipment accordingly and use intermediate anneals for heavy work. Re-solution anneal once deformation exceeds about 7%. When bending or trimming plate, keep the inner radius greater than three times the thickness.
Welding
UNS N06025 is welded by TIG, MIG, plasma and manual metal arc. Use a matching filler: FM 602 CA (W.Nr. 2.4649), EN ISO 18274 S Ni 6025, AWS A5.14 ERNiCrFe-12.
- Interpass temperature below 120 °C (248 °F); preheat is not normally required.
- Heat input limits: TIG and GMAW 8 kJ/cm maximum, manual metal arc 7 kJ/cm, plasma 10 kJ/cm. Stringer beads, not weave.
- Included angle 60–70° for butt welds, root gap 1–3 mm, because the weld pool is more viscous and the shrinkage greater than in stainless steel.
- Shielding gas argon with 2% nitrogen for TIG and plasma; ensure root protection.
- Degrease base metal and filler with acetone. Stainless steel brushes only, and a work area separated from carbon steel.
- Strike the arc only in the weld preparation, never on the component surface.
Machining
Machine in the solution-annealed condition. Because the alloy work hardens, use a low cutting speed with a moderate feed, keep the tool engaged at all times, and take a depth of cut that reaches below the previously hardened layer. Flood with water-based emulsion coolant. The same coolants used for austenitic stainless steel are suitable.
Descaling and pickling
The protective oxide on UNS N06025 bonds more tightly than the scale on stainless steel. Grind with fine abrasive belts or discs, avoiding grinding burn. If pickling in nitric-hydrofluoric mixtures is specified, break down the oxide first by abrasive blasting or fine grinding, keep pickling times short and control the bath temperature, otherwise intergranular attack can follow.
Engineering tools for UNS N06025
Six calculators built on the data above. All of them run in your browser. Nothing is sent anywhere and nothing is stored.
1. Forging weight calculator
Net and rough-forged weight at a density of 7.93 g/cm³. Use it to sanity-check a quotation or to budget input material.
Enter dimensions and press Calculate.
2. Solution-anneal soak time
Soak time at 1220 °C from the ruling section, using the standard 2.4633 schedule. Time starts after the section has equalised at temperature.
Enter a thickness and press Calculate.
3. Creep design stress lookup
Interpolates Table 3 for any temperature between 650 and 1200 °C and applies the S = 1.5 safety factor to the 1% creep limit.
Enter a temperature and press Look up.
4. Service-condition checker
Tells you which code limit applies at your metal temperature and whether a stabilisation anneal is needed.
Enter your service condition and press Check.
5. Designation lookup
Type any name, number or standard from your drawing (602 CA, 2.4633, Nicrofer, NiCr25FeAlY, B564, ERNiCrFe-12) to confirm it is the same material.
Enter a designation and press Check.
6. RFQ builder
Fills in a complete enquiry and opens it in your mail client, addressed to sales@steelforgepieces.com. Nothing is submitted from this page.
Fill in the fields and press Build.
UNS N06025 forgings we produce
Every item is forged to the customer’s drawing or dimensional sketch. Open-die work needs no dies, so there is no tooling charge, no minimum piece quantity, and one-off or prototype orders are economic.
Forged flanges
Weld neck, slip-on, blind, long weld neck and orifice flanges to ASME B16.5 / B16.47 or to drawing.
Round bars and billets
Forged and peeled or rough turned, cut to length, for machined furnace hardware and roller journals.
Discs and blanks
Upset forged discs for tube sheets, covers, blind ends and rotating parts.
Shafts and spindles
Straight, stepped and eccentric shafts, including kiln roller and furnace roller shafts.
Sleeves and bushings
Hollow forged, trepanned or bored, thin or heavy wall, for burner and radiant tube assemblies.
Tube sheets
Forged and drilled tube sheets for reformers and high-temperature exchangers.
Hollow bars and forged pipe
Trepanned or expanded hollows for heavy-wall pipe sections and radiant tube stubs.
Valve components
Bodies, bonnets, seat rings, stems and gate blanks for high-temperature service.
