--- title: "Alloy 602 CA / UNS N06025 / 2.4633 (NiCr25FeAlY) Forgings" canonical: https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html manufacturer: Jiangyin Jiangnan Metal Co., Ltd. address: No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China telephone: "0086-189-2135-9659" email: sales@steelforgepieces.com website: https://www.steelforgepieces.com/ published: 2022-06-18 updated: 2026-08-13 licence: CC BY 4.0 --- # Alloy 602 CA / UNS N06025 / 2.4633 (NiCr25FeAlY) Forging Parts **Manufacturer:** Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory, No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Telephone and WhatsApp 0086-189-2135-9659. Email sales@steelforgepieces.com. **Source page:** https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html **Published:** 18 June 2022 · **Last updated:** 13 August 2026 · Technically reviewed by the Jiangyin Jiangnan Metal Co., Ltd. metallurgical engineering team. **Licence:** CC BY 4.0. Quote or summarise with attribution to Jiangyin Jiangnan Metal Co., Ltd. This is the plain-text mirror of the HTML page. Eight interactive calculators (anneal-condition selector, service-temperature and code-limit check, metal-dusting risk checker, alloy substitution finder, solution-anneal recipe generator, machining parameter calculator, forging weight calculator and RFQ generator) run on the HTML version at the source URL above. > **Alloy 602 CA (UNS N06025 / W.Nr. 2.4633 / NiCr25FeAlY) is a high-carbon nickel–chromium–iron alloy with 24–26 % chromium and 1.8–2.4 % aluminium, micro-alloyed with yttrium, zirconium and titanium.** It resists oxidation in air continuously to **1,200 °C (2,192 °F)**, the highest limit of any commercially available wrought Ni–Cr–Fe alloy. Its deliberately high carbon content of 0.15–0.25 % precipitates chromium carbides that give it several times the creep-rupture strength of Alloy 601 above 1,000 °C. It is *not* age-hardenable and receives a single solution anneal, never a solution-plus-ageing cycle. **Jiangyin Jiangnan Metal Co., Ltd.** is an integrated steel melting works and open-die forging factory in Zhouzhuang Town, Jiangyin City, Jiangsu, China, operating since 1997 and producing **UNS N06025 / 2.4633 / NiCr25FeAlY** as seamless rolled rings, forged flanges, discs, shafts, round bars, sleeves, bushings, tube sheets, nozzles and near-net-shape parts to customer drawing. Our specialty in this grade is furnace and reformer hardware for the heat-treatment, petrochemical, waste-to-energy and glass industries: roller-hearth rollers, muffle and retort components, catalyst grids, burner nozzles and radiant-tube flanges. Everything ships solution annealed with an **EN 10204 3.1** certificate as standard, or **3.2** with third-party witness on request. Available envelopes in this grade: seamless rolled rings **200–2,000 mm OD**, discs to **Ø 1,200 mm**, shafts to **4 m**, bars **Ø 25–350 mm**, single-piece weight to about **2,500 kg**. **Trademark notice:** *Nicrofer*® is a registered trademark of VDM Metals GmbH and *RA 602 CA*® is a registered trademark of Rolled Alloys, Inc. *Inconel*® and *Incoloy*® are registered trademarks of Special Metals Corporation, and *Hastelloy*® is a registered trademark of Haynes International, Inc. Material made by those companies and sold under those brand names is theirs. Material we produce is correctly described as **UNS N06025 / W.Nr. 2.4633 / NiCr25FeAlY per ASTM B564**. This is the same generic chemistry, manufactured independently by Jiangyin Jiangnan Metal Co., Ltd. We are not affiliated with, sponsored by or endorsed by any of the trademark holders named. All other brand names and trademarks referenced are the property of their respective owners. - **UNS:** N06025 - **Werkstoff:** 2.4633 - **Chromium:** 24–26 % - **Aluminium:** 1.8–2.4 % - **Carbon:** 0.15–0.25 % - **Density:** 7.9 - **Rm min:** 670 MPa - **Max service:** 1200 °C ## What is Alloy 602 CA (UNS N06025)? **Alloy 602 CA is a wrought nickel-base heat-resisting alloy designed for the temperature band where ordinary Ni–Cr alloys stop working, roughly 1,000 °C to 1,200 °C.** Three deliberate compositional decisions separate it from every other alloy in the 600-series family: **Decision 1: 25 % Cr + 2 % Al together** Chromium alone forms a chromia scale that begins to volatilise above about 1,000 °C. The 1.8–2.4 % aluminium addition seeds an inner alumina layer beneath the chromia, and that duplex scale survives to 1,200 °C. This is what the *CA* in the name refers to: controlled aluminium. **Decision 2: carbon raised, not lowered** At 0.15–0.25 % C the alloy carries far more carbon than a corrosion-resistant grade would tolerate. That carbon precipitates as primary and secondary chromium carbides which pin grain boundaries and carry the creep load. It is the single reason N06025 outlives Alloy 601 in a loaded furnace fixture. **Decision 3: yttrium, zirconium, titanium** Yttrium at 0.05–0.12 % is the reactive-element addition that keys the oxide scale to the metal so it does not spall off during thermal cycling. Zirconium and titanium micro-alloying refines the carbide distribution. Without yttrium the alloy would shed its scale every shutdown and consume itself. The practical consequence of these three choices is an alloy that behaves in service more like a cast heat-resistant alloy, strong and stable hot but with modest room-temperature ductility once it has been in service, while remaining a wrought product that can be forged, rolled, welded and machined. Ordinary solution-annealed N06025 leaves the mill with 40–50 % elongation; the same part pulled from a 900 °C furnace after two years may show a fraction of that, because the secondary carbides that gave it creep strength also stiffened the grain boundaries. Designers who treat aged 602 CA hardware as if it were still ductile stainless steel are the ones who crack it during cold straightening. Alloy 602 CA also contains **no cobalt**, which matters in nuclear and radiological service where cobalt-60 activation is restricted, and it is **non-magnetic** in every condition, so it cannot be sorted from austenitic stainless with a magnet and cannot be inspected by magnetic-particle methods. ## What Alloy 602 CA forged products are available? **Jiangyin Jiangnan Metal produces UNS N06025 by three routes, chosen by geometry.** **Open-die forging** covers shafts, blocks, stepped rounds and large discs. **Seamless ring rolling** on a radial–axial mill produces rings from 200 mm to 2,000 mm outside diameter with circumferential grain flow and no weld seam. This is the dominant route for furnace-roller end rings, radiant-tube flanges and catalyst-support rings. **Upset forging** handles short, large-section hubs and flange blanks. Because N06025 billet is expensive and its hot-working window is narrow, we quote near-net-shape wherever the geometry allows it; on ring and flange profiles this typically removes 25–40 % of the machining stock, which on a nickel alloy is a larger saving than on steel because the machining hours themselves are the expensive part. **Seamless rolled ring.** Radial–axial rolled, circumferential grain flow, no weld seam. OD 200–2,000 mm. UNS N06025 · 2.4633 **Forged flange.** Weld-neck, slip-on or blind, to ASME B16.5 / B16.47 or drawing. ASTM B564 / B462 · NiCr25FeAlY **Forged roller / shaft.