AL-6XN (UNS N08367) - 6Mo Super Austenitic Supplier of Bars, Tubes & Plates | Shanghai Hangbo Alloy Group
Date: 2026年8月10日 Categories: News Views: 286
By Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier | ISO 9001:2015 | Est. 2012
Contact: sales@hangboalloy.com | hangbo@nickel-alloy.com | WhatsApp (Lisa): +86 13611656360
Quick Answer: What Is AL-6XN?
AL-6XN (UNS N08367 / W.Nr. 1.4529) is the original 6% molybdenum super austenitic stainless steel — the alloy that defined the 6Mo class in the 1970s — delivering seawater-grade pitting resistance (PREN >=45) combined with excellent strength and fabricability. It is widely used for seawater heat exchangers, FGD scrubbers, desalination plants, and offshore firewater systems where 316L fails within months but nickel alloys are over-specified. Shanghai Hangbo Alloy Group supplies AL-6XN as round bars, seamless tubes, and plates.
Industry Pain Point: Shipboard seawater cooling systems using 316L tubes experience crevice corrosion at tube-to-tubesheet joints within 12-24 months of service — a maintenance burden that drives the entire naval and offshore fleet toward 6Mo materials. AL-6XN, with its 6.3% Mo + 0.22% N chemistry, resists crevice corrosion in ambient and moderately heated seawater indefinitely, and is the economically optimum choice between 316L (fails) and C-276 (overkill at 5x cost).
Key Properties at a Glance
| Property | Value |
|---|---|
| UNS Number | N08367 |
| W.Nr. | 1.4529 |
| Density | 8.06 g/cm3 |
| PREN | >= 45 |
| Tensile (Ann.) | >= 690 MPa (100 ksi) |
| Yield (Ann.) | >= 310 MPa (45 ksi) |
| Elongation (Ann.) | >= 30% |
| Key Standards | ASTM B688, B676, B691 |
Product Overview
AL-6XN, developed by Allegheny Ludlum, established the 6% Mo super austenitic class that 254SMO and others later joined. Its chemistry -- 20.5% Cr, 24% Ni, 6.3% Mo, 0.22% N -- provides:
- PREN >= 45: Seawater-grade pitting and crevice corrosion resistance.
- High strength (>=310 MPa yield): Solid-solution + nitrogen strengthening.
- Excellent fabricability: Weldable, formable, machinable — the most fabrication-friendly 6Mo grade.
Shanghai Hangbo Alloy Group supplies AL-6XN in bars, seamless tubes, and plates.
Executive Standards
| Product Form | ASTM |
|---|---|
| Plate, Sheet & Strip | ASTM B688 |
| Seamless Pipe & Tube | ASTM B676 |
| Welded Pipe | ASTM B675 |
| Bar & Rod | ASTM B691 |
| Forgings | ASTM B564 |
Chemical Composition (wt.%)
| Element | Min | Max | Role |
|---|---|---|---|
| Cr | 20.0 | 22.0 | Passivity |
| Ni | 23.5 | 25.5 | Austenite stability; SCC resistance |
| Mo | 6.0 | 7.0 | Pitting/crevice resistance |
| N | 0.18 | 0.25 | Strength + PREN |
| C | -- | 0.03 | Ultra-low |
| Mn | -- | 2.0 | Deoxidizer |
| Fe | Balance | -- | Matrix |
Mechanical & Physical Properties
Room-Temperature (Solution-Annealed)
| Property | Value |
|---|---|
| Tensile Strength | >= 690 MPa (100 ksi) |
| Yield Strength 0.2% | >= 310 MPa (45 ksi) |
| Elongation | >= 30% |
| Hardness | <= 100 HRB |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.06 g/cm3 |
| Thermal Conductivity | ~12 W/m-K |
| Magnetic | Non-magnetic |
Heat Treatment
Solution Annealing: 1120-1170C (2050-2140F), water quench. No precipitation hardening.
Industry Applications
| Industry | Component | Why AL-6XN? |
|---|---|---|
| Marine | Seawater heat exchangers, firewater systems | Seawater crevice corrosion resistance |
| Offshore | Cooling water piping, sprinkler systems | 6Mo class in harsh chloride service |
| Desalination | Brine heaters, evaporator tubes | Elevated-temperature brine resistance |
| FGD | Absorber internals, outlet ducting | Acid + chloride combined |
| Chemical | Chloride-bearing process streams | Broad chloride tolerance |
| Pulp & Paper | Bleach plant equipment | ClO₂ + chloride service |
Quality Assurance: 7-Stage
- Raw Material: Cr, Ni, Mo verified by OES.
- Melt: Mo +/-0.2%, N +/-0.02%, C <=0.02% internal.