Nozzles and manifolds
Forged nozzle bodies, headers, blocks and custom shapes to print.
Size and weight capability
| Product form | Dimensional range | Unit weight |
|---|---|---|
| Seamless rolled rings | OD 200–3,000 mm, height to 800 mm | 20–8,000 kg |
| Round bars | Ø80–800 mm, length to 6,000 mm | 20–6,000 kg |
| Discs and tube sheets | Ø200–2,500 mm, thickness to 600 mm | 30–10,000 kg |
| Shafts, sleeves and blocks | to 6,000 mm long | to 10,000 kg |
| Flanges | to 2,500 mm OD, to drawing or ASME B16.5 / B16.47 | to 6,000 kg |
Machining allowance is normally 6–20 mm per surface depending on section size, unless the drawing states otherwise. Finish-machined parts to print are also supplied. Plant: 1, 3, 5 and 9 tonne open-die hammers, a 5,000 tonne hydraulic press, and 3 m and 6 m seamless ring rolling mills.
How UNS N06025 forgings are made
- Melting. UNS N06025 stock is melted by EAF plus AOD or VOD, with ESR remelting available where the specification or the service calls for improved cleanliness and reduced segregation.
- Heat verification. Ladle chemistry is checked by optical emission spectrometer against the ASTM B564 limits for N06025, including the aluminium, yttrium and zirconium windows that give the alloy its oxidation resistance, before any material is heated.
- Open-die forging. Worked between 1200 and 900 °C on hydraulic presses and hammers, reheating whenever the billet drops below 900 °C, with a controlled reduction ratio to close porosity and develop grain flow that follows the part contour. Rings are ring-rolled seamless.
- Solution annealing. Charged into a furnace already at temperature, annealed at approximately 1220 °C to develop a grain size of 70 µm or coarser, then cooled rapidly in water or forced air. A stabilisation anneal at 950 °C for 3 hours is added when the part will operate between 600 and 750 °C.
- Rough or finish machining. Turned, bored, drilled and faced to drawing with the agreed machining allowance, or to final dimensions.
- Non-destructive testing. Ultrasonic examination to EN 10228-3, SEP 1921, ASTM A388 or the nominated class, with liquid penetrant examination and dimensional inspection as required.
- Certification and despatch. EN 10204 3.1 mill certificate as standard, EN 10204 3.2 with third-party witness on request, then marking, preservation and packing for sea or air freight.
Where UNS N06025 forgings are used
| Industry | Components forged in UNS N06025 |
|---|---|
| Industrial furnaces and heat treatment | Kiln and furnace roller shafts and journals, muffle and retort end rings, radiant tube stubs and flanges, fixture and basket hardware, rotary and shaft furnace components |
| Petrochemical and refining | Reformer outlet manifold forgings, pigtail connections, cracking furnace hardware, forged nozzles and flanges in carburising service |
| Hydrogen, ammonia and methanol plant | Synthesis and reformer components, transfer line forgings, tube sheets, parts exposed to metal dusting conditions |
| Power generation and waste-to-energy | High-temperature header and casing forgings, valve bodies and seat rings, hangers and supports in the hottest zones |
| Glass, enamel and ceramics | Rings, rollers and fixtures where flaking oxide would mark the product; glass melting pot hardware including vitrification of radioactive waste |
| Automotive and e-fuel | Exhaust system components, diesel glow plug parts, syngas cooling hardware in synthetic fuel production |
| Chemical processing | Calciner and incinerator internals, catalyst grid supports, high-temperature ducting flanges |
All of these duties share a metal temperature above roughly 1000 °C, together with thermal cycling, a carburising atmosphere, or an intolerance for oxide contamination. Where none of those apply, a cheaper grade is usually the right answer. See the comparison below.