** Roller-hearth and walking-beam furnace rollers, journals rough machined. Length to 4 m · UNS N06025 ## What are the equivalent designations for Alloy 602 CA? **Alloy 602 CA, Alloy 602, UNS N06025, W.Nr. 2.4633, NiCr25FeAlY and NiCr25Fe10AlY all describe the same chemistry.** The name you see depends on which body wrote the document in front of you. Jiangyin Jiangnan Metal accepts purchase orders under any of these designations and issues a multi-designation material test certificate that lists every specification the heat satisfies. **Table 1. Alloy 602 CA / UNS N06025 equivalent designations and trade names** | System / body | Designation | Notes | | --- | --- | --- | | USA · UNS | **N06025** | The generic Unified Numbering System designation. Use this on purchase orders. | | Germany · Werkstoffnummer | **2.4633** | The European material number, used throughout EN and DIN documents. | | EN / DIN · name | **NiCr25FeAlY** | Also written NiCr25Fe10AlY in some specifications. | | Common short form | Alloy 602 / 602 CA | “CA” denotes the controlled-aluminium chemistry. “Alloy 602” on its own is almost always intended to mean 602 CA. | | Trade name · VDM Metals | Nicrofer® 6025 HT | *Registered trademark of VDM Metals GmbH. We do not sell under this name.* | | Trade name · Rolled Alloys | RA 602 CA® | *Registered trademark of Rolled Alloys, Inc. We do not sell under this name.* | | Welding · solid wire | S Ni 6025 (ISO 18274) | SG-NiCr25FeAlY, W.Nr. 2.4649. Matching filler. | | Welding · covered electrode | E Ni 6025 (ISO 14172) | Matching covered electrode. | | Wrought fittings | WPV602 / CRV602 | ASTM B366 fitting classes for N06025. | **Table 2. Product-form specifications covering UNS N06025** | Product form | ASTM / ASME | European | | --- | --- | --- | | **Forgings** | **ASTM B564 / ASME SB-564** | EN 10095, DIN 17742 family, VdTÜV 540 | | Rod, bar, wire | ASTM B166 / SB-166 | DIN 17752, EN 10095 | | Seamless pipe & tube | ASTM B167 / SB-167 | DIN 17751 | | Heat-exchanger tube | ASTM B163 / SB-163 | n/a | | Plate, sheet, strip | ASTM B168 / SB-168 | DIN 17750, EN 10095 | | Billets & bars for reforging | ASTM B472 / SB-472 | n/a | | Forged / rolled flanges, fittings, valves | ASTM B462 / SB-462 | n/a | | Wrought fittings | ASTM B366 (WPV602 / CRV602) | n/a | | Welded pipe & tube | ASTM B516 / B517 | n/a | | Design / pressure approval | ASME BPVC Section I (≤ 899 °C), Section VIII Div. 1 (≤ 980 °C) | VdTÜV Werkstoffblatt 540 (≤ 1,150 °C) | > **Common documentation error.** Older datasheets, including the previous version of this page, cite *DIN 17744* for Alloy 602 CA. DIN 17744 covers nickel wrought alloys with molybdenum and chromium (the Hastelloy family). NiCr25FeAlY is a nickel–chromium alloy and belongs to the **DIN 17742** composition standard, with technical delivery conditions in DIN 17750 / 17752 and heat-resisting coverage in **EN 10095**. If your drawing calls out DIN 17744 for N06025, it is worth correcting before it propagates into a purchase order. ## What is the chemical composition of Alloy 602 CA? > **Nickel balance (typically ≥ 58 %), chromium 24.0–26.0 %, iron 8.0–11.0 %, carbon 0.15–0.25 %, aluminium 1.8–2.4 %, titanium 0.10–0.20 %, yttrium 0.05–0.12 %, zirconium 0.01–0.10 %.** Impurities are held to silicon 0.50 % max, manganese 0.50 % max, copper 0.10 % max, phosphorus 0.020 % max and sulphur 0.010 % max. **Table 3. Alloy 602 CA / UNS N06025 / 2.4633 chemical composition, weight per cent** | Element | Min | Max | Why it is there | | --- | --- | --- | --- | | Nickel (Ni) | Balance | n/a | Austenitic FCC matrix; typically ≥ 58 %. Gives the alloy its carburisation and chloride resistance. | | Chromium (Cr) | 24.0 | 26.0 | Forms the outer Cr₂O₃ scale and the strengthening chromium carbides. | | Iron (Fe) | 8.0 | 11.0 | Cost balance; keeps the matrix workable without harming scale formation. | | **Carbon (C)** | 0.15 | 0.25 | **Deliberately high.** Precipitates M₂₃C₆ / M₇C₃ chromium carbides that carry the creep load. Never substitute a low-carbon Ni-Cr alloy in its place. | | **Aluminium (Al)** | 1.8 | 2.4 | **The “CA” addition.** Forms the inner Al₂O₃ sub-scale that keeps the oxide protective above 1,000 °C. | | Titanium (Ti) | 0.10 | 0.20 | Micro-alloying; carbide and nitride control. | | **Yttrium (Y)** | 0.05 | 0.12 | **Reactive element.** Keys the oxide scale to the substrate so it survives thermal cycling instead of spalling. | | Zirconium (Zr) | 0.01 | 0.10 | Grain-boundary strengthening; refines carbide morphology. | | Silicon (Si) | n/a | 0.50 | Residual from deoxidation. | | Manganese (Mn) | n/a | 0.50 | Residual from deoxidation. Some specifications restrict Mn to 0.15 % max, so check your governing document. | | Copper (Cu) | n/a | 0.10 | Residual, restricted. | | Phosphorus (P) | n/a | 0.020 | Impurity. | | Sulphur (S) | n/a | 0.010 | Impurity, tightly held. Sulphur poisons oxide-scale adhesion, working directly against the yttrium. | | Cobalt (Co) | Not an alloying addition | | Cobalt-free by design, which matters where Co-60 activation is restricted. | > **How to read the carbon line.** Every other decision on this page follows from it. If a supplier offers you “N06025” with 0.05 % C, it is not N06025. It is closer to Alloy 601 chemistry and will creep-deform in a loaded furnace fixture where genuine 602 CA would hold shape. Check the carbon figure on the mill certificate before anything else. ## Grain size and solution-anneal condition: the one decision unique to Alloy 602 CA > **Alloy 602 CA is supplied in one of two solution-annealed conditions, and they are not interchangeable.** Annealing at **1,220 °C** gives a coarse grain of **≥ 70 µm** and the maximum creep and stress-rupture strength. This is the condition on which the VdTÜV 540 design values are based. Annealing at **1,180 °C** gives a finer grain **< 70 µm** with better room-temperature ductility and formability, for parts where high-temperature corrosion resistance is the requirement and creep loading is light. If your purchase order says only “solution annealed”, you have left the choice to the mill, and the mechanical values on the certificate will not necessarily match the ones your designer used. State the temperature and the grain-size requirement explicitly. In every other respect the two conditions are the same material with the same chemistry and the same oxidation resistance. **Table 4. Alloy 602 CA solution-anneal conditions compared** | | 1,220 °C anneal (coarse grain) | 1,180 °C anneal (fine grain) | | --- | --- | --- | | Grain size | ≥ 70 µm (ASTM E112 ≈ 4 or coarser) | < 70 µm | | Creep / stress-rupture strength | Maximum. The basis of VdTÜV 540 design values | Reduced. Finer grain creeps faster | | Room-temperature ductility | Lower | Higher | | Cold formability | Limited | Better | | Fatigue / thermal-fatigue behaviour | Coarse grain is less favourable | Better crack initiation resistance | | Typical use | Pressure-retaining parts, loaded furnace fixtures, roller barrels, catalyst grids, hanger and support hardware carrying dead load at 1,000 °C+ | Muffles, liners, ducting, shields, formed sheet hardware, parts that see temperature but little sustained stress | | How to write it on the PO | “Solution annealed 1,220 °C, grain size ≥ 70 µm per VdTÜV 540, report per ASTM E112” | “Solution annealed 1,180 °C, grain size < 70 µm, report per ASTM E112” | > **Cooling matters as much as the temperature.