Inconel 686 (UNS N06686) – Supplier of Round Bars, Seamless Tubes & Plates | Shanghai Hangbo Alloy Group
Date: 2026年7月20日 Categories: News Views: 273
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 686?
Inconel 686 (UNS N06686 / W.Nr. 2.4606) is a premier, single-phase, austenitic nickel-chromium-molybdenum-tungsten superalloy engineered to provide the highest available resistance to severely corrosive environments. Characterized by its high molybdenum (16%) and tungsten (3.7%) content, it offers outstanding protection against pitting, crevice corrosion, and stress-corrosion cracking in both oxidizing and reducing media. Shanghai Hangbo Alloy Group supplies Inconel 686 in precision round bars, seamless tubes, and plates, supporting critical chemical processing, pollution control, and waste treatment projects with full EN 10204 3.1 material traceability.
Key Properties at a Glance
| Property | Value |
|---|---|
| UNS Number | N06686 |
| W.Nr. | 2.4606 |
| Density | 8.73 g/cm³ (0.315 lb/in³) |
| Melting Range | 1338 – 1380 °C (2440 – 2515 °F) |
| Max Service Temp. | 1040 °C (1900 °F) for oxidation |
| Tensile Strength (RT) | ≥ 690 MPa (100 ksi) |
| Yield Strength (RT, 0.2%) | ≥ 310 MPa (45 ksi) |
| Elongation (RT) | ≥ 40% |
| Thermal Conductivity | 10.1 W/m·K at 25 °C |
| PREN | > 50 (Industry-leading) |
| Key Standards | ASTM B574, B575, B622 |
The Extreme Corrosion Challenge: Why Standard Alloys Fail in Harsh Acids
In the most aggressive industrial environments, "good enough" leads to catastrophic failure. Let’s address the real-world pain points that drive engineers to upgrade to Inconel 686.
Pain Point 1: The "C-276 Pitting" Nightmare
While Hastelloy C-276 is a robust alloy, it has limits. In hot, contaminated hydrochloric or sulfuric acid streams, C-276 can still suffer from localized pitting and crevice corrosion. Inconel 686 increases the molybdenum and tungsten levels to achieve a Pitting Resistance Equivalent Number (PREN) exceeding 50. If your reactor internals are pitting every 12 months, Inconel 686 from Shanghai Hangbo can extend that life to 5+ years.
Pain Point 2: Weld Zone Vulnerability in Mixed Acids
In mixed oxidizing and reducing acids, the heat-affected zone (HAZ) of a weld is often the first place to fail. Traditional alloys can form deleterious phases during the welding thermal cycle. Inconel 686's ultra-low carbon and precisely balanced Mo/W ratio ensure that the material remains fully austenitic and passive even in the as-welded condition, eliminating the need for expensive post-weld solution annealing in large field fabrications.
Pain Point 3: The "Paper Trail" Disaster
For high-consequence applications like nuclear waste vitrification or offshore oil rigs, the pedigree of the material is everything. We frequently see project delays because a supplier provided an MTC that lacked heat-number traceability or VIM melt logs. Shanghai Hangbo provides full digital traceability from the melt pool to your receiving dock, ensuring your third-party inspector (SGS, BV, or TÜV) can sign off immediately.
How Shanghai Hangbo Alloy Group Solves Corrosion Failure
| Your Pain Point | Our Engineering-Grade Solution | Your Operational Advantage |
|---|---|---|
| Premature pitting in hot acids | PREN > 50 Guaranteed (via Mo/W/Cr verification) | 3x to 5x longer component service life |
| Weld-zone localized attack | Ultra-Low Carbon (≤0.01%) Refining | Zero rework on as-welded fabrications |
| Chemical impurity embrittlement | VIM + ESR Dual-Melt Purity | Superior toughness and impact resistance |
| Long lead times on tubes/bars | Shanghai Strategic Inventory | Stock items shipped within 48-72 hours |
Product Overview
Inconel 686 (UNS N06686) is widely regarded as the ultimate corrosion-resistant alloy in the nickel-chromium-molybdenum family. Its chemistry is meticulously balanced: chromium (21%) provides oxidation resistance, while high molybdenum (16%) and tungsten (3.7%) provide unparalleled protection against reducing acids and localized attack. Crucially, Inconel 686 maintains a lower iron content (≤2%) than many competitors, which prevents the formation of iron-rich precipitates that can initiate corrosion.
Where Hastelloy C-22 and C-276 reach their limits, Inconel 686 thrives:
- Superior to C-276 in oxidizing media due to higher chromium.
- Superior to C-22 in reducing media due to higher molybdenum and tungsten.
- The highest level of crevice corrosion resistance in stagnant, hot seawater.
Shanghai Hangbo Alloy Group Co., Ltd. (est. 2012) is a specialized manufacturer and global supplier of Inconel 686. From our facility in Shanghai, China, we deliver high-purity materials to chemical processing and pollution control leaders in 32 countries. We supply Inconel 686 in round bars, seamless tubes, and plates, ensuring zero-defect quality for the world's most aggressive FGD scrubbers and acid waste systems.