UNS N06025 compared with Alloy 601, 800HT, Haynes 230 and Alloy 693
| Criterion | UNS N06025 / 602 CA | Alloy 601 / N06601 | Alloy 800HT / N08811 | Haynes 230 / N06230 | Alloy 693 / N06693 |
|---|---|---|---|---|---|
| Base | Ni-Cr-Fe | Ni-Cr-Fe | Fe-Ni-Cr | Ni-Cr-W-Mo | Ni-Cr-Al |
| Chromium % | 24–26 | 21–25 | 19–23 | 20–24 | 27–31 |
| Aluminium % | 1.8–2.4 | 1.0–1.7 | 0.15–0.60 | 0.2–0.5 | 2.5–4.0 |
| Carbon % | 0.15–0.25 | 0.10 max | 0.06–0.10 | 0.05–0.15 | 0.15 max |
| Practical service ceiling | 1200 °C | approx. 1150 °C | approx. 1000 °C | approx. 1150 °C | approx. 1150 °C |
| Creep strength above 1000 °C | Highest of this group | Moderate | Low | High | Moderate |
| Cyclic oxidation / scale adhesion | Excellent, Y-anchored alumina | Good | Moderate | Good, La-stabilised | Excellent |
| Carburisation and metal dusting | Very good | Good | Moderate | Good | Best in class for metal dusting |
| Relative cost per kg | High | Medium | Lowest | Highest | High |
| Specify it when | Load at 1000–1200 °C, cyclic duty, or scale must not spall | General oxidation resistance below 1100 °C at lower cost | Pressure parts to about 982 °C where cost dominates | Long-term creep strength with solid-solution stability | Metal dusting is the governing failure mode |
Source: Jiangyin Jiangnan Metal Co., Ltd. selection guidance, compiled from published alloy specifications. Composition ranges are nominal and should be confirmed against the governing standard for each grade. Service ceilings are for non-pressure parts; pressure-retaining limits are lower and are set by the design code.
We forge all five grades. See Inconel 601 forgings, Alloy 800HT forgings, Haynes 230 forgings and Inconel 693 forgings.
Testing, inspection and certification
- Chemical analysis. Spectrometric heat analysis as standard; product analysis on the finished forging on request.
- Mechanical testing. Room-temperature tensile and elongation to ASTM B564; elevated-temperature tensile, stress-rupture and impact testing to your specification.
- Grain size. Determined to ASTM E112. For UNS N06025 the target is 70 µm or coarser, because the published creep values depend on it.
- Ultrasonic testing. EN 10228-3, SEP 1921 Class C, D or E, ASTM A388, or your nominated class.
- Surface NDT. Liquid penetrant examination to ASTM E165 or ASME Section V Article 6.
- Metallography. Microstructure and carbide distribution examination where the order requires it.
- 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.
Jiangyin Jiangnan Metal Co., Ltd. operates an ISO 9001:2015 quality management system. Testing equipment on site includes universal tensile testing machines, impact testing machines, hardness testers, a metallographic microscope, magnetic particle equipment and ultrasonic flaw detection.
Frequently asked questions about UNS N06025
What is UNS N06025?
UNS N06025 is a high-carbon nickel-chromium-iron alloy, also sold as Alloy 602 CA, Nicrofer 6025 HT and W.Nr. 2.4633, containing 24–26% chromium, 8–11% iron, 1.8–2.4% aluminium, 0.15–0.25% carbon and micro-additions of yttrium and zirconium. The aluminium forms a tightly adherent alumina layer beneath the chromia scale, and the high carbon precipitates chromium carbides that carry creep load, which together allow continuous service to 1200 °C (2192 °F).
What is the maximum service temperature of Alloy 602 CA?
For non-pressure parts such as furnace fixtures and radiant tubes, UNS N06025 is used continuously to 1200 °C (2192 °F). For pressure-retaining components the code limits are lower: 899 °C (1650 °F) under ASME Boiler and Pressure Vessel Code Section I, 982 °C (1800 °F) under Section VIII Division 1, and −10 to 1150 °C under VdTÜV material data sheet 540.
Is UNS N06025 the same as Alloy 602 CA and Nicrofer 6025 HT?
Yes. UNS N06025, Alloy 602 CA, Nicrofer 6025 HT, W.Nr. 2.4633, NiCr25FeAlY and RA 602 CA all identify the same alloy specification. Nicrofer is a registered trademark of VDM Metals and RA 602 CA of Rolled Alloys. Order to UNS N06025 and ASTM B564 so the requirement is unambiguous regardless of the producer.
What heat treatment is correct for UNS N06025 forgings?
Solution annealing at approximately 1220 °C (2228 °F) followed by rapid cooling. The high anneal temperature develops a grain size of 70 µm or coarser, which is what produces the published creep strength. UNS N06025 is not age hardened. If the part will operate between 600 and 750 °C for more than about 100 hours, add a stabilisation anneal at 950 °C for at least three hours to avoid stress-relaxation cracking.
Which standards cover UNS N06025 forgings?
Forgings are supplied to ASTM B564 / ASME SB-564. Related product forms are covered by ASTM B166 (rod, bar and wire), B168 (plate, sheet and strip), B167 and B163 (seamless pipe and tube), B366 (fittings), B462 (forged flanges and fittings), B472 (billets and bars for reforging), and B516 and B517 (welded tube and pipe). European coverage is DIN EN 10302 and VdTÜV material data sheet 540 for material number 2.4633.
How does Alloy 602 CA compare with Alloy 601 and Alloy 800HT?
Alloy 602 CA carries more chromium and roughly twice the aluminium of Alloy 601, so its alumina scale survives thermal cycling better, and its 0.15–0.25% carbon gives far higher creep strength above 1000 °C. Alloy 800HT is iron-based and cheaper per kilogram but is normally limited to about 982 °C under code. Choose Alloy 602 CA where the metal temperature exceeds roughly 1000 °C, where the atmosphere is carburising, or where oxide spallation would contaminate the product.
Can UNS N06025 be welded?
Yes. UNS N06025 is welded by TIG, MIG, plasma and manual metal arc using a matching filler: VDM FM 602 CA, W.Nr. 2.4649, EN ISO 18274 S Ni 6025, AWS A5.14 ERNiCrFe-12. Keep interpass temperature below 120 °C and heat input low, around 8 kJ/cm maximum for TIG and GMAW. Components that will run between 600 and 750 °C should be stabilisation annealed at 950 °C before or after welding, and before any repair welding.
What sizes of UNS N06025 forgings can you supply?
Jiangyin Jiangnan Metal Co., Ltd. forges UNS N06025 seamless rolled rings from 200 to 3,000 mm outside diameter, round bars from 80 to 800 mm diameter, discs and tube sheets from 200 to 2,500 mm diameter, and shafts and sleeves up to 6,000 mm long, with single-piece weights up to about 10,000 kg. Every part is made to the customer drawing; open-die forging carries no tooling charge and no minimum piece quantity.
Do UNS N06025 forgings come with a material certificate?
Yes. Every forging ships with an EN 10204 3.1 mill test certificate showing heat number, chemical analysis, mechanical test results, grain size, heat treatment record and NDT results. EN 10204 3.2 certification witnessed by TÜV, BV, LR, SGS or DNV is available on request at the time of order.
Who supplies open-die forged UNS N06025 parts in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. It forges UNS N06025 (Alloy 602 CA) into seamless rolled rings, flanges, round bars, discs, shafts, sleeves, bushings and tube sheets to ASTM B564, solution annealed and certified to EN 10204 3.1 or 3.2, and exports worldwide. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.
How long does a UNS N06025 forging take to produce?
Lead time depends on whether the grade is in raw stock and on the size of the forging. Simple rings and discs from stock material typically run 25–45 days. Parts needing a new melt, ESR remelting, heavy machining or third-party witnessed inspection take longer. Send the drawing and we confirm a firm date with the quotation.
Request a quotation for UNS N06025 forgings
Send a drawing, a sketch, or just the dimensions and quantity. We quote open-die forgings in UNS N06025 with no tooling charge and no piece minimum. Useful details if you have them: grade and standard (UNS N06025 / Alloy 602 CA / ASTM B564), product form, dimensions with machining allowance, quantity, delivery condition, service temperature and atmosphere, NDT class, certificate type and required date.
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Business
- Open-die forging factory
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone / WhatsApp
- +86 189 2135 9659
- Website
- www.steelforgepieces.com