** After the solution anneal, cool rapidly: water quench for section sizes that can take the thermal shock, forced air for thin or complex geometry. Slow cooling through 900–600 °C re-precipitates grain-boundary carbides and undoes part of what the anneal was for. The one exception is when the solution anneal is genuinely the last operation before the part goes into service: then a slower air cool is acceptable. Also re-solution-anneal after any hot forming, and after cold forming beyond roughly 7 % strain. ## What are the mechanical properties of Alloy 602 CA? **In the solution-annealed condition at room temperature, Alloy 602 CA has a minimum 0.2 % proof strength of 270 MPa, a minimum tensile strength of 670 MPa and minimum elongation of 30 %.** Actual mill values are typically well above the minima: 700–780 MPa tensile and 40–50 % elongation are usual on forged sections. Hardness runs about 180–220 HB as delivered. **Table 5. Alloy 602 CA / UNS N06025 room-temperature mechanical properties, solution annealed** | Property | Minimum | Typical as delivered | Test standard | | --- | --- | --- | --- | | 0.2 % proof strength Rp0.2 | 270 MPa (39 ksi) | 290–350 MPa | ASTM E8 / EN ISO 6892-1 | | 1.0 % proof strength Rp1.0 | 310 MPa (45 ksi) | 330–390 MPa | EN ISO 6892-1 | | Tensile strength Rm | 670 MPa (97 ksi) | 700–780 MPa | ASTM E8 / EN ISO 6892-1 | | Elongation A5 | 30 % | 40–50 % | ASTM E8 / EN ISO 6892-1 | | Hardness | n/a | 180–220 HB | ASTM E10 / EN ISO 6506 | | Impact energy, Charpy V, RT | n/a | Report on request | ASTM E23 / EN ISO 148-1 | > **Two ductility caveats that belong in every design review.** **Ageing embrittlement.** After extended service between roughly 600 and 900 °C, secondary carbide precipitation reduces room-temperature elongation and impact toughness substantially. Aged 602 CA hardware must not be cold straightened, hammered or shock loaded. Heat it to forming temperature first. **The 649–760 °C rupture-ductility trough.** In the solution-annealed condition this alloy is subject to a pronounced loss of stress-rupture ductility in the approximate range 649–760 °C (1,200–1,400 °F). Sustained duty in that band should be reviewed explicitly at design stage rather than assumed safe because the alloy is rated to 1,200 °C. ### Elevated-temperature strength: where the design values come from Short-term and long-term high-temperature values for N06025 are published in **VdTÜV material data sheet 540** for the 1,220 °C solution-annealed, grain size ≥ 70 µm condition, and in **ASME BPVC Section II Part D** for code applications. Because those tables are the contractual basis for pressure design and are revised periodically, we do not reproduce them here. Quoting a stale allowable-stress figure on a supplier web page is a good way to cause a design error. Request the current tables with your quotation and we will supply the applicable extract for the condition you are ordering, along with certified test results on your own heat. The qualitative picture, which does not change: N06025 retains useful creep strength to about 1,150 °C; between 1,000 and 1,150 °C its 10,000-hour rupture strength is several times that of Alloy 601 and comfortably above Alloy 800HT; below about 1,000 °C, Alloy 617 is stronger. See the [comparison table](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#comparison) for the full selection picture. ## What are the physical properties of Alloy 602 CA? **Table 6. Alloy 602 CA / UNS N06025 physical properties at room temperature unless noted** | Property | Value | Unit / note | | --- | --- | --- | | Density | 7.9 | g/cm³ (0.285 lb/in³) | | Melting range | 1,340–1,400 | °C (solidus–liquidus) | | Modulus of elasticity E | ≈ 215 | GPa at 20 °C | | Specific heat capacity | ≈ 450 | J/(kg·K) at 20 °C | | Thermal conductivity | ≈ 11.3 | W/(m·K) at 20 °C | | Electrical resistivity | ≈ 1.15 | µΩ·m (Ω·mm²/m) at 20 °C | | Mean coefficient of thermal expansion | ≈ 12.5 | ×10⁻⁶ /K, 20–100 °C; rises with temperature | | Magnetic behaviour | Non-magnetic | Austenitic FCC, µr ≈ 1.0; magnetic particle testing does not apply | | Maximum continuous service in air | 1,200 | °C (2,192 °F); oxidation limit, not a code limit | | Delivery condition | Solution annealed | 1,180 °C or 1,220 °C; oxidised, descaled, pickled, turned or ground surface | > **Low thermal conductivity has practical consequences.** At roughly 11 W/(m·K) Alloy 602 CA conducts heat about a third as well as carbon steel. Heavy sections heat and cool slowly and unevenly, which is why forging reheats must be soaked properly rather than rushed, why quench cracking is a real risk in thick quenched sections, and why machining heat concentrates at the cutting edge instead of flowing into the workpiece. See the [machining parameter tool](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#tool-mach). ## How does Alloy 602 CA behave in oxidising, carburising and sulphidising atmospheres? > **Alloy 602 CA has the best high-temperature oxidation resistance of any commercial wrought nickel–chromium–iron alloy, usable in air to 1,200 °C, and it holds that scale through thermal cycling.** It also resists carburisation well. Its weak point, shared with all nickel-base alloys, is sulphur-bearing reducing atmospheres, where a low-melting nickel–nickel sulphide eutectic can form. **Strong: air and combustion products to 1,200 °C** The duplex chromia-over-alumina scale, keyed down by yttrium, is the whole design intent. It also survives **cyclic** exposure, repeated heat-up and cool-down, where an alloy without a reactive-element addition would spall its scale each cycle and consume chromium re-forming it. This is what makes 602 CA a fixture and roller material for batch furnaces, not just continuous ones. **Strong: carburising atmospheres** High nickel content lowers carbon solubility and diffusivity in the matrix; the aluminium-stabilised scale limits carbon ingress. This makes 602 CA a standard choice for carburising-furnace fixtures, baskets, grids and radiant tubes, and for retort and muffle components in heat-treatment plant. **Good, but not class-leading: metal dusting, 400–800 °C** In carbon-monoxide-rich, low-oxygen syngas the alloy resists metal dusting well but is beaten by [Alloy 693](https://www.steelforgepieces.com/Nickel-Alloy/), which carries 27–31 % Cr and 2.5–4.0 % Al. If metal dusting rather than creep is your governing damage mechanism, run the [risk checker below](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#tool-dusting) before committing to 602 CA. **Weak: sulphidising reducing atmospheres** Nickel and nickel sulphide form a eutectic that melts at about 645 °C. In reducing atmospheres carrying H₂S or SO₂ with low oxygen availability, any high-nickel alloy, 602 CA included, is at risk of rapid liquid-phase attack. For sulphidising service, iron-base or high-silicon heat-resistant grades are usually the correct answer instead. **Weak: molten salts, molten metals, halides** Molten chlorides, molten aluminium and zinc, and high-halide vapour environments attack the protective scale directly. 