Titanium Ti-4Al-4Mo-2Sn
EN 3.7185 · also IMI 550
Ti-4Al-4Mo-2Sn (IMI 550, material number 3.7185) is a high-strength near-alpha/alpha-beta titanium alloy (Ti-4Al-4Mo-2Sn-0.5Si) developed for elevated-temperature aero-engine discs and compressor components.
Reference datasheet — Ti-4Al-4Mo-2Sn is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the STA condition
Ti-4Al-4Mo-2Sn tempers and conditions
Ti-4Al-4Mo-2Sn is supplied in 4 conditions, soft to hard. STA is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for stock bar/forgings that will be machined and heat treated later, or where maximum ductility and stability matter more than peak strength. | 900 | 1,010 | 16 | 32 HRC | — |
β-processed / β-annealed + aged | Choose when damage tolerance, creep and crack-growth resistance outrank ductility — transformed-β structure trades tensile elongation for toughness. | 970 | 1,080 | 8 | 35 HRC | — |
Stress relieved | Applied to welded or heavily machined parts to remove residual stress with only a small strength change from the prior condition. | 990 | 1,100 | 14 | 35 HRC | 1.1 % IACS |
STADefault Solution treated and aged | Standard supply condition for aero-engine discs, shafts and high-strength forgings up to ~425 °C; use for peak strength in sections under ~50–75 mm. | 1,030 | 1,150 | 13 | 36 HRC | — |
What is Ti-4Al-4Mo-2Sn?
Ti-4Al-4Mo-2Sn (IMI 550, material number 3.7185) is a high-strength near-alpha/alpha-beta titanium alloy (Ti-4Al-4Mo-2Sn-0.5Si) developed for elevated-temperature aero-engine discs and compressor components. Supplied annealed, STA, beta-STA or stress relieved, it reaches 1030 MPa yield, 1150 MPa tensile, 13 % elongation, 332 HB / 36 HRC and 114 GPa modulus, with service to 425 °C and a corrosion rating of 85. It is a hot-work alloy: formability (10), weldability (28) and machinability (16) are all poor, so welding is avoided on rotating parts. Ti-6Al-4V is the more available alternative below 400 °C. Ti-4Al-4Mo-2Sn has a density of 4.6 g/cm³ (0.166 lb/in³), heavier than 87% of titanium grades. It melts at 1,620°C (2,948 °F). Ti-4Al-4Mo-2Sn has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 95% of titanium grades. Elongation at break is 13% and the elastic modulus is 114 GPa (16.5 Msi).
What is Ti-4Al-4Mo-2Sn used for?
- Jet engine compressor discs
- High-temperature fasteners
- Compressor blades and blisks
- Engine shafts and spacers
- Forged aero-engine rotating hardware
- Highly loaded airframe fittings
Advantages
- High strength — 1,030 MPa (149 ksi), better than 95% of titanium grades
- High service temperature — 425°C (797 °F), better than 85% of titanium grades
Limitations
- Difficult to weld — 28/100, worse than 99% of titanium grades
- Limited formability — 10/100, worse than 99% of titanium grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 90% of titanium grades
Ti-4Al-4Mo-2Sn properties
Typical room-temperature values for Ti-4Al-4Mo-2Sn-STA; bars are the position among titanium grades.
Physical3
Ti-4Al-4Mo-2Sn has a density of 4.6 g/cm³ (0.166 lb/in³), heavier than 87% of titanium grades. It melts at 1,620°C (2,948 °F).
Mechanical16
Ti-4Al-4Mo-2Sn has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 95% of titanium grades. Elongation at break is 13% and the elastic modulus is 114 GPa (16.5 Msi).
Thermal6
Ti-4Al-4Mo-2Sn is rated for continuous service to 425°C (797 °F). It conducts heat at 7.1 W/m·K (4.1 BTU/hr·ft·°F), worse than 68% of titanium grades. Thermal expansion is 9.4 µm/m·K (5.22 µin/in·°F).
Electrical3
Ti-4Al-4Mo-2Sn conducts electricity at 1.1 % IACS, worse than 67% of titanium grades.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), worse than 93% of titanium grades.
Sustainability4
Producing a kilogram of Ti-4Al-4Mo-2Sn takes about 700 MJ of energy and emits 45 kg of CO₂ — more than 74% of titanium grades. Typical recycled content is 25%.
Manufacturability8
Ti-4Al-4Mo-2Sn's machinability is poor (16/100, worse than 93% of titanium grades); weldability poor (28/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the titanium family
Yield strength against density for every titanium grade FabDigit runs. Ti-4Al-4Mo-2Sn is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Ti-4Al-4Mo-2Sn
Is Ti-4Al-4Mo-2Sn easy to machine?
Machine like a hard α+β titanium: rigid setup, sharp uncoated-carbide or PVD-coated tools, ~25–45 m/min in the STA condition, high-pressure flood coolant, positive feed to avoid work-hardening and never dwell.
Can Ti-4Al-4Mo-2Sn be welded?
GTAW/EBW/plasma in full inert shielding is possible but the aged microstructure is destroyed — post-weld solution + age (or at minimum stress relief) is required and weld ductility remains low, so welding is avoided on rotating parts.
Can Ti-4Al-4Mo-2Sn be formed, bent or molded?
Essentially a hot-work alloy: forge/roll just below the ~975 °C β transus and hot form at 700–850 °C; cold forming is limited to very gentle bends on annealed thin stock.
Ti-4Al-4Mo-2Sn 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 |
|---|---|---|
| Alα stabiliser | 3 – 5 | 4 |
| Moβ stabiliser, solid-solution strengthening | 3.5 – 4.5 | 4 |
| Sn | 1.5 – 2.5 | 2 |
| Sicreep resistance via silicide precipitation | 0.3 – 0.7 | 0.5 |
| Fe | ≤ 0.2 | |
| O | ≤ 0.2 | 0.13 |
| C | ≤ 0.08 | |
| N | ≤ 0.05 | |
| H | ≤ 0.01 | |
| Ti | balance |
What surface finishes work on Ti-4Al-4Mo-2Sn?
Grit blast plus chemical (HF/HNO3) pickle to remove alpha case, then Type II anodize, ion nitriding or dry-film lube for galling/fretting control; polishes well but never leave scale from hot working.
Surface treatments FabDigit runs on titanium parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Titanium Ti-4Al-4Mo-2Sn in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 3.7185
- Trade names
- IMI 550
How much does Ti-4Al-4Mo-2Sn cost?
Ti-4Al-4Mo-2Sn is a high-cost titanium ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Ti-4Al-4Mo-2Sn — frequently asked
What is Ti-4Al-4Mo-2Sn used for?
Ti-4Al-4Mo-2Sn is typically used for jet engine compressor discs, high-temperature fasteners, compressor blades and blisks, engine shafts and spacers, forged aero-engine rotating hardware and highly loaded airframe fittings. In short: high-strength engine disc alloy; service to 425 °C; forged, not formed.
What is the yield strength of Ti-4Al-4Mo-2Sn?
Ti-4Al-4Mo-2Sn has a typical yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 95% of titanium grades. Strength varies by condition: see the 4 listed tempers.
Is Ti-4Al-4Mo-2Sn easy to machine?
Not especially — machinability is rated poor (16/100, worse than 93% of titanium grades). Machine like a hard α+β titanium: rigid setup, sharp uncoated-carbide or PVD-coated tools, ~25–45 m/min in the STA condition, high-pressure flood coolant, positