Inconel 602CA (UNS N06025) – High-Temperature Carburization-Resistant Alloy Supplier of Round Bars, Tubes & Plates | Shanghai Hangbo Alloy Group
Date: 2026年7月22日 Categories: News Views: 378
By Shanghai Hangbo Alloy Group Co., Ltd. | ISO 9001:2015 Certified | Est. 2012 | Shanghai, China
Contact: sales@hangboalloy.com | hangbo@nickel-alloy.com | WhatsApp: +86 13611656360
Quick Answer: What Is Inconel 602CA?
Inconel 602CA (UNS N06025 / W.Nr. 2.4633 / VDM Alloy 602CA) is a high-carbon nickel-chromium-iron alloy micro-alloyed with aluminum, yttrium, titanium, and zirconium that forms a self-healing aluminum oxide (Al₂O₃) protective scale — the metallurgical gold standard for resisting oxidation, carburization, and metal dusting at temperatures up to 1200°C (2190°F). Unlike conventional chromia (Cr₂O₃)-forming alloys that lose their protective oxide above ~1000°C due to CrO₃ volatilization, 602CA's alumina scale remains thermodynamically stable to the alloy's melting point. Shanghai Hangbo Alloy Group supplies Inconel 602CA as round bars, seamless tubes, and plates with full ASTM B166/B167/B168 certification.
Industry Pain Point: Ethylene plant operators routinely replace radiant cracking coils every 3–5 years due to carburization embrittlement and metal dusting — a multi-million-dollar turnaround cost. Inconel 602CA extends coil life to 6–10+ years because the Al₂O₃ scale is impermeable to carbon diffusion, eliminating the primary failure mechanism at its root.
Key Properties at a Glance
| Property | Value |
|---|---|
| UNS Number | N06025 |
| W.Nr. | 2.4633 |
| Density | 7.93 g/cm³ (0.286 lb/in³) |
| Melting Range | 1370–1415°C (2500–2580°F) |
| Max Continuous Service Temp. | ~1200°C (2190°F) |
| Tensile Strength (RT, Annealed) | ≥ 680 MPa (≥ 99 ksi) |
| Yield Strength 0.2% (RT, Annealed) | ≥ 310 MPa (≥ 45 ksi) |
| Elongation (RT) | ≥ 35% |
| Thermal Conductivity (20°C) | ~11.3 W/m·K |
| Oxide Scale Type | Al₂O₃ (alumina) — not Cr₂O₃ |
| Key Standards | ASTM B166, B167, B168, B564, AMS 5878 |
Product Overview
Inconel 602CA belongs to a rare and strategically important class of high-temperature alloys: alumina formers. While 95% of commercial heat-resistant alloys rely on chromium oxide (Cr₂O₃) scales for oxidation protection, Cr₂O₃ has a fatal high-temperature weakness — above approximately 1000°C, it reacts with oxygen to form volatile CrO₃ gas, progressively thinning the protective oxide until base-metal oxidation accelerates catastrophically. This mechanism, called breakaway oxidation, is the dominant cause of radiant coil retirement in ethylene crackers and steam reformers.
602CA solves this problem metallurgically. Its elevated aluminum content (1.8–2.4% Al) — deliberately positioned within the solid-solution range to avoid gamma-prime embrittlement — forms a thin, adherent Al₂O₃ scale at service temperature. Alumina has three decisive advantages over chromia:
- Thermodynamic stability — Al₂O₃ does not volatilize below the alloy's melting point. There is no "scale failure" temperature.
- Carbon diffusion barrier — Al₂O₃ is ~100× less permeable to carbon than Cr₂O₃, making 602CA the premier carburization-resistant wrought alloy below 1200°C.
- Self-healing — if the scale is mechanically damaged (thermal cycling, erosion), aluminum diffuses rapidly from the alloy matrix to re-form Al₂O₃ at the damage site.
The unique micro-alloying package — yttrium (Y: 0.05–0.12%) + zirconium (Zr: 0.01–0.10%) + titanium (Ti: 0.1–0.2%) — acts as a scale adhesion promoter ("reactive element effect"): Y and Zr atoms segregate to the oxide-metal interface and mechanically peg the Al₂O₃ scale to the substrate, preventing spallation during thermal cycling between ambient and 1100°C.