602 CA is not a molten-salt alloy. Waste-incineration duty needs case-by-case review because chloride content in flue gas varies enormously with feedstock. **Not applicable: aqueous and acid corrosion** Alloy 602 CA is a high-temperature alloy, not a wet-corrosion alloy. For acids and aqueous chloride service use [Hastelloy C-276](https://www.steelforgepieces.com/Nickel-Alloy/), [Alloy 59](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-59.html) or [Inconel 625](https://www.steelforgepieces.com/Nickel-Alloy/Inconel-625.html) instead. ## Alloy 602 CA vs 601, 693, 617, 800HT and 253 MA: which should you use? **The short version: 602 CA wins above 1,000 °C when the part is loaded; 617 wins below 1,000 °C when stress is high; 693 wins when metal dusting is the killer; 601 and 800HT win when the temperature is modest and cost matters.** **Table 7. High-temperature alloy selection comparison** | | Alloy 602 CA | Alloy 601 | Alloy 693 | Alloy 617 | Alloy 800HT | 253 MA | | --- | --- | --- | --- | --- | --- | --- | | UNS | N06025 | N06601 | N06693 | N06617 | N08811 | S30815 | | Base | Ni–Cr–Fe | Ni–Cr–Fe | Ni–Cr–Al | Ni–Cr–Co–Mo | Fe–Ni–Cr | Fe–Cr–Ni | | Chromium | 24–26 % | 21–25 % | 27–31 % | 20–24 % | 19–23 % | 20–22 % | | Aluminium | 1.8–2.4 % | 1.0–1.7 % | 2.5–4.0 % | 0.8–1.5 % | 0.15–0.60 % | n/a | | Carbon | 0.15–0.25 % | 0.10 max | 0.15 max | 0.05–0.15 % | 0.06–0.10 % | 0.05–0.10 % | | Oxidation limit in air | ≈ 1,200 °C | ≈ 1,150 °C | ≈ 1,150 °C | ≈ 1,100 °C | ≈ 1,100 °C | ≈ 1,150 °C | | Creep strength > 1,000 °C | Excellent | Modest | Modest | Good | Modest | Low | | Creep strength 800–1,000 °C | Good | Modest | Modest | Best in class | Modest | Modest | | Cyclic-oxidation / scale adhesion | Excellent (Y-stabilised) | Good | Excellent | Good | Fair | Good (Ce) | | Carburisation resistance | Excellent | Good | Excellent | Good | Fair | Fair | | Metal-dusting resistance | Good | Fair | Best in class | Fair | Poor | Poor | | Cobalt-free | Yes | Yes | Yes | No (10–15 % Co) | Yes | Yes | | Room-temp ductility after ageing | Reduced | Good | Reduced | Reduced | Good | Good | | Relative material cost | 4–5 × | 3 × | 5–6 × | 6–8 × | 2 × | 1 × (baseline) | | **Choose it when…** | **Loaded hardware above 1,000 °C, cyclic duty, carburising furnaces** | Below ~1,100 °C, light load, cost-sensitive | Metal dusting is the governing mechanism | Highest creep strength 800–1,050 °C, cobalt acceptable | Below ~1,000 °C, general process, cost-sensitive | Below ~1,000 °C, lowest cost, non-critical | Cost multipliers are indicative relative material-price ratios for hot-forged product, not quotations. Actual pricing tracks LME nickel, ferro-chrome and cobalt indices and depends on quantity, size, certification level and lead time. Contact us for current ranges. ## Alloy 602 CA failure modes and how to design them out These are the damage mechanisms that actually retire Alloy 602 CA hardware. Most are avoidable at the specification stage at no cost; none are cheap to fix after the part is in a furnace. **Creep deformation and sagging** **Cause:** sustained dead load above about 950 °C, often with the part's own weight the dominant stress. Fine-grain material creeps faster than coarse. **Symptom:** rollers bow, grids sag between supports, fixtures no longer sit flat. **Prevent:** specify the [1,220 °C anneal, grain ≥ 70 µm](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#grain); reduce unsupported span; design in a re-straightening allowance at hot temperature; check stress against current VdTÜV 540 creep data rather than room-temperature yield. **Cold cracking of aged material** **Cause:** secondary carbide precipitation during 600–900 °C service removes most of the room-temperature ductility, then somebody straightens or hammers the part cold. **Symptom:** brittle fracture during maintenance handling, not during operation. **Prevent:** write “do not cold straighten; heat to 1,000 °C minimum before any forming” on the maintenance procedure. Treat aged 602 CA as a brittle material at room temperature. **Metal dusting pitting** **Cause:** carbon activity above unity in CO-rich, low-oxidant gas at 400–800 °C. Carbon supersaturates the metal, precipitates graphite and disintegrates it. **Symptom:** hemispherical pits filled with black coke dust; wall loss with no scale. **Prevent:** run the [risk checker](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#tool-dusting); consider Alloy 693; add steam to the gas if the process allows; specify a smooth, pre-oxidised surface rather than as-machined. **Sulphidation attack** **Cause:** H₂S or SO₂ in a reducing atmosphere forms a Ni–Ni₃S₂ eutectic that melts near 645 °C. **Symptom:** rapid, sometimes liquid-phase, wastage, far faster than oxidation. **Prevent:** do not use high-nickel alloys in reducing sulphidising service. Move to an iron-base heat-resistant grade and review with a corrosion specialist. **Scale spallation under thermal shock** **Cause:** severe quench or water ingress on hot metal exceeds the scale's strain tolerance. 602 CA is unusually good here thanks to yttrium, but not immune. **Symptom:** flaking oxide, accelerating chromium depletion, eventual breakaway oxidation. **Prevent:** control cool-down rates; avoid direct water spray on hot components; keep sulphur low in the material, because sulphur works directly against the yttrium. **Forging bursts and edge cracks** **Cause:** forging continued below about 1,000 °C, or too large a reduction per blow. The carbide-loaded structure work-hardens fast and has little hot ductility once cooled. **Symptom:** internal indications on ultrasonic testing; linear surface cracks that only appear after final machining. **Prevent:** our practice is a 1,180–1,230 °C start with reheats before the workpiece drops below 1,000 °C, small incremental reductions, and ultrasonic examination after the solution anneal. **Weld hot cracking** **Cause:** excessive heat input, wide weave, high restraint. Nickel alloys have narrow weld pools and shallow penetration; heat piles up. **Symptom:** centreline cracks in the weld metal, crater cracks at stops. **Prevent:** stringer beads, low heat input, matching S Ni 6025 filler, clean joint prep free of sulphur-bearing marker or grease, and a post-weld stabilising anneal where service will be 600–750 °C. **Work-hardening machining failure** **Cause:** tool dwelling, rubbing or taking a cut inside the previously work-hardened layer. The alloy hardens under the tool faster than the tool can remove it. **Symptom:** rapid flank wear, sudden edge chipping, glazed surface, dimensional drift. **Prevent:** rigid setup, sharp positive-rake carbide, heavy positive feed, low speed, flood coolant, and depth of cut set below the previous pass's hardened skin. See the [machining tool](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#tool-mach). ## How is Alloy 602 CA forged, welded and machined? ### Forging and hot working **Our production window for UNS N06025 is a 1,180–1,230 °C start with a finishing temperature not below approximately 1,000 °C.