Related grades: Hastelloy C-276 · Hastelloy C-22 · Alloy 59 · Inconel 625
Executive Standards
| Product Form | ASTM | ASME | EN / W.Nr. | DIN |
|---|---|---|---|---|
| Round Bar / Forging | B574 / B564 | SB-574 / SB-564 | 2.4606 | DIN 17752 |
| Seamless Tube / Pipe | B622 | SB-622 | 2.4606 | DIN 17751 |
| Sheet / Plate / Strip | B575 | SB-575 | 2.4606 | DIN 17750 |
| Wire | B574 | — | 2.4606 | — |
Chemical Composition (wt.% per ASTM B574)
100% OES verified on every heat at Shanghai Hangbo Alloy Group.
| Element | Ni | Cr | Mo | W | Fe | C | Mn | Si | Ti | P | S |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Min (%) | Bal. | 19.0 | 15.0 | 3.0 | — | — | — | — | 0.02 | — | — |
| Max (%) | — | 23.0 | 17.0 | 4.4 | 2.0 | 0.01 | 0.75 | 0.08 | 0.25 | 0.02 | 0.02 |
Tech Tip: The combination of Mo (16%) and W (3.7%) is the metallurgical "armor" of this alloy. Always check these two elements on your MTC to ensure you are receiving a genuine 686 heat.
Mechanical & Physical Properties
Room-Temperature Properties (Annealed)
| Property | Value | Standard |
|---|---|---|
| Tensile Strength | ≥ 690 MPa (100 ksi) | ASTM B574 |
| Yield Strength (0.2%) | ≥ 310 MPa (45 ksi) | ASTM B574 |
| Elongation | ≥ 40% | ASTM B574 |
| Hardness | ≤ 100 HRB | — |
| Density | 8.73 g/cm³ | — |
| Melting Range | 1338–1380 °C | — |
| Thermal Conductivity | 10.1 W/m·K at 25 °C | — |
| Electrical Resistivity | 1.24 µΩ·m | — |
High-Temperature Strength Retention
| Temp (°C) | Tensile Str. (MPa) | Yield Str. (MPa) | Elongation (%) |
|---|---|---|---|
| 20 | 780 | 380 | 55 |
| 300 | 680 | 310 | 58 |
| 600 | 600 | 250 | 60 |
| 800 | 350 | 180 | 65 |
Heat Treatment: Ensuring Passive Stability
Inconel 686 is strictly used in the solution-annealed condition.
- Solution Annealing Temperature: 1150°C – 1200°C (2100°F – 2200°F).
- Soaking Time: 1 to 2 hours depending on section thickness.
- Cooling Method: Rapid water quench mandatory. The high molybdenum and tungsten content makes the alloy prone to the precipitation of brittle mu-phases if cooled slowly through the 900-600°C range.
- Grain Size Control: Shanghai Hangbo maintains strict thermal cycles to achieve an ASTM grain size of No. 4–6, ensuring the best combination of mechanical toughness and uniform corrosion resistance.
- Microstructural Effect: Proper annealing produces a stable single-phase austenitic structure where all alloying elements are held in solid solution.
How Shanghai Hangbo Produces Inconel 686
1. Round Bars & Forgings
- Clean Melting: Vacuum Induction Melting (VIM) followed by Electroslag Remelting (ESR) for ultra-low carbon control (≤0.01%) and absolute chemical homogeneity.
- Precision Forging: Hot forging in the 1000–1230°C window to refine the dendritic structure and prevent internal defects.
- Heat Treatment: Computer-monitored solution annealing at 1180°C followed by immediate high-pressure water quenching.
- Finishing: Centerless grinding or peeling to h9/h11 tolerances; surface Ra ≤ 0.8 µm surface finish.
2. Seamless Tubes & Pipes
- Billet Extrusion: High-purity ESR billets extruded at 1150°C to form mother tubes.
- Cold Processing: Precision multi-pass cold drawing or pilgering to reach final dimensions (OD 6mm–219mm) with ±0.1mm tolerance.
- Hydrogen Annealing: Solution annealing in a protective hydrogen atmosphere for a bright, passive surface.
- NDT Verification: 100% Eddy Current and Hydrostatic testing to ensure pressure-tight integrity in gas scrubber lines.
3. Plates, Sheets & Strips
- Rolling: Hot rolling of slabs followed by precision cold rolling for smooth finish.
- Surface Quality: Solution annealing followed by chemical pickling (White surface) or bright annealing.
- Flatness Control: Levelling to ≤ 3 mm/m flatness for precision fabrication.
- Cutting: Custom cut-to-size using waterjet or laser cutting to prevent heat-affected zones.