- Hot Working: 1150-1200C, finishing >=1000C, reduction >=4:1.
- Solution Anneal: 1120-1170C, WQ. Hardness <=100 HRB.
- Corrosion Test: ASTM G48 Method A (CPT) per lot.
- NDE: 100% UT bars >=50mm; ET/hydro tubes. PMI every piece.
- Documentation: EN 10204 3.1 MTC. SGS/TUV/BV witness.
Frequently Asked Questions
Q1: What is AL-6XN used for?
Seawater heat exchangers, offshore firewater systems, FGD scrubbers, desalination brine heaters, and chloride-bearing chemical processes.
Q2: AL-6XN vs 254SMO?
Both 6Mo class (PREN 45 vs 43). AL-6XN: higher Ni (24% vs 18%) for better SCC resistance, original 6Mo grade. 254SMO: slightly higher strength. Functionally interchangeable for most seawater duty.
Q3: AL-6XN vs 316L?
PREN 45 vs 24; yield 310 vs 205 MPa; seawater service indefinite vs months. Cost premium 3-4x, justified where 316L fails.
Q4: Is it weldable?
Yes, with ERNiCrMo-3 (625) or matching filler.
Q5: What is the price?
$25-45/kg EXW. Contact sales@hangboalloy.com.
Q6: Product forms?
Bars (6-250mm), tubes (OD 10-219mm), plates (3-50mm). SGS available.
Q7: What heat treatment?
Solution annealing at 1120-1170°C, water quench.
Q8: Is it magnetic?
No -- fully austenitic.
Q9: What is the density?
8.06 g/cm3.
Q10: Does Shanghai Hangbo ship internationally?
Yes -- FOB/CIF/DAP to 40+ countries.
Q11: What standards apply?
ASTM B688 (plate), B676 (tube), B691 (bar), B564 (forging).
Q12: Can it handle hot seawater?
Resists crevice corrosion in ambient to ~35C seawater; for hot seawater use 27-7MO or Alloy 31.
Q13: What is the max service temperature?
~400C continuous.
Q14: Why nitrogen?
Nitrogen (0.18-0.25%) boosts PREN and provides solid-solution strength.
Q15: Is it NACE-qualified?
Moderate sour service per NACE MR0175 (limited); for high H₂S use G-50 or 27-7MO.
Contact Shanghai Hangbo Alloy Group
| Channel | Details |
|---|---|
| Company | Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier |
| Website | www.nickel-alloy.com |
| Email (Sales) | sales@hangboalloy.com |
| Email (Technical) | hangbo@nickel-alloy.com |
| WhatsApp (Lisa) | +86 13611656360 |
| Address | Room 1508, No. 288 Shiyi Road, Baoshan District, Shanghai 200940, China |
Shanghai Hangbo Alloy Group - Complete Product Range
| Family | Available Grades |
|---|---|
| Pure Nickel | NI200, NI201, N4, N5, N6 |
| Monel | 400, 401, 404, K-500, R-405 |
| Inconel | 600, 601, 617, 625, 690, 693, 718, X-750, 725 |
| Incoloy | 800, 800H, 800HT, 825, 925, 926, 945, A-286, 25-6HN, 27-7MO |
| Hastelloy | C-276, C-22, C-2000, C-4, G-30, G-35, G-50, X, B-2, B-3, B-4, HYBRID-BC1, N |
| Super Austenitic | 904L, Alloy 28, Alloy 31, 254SMO, 20Mo-6, AL-6XN |
| Chromium-Rich | Alloy 33 |
| High-Strength Stainless | Nitronic 50, Nitronic 60, PH13-8Mo |
| Chlorination-Resistant | Alloy 45 |
| Nimonic | 75, 80A, 90, 95, 105, 115, 263 |
| Haynes | 25, 188, 214, 230, 242, 282, 556, HR-120, HR-160 |
| RA Series | RA330, RA333 |
| Precision | 1J22, 1J46, 1J50, 1J79, 1J85, 3J21, 4J32, 4J36, 4J45 |
| High-Strength | 18Ni250, 18Ni300, AerMet 100 |
| Heating | Cr20Ni80, Cr40Ni60 |
| Specialty | Alloy 20, Alloy 59, Inconel 686, 602CA |
Product Forms: Bars(6-500mm) | Tubes(OD 6-610mm) | Plates(0.1-100mm) | Forgings | Welded Pipes | Fittings | Wire(0.05-10mm) | Strip(0.02-4.0mm)
SGS/BV/TUV. Contact: sales@hangboalloy.com | WhatsApp (Lisa): +86 13611656360 | www.nickel-alloy.com