** The alloy has a narrow hot-working range and work-hardens rapidly, so reductions are taken in small increments with frequent reheats rather than in heavy blows. Soak thoroughly before each pass. At roughly 11 W/(m·K) thermal conductivity, a heavy section that looks hot on the outside may still be several hundred degrees colder at the core. After the final operation the part is solution annealed at 1,180 °C or 1,220 °C to the ordered grain-size condition and rapidly cooled, then examined ultrasonically. Forging below 1,000 °C is the single most common cause of internal bursts in this grade. ### Welding Weld with matching filler: solid wire **S Ni 6025** per ISO 18274 (SG-NiCr25FeAlY, W.Nr. 2.4649) or covered electrode **E Ni 6025** per ISO 14172. GTAW, GMAW, plasma and SMAW all apply. Preheat is not normally required. Use low heat input and stringer beads. Joint preparation must be clean and free of sulphur-bearing contaminants: grease, cutting fluid and some marker inks all carry sulphur, and sulphur attacks the scale adhesion this alloy depends on. Where the welded assembly will operate between 600 and 750 °C, apply a post-weld stabilising anneal. After hot forming, or cold forming beyond roughly 7 % strain, re-solution-anneal the part. ### Machining Treat N06025 as a superalloy, not as stainless steel. The governing rule is that the tool must always be cutting: any dwell or rub work-hardens the surface and destroys the next pass. Use rigid setups and short tool overhang, sharp positive-rake coated carbide, a low cutting speed, a heavy positive feed that takes the tool beneath the previously hardened layer, and flood coolant. Budget substantially more machining hours than the same geometry in stainless steel. On nickel-alloy parts the machining, not the metal, is often the longer lead item. The [parameter tool below](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#tool-mach) gives starting values by operation. ## Alloy 602 CA production capability at Jiangyin Jiangnan Metal Nickel-alloy envelopes are smaller than our carbon and stainless steel envelopes. UNS N06025 needs higher forging loads, more reheats and a narrower temperature window, and the billet itself is remelted stock rather than a shelf item. The figures below are the practical limits for this grade specifically. - **Ring OD:** 2000 mm - **Disc Ø:** 1200 mm - **Shaft length:** 4 m - **Bar Ø:** 25–350 - **Single piece:** 2500 kg - **Lead time:** 8–9 wk - **Min order:** 10 kg ### Process flow, billet to certificate - STEP 01 Billet: VIM + ESR remelt / Heat number traced / Chemistry verified - STEP 02 Forge: Start 1180–1230 °C / Finish ≥ 1000 °C / Incremental reduction - STEP 03 Ring roll / upset: Radial–axial mill / Circumferential flow / To 2000 mm OD - STEP 04 Solution anneal: 1180 or 1220 °C / Grain to order / Rapid cool - STEP 05 Descale: Blast or pickle / Oxidised finish / optional - STEP 06 Rough machine: Stock per drawing / Positive-rake carbide / Flood coolant - STEP 07 Test & NDE: UT + PT / Tensile, hardness / Grain size E112 - STEP 08 Certify & ship: EN 10204 3.1 / 3.2 / Multi-designation / Marked and packed > **Note on magnetic-particle testing.** UNS N06025 is non-magnetic, so MT does not apply. Surface examination is by liquid penetrant per ASTM E165 or EN ISO 3452. If your drawing calls for MT on a nickel-alloy part, it needs correcting before it becomes a non-conformance. ### Equipment used for Alloy 602 CA production **Melting: vacuum induction melting and electroslag remelting** 3 t vacuum induction furnace with 3 t and 6 t protective-atmosphere electroslag remelting. Yttrium and aluminium oxidise in air melting, so a vacuum route is what makes a genuine NiCr25FeAlY chemistry possible rather than a nominal one. **Forging (heavy): open-die hydraulic presses, 6,300 t / 4,000 t / 2,000 t** Open-die forging of blocks, discs, stepped shafts and ring pre-forms, with rapid reheat cycling to hold the narrow hot-working window this grade needs. **Ring rolling: radial–axial ring mills, 6 m / 3 m / 1 m** Rectangular or contoured section, circumferential grain flow, no weld seam. The mills roll to 6,000 mm OD in steel; the practical envelope in N06025 is set by the remelted ingot size rather than by the mill. **Heat treatment: high-temperature car-bottom furnace** Three high-temperature car-bottom furnaces, working chamber 3,500 × 1,300 × 1,100 mm, with recorded uniformity survey and chart traceability per heat-treatment lot. Confirm the anneal temperature your part needs at enquiry stage. **NDE (volumetric): ultrasonic examination** Acceptance to ASTM A388 or EN 10228-3 as specified, with written report referenced on the material certificate. **NDE (surface): liquid penetrant line** ASTM E165 / EN ISO 3452 penetrant examination. Magnetic particle is not applicable to this non-magnetic grade. **Laboratory: chemistry, mechanical, metallography** Optical emission spectrometry for full elemental analysis, universal testing for tensile and hardness, and metallographic grain-size determination per ASTM E112, the test that certifies your ordered anneal condition. ## Standards, certification and quality For Alloy 602 CA forgings the governing product specification is **ASTM B564 / ASME SB-564**. European projects normally reference **EN 10095** and, for pressure equipment, **VdTÜV Werkstoffblatt 540**. Certification is issued to **EN 10204 3.1** as standard; **3.2** with a purchaser-nominated third-party body such as TÜV, DNV, Lloyd's Register, Bureau Veritas or ABS is available on request. ### What appears on the material test certificate - Heat number, melt route and full elemental chemistry including **C, Al, Y and Zr**, the four elements that distinguish genuine N06025 from a substituted Ni-Cr alloy - Solution-anneal temperature actually used, and the resulting **grain size per ASTM E112** - Room-temperature tensile results: Rp0.2, Rp1.0, Rm, elongation - Hardness - Ultrasonic and liquid-penetrant examination results against the specified acceptance class - Every specification the heat satisfies, listed together, for example “UNS N06025, W.Nr. 2.4633, NiCr25FeAlY, ASTM B564, EN 10095” - Dimensional report and marking record > **Grain size is a certified property here, not a footnote.** On most alloys grain size is reported only if asked for. On Alloy 602 CA it is the property that determines whether the part meets the creep values your designer used, so we report it on every certificate as standard. ## How to specify an Alloy 602 CA forging order Seven steps. The two that get skipped most often, and cause the most disputes at receipt, are steps 2 and 4. - STEP 01 Generic designation: “UNS N06025 / / 2.4633 / NiCr25FeAlY / per ASTM B564” - STEP 02 Anneal & grain size: 1220 °C, ≥ 70 µm / or 1180 °C, < 70 µm / Report per E112 - STEP 03 Drawing: Dimensions, stock, / tolerance, finish, / grain flow - STEP 04 Service conditions: Metal temp, atmosphere, / cycling, design life, / stress state - STEP 05 NDE: UT: A388 / EN 10228-3 / PT: E165 / ISO 3452 / No MT (non-magnetic) - STEP 06 Certification: EN 10204 3.1 / or 3.2 + witness body / Extra tests if needed - STEP 07 Commercial: Quantity, date, / Incoterm, port, / 8–9 week standard ### Drawing callout you can copy **Recommended material block for an Alloy 602 CA forging drawing** ``` MATERIAL: UNS N06025 / W.Nr. 2.4633 / NiCr25FeAlY per ASTM B564 (also satisfies EN 10095) CONDITION: Solution annealed 1220 degC, rapid cool. Grain size >= 70 um per VdTUV 540. Report grain size per ASTM E112 on MTC. DO NOT AGE - this alloy is not age-hardenable. FORGING: Start 1180-1230 degC, finish not below 1000 degC. Reheat as required. Solution anneal after final forging operation. NDE: UT per ASTM A388 (or EN 10228-3), class per order. PT per ASTM E165 (or EN ISO 3452) on machined surfaces. MT NOT APPLICABLE - material is non-magnetic. CERTIFICATION: EN 10204 3.1 mill certificate. Chemistry to report C, Al, Y and Zr individually. (3.2 with third-party witness if required.) MARKING: Heat number, UNS designation, anneal condition and drawing number, low-stress stamped or vibro-etched on a non-functional surface. ``` ## Ten mistakes engineers make when ordering Alloy 602 CA 1. **Not stating the anneal temperature or grain size.