Shanghai Hangbo Alloy Group stocks Inconel 602CA in centrifugal cast tube form (for ethylene radiant coils), hot-rolled round bars for furnace component machining, and plates for fabricated box-type furnace retorts.
Executive Standards
| Product Form | ASTM | ASME | AMS | W.Nr./VDM |
|---|---|---|---|---|
| Round Bar & Rod | ASTM B166 | ASME SB-166 | — | VDM Alloy 602CA |
| Seamless Pipe & Tube | ASTM B167 | ASME SB-167 | — | Nicrofer 6025 HT |
| Plate, Sheet & Strip | ASTM B168 | ASME SB-168 | AMS 5878 | 2.4633 |
| Forgings | ASTM B564 | ASME SB-564 | — | — |
| Centrifugal Cast Tube | ASTM A608 (HK/HP-type) | — | — | Proprietary specification |
| Welding Filler | AWS A5.14 ERNiCrFe-12 (FM 602CA) | — | — | Nicrofer S 6025 |
Chemical Composition (wt.% per ASTM B166/B168 – 100% OES Verified)
| Element | Min | Max | Role in Inconel 602CA |
|---|---|---|---|
| Nickel (Ni) | Balance | — | Austenitic matrix; provides high-temperature strength and carburization resistance |
| Chromium (Cr) | 24.0 | 26.0 | Solid-solution strengthener; contributes to Al₂O₃ nucleation; reservoir for re-healing |
| Iron (Fe) | 8.0 | 11.0 | Austenite stabilizer; economic alloying element |
| Carbon (C) | 0.15 | 0.20 | Intentionally high — forms Cr-rich M₂₃C₆ and M₇C₃ carbides for creep strength; the high Cr:Fe ratio prevents deleterious carbide network formation |
| Aluminum (Al) | 1.8 | 2.4 | The defining element — forms protective Al₂O₃ scale; kept <3% to avoid Ni₃Al (γ′) precipitation hardening |
| Yttrium (Y) | 0.05 | 0.12 | Reactive element — pegs Al₂O₃ scale to substrate; prevents thermal-cycling spallation |
| Titanium (Ti) | 0.10 | 0.20 | Synergistic with Y/Zr for scale adhesion; minor carbide former |
| Zirconium (Zr) | 0.01 | 0.10 | Grain-boundary pinning + scale adhesion reinforcement |
| Manganese (Mn) | — | 0.50 | Deoxidizer |
| Silicon (Si) | — | 0.50 | Deoxidizer; kept low — high Si would form low-melting Ni-Si eutectics during welding |
| Copper (Cu) | — | 0.10 | Impurity control |
| Sulfur (S) | — | 0.010 | Ultra-low S preserves hot workability and weldability |
| Phosphorus (P) | — | 0.020 | Impurity control |
Key chemistry insight: 602CA's high carbon (0.15–0.20%) — deliberately higher than virtually all other wrought high-temperature alloys — is NOT a liability. The 25% chromium content ensures carbon precipitates as discrete, stable Cr-rich carbides (M₂₃C₆ / M₇C₃) rather than chromium-depleted continuous grain-boundary films. These carbides pin grain boundaries during high-temperature service, providing creep rupture strength without the sensitization penalty that would occur in a leaner-chromium alloy.
