ASTM B366 / B564 BW ELBOWS UNS N08367 AL6XN AISI / ASME B16.28 STAINLESS STEEL FITTINGS
ASTM B366 / B564 BW Elbows UNS N08367 AL6XN AISI / ASME B16.28 Stainless Steel Fittings
AL6XN Overview
AL6XN is a superaustenitic stainless steel with outstanding resistance to chloride pitting, crevice corrosion and stress corrosion cracking. AL6XN is a 6 moly alloy that was developed for and is used in highly aggressive environments. It has high nickel (24%), molybdenum (6.3%), nitrogen and chromium contents that give it excellent resistance to chloride stress corrosion cracking, chloride pitting, and exceptional general corrosion resistance. AL6XN is primarily used for its improved pitting and crevice corrosion resistance in chlorides. It is a formable and weldable stainless steel.
Because of its nitrogen content, AL6XN has greater tensile strength than common austentitic stainlesses, while retaining high ductility and impact strength.
Corrosion Resistance
Chromium, molybdenum, nickel and nitrogen all contribute to overall resistance to corrosion by various media. Chromium is the principal agent for conferring corrosion resistance in neutral or oxidizing environments. Chromium, molybdenum and nitrogen increase resistance to pitting corrosion. Nickel imparts the austenitic structure. Nickel and molybdenum both provide increased resistance to chloride stress corrosion cracking in reducing environments.
What are the characteristics of AL-6XN?
Excellent resistance to pitting and crevice corrosion in chloride solutions
Practical immunity to stress corrosion in NaCl environments
High Strength and toughness
Chemical Composition, %
| Ni | Cr | Mo | C | N | Mn | Si | P | S | Cu | Fe |
| 23.5-25.5 | 20.00-22.00 | 6.00-7.00 | 0.03 Max | 0.18-0.25 | 2.0 Max | 1.00 Max | .040 Max | 0.03 Max | 0.75 Max | Remainder |
In what applications is AL-6XN used?
Reverse osmosis desalination equipment and pumps
FGD Scrubbers
Chemical process tanks and pipelines
Seawater heat exchangers
Tall oil distillation columns and packing
Offshore oil and gas production equipment
Pulp bleaching plant washers, vats, press rolls and pipelines
ASTM Specifications
| Pipe Welded | Tube Welded | Sheet/Plate | Bar | Flanges & Fittings |
| B675, A312 | B676, A249 | B688, A240 | B691, A479 | B366, A182 |
Mechanical Properties
Representative Tensile and Impact Properties, Plate
| Temp. °F (°C) | Ult. Tensile Strength, psi | .2% Yield Strength, psi | Elongation in 2”, percent | Charpy V-Notch Toughness, ft-lb |
| -450 (-268) | 218,000 | 142,000 | 36 | 353* |
| -320 (-196) | 196,000 | 107,000 | 49 | 85 |
| -200 (-129) | - | - | - | 100 |
| 70 (21) | 108,000 | 53,000 | 47 | 140 |
| 200 (93) | 99,900 | 49,400 | 47 | - |
| 400 (204) | 903,000 | 40,400 | 46 | - |
| 600 (316) | 86,000 | 36,300 | 47 | - |
| 800 (427) | 87,000 | 36,000 | 48 | - |
*For welded pipe and tube, a joint efficiency factor of .85 must be applied.
* AL-6XN® is a registered trademark of the Allegheny Ludlum Corporation
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