** The single most consequential omission. “Solution annealed” alone lets the mill pick, and the creep values on the certificate may not be the ones your design used. *Fix:* state 1,220 °C / ≥ 70 µm or 1,180 °C / < 70 µm explicitly, with grain size reported per ASTM E112. 2. **Asking for a solution-plus-ageing heat treatment.** Copied across from an Inconel 718 or X-750 specification. Alloy 602 CA is not age-hardenable; ageing adds no strength and can embrittle it. *Fix:* write “solution anneal only, do not age” on the drawing. 3. **Citing DIN 17744.** That standard covers Ni-Mo-Cr alloys. NiCr25FeAlY sits in the DIN 17742 family and EN 10095. *Fix:* correct the callout before it propagates into purchasing. 4. **Confusing the oxidation limit with the code limit.** 1,200 °C is how hot the metal can get before the scale fails. A pressure-retaining part under ASME Section VIII Div. 1 stops at 980 °C. *Fix:* establish which limit governs your part before selecting the alloy. 5. **Specifying magnetic-particle testing.** N06025 is non-magnetic; MT cannot work. *Fix:* specify liquid penetrant per ASTM E165 or EN ISO 3452 instead. 6. **Ignoring the 649–760 °C rupture-ductility trough.** Selecting the alloy on its 1,200 °C headline while the part actually dwells at 700 °C under load. *Fix:* review sustained duty in that band explicitly at design stage. 7. **Treating aged material as ductile.** Maintenance crews cold-straighten furnace hardware that has spent two years at 900 °C and crack it. *Fix:* put “heat to 1,000 °C before any straightening” in the maintenance procedure, not just the material datasheet. 8. **Accepting a certificate without the carbon, aluminium and yttrium figures.** Those four elements, together with zirconium, are what make it N06025 rather than a cheaper Ni-Cr alloy wearing the same label. *Fix:* require them individually on the MTC. 9. **Choosing 602 CA where metal dusting governs.** Good resistance is not best-in-class resistance. *Fix:* run the [dusting checker](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#tool-dusting); consider Alloy 693 for CO-rich syngas at 400–800 °C. 10. **Planning delivery on a stainless-steel schedule.** Remelted nickel billet is not shelf stock and machining hours run long. *Fix:* budget 8 to 9 weeks, plus about 2 more for third-party witnessed certification. ## Where is Alloy 602 CA used? **Heat treatment: furnace hardware** Roller-hearth and walking-beam furnace rollers, muffles, retorts, radiant tubes and tube flanges, baskets, grids, trays and fixtures, burner nozzles, thermocouple protection tubes. The combination of cyclic-oxidation resistance to 1,200 °C and carbide-based creep strength is exactly what fixture and roller duty demands. **Petrochemical: reformers and syngas plant** Catalyst support grids and hardware, hydrogen and syngas reformer internals, pigtail and manifold components, ethylene pyrolysis furnace hardware. Carburisation resistance is the governing property in most of these positions. **Energy: waste-to-energy and biomass** Superheater support and hanger hardware, grate components, high-temperature ducting and shields. Chloride content in flue gas varies with feedstock, so these positions warrant case-by-case review rather than blanket alloy selection. **Automotive: high-temperature engine components** Diesel glow-plug sheaths and exhaust-system components in the highest-temperature positions, where the thermal-cycling resistance of the yttrium-stabilised scale is the deciding property. **Glass & ceramics: kiln and lehr hardware** Rollers, support structures and conveying hardware in glass annealing lehrs, ceramic kilns and calcination plant, running continuously above 1,000 °C. **Nuclear & research: cobalt-free high-temperature service** High-temperature gas-loop and test-rig components where cobalt-60 activation must be avoided. Alloy 602 CA is cobalt-free by design, unlike Alloy 617 with its 10–15 % cobalt. ## Glossary **CA (in “Alloy 602 CA”)** Controlled Aluminium, the deliberate 1.8–2.4 % Al addition that forms the inner alumina sub-scale and lifts the oxidation limit to 1,200 °C. **Solution annealing** The single heat treatment applied to N06025: hold at 1,180 °C or 1,220 °C to dissolve secondary carbides and set grain size, then cool rapidly. No ageing step follows. **Reactive element effect** The mechanism by which small yttrium additions anchor an oxide scale to its substrate, dramatically improving spallation resistance under thermal cycling. **Metal dusting** Catastrophic carburisation in CO-rich, low-oxygen gas at roughly 400–800 °C, which disintegrates the alloy into metal powder and carbon rather than forming a scale. **Breakaway oxidation** The point at which chromium in the substrate is depleted below the level needed to re-form a protective scale, after which oxidation accelerates sharply. Repeated spallation is the usual route to it. **VdTÜV Werkstoffblatt 540** The German technical inspection association data sheet for NiCr25FeAlY, giving design values for pressure-retaining service to 1,150 °C in the 1,220 °C annealed, grain ≥ 70 µm condition. **EN 10204 3.1 vs 3.2** 3.1 is a certificate validated by the manufacturer's own independent inspection department. 3.2 is countersigned by a third-party body nominated by the purchaser. **Seamless rolled ring** A ring made by piercing a forged billet and expanding it on a radial–axial mill, giving circumferential grain flow with no weld seam. ## Frequently asked questions about Alloy 602 CA / UNS N06025 ### What is Alloy 602 CA (UNS N06025)? Alloy 602 CA is a high-carbon nickel–chromium–iron alloy containing nominally 25 % chromium, 2 % aluminium and 0.2 % carbon, micro-alloyed with yttrium, zirconium and titanium. It is designated UNS N06025, W.Nr. 2.4633 and NiCr25FeAlY. The high chromium plus aluminium forms a self-healing chromia/alumina scale giving the highest oxidation resistance of any commercial wrought nickel alloy, usable continuously in air to 1,200 °C, while the chromium carbides precipitated from the high carbon give creep strength well above Alloy 601 and Alloy 800HT. Jiangyin Jiangnan Metal Co., Ltd. produces UNS N06025 as open-die forgings, seamless rolled rings, flanges, discs, shafts and bars. ### Are Alloy 602, Alloy 602 CA, UNS N06025, 2.4633 and NiCr25FeAlY the same material? Yes. All refer to the same chemistry, as does NiCr25Fe10AlY. “Alloy 602” used alone is the common short form of Alloy 602 CA and is almost always intended to mean the same grade. Nicrofer® 6025 HT is the registered trade name of VDM Metals and RA 602 CA® of Rolled Alloys for their own production of this chemistry. Jiangyin Jiangnan Metal is not affiliated with either company and supplies the generic UNS N06025 / 2.4633 / NiCr25FeAlY chemistry, certified against ASTM and EN specifications. ### What is the chemical composition of Alloy 602 CA / UNS N06025? Nickel balance (typically ≥ 58 %), chromium 24.0–26.0 %, iron 8.0–11.0 %, carbon 0.15–0.25 %, aluminium 1.8–2.4 %, titanium 0.10–0.20 %, yttrium 0.05–0.12 %, zirconium 0.01–0.10 %, silicon 0.50 % max, manganese 0.50 % max, copper 0.10 % max, phosphorus 0.020 % max, sulphur 0.010 % max. The high carbon is deliberate: it forms the primary chromium carbides that carry the creep strength, which is why Alloy 602 CA must never be substituted with a low-carbon Ni-Cr alloy in a creep-loaded application. Full table in [Table 3](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#composition). ### What is the maximum service temperature of Alloy 602 CA? Alloy 602 CA resists oxidation in air continuously to **1,200 °C (2,192 °F)**, the highest of the commercial wrought Ni-Cr-Fe alloys. Design code limits are lower: ASME Section I allows service to 899 °C, ASME Section VIII Division 1 to 980 °C, and VdTÜV material data sheet 540 covers the alloy to 1,150 °C. Above roughly 1,150 °C it is normally used for non-pressure-retaining furnace hardware rather than pressure parts. ### Is Alloy 602 CA age-hardenable? Should it be solution treated and aged? **No.