Mechanical & Physical Properties
Room-Temperature Mechanical Properties (Solution-Annealed, 1150–1200°C/WQ)
| Property | Value | Standard |
|---|---|---|
| Tensile Strength (Rm) | ≥ 680 MPa (≥ 99 ksi) | ASTM B166/B168 |
| Yield Strength 0.2% (Rp0.2) | ≥ 310 MPa (≥ 45 ksi) | ASTM B166/B168 |
| Elongation (A5, 50 mm) | ≥ 35% | ASTM B166/B168 |
| Hardness | 180–220 HBW (typical) | — |
| Young's Modulus (20°C) | 220 GPa (31.9 × 10³ ksi) | — |
Elevated-Temperature Strength Retention
| Temperature | Tensile Strength (MPa, typical) | Yield Strength (MPa, typical) | Elongation (%, typical) |
|---|---|---|---|
| 20°C | 720 | 350 | 40 |
| 600°C (1112°F) | 590 | 250 | 42 |
| 800°C (1472°F) | 350 | 200 | 50 |
| 1000°C (1832°F) | 100 | 50 | 65 |
| 1100°C (2012°F) | 55 | 25 | 70 |
Creep rupture strength (typical):
| Temperature | Stress for 10,000 h rupture (MPa) | Stress for 100,000 h rupture (MPa) |
|---|---|---|
| 800°C | ~45 | ~28 |
| 900°C | ~18 | ~10 |
| 1000°C | ~8 | ~4.5 |
| 1100°C | ~3 | ~1.5 |
Physical Properties
| Property | at 20°C | at 200°C | at 600°C | at 800°C | at 1000°C | Unit |
|---|---|---|---|---|---|---|
| Density | 7.93 | — | — | — | — | g/cm³ |
| Thermal Conductivity | 11.3 | 12.6 | 20.0 | 23.5 | 26.0 | W/m·K |
| Specific Heat | 420 | 450 | 530 | 560 | 600 | J/kg·K |
| Electrical Resistivity | 1.30 | 1.31 | 1.36 | 1.38 | 1.40 | μΩ·m |
| Mean Thermal Expansion (20°C–T) | — | 13.5 | 15.0 | 15.5 | 16.1 | μm/m·°C |
Heat Treatment
Solution Annealing
| Parameter | Specification |
|---|---|
| Temperature | 1150–1200°C (2100–2190°F) |
| Soak Time | 1–2 hours depending on section thickness; minimum 1 hour for sections ≤ 25 mm |
| Cooling Method | Water quench or rapid air cool. Water quench preferred for sections ≥ 10 mm to avoid Cr-carbide precipitation in the 600–800°C range. |
| Grain Size Target | ASTM 3–5 (coarser grain improves creep resistance above 900°C) |
Metallurgical objective: Solution annealing dissolves all chromium carbides formed during hot working and homogenizes the aluminum distribution. 602CA is NOT precipitation-hardenable — it is a solid-solution and carbide-strengthened alloy. No aging treatment is applied or required. The high-temperature strength derives from (a) nickel-chromium solid solution, (b) grain-boundary chromium carbides that pin grain boundaries against creep deformation, and (c) work hardening retained from the manufacturing process.
Critical process note: Unlike most heat-resistant alloys where rapid quenching is essential to prevent sigma phase, 602CA's high Ni:Cr ratio and iron content suppress sigma-phase nucleation entirely. The quenching requirement in 602CA exists solely to avoid chromium carbide precipitation — not sigma — making it more forgiving to process than duplex or super austenitic grades. Water quenching does not embrittle 602CA.
Production Process
1. Round Bars & Forgings
- Melting: VIM (Vacuum Induction Melting) primary melt to achieve precise aluminum (1.8–2.4%) and yttrium (0.05–0.12%) control — both elements have high oxygen affinity and would be lost to slag in air-melt or even AOD processes. ESR (Electroslag Remelting) is standard for bars ≥ Ø100 mm to ensure micro-cleanliness.
- Hot Forging / Rolling: Billet heated to 1150–1200°C. Forged or hot-rolled with minimum 4:1 reduction ratio. Finishing temperature maintained above 950°C. 602CA's high carbon content provides excellent hot strength, but requires 15–20% more forging press tonnage than Inconel 600/601.
- Solution Annealing: 1150–1200°C, water quench. Furnace charts verified for uniform soak — cold spots in the furnace produce unmelted carbides that reduce ductility.
- Straightening, UT & Finishing: Multi-roll straightening. 100% ultrasonic testing per ASTM B166 for bars ≥ Ø50 mm. PMI on every piece. Macro-etch inspection for center soundness and carbide distribution.
2. Seamless Tubes & Pipes
- Hollow Preparation: Hot-extruded from annealed billet at 1150–1200°C, or centrifugal cast for large-diameter radiant coil tubes (the dominant product form for ethylene furnace applications).
- Cold Pilgering: For precision tube dimensions, multi-pass cold reduction with intermediate solution anneals (1150–1200°C, water quench) between passes. Total cold reduction 30–50%.
- Final Annealing: 1150–1200°C bright anneal in hydrogen or cracked ammonia atmosphere (for tubes ≤ OD 50 mm) to preserve surface finish.
- Testing: 100% hydrostatic or eddy current testing per ASTM E426. Destructive tensile testing per heat. Microstructural examination for carbide morphology in the tube wall center (critical for creep resistance prediction).
