Titanium IMI 685 AB-ANN
Heat-treated state
AB-ANN = α+β annealed
Choose when room-temperature ductility and smooth-specimen fatigue matter more than creep; loses much of the high-temperature advantage.
Values for the AB-ANN condition
Other IMI 685 tempers and conditions
IMI 685 is listed in 4 conditions; see the grade overview at IMI 685.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As-forged / forging stock (pre heat-treatment) | Disc/ring forging blanks and bar stock supplied for customer-controlled beta heat treatment; properties not certified in this state. | 840 | 950 | 12 | 32 HRC | 1.1 % IACS |
Stress relieved | Applied after heavy machining or welding of BSTOA parts to relieve residual stress without altering the beta-processed microstructure. | 865 | 980 | 11 | 33 HRC | 1.1 % IACS |
BSTOADefault Beta solution treated (≈1050 °C), oil quenched, aged 550 °C/24 h | Choose this beta solution treated (approx. 1050 °C), oil quenched and 550 °C/24 h aged condition, the standard engine-disc route, for best creep and crack-growth resistance to about 520 °C. | 870 | 990 | 11 | 33 HRC | — |
AB-ANNThis page Α+β annealed | Choose when room-temperature ductility and smooth-specimen fatigue matter more than creep; loses much of the high-temperature advantage. | 900 | 1,000 | 15 | 34 HRC | 1.1 % IACS |
What is IMI 685 AB-ANN?
IMI 685 AB-ANN is IMI 685 heat treated to AB-ANN — choose when room-temperature ductility and smooth-specimen fatigue matter more than creep; loses much of the high-temperature advantage. IMI 685 AB-ANN has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 82% of titanium grades. Elongation at break is 15% and the elastic modulus is 122 GPa (17.7 Msi). IMI 685 AB-ANN has a density of 4.45 g/cm³ (0.161 lb/in³), lighter than 81% of titanium grades. It melts at 1,600°C (2,912 °F). BSTOA is the default condition FabDigit quotes; AB-ANN is available on request or by drawing note.
Advantages
- Stiff — 122 GPa (17.7 Msi), better than 100% of titanium grades
- High service temperature — 450°C (842 °F), better than 87% of titanium grades
- High strength — 900 MPa (131 ksi), better than 82% of titanium grades
Limitations
- Hard to polish — 60/100, worse than 97% of titanium grades
- Low fracture toughness — 50 MPa·√m (45.5 ksi·√in), worse than 96% of titanium grades
- Difficult to weld — 45/100, worse than 92% of titanium grades
IMI 685 AB-ANN properties
Typical room-temperature values for IMI 685 AB-ANN; 22 are specific to this condition. Other listed values are IMI 685 reference data and may not represent this condition. Bars are the position among titanium grades.
Physical3
IMI 685 AB-ANN has a density of 4.45 g/cm³ (0.161 lb/in³), lighter than 81% of titanium grades. It melts at 1,600°C (2,912 °F).
Mechanical15
IMI 685 AB-ANN has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 82% of titanium grades. Elongation at break is 15% and the elastic modulus is 122 GPa (17.7 Msi).
Thermal6
IMI 685 AB-ANN is rated for continuous service to 450°C (842 °F). It conducts heat at 7 W/m·K (4.04 BTU/hr·ft·°F), worse than 76% of titanium grades. Thermal expansion is 9.3 µm/m·K (5.17 µin/in·°F).
Electrical3
IMI 685 AB-ANN conducts electricity at 1.1 % IACS, worse than 67% of titanium grades.
Chemical & Environmental3
Corrosion resistance is excellent (86/100), worse than 86% of titanium grades.
Sustainability4
Producing a kilogram of IMI 685 AB-ANN takes about 650 MJ of energy and emits 40 kg of CO₂ — less than 75% of titanium grades. Typical recycled content is 15%.
Manufacturability8
IMI 685 AB-ANN's machinability is poor (20/100, worse than 68% of titanium grades); weldability fair (45/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with IMI 685 AB-ANN
Is IMI 685 easy to machine?