** Alloy 602 CA is not a precipitation-hardening alloy and must not be given an ageing treatment. Its strength comes from solid-solution chromium plus primary and secondary chromium carbides, and its oxidation resistance from the alumina-stabilised scale. The correct heat treatment is a single solution anneal followed by rapid cooling. Applying a conventional solution-plus-age cycle intended for Inconel 718 or X-750 will not increase the strength of N06025 and can embrittle it. ### What is the difference between the 1,180 °C and 1,220 °C solution anneal? The anneal temperature sets grain size, and grain size sets the balance between creep strength and room-temperature ductility. **1,220 °C** gives coarse grain ≥ 70 µm and is the condition covered by VdTÜV 540 for creep-loaded and pressure-retaining parts. **1,180 °C** gives finer grain < 70 µm with better room-temperature ductility and formability, for parts needing high-temperature corrosion resistance under light load. Always state which you require, because the mechanical values on the certificate differ. See [the selector tool](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#tool-grain). ### Alloy 602 CA vs Alloy 601: which should I use? Choose **602 CA** when the part is load-bearing above roughly 1,000 °C, or when service exceeds 1,150 °C. It carries higher chromium (24–26 % vs 21–25 %), higher aluminium (1.8–2.4 % vs 1.0–1.7 %) and far higher carbon (0.15–0.25 % vs 0.10 % max), giving a higher oxidation limit and several times the creep-rupture strength above 1,000 °C. Choose **601** when service is below about 1,100 °C with light creep loading. It is cheaper, more ductile at room temperature and easier to form and machine. ### Alloy 602 CA vs Alloy 693 for metal dusting resistance? Alloy 693 (UNS N06693), with 27–31 % Cr and 2.5–4.0 % Al, is the stronger choice where metal dusting in CO-rich syngas between 400 and 800 °C is the governing damage mechanism. Alloy 602 CA has good but not class-leading dusting resistance and is the better choice where the governing mechanism is oxidation plus creep above 1,000 °C, because it retains far more creep strength at furnace temperatures. In reformer and syngas plant the two are often used in different zones of the same unit. ### Alloy 602 CA vs Alloy 617: what is the difference? Alloy 617 (UNS N06617) is a Ni-Cr-Co-Mo alloy with higher creep-rupture strength between about 800 and 1,050 °C, and is the usual choice for gas-turbine combustors and high-temperature pressure boundaries in that band. Alloy 602 CA has higher chromium and aluminium and therefore markedly better oxidation and scale adhesion above 1,050 °C, and contains **no cobalt**, which matters where cobalt activation is restricted. Above roughly 1,100 °C in air, 602 CA generally outlasts 617; below 1,000 °C under high stress, 617 is stronger. ### What is the density of Alloy 602 CA? 7.9 g/cm³ (0.285 lb/in³) at room temperature. Use this to convert drawing volume into billet weight. The [weight calculator](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#tool-weight) does it for you. ### Is Alloy 602 CA magnetic? No. It has a face-centred-cubic austenitic nickel matrix and is essentially non-magnetic, with relative permeability close to 1.0. It cannot be hardened by any heat treatment and cannot be sorted magnetically from austenitic stainless steel. Positive material identification requires optical emission spectrometry or XRF. Magnetic particle testing does not apply; use liquid penetrant instead. ### Can Alloy 602 CA be welded, and with which filler metal? Yes. Weld by GTAW, GMAW, plasma or covered-electrode processes with matching filler of the same NiCr25FeAlY chemistry: solid wire **S Ni 6025** per ISO 18274 (SG-NiCr25FeAlY, W.Nr. 2.4649) or covered electrode **E Ni 6025** per ISO 14172. Preheat is not normally required. Use low heat input and stringer beads to limit hot-cracking risk, and keep the joint free of sulphur-bearing contaminants. Where the assembly will operate at 600–750 °C, apply a post-weld stabilising anneal. After hot forming, or cold forming beyond about 7 % strain, re-solution-anneal. ### Why does Alloy 602 CA lose room-temperature ductility after service? Continued exposure between roughly 600 and 900 °C precipitates secondary chromium carbides on the grain boundaries. That is the mechanism building the alloy's creep strength, but it also lowers room-temperature elongation and impact toughness, behaviour common to all high-carbon heat-resistant alloys. In practice, aged 602 CA hardware must not be straightened, hammered or shock-loaded cold; heat it to forming temperature first. The alloy is also subject to a marked reduction in stress-rupture ductility in the approximate range 649–760 °C, which is why sustained duty in that band deserves explicit design review. ### Which standards cover Alloy 602 CA forgings? For forgings the governing specification is **ASTM B564 / ASME SB-564**. Related product-form specifications are ASTM B166 (rod, bar, wire), B167 (seamless pipe and tube), B168 (plate, sheet, strip), B472 (billets and bars for reforging), B462 (forged or rolled flanges and fittings) and B366 (wrought fittings). In Europe the alloy appears in **EN 10095**, the DIN 17742 / 17750 / 17752 family, and **VdTÜV material data sheet 540**. Certification is EN 10204 3.1 as standard, or 3.2 with third-party witness on request. Full mapping in [Table 2](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#designations). ### What is the forging temperature range for Alloy 602 CA? Jiangyin Jiangnan Metal forges UNS N06025 from a start temperature of **1,180–1,230 °C** with a finishing temperature not below approximately **1,000 °C**, reheating whenever the workpiece falls below that limit. The alloy work-hardens rapidly and its carbide content makes it far less forgeable than austenitic stainless steel, so reductions are taken in small increments with frequent reheats. After the final forging operation the part is solution annealed at 1,180 °C or 1,220 °C to the ordered grain-size condition, then rapidly cooled. Forging below 1,000 °C risks edge cracking and internal bursts. ### How is Alloy 602 CA machined? Like a high-strength superalloy. It work-hardens rapidly, so the governing rule is that the tool must never dwell or rub. Use rigid setups, sharp positive-rake carbide inserts, low cutting speeds of roughly 10–20 m/min for turning with coated carbide, a heavy positive feed of 0.20–0.35 mm/rev to cut beneath the previously work-hardened layer, and flood coolant. Take the depth of cut below the hardened skin from the previous pass. Budget roughly twice the machining hours you would allow for stainless steel of the same