3. Plates, Sheets & Strips
- Hot Rolling: Slab heated to 1150–1200°C, multi-pass hot rolling with finishing temperature above 950°C. High carbon content increases hot strength — expect 10–15% higher rolling loads than Inconel 601.
- Solution Annealing: 1150–1200°C, water quench. For thin-gauge sheet (≤ 3 mm), bright anneal in hydrogen atmosphere eliminates pickling requirement.
- Leveling & Cutting: Precision leveling to flatness specification. Plasma, laser, or waterjet cutting to final dimensions.
- Surface & NDE: Pickling + passivation per ASTM A380 if oxidized surface present. 100% visual inspection. Ultrasonic testing per ASTM A435 on request.
Industry Applications
| Industry | Typical Component | Why Inconel 602CA? |
|---|---|---|
| Petrochemical — Ethylene | Radiant cracking coils, quench boilers, transfer line exchangers | Al₂O₃ scale blocks carbon diffusion → 2× coil life vs. HP-modified (Nb) cast alloys; eliminates carburization-driven embrittlement |
| Heat Treatment Furnaces | Radiant tubes, burner nozzles, muffle liners, retorts | Oxidation resistance to 1200°C without CrO₃ volatilization; maintains structural integrity in cycling service |
| Automotive | High-performance exhaust manifold components, turbocharger housings, EGR cooler tubes | Alumina scale survives exhaust-gas thermal cycling (ambient ↔ 1000°C) where chromia formers spall within 500 cycles |
| Chemical — Catalyst Production | Calciner tubes, catalyst support grids | Resists simultaneous carburization + oxidation in hydrocarbon-rich atmospheres at 900–1100°C |
| Solar Thermal Power | Central receiver tubes, thermal storage heat exchangers | Withstands molten salt corrosion + daily thermal cycling (300°C → 1100°C → 300°C); Al₂O₃ scale immune to nitrate/nitrite salt attack |
| Glass Industry | Thermocouple protection tubes, feeder plungers, stirrers | Resists molten glass corrosion + maintains dimensional stability at 1100–1200°C |
Quality Assurance: 7-Stage Zero-Defect Inspection
- Raw Material Verification: Incoming nickel, chromium, and aluminum raw materials tested by OES (ASTM E1086) and ICP-MS for trace element fingerprint. Yttrium purity verified to ≥ 99.9% — yttrium oxide contamination at the ppm level can nucleate slag inclusions that become fatigue crack initiation sites.
- VIM Melt Chemistry: In-process chemistry sampling at melt stage. Aluminum verified by optical emission spectroscopy within ±0.05% of target; yttrium by ICP-OES to ±0.005%. Carbon content verified by combustion analysis (ASTM E1019). Heats failing any elemental window are fully scrapped — no blending permitted.
- Hot Working Surveillance: Infrared pyrometry on all hot-working operations. Temperature excursions above 1250°C trigger lot quarantine for incipient melting (liquation) inspection. Forging/rolling reduction ratio verified ≥ 4:1.
- Solution Annealing Verification: Digital furnace chart recording. Rapid conformity check: hardness testing (HBW) on each annealed lot — hardness > 220 HBW triggers full metallographic examination for undissolved carbides.
- Destructive Mechanical Testing (Per Heat/Lot): Room-temperature tensile per ASTM E8 (round bar) or A370 (tube/plate). Elevated-temperature tensile at specified design temperature on request. Charpy-V impact on request. Microstructural examination: carbide morphology rating (discrete globular preferred; continuous grain-boundary films rejected) per ASTM E112 grain size + qualitative carbide assessment.
- Non-Destructive Examination: 100% ultrasonic testing on bars ≥ Ø50 mm per ASTM B166. 100% eddy current or hydrostatic on tubes. PMI (portable OES) on every finished piece — aluminum channel verification is the go/no-go acceptance criterion.
- Final Documentation & Shipment: EN 10204 Type 3.1 Mill Test Certificate with full chemistry (including Y, Zr, Ti trace), mechanical test results, grain size measurement, carbide morphology rating, and dimensional report. Third-party inspection by SGS, Bureau Veritas, TÜV Rheinland, or Lloyd's Register available.
Frequently Asked Questions
Q1: What is Inconel 602CA used for?
