Stainless Steel AL-6XN HF-A
Heat-treated state
UNS N08367 · ASTM A240/B688 · EN 1.4529
HF-A = hot Finished / Forged + Solution Annealed
Choose for heavy bar, flanges and valve forgings per ASTM A479/B691 where full annealed corrosion performance is required.
Values for the HF-A condition
Other AL-6XN tempers and conditions
AL-6XN is listed in 7 conditions; see the grade overview at AL-6XN.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
HF-AThis page Hot Finished / Forged + Solution Annealed | Choose for heavy bar, flanges and valve forgings per ASTM A479/B691 where full annealed corrosion performance is required. | 350 | 720 | 45 | 175 HB | 1.9 % IACS |
Solution AnnealedDefault 1100–1180 °C, water quenched | Standard supply condition for plate, sheet, pipe, tube and forgings — maximum corrosion resistance and ductility. | 365 | 745 | 45 | 180 HB | — |
As-welded deposit | Reference condition for weldments; autogenous welds suffer Mo segregation and should be over-alloyed with ERNiCrMo-3 or re-annealed. | 400 | 700 | 30 | 190 HB | 1.9 % IACS |
Cold drawn | Pick for close-tolerance shafting and fasteners needing higher yield strength and better surface finish than hot-finished bar. | 620 | 860 | 25 | 24 HRC | 1.9 % IACS |
1/4 Hard | Use where moderate strength increase is needed but some bending/forming remains, e.g. springs-back-tolerant strip parts. | 690 | 900 | 20 | 27 HRC | 1.9 % IACS |
1/2 Hard | Choose for high-strength flat springs, clips and diaphragms in chloride service where forming is limited to simple bends. | 830 | 1,030 | 12 | 32 HRC | 1.9 % IACS |
Full Hard | Highest strength condition, for wire, wedge wire screens and spring elements; essentially no formability left. | 1,100 | 1,250 | 5 | 38 HRC | 1.9 % IACS |
What is AL-6XN HF-A?
AL-6XN HF-A is AL-6XN heat treated to HF-A — choose for heavy bar, flanges and valve forgings per ASTM A479/B691 where full annealed corrosion performance is required. AL-6XN HF-A has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 720 MPa (104 ksi) — weaker than 52% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi). AL-6XN HF-A has a density of 8.06 g/cm³ (0.291 lb/in³), heavier than 98% of stainless steel grades. It melts at 1,320°C (2,408 °F). Solution Annealed is the default condition FabDigit quotes; HF-A is available on request or by drawing note.
Advantages
- Good corrosion resistance — 88/100, better than 97% of stainless steel grades
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- Poor heat conductor — 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades
- Difficult to machine — 25/100, worse than 88% of stainless steel grades
- High embodied carbon — 6 kg CO₂/kg, worse than 88% of stainless steel grades
- Low electrical conductivity — 1.9 % IACS, worse than 84% of stainless steel grades
AL-6XN HF-A properties
Typical room-temperature values for AL-6XN HF-A; 22 are specific to this condition. Other listed values are AL-6XN reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
AL-6XN HF-A has a density of 8.06 g/cm³ (0.291 lb/in³), heavier than 98% of stainless steel grades. It melts at 1,320°C (2,408 °F).
Mechanical15
AL-6XN HF-A has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 720 MPa (104 ksi) — weaker than 52% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
AL-6XN HF-A is rated for continuous service to 425°C (797 °F). It conducts heat at 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades. Thermal expansion is 15.3 µm/m·K (8.5 µin/in·°F).
Electrical3
AL-6XN HF-A conducts electricity at 1.9 % IACS, worse than 84% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 97% of stainless steel grades.
Sustainability4
Producing a kilogram of AL-6XN HF-A takes about 85 MJ of energy and emits 6 kg of CO₂ — more than 92% of stainless steel grades. Typical recycled content is 40%.
Manufacturability7
AL-6XN HF-A's machinability is poor (25/100, worse than 88% of stainless steel grades); weldability very good (75/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AL-6XN HF-A
Is AL-6XN easy to machine?
