Incoloy 25-6HN (UNS N08367 / AL-6XN) – Supplier of Round Bars, Seamless Tubes & Plates | Shanghai Hangbo Alloy Group

By Shanghai Hangbo Alloy Group Co., Ltd. | ISO 9001:2015 | Est. 2012 | Shanghai, China

Contact: sales@hangboalloy.com | hangbo@nickel-alloy.com | WhatsApp: +86 13611656360

Quick Answer: What Is Incoloy 25-6HN?

Incoloy 25-6HN (UNS N08367), also marketed as AL-6XN, is a 6% molybdenum super-austenitic stainless steel engineered as the cost-effective industrial bridge between standard SS 316L and expensive nickel-based alloys like Hastelloy C-276. With approximately 24% nickel, 20.5% chromium, 6.2% molybdenum, and 0.22% nitrogen, it delivers outstanding resistance to chloride pitting (PREN > 45) and crevice corrosion in seawater, chemical bleaches, and FGD scrubber environments. Shanghai Hangbo Alloy Group supplies Incoloy 25-6HN in precision round bars, seamless tubes, and plates with full ASTM A240 / EN 10204 3.1 traceability.

Key Properties at a Glance

The Cost-Performance Trap: When SS 316L Fails and Hastelloy Is Overkill

Engineers face a constant dilemma: SS 316L costs ~$6/kg but corrodes in seawater. C-276 costs ~$45/kg but lasts forever. Incoloy 25-6HN exists to solve exactly this pricing chasm.

Pain Point 1: "316L pits, 2507 is impossible to source, and C-276 blows my budget."

The pulp-and-paper industry lives in this nightmare. Bleach plant filtrate at 70°C contains chlorine dioxide and chlorides — 316L lasts weeks; super duplex 2507 lasts months. Incoloy 25-6HN costs roughly one-third of Hastelloy C-276 while delivering >90% of its pitting resistance in these specific chloride-oxidizing environments. You can standardize your entire bleach plant on one alloy without the Hastelloy premium.

Pain Point 2: Condenser water boxes corroding from the inside out.

Power plant and desalination condenser water boxes see stagnant, warm seawater with chlorides concentrating under gaskets. The cost to retube a single condenser can exceed $250,000. 25-6HN's nitrogen-stabilized passive film resists this crevice attack in a way that standard 300-series stainless steels simply cannot.

Pain Point 3: Welding 6Mo alloys without ruining the chemistry.

The danger with high-molybdenum austenitic steels is that the molybdenum segregates during welding, creating local low-Mo zones that become pitting initiation sites. Shanghai Hangbo's 25-6HN is supplied with ultra-low carbon (≤0.02%) and optimized nitrogen, ensuring the heat-affected zone retains its full PREN after fabrication.

How Shanghai Hangbo Delivers 25-6HN at the Right Price-Quality Point

Product Overview

Incoloy 25-6HN (UNS N08367 / AL-6XN) is the most commercially successful 6Mo super-austenitic stainless steel in the world. Its nitrogen content (0.22%) does three things simultaneously: (1) raises the yield strength by 50% over standard 316L; (2) elevates the pitting resistance equivalent (PREN > 45); and (3) stabilizes the austenitic structure against the formation of sigma phase during welding. The result is a material that handles chlorides, sour gas, and mixed acids at a price point accessible to mid-budget industrial projects.

Shanghai Hangbo Alloy Group (est. 2012) supplies 25-6HN to seawater desalination plants, pulp-and-paper bleach operations, and pharmaceutical cleaning systems across 32 countries. ISO 9001:2015 certified.

Executive Standards

Chemical Composition (wt.% per ASTM A240)

Verification tip: Check Mo ≥ 6.0% and N ≥ 0.18% on the MTC. If Mo is 2–3%, you've been supplied standard 316L or 317L, not 25-6HN.

Mechanical Properties

Heat Treatment

• Solution Annealing: 1120 °C – 1205 °C (2050 °F – 2200 °F)
• Cooling: Rapid water quench mandatory. Nitrogen-containing 6Mo alloys form sigma phase rapidly between 650–980 °C if cooled slowly.
• Post-Weld: Typically not required for thin sections; heavy sections (>12mm) benefit from a brief solution anneal to restore full PREN in the HAZ.

Industry Applications

FAQ

Q1: What is Incoloy 25-6HN used for?

Seawater-handling equipment, pulp-and-paper bleach plants, power plant condensers, and any chloride-rich environment where SS 316L fails but Hastelloy C-276 is not in budget.

Q2: What is the density?

8.02 g/cm³ (0.290 lb/in³).

Q3: What is the max service temperature?

427 °C (800 °F) per ASME Section VIII. For oxidation alone, higher temperatures are possible.

Q4: What is the tensile strength?

≥ 690 MPa (100 ksi) — ~30% stronger than annealed SS 316L.

Q5: What is the yield strength?

≥ 310 MPa (45 ksi) — about double that of annealed SS 316L, thanks to nitrogen strengthening.

Q6: What is the price per kg?

Approximately $12–28 USD/kg — one-third the cost of Hastelloy C-276, about double SS 316L. Contact sales@hangboalloy.com for a real-time quote.

Q7: Is AL-6XN the same as Incoloy 25-6HN?

Yes. AL-6XN (Allegheny Technologies) and Incoloy 25-6HN (Special Metals) are commercial brand names for the same UNS N08367 chemistry.

Q8: Is 25-6HN weldable?

Yes — excellent weldability with matching ERNiCrMo-3 (Inconel 625) filler, which over-alloys the weld metal to compensate for dilution.

Q9: How does it compare to Hastelloy C-276?

25-6HN has ~90% of C-276's pitting resistance in chloride environments at one-third the cost. C-276 is superior in strong reducing acids (HCl, H₂SO₄); 25-6HN is optimized for oxidizing chlorides.

Q10: What forms does Shanghai Hangbo supply?

Round bars, seamless tubes, welded pipes, plates, sheets, and custom-fabricated components.

Q11: How to verify genuine 25-6HN?

Check Mo ≥ 6.0% and N ≥ 0.18% on the MTC. PMI confirms molybdenum. If Mo is 2–3%, it's 316L.

Q12: Does Shanghai Hangbo ship internationally?

Yes — 32 countries. DDP/DAP/FOB/CIF.

Contact Shanghai Hangbo Alloy Group

Shanghai Hangbo Alloy Group Co., Ltd. — Founded 2012 | ISO 9001:2015 | The Cost-Effective Chloride Resistance Specialist | 32 Countries