602CA is the premier alloy for ethylene cracking furnace radiant coils — the hottest and most carburization-aggressive component in the petrochemical industry. It is also used for heat treatment furnace radiant tubes and muffles operating at 1000–1200°C, automotive turbocharger and EGR components subject to severe thermal cycling, calciner tubes in catalyst production, central receiver tubes in concentrated solar power (CSP) plants, and glass-making thermocouple protection tubes. The common thread: all applications involve temperatures above 950°C where conventional chromia-forming alloys fail through oxide volatilization or carburization.
Q2: What is the density of Inconel 602CA?
7.93 g/cm³ (0.286 lb/in³) at 20°C. This is comparable to Inconel 600 (8.47 g/cm³) and Inconel 601 (8.05 g/cm³). Mass estimation formula: Weight (kg) = 7.93 × Volume (cm³) ÷ 1000.
Q3: What is the maximum service temperature of Inconel 602CA?
Approximately 1200°C (2190°F) for continuous service in oxidizing atmospheres. The Al₂O₃ scale remains protective to the alloy's solidus temperature (~1370°C), making 602CA's practical limit higher than any commercially available wrought chromia former. In comparison, Inconel 601 (Cr₂O₃ former) is typically rated to ~1100°C before breakaway oxidation begins. Above 1200°C, the alloy's creep strength — not oxidation resistance — becomes the limiting factor.
Q4: What is the melting point of Inconel 602CA?
The melting range is 1370–1415°C (2500–2580°F). The relatively narrow melting range (~45°C) compared to most cast high-temperature alloys (~100+°C) is a consequence of the tightly controlled composition limits demanded by the VIM melting process.
Q5: What is the tensile strength of Inconel 602CA?
In the solution-annealed condition, minimum tensile strength is ≥ 680 MPa (≥ 99 ksi) per ASTM B166/B168. Typical values from production heats range 700–760 MPa. At 1000°C, tensile strength drops to approximately 100 MPa, and at 1100°C to approximately 55 MPa — values adequate for self-supporting radiant tube applications where loads are primarily thermal-expansion-derived rather than pressure-derived.
Q6: What is the yield strength of Inconel 602CA?
Minimum 0.2% offset yield strength is ≥ 310 MPa (≥ 45 ksi) at room temperature. At 800°C, yield strength is approximately 200 MPa; at 1000°C, approximately 50 MPa. The yield-to-tensile ratio increases from ~0.45 at room temperature to ~0.55 at 1000°C, reflecting the increasing contribution of grain-boundary carbide pinning to strength at high temperatures.
Q7: What is the elongation of Inconel 602CA?
Minimum elongation (A5) is ≥ 35% at room temperature, with typical values of 38–45%. Elongation actually increases with temperature — reaching > 60% at 1000°C — as the FCC austenitic matrix becomes more ductile and deformation shifts from slip-dominated to diffusion-assisted creep mechanisms. This hot ductility is critical for thermal fatigue resistance: 602CA radiant tubes accommodate thermal-expansion strain through creep relaxation rather than crack initiation.
Q8: What are the full mechanical properties of Inconel 602CA?
Solution-annealed (1150–1200°C/WQ) minimum properties: tensile strength ≥ 680 MPa (99 ksi), yield strength ≥ 310 MPa (45 ksi), elongation ≥ 35%, hardness 180–220 HBW. At 1000°C: tensile ~100 MPa, yield ~50 MPa, elongation ~65%. Creep rupture strength at 1000°C: ~8 MPa for 10,000-hour life, ~4.5 MPa for 100,000-hour life. The dominant design criterion for 602CA radiant coils is creep rupture life, not short-term tensile properties — this is why grain size (ASTM 3–5, deliberately coarser than typical wrought products) is a specified quality parameter.
Q9: What heat treatment does Inconel 602CA require?
Solution annealing at 1150–1200°C (2100–2190°F) followed by water quenching or rapid air cooling. Soak time: 1–2 hours depending on section thickness. This treatment dissolves chromium carbides formed during hot working and homogenizes the aluminum distribution for uniform Al₂O₃ scale formation in service. No aging or precipitation hardening treatment is required — 602CA is purely solid-solution and carbide-strengthened.
Q10: What is the solution annealing temperature for Inconel 602CA?