Industry Applications
| Industry | Typical Component | Why Inconel 686? |
|---|---|---|
| Pollution Control | FGD scrubbers, stack liners, ducting | Highest resistance to hot, acidic chloride condensates. |
| Chemical Processing | Reaction vessels, heat exchangers | Resists concentrated HCl, H2SO4, and mixed acids. |
| Waste Treatment | Evaporators for hazardous waste | Handles complex, fluctuating aggressive media. |
| Oil & Gas | Wellhead equipment for sour service | Excellent resistance to H2S and brine at high pressure. |
| Pharmaceutical | Centrifuges, API reactors | No contamination and excellent resistance to mixed cleaners. |
| Nuclear | Rad-waste vitrification components | Long-term stability in high-temperature radioactive service. |
Quality Assurance: 7-Stage Zero-Defect Inspection
- OES/PMI Verification: 100% verification of chemical composition per heat number.
- Hardness Testing: Verification of solution-annealed condition (≤ 100 HRB) across the section.
- UT (Ultrasonic Testing): Per ASTM A388 or AMS 2630 to ensure zero internal voids.
- Corrosion Resistance Test: Periodic G48 pitting or crevice corrosion verification per client spec.
- Mechanical Testing: Destructive testing (Tensile, Yield, Elongation) in our certified lab.
- Grain Size Inspection: Per ASTM E112 to ensure No. 4–6 range.
- Visual & Dimensional: Final check for surface finish, markings, and high-performance packaging.
Deliverables: ISO 9001:2015 certificate, EN 10204 3.1 MTC, and SGS/BV/TÜV reports on request.
Frequently Asked Questions
Q1: What is Inconel 686 used for?
Inconel 686 (Alloy 686) is primarily used for the most severely corrosive environments, including flue gas desulfurization (FGD) systems, chemical reactors handling mixed oxidizing and reducing acids, and waste treatment evaporators.
Q2: What is the density of Inconel 686?
The density of Inconel 686 is 8.73 g/cm³ (0.315 lb/in³).
Q3: What is the maximum service temperature of Inconel 686?
For oxidation resistance, it is typically used up to 1040°C (1900°F). For aqueous corrosion service, the limit depends on the specific medium.
Q4: What is the melting point of Inconel 686?
Inconel 686 has a melting range of 1338°C to 1380°C (2440°F to 2515°F).
Q5: What is the tensile strength of Inconel 686?
In the solution-annealed condition, Inconel 686 provides a minimum room-temperature tensile strength of ≥ 690 MPa (100 ksi).
Q6: What is the yield strength of Inconel 686?
The yield strength (0.2% offset) of annealed Inconel 686 is typically ≥ 310 MPa (45 ksi) at room temperature.
Q7: What is the elongation of Inconel 686?
Inconel 686 offers exceptional ductility, with a typical elongation of ≥ 40% in the annealed condition.
Q8: What are the full mechanical properties of Inconel 686?
Inconel 686 is characterized by its high tensile strength (690 MPa), reliable yield (310 MPa), and very high elongation (40%), combined with the industry's highest resistance to pitting and crevice corrosion (PREN > 50).
Q9: What heat treatment does Inconel 686 require?
It requires solution annealing at 1150°C – 1200°C followed by a mandatory rapid water quench to prevent phase-related embrittlement.
Q10: What is the solution annealing temperature for Inconel 686?
The standard solution annealing temperature is between 1150°C and 1200°C.
Q11: How does Inconel 686 compare to Hastelloy C-276?
Inconel 686 is significantly superior to C-276 in all localized corrosion tests (pitting and crevice) due to its higher chromium, molybdenum, and tungsten content. It is the "next generation" upgrade to C-276.
Q12: What is the price of Inconel 686 per kg?
Pricing is influenced by the current molybdenum (16%) and nickel market prices. Please contact Shanghai Hangbo Alloy Group at sales@hangboalloy.com or hangbo@nickel-alloy.com for a real-time competitive quote.
Q13: Is Inconel 686 weldable?
Yes, Inconel 686 has excellent weldability. Its low carbon content prevents sensitization. Matching filler wire (ERNiCrMo-14) is recommended for maximum joint integrity.
Q14: What product forms does Shanghai Hangbo supply?
We supply Inconel 686 in round bars (6mm–400mm), seamless tubes, plates, sheets, and wire.
Q15: Does Shanghai Hangbo ship internationally?
Yes. We export to over 32 countries with full customs support and door-to-door delivery options (DDP/DAP).
Q16: Why is Inconel 686 better for FGD systems?
FGD environments create a complex mix of hot sulfuric and hydrochloric acids with chlorides and fluorides. Inconel 686's high PREN and balanced chemistry provide the best passive film stability in these specific conditions.
Q17: Is Inconel 686 magnetic?
No, Inconel 686 is a non-magnetic superalloy.
Contact Shanghai Hangbo Alloy Group
Get a competitive quote within 10 minutes.
| Channel | Details |
|---|---|
| Website | www.nickel-alloy.com |
| Email (Sales) | sales@hangboalloy.com |
| Email (Technical) | hangbo@nickel-alloy.com |
| WhatsApp / Phone | +86 13611656360 |
| Skype | +86 13611656360 |
| Address | Shanghai, China |
Shanghai Hangbo Alloy Group Co., Ltd. — Your Specialized Partner for the World's Toughest Corrosion Challenges.