Low speed, high feed, rigid setup, sharp uncoated carbide and flood high-pressure coolant; the Widmanstätten BSTOA structure work-hardens and burns easily, avoid dwell and light rubbing cuts.
Can IMI 685 be welded?
GTAW/EBW in high-purity argon or vacuum with full back purge; weld metal is brittle-prone, so use matching filler, control interstitials and stress relieve at 600–650 °C afterwards.
Can IMI 685 be formed, bent or molded?
Hot work only — forge/roll near or above the beta transus (~1020 °C) with controlled cooling; cold formability is minimal.
What surface finishes work on IMI 685?
Pickle in HNO₃/HF to remove alpha case after hot work; shot peen critical fillets for fatigue, colour anodise for identification, avoid cadmium/silver contact plating.
IMI 685 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 |
|---|---|---|
| Alalpha stabiliser | 5.7 – 6.3 | 6 |
| Zrsolid-solution strengthener | 4.5 – 5.5 | 5 |
| Mobeta stabiliser | 0.4 – 0.6 | 0.5 |
| Sikey creep strengthener (silicide precipitation) | 0.2 – 0.3 | 0.25 |
| Fe | ≤ 0.05 | — |
| Okept low for creep and toughness | ≤ 0.1 | 0.07 |
| C | ≤ 0.04 | — |
| N | ≤ 0.04 | — |
| Hmax, bar/forgings | ≤ 0.01 | — |
| Ti | balance | — |
IMI 685 AB-ANN — frequently asked
What is IMI 685 AB-ANN used for?
IMI 685 AB-ANN is typically used for fan discs, compressor discs, compressor blades, HP compressor drum sections, engine ring and spacer forgings and blade retention hardware. In short: creep-resistant engine disc alloy; 520 °C near-alpha capability; hot-work-only forging grade.
What is the yield strength of IMI 685 AB-ANN?
IMI 685 AB-ANN has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 82% of titanium grades. Strength varies by condition: see the 4 listed tempers.
Is IMI 685 AB-ANN easy to machine?
Not especially — machinability is rated poor (20/100, worse than 68% of titanium grades). Low speed, high feed, rigid setup, sharp uncoated carbide and flood high-pressure coolant; the Widmanstätten BSTOA structure work-hardens and burns easily, avoid dwell and light rubbing cuts.
Can IMI 685 AB-ANN be welded?
With care — weldability is rated fair (45/100). GTAW/EBW in high-purity argon or vacuum with full back purge; weld metal is brittle-prone, so use matching filler, control interstitials and stress relieve at 600–650 °C afterwards.
What surface finishes work on IMI 685 AB-ANN?
Pickle in HNO₃/HF to remove alpha case after hot work; shot peen critical fillets for fatigue, colour anodise for identification, avoid cadmium/silver contact plating.
Can IMI 685 AB-ANN be formed, bent or molded?
Hot work only — forge/roll near or above the beta transus (~1020 °C) with controlled cooling; cold formability is minimal.
What is the maximum service temperature of IMI 685 AB-ANN?
IMI 685 AB-ANN is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between IMI 685 BSTOA and IMI 685 AB-ANN?
BSTOA is the default condition — choose this beta solution treated (approx. 1050 °C), oil quenched and 550 °C/24 h aged condition, the standard engine-disc route, for best creep and crack-growth resistance to about 520 °C. AB-ANN: choose when room-temperature ductility and smooth-specimen fatigue matter more than creep; loses much of the high-temperature advantage. Yield strength is 870 MPa in BSTOA versus 900 MPa in AB-ANN.
Sources
- IMI 685 titanium alloy data sheet — IMI Titanium / Timet UK (1990)
- Materials Properties Handbook: Titanium Alloys — ASM International (1994)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Titanium: A Technical Guide — ASM International (2000)
- DTD 5153/5163 (IMI 685 bar and forgings) — UK MoD / BSI (1980)
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.