1150–1200°C (2100–2190°F). The lower bound (1150°C) ensures complete carbide dissolution; the upper bound (1200°C) prevents excessive grain growth that would reduce room-temperature ductility without providing additional creep benefit. Compared to Inconel 601 (typically annealed at 980–1040°C), 602CA requires approximately 150°C higher annealing temperature because the higher chromium and carbon content produces more stable carbides requiring higher dissolution temperature.
Q11: How does Inconel 602CA compare to Inconel 601?
| Property | Inconel 602CA (N06025) | Inconel 601 (N06601) | Winner |
|---|---|---|---|
| Oxide Scale Type | Al₂O₃ (alumina) | Cr₂O₃ (chromia) | 602CA — no high-temperature volatilization |
| Max Service Temp | ~1200°C | ~1100°C | 602CA — +100°C advantage |
| Carburization Resistance | Excellent (Al₂O₃ carbon barrier) | Good (Cr₂O₃ barrier) | 602CA — ~5× longer coil life in ethylene service |
| Chromium Content | 24–26% | 21–25% | Similar |
| Aluminum Content | 1.8–2.4% | 1.0–1.7% | 602CA — deliberate alumina former |
| Carbon Content | 0.15–0.20% | ≤0.10% | 601 — but 602CA's high C is intentional for creep |
| Creep Strength at 1000°C | ~8 MPa / 10k h | ~3 MPa / 10k h | 602CA — 2.5–3× superior |
| Cost Premium over 601 | — | — | 602CA: 1.3–1.6× 601 material cost, 2–3× service life |
The rule: If your application operates above 1050°C, or involves carburizing atmospheres, Inconel 602CA delivers a lower total cost of ownership despite the higher upfront material cost. If operating below 1000°C in clean oxidizing conditions, Inconel 601 may suffice.
Q12: What is the price of Inconel 602CA per kg?
Indicative EXW pricing for Inconel 602CA round bars ranges \$35–55/kg, with seamless tubes 20–35% higher and plates 5–10% lower. The premium over Inconel 601 (typically \$25–35/kg) reflects the VIM-only melting requirement (aluminum/ytterbium control cannot be achieved in air-melt or AOD) and the higher nickel-plus-chromium content. However, total-lifecycle cost in ethylene furnace service typically favors 602CA by a factor of 2–3× due to extended coil replacement intervals. Shanghai Hangbo Alloy Group returns firm quotations within 2 business hours — email sales@hangboalloy.com with your specification and required quantity.
Q13: Is Inconel 602CA weldable?
Yes, using GTAW (TIG) and GMAW (MIG) processes with matching filler metal ERNiCrFe-12 (FM 602CA / Nicrofer S 6025 per AWS A5.14). Key welding parameters: preheat not required; interpass temperature ≤ 150°C (300°F); heat input 0.8–1.5 kJ/mm; shielding gas Ar + 2% H₂ or pure argon; post-weld solution anneal is generally not required for service below 1000°C. For dissimilar welding (602CA to HP-modified cast tube, 602CA to Inconel 601), ERNiCrFe-12 filler is compatible. The yttrium and zirconium in the filler metal replicate the reactive-element effect in the weld metal, ensuring the Al₂O₃ scale integrity across the weld zone.
Q14: What product forms does Shanghai Hangbo supply for Inconel 602CA?
We supply Inconel 602CA in round bars (Ø6–300 mm, hot-rolled or forged, solution-annealed and peeled), seamless tubes (OD 10–219 mm, wall 1.5–25 mm, per ASTM B167), centrifugal cast tubes (OD 60–500 mm, wall 5–30 mm, as-cast or machined — the dominant product form for ethylene radiant coils), plates (3–50 mm thickness, per ASTM B168 / AMS 5878), forgings (discs, rings, tube sheets, flanges per ASTM B564), and welding wire (ERNiCrFe-12, spooled per AWS A5.14).
Q15: Does Shanghai Hangbo ship Inconel 602CA internationally?
Yes. We export to 40+ countries with terms FOB Shanghai, CIF, CFR, and DAP. Typical destinations include USA, Germany, Netherlands (Rotterdam — major ethylene hub), Saudi Arabia, UAE, Singapore, South Korea, and Japan. Stock items ship within 2–4 weeks; VIM mill-order production lead time is 8–12 weeks. Centrifugal cast radiant tube orders (custom OD/wall/length) require 10–14 weeks including pattern preparation and NDE. Air freight available for urgent ≤ 200 kg shipments. All documentation: commercial invoice, packing list, certificate of origin, EN 10204 3.1 MTC with full trace element report.