Machines like a nickel alloy: rigid setups, positive-rake sharp carbide, heavy depth of cut, 20–35 m/min, flood coolant — never dwell or rub, since it work-hardens instantly.
Can AL-6XN be welded?
GTAW/GMAW/SMAW with over-alloyed Ni filler (ERNiCrMo-3 / ENiCrMo-3, or ERNiCrMo-10) to offset Mo segregation; low heat input, interpass <100 °C, no preheat, no PWHT normally required.
Can AL-6XN be formed, bent or molded?
Cold forms well but needs ~50% more press force than 304 and generous bend radii; hot work 1150–1200 °C and always re-solution anneal + water quench afterwards.
What surface finishes work on AL-6XN?
Pickle in HNO₃-HF or bead-blast plus passivation to restore the Mo-rich passive film; electropolishing gives the best pitting performance for pharma/seawater service.
AL-6XN chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | ≤ 0.03 | 0.02 |
| Mn | ≤ 2 | 0.4 |
| Si | ≤ 1 | 0.4 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.03 | 0 |
| Cr | 20 – 22 | 20.8 |
| Ni | 23.5 – 25.5 | 24.2 |
| Mo | 6 – 7 | 6.3 |
| N | 0.18 – 0.25 | 0.22 |
| Cu | ≤ 0.75 | 0.2 |
| Febalance, ≈47% | balance | — |
AL-6XN HF-A — frequently asked
What is AL-6XN HF-A used for?
AL-6XN HF-A is typically used for seawater cooling pipework, pharmaceutical reactors and vessels, heat exchanger tube and tubesheets, flue-gas desulfurization ducting, desalination plant piping and chemical process tanks. In short: super-austenitic seawater stainless.
What is the yield strength of AL-6XN HF-A?
AL-6XN HF-A has a typical yield strength of 350 MPa (50.8 ksi) and a tensile strength of 720 MPa (104 ksi) — weaker than 52% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is AL-6XN HF-A easy to machine?
Not especially — machinability is rated poor (25/100, worse than 88% of stainless steel grades). Machines like a nickel alloy: rigid setups, positive-rake sharp carbide, heavy depth of cut, 20–35 m/min, flood coolant — never dwell or rub, since it work-hardens instantly.
Can AL-6XN HF-A be welded?
Yes — weldability is rated very good (75/100). GTAW/GMAW/SMAW with over-alloyed Ni filler (ERNiCrMo-3 / ENiCrMo-3, or ERNiCrMo-10) to offset Mo segregation; low heat input, interpass <100 °C, no preheat, no PWHT normally required.
What surface finishes work on AL-6XN HF-A?
Pickle in HNO₃-HF or bead-blast plus passivation to restore the Mo-rich passive film; electropolishing gives the best pitting performance for pharma/seawater service.
Can AL-6XN HF-A be formed, bent or molded?
Cold forms well but needs ~50% more press force than 304 and generous bend radii; hot work 1150–1200 °C and always re-solution anneal + water quench afterwards.
What is the maximum service temperature of AL-6XN HF-A?
AL-6XN HF-A is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AL-6XN Solution Annealed and AL-6XN CW-FH?
Solution Annealed is the default condition — standard supply condition for plate, sheet, pipe, tube and forgings — maximum corrosion resistance and ductility. CW-FH: highest strength condition, for wire, wedge wire screens and spring elements; essentially no formability left. Yield strength is 365 MPa in Solution Annealed versus 1,100 MPa in CW-FH.
Can FabDigit make parts in AL-6XN HF-A?
Yes — AL-6XN HF-A is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- AL-6XN Alloy (UNS N08367) Technical Data Sheet — ATI (Allegheny Technologies) (2020)
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip — ASTM International (2023)
- ASTM B688 / B691 / B675 / B676 — UNS N08367 plate, bar, pipe and tube — ASTM International (2021)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- AL-6XN alloy data and corrosion tables — Rolled Alloys (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.