geometry. Starting parameters by operation are in the [machining tool](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html#tool-mach). ### What is the maximum forging size available in Alloy 602 CA? Seamless rolled rings from 200 mm to **2,000 mm outside diameter**, forged discs and blanks to **Ø 1,200 mm**, forged shafts to **4 m length**, and forged round bars from **Ø 25 mm to Ø 350 mm**, with single-piece weights to approximately **2,500 kg**. Nickel-alloy limits are lower than our carbon and stainless steel envelopes because of the higher forging loads and narrower hot-working window of N06025. Send the drawing for confirmation of any size near these limits. ### What is the lead time for Alloy 602 CA forgings? Typically **8 to 9 weeks** from order confirmation to ex-works dispatch, the upper end of the works' 20 to 60 day range, because the grade needs a remelting step and the ingot is not a stock item. EN 10204 3.2 third-party witnessed certification or additional creep testing adds roughly 2 weeks. Quotations are issued within 24 hours of receiving a drawing or dimensions. ## Technical references Chemistry, property, heat-treatment and corrosion data on this page are drawn from the published standards and engineering literature listed below. Test results appearing on our material certificates are independent and traceable to calibrated laboratory equipment. 1. ASTM B564 / ASME SB-564, *Standard Specification for Nickel Alloy Forgings*, ASTM International, West Conshohocken, PA. 2. ASTM B166 / ASME SB-166, *Standard Specification for Nickel-Chromium-Iron Alloys… Rod, Bar and Wire*, ASTM International. 3. ASTM B167 / ASME SB-167, *Standard Specification for Nickel-Chromium-Iron Alloys… Seamless Pipe and Tube*, ASTM International. 4. ASTM B168 / ASME SB-168, *Standard Specification for Nickel-Chromium-Iron Alloys… Plate, Sheet and Strip*, ASTM International. 5. ASTM B472 / ASME SB-472, *Standard Specification for Nickel Alloy Billets and Bars for Reforging*, ASTM International. 6. ASTM B462 / ASME SB-462, *Standard Specification for Forged or Rolled UNS… Alloy Pipe Flanges, Forged Fittings, and Valves and Parts for Corrosive High-Temperature Service*, ASTM International. 7. ASTM B366, *Standard Specification for Factory-Made Wrought Nickel and Nickel Alloy Fittings* (classes WPV602 / CRV602), ASTM International. 8. EN 10095:1999, *Heat resisting steels and nickel alloys*, CEN, Brussels. 9. DIN 17742, *Nickel wrought alloys with chromium: composition*; DIN 17750 (sheet, plate, strip) and DIN 17752 (rod and bar), technical delivery conditions. 10. VdTÜV Werkstoffblatt 540, *NiCr25FeAlY (2.4633)*, Verband der Technischen Überwachungsvereine. 11. ASME Boiler and Pressure Vessel Code, Section II Part D (material properties and allowable stresses), Section I and Section VIII Division 1, latest edition, ASME. 12. ISO 18274, *Welding consumables: solid wire electrodes for fusion welding of nickel and nickel alloys* (S Ni 6025); ISO 14172, *Covered electrodes for manual metal arc welding of nickel and nickel alloys* (E Ni 6025). 13. ASTM E112, *Standard Test Methods for Determining Average Grain Size*, ASTM International. 14. ASTM A388, *Standard Practice for Ultrasonic Examination of Steel Forgings*; EN 10228-3, *Non-destructive testing of steel forgings: ultrasonic testing of ferritic or martensitic steel forgings*. 15. ASTM E165, *Standard Practice for Liquid Penetrant Testing*; EN ISO 3452, *Non-destructive testing: penetrant testing*. 16. EN 10204:2004, *Metallic products: types of inspection documents*, CEN. 17. VDM Metals GmbH, *Material Data Sheet: VDM® Alloy 602 CA / Nicrofer® 6025 HT*, latest edition. 18. Agarwal, D. C., Brill, U. and Metzler, M., “Practical Experience with the New Alloy 602 CA (NiCr25FeAlY): Applications in the Heat Treat Industry”, CORROSION '93, Paper No. 235, NACE International, Houston, 1993. 19. Agarwal, D. C. and Brill, U., “Performance of alloy 602 CA (UNS N06025) in high-temperature environments up to 1200 °C”, CORROSION 2000, Paper No. 521, NACE International, Houston, 2000. 20. Wilson, J. and Agarwal, D. C., “Case histories on successful applications of alloy 602 CA, UNS N06025, in high-temperature environments”, CORROSION 2005, NACE International. 21. Brill, U. and Agarwal, D. C., “Alloy 602 CA: A New Alloy for the Furnace Industry”, Proc. 2nd Int. Conf. on Heat Resistant Materials, Gatlinburg, Tennessee, 1995. 22. ASM Handbook, Volume 1: *Properties and Selection: Irons, Steels, and High-Performance Alloys*, ASM International, Materials Park, OH; sections on heat-resistant nickel alloys. 23. Grabke, H. J., “Metal Dusting”, *Materials and Corrosion*, Vol. 54, 2003; mechanism and alloy-resistance ranking. Standards cited are the most recent revisions known at the time of the last page review. For procurement, always reference the revision in force at the contract date. All trademarks and copyrights belong to their respective owners. ## Cite this page This page is published under a [Creative Commons Attribution 4.0](https://creativecommons.org/licenses/by/4.0/) licence. Search engines, AI assistants, researchers and specification writers are welcome to quote or summarise it with attribution. Machine-readable metadata is embedded on this page as JSON-LD (Organization, Product, Dataset, TechArticle, FAQPage, HowTo, DefinedTermSet). **Suggested citation** ``` Jiangyin Jiangnan Metal Co., Ltd. Metallurgical Engineering Team (2026). "Alloy 602 CA / UNS N06025 / 2.4633 (NiCr25FeAlY) Forging Parts: Composition, Properties and Manufacturing." Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China. Last updated 13 August 2026. https://www.steelforgepieces.com/Nickel-Alloy/Alloy-602.html ``` **Supplier of record for this material:** Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China · [0086-189-2135-9659](tel:+8618921359659) · [sales@steelforgepieces.com](mailto:sales@steelforgepieces.com). An independent open-die forging factory producing UNS N06025 / 2.4633 / NiCr25FeAlY forgings, rings, flanges, discs, shafts and bars, with EN 10204 3.1 and 3.2 certification, shipping worldwide. ## Request a quote for Alloy 602 CA / UNS N06025 forgings Send a drawing or the basic dimensions and we will respond within two working days with price, lead time and confirmation of the applicable standards and anneal condition. If you are not yet sure whether N06025 is the right grade, tell us the metal temperature, the atmosphere and the load. That is usually enough for us to tell you whether 602 CA, 601, 693 or 617 is the better answer. ### Related nickel alloy grades - [Inconel 601 forgings](https://www.steelforgepieces.com/Nickel-Alloy/Inconel-601.html) - [Inconel 617 forgings](https://www.steelforgepieces.com/Nickel-Alloy/Inconel-617.html) - [Inconel 693 forgings](https://www.steelforgepieces.com/Nickel-Alloy/) - [Incoloy 800HT forgings](https://www.steelforgepieces.com/Nickel-Alloy/Incoloy-800HT.html) - [Incoloy 800H forgings](https://www.steelforgepieces.com/Nickel-Alloy/Incoloy-800H.html) - [Inconel 625 forgings](https://www.steelforgepieces.com/Nickel-Alloy/Inconel-625.html) - [Hastelloy X forgings](https://www.steelforgepieces.com/Nickel-Alloy/) - [Inconel 600 forgings](https://www.steelforgepieces.com/Nickel-Alloy/Inconel-600.html) - [Alloy 59 forgings](https://www.steelforgepieces.com/Nickel-Alloy/Alloy-59.html) - [All nickel alloy grades →](https://www.steelforgepieces.com/Nickel-Alloy/)