Q16: Why is the aluminum content critical in Inconel 602CA?
Aluminum at 1.8–2.4% is the defining metallurgical feature of 602CA. At service temperature, aluminum atoms diffuse to the alloy surface and react with oxygen to form a continuous, adherent Al₂O₃ (alpha-alumina) scale approximately 1–3 μm thick. This scale has three decisive advantages over the Cr₂O₃ scale formed by Inconel 600/601: (1) No high-temperature volatilization — Cr₂O₃ oxidizes to volatile CrO₃ above ~1000°C, progressively consuming the protective scale; Al₂O₃ is stable to >2000°C. (2) Impermeable carbon barrier — Al₂O₃ is ~100× less permeable to interstitial carbon diffusion than Cr₂O₃, making 602CA immune to the carburization embrittlement that limits chromia-forming alloys to 3–5 years in ethylene service. (3) Self-healing — aluminum's higher diffusivity in nickel vs. chromium in nickel means a damaged oxide layer re-forms faster. The aluminum range is deliberately capped at 2.4% to stay within the solid-solution limit: exceeding ~3% Al would precipitate gamma-prime (Ni₃Al), producing an age-hardening alloy that would lose strength catastrophically above 800°C.
Q17: What is the difference between Inconel 602CA and cast HP-modified alloys for ethylene furnace tubes?
| Property | Inconel 602CA (Wrought) | HP-Modified (Cast, ~25Cr-35Ni-Nb) | Advantage |
|---|---|---|---|
| Manufacturing | VIM + hot extrusion/forging | Static or centrifugal casting | 602CA — finer grain, no casting defects |
| Oxide Scale | Al₂O₃ (no CrO₃ volatilization) | Cr₂O₃ (volatilizes above ~1050°C) | 602CA — decisive above 1050°C |
| Carburization Rate | ~0.1 mm/year at 1100°C | ~0.5–1.0 mm/year at 1100°C | 602CA — 5–10× slower |
| Typical Coil Life | 6–10+ years | 3–5 years | 602CA — 2× replacement interval |
| Material Cost | ~3× HP-modified | Baseline | HP-modified — lower upfront |
| Repair Weldability | Excellent (matching filler) | Challenging (aged cast structure) | 602CA — easier maintenance |
| Max Tube Length | ~12 m (forge/extrusion limit) | ~6 m (casting pattern limit) | 602CA — fewer girth welds |
The emerging best practice in ethylene plant design is a hybrid furnace: HP-modified cast tubes for the lower-temperature convection section (600–950°C), transitioning to Inconel 602CA wrought or centrifugal-cast tubes for the radiant section (950–1150°C) where carburization and oxide volatilization are the dominant degradation mechanisms.
Contact Shanghai Hangbo Alloy Group
| Channel | Details |
|---|---|
| Company | Shanghai Hangbo Alloy Group Co., Ltd. (宝昭实业（上海）有限公司) |
| Website | www.nickel-alloy.com |
| Email (Sales) | sales@hangboalloy.com |
| Email (Technical) | hangbo@nickel-alloy.com |
| +86 13611656360 | |
| Skype | live:specialalloy001 |
| Address | Room 1508, No. 288 Shiyi Road, Baoshan District, Shanghai 200940, China |
| ISO Certification | ISO 9001:2015 — View certificate on request |
| Response Time | ≤ 10 minutes during business hours (Mon–Fri, 08:00–18:00 GMT+8) |
Your Next Step
Email sales@hangboalloy.com with your Inconel 602CA specification:
- Product form: Bar / Tube / Centrifugal cast tube / Plate / Forging
- Dimensions: OD × wall / diameter × length, in mm or inches
- Required standard: ASTM B166 / B167 / B168 / B564 / AMS 5878
- Service conditions: Maximum operating temperature, atmosphere (oxidizing / carburizing / both), design life requirement
- Delivery destination: Full address + preferred incoterm (FOB / CIF / DAP)
Our metallurgy team can review your furnace tube failure history and provide a comparative life-cycle cost analysis for 602CA vs. your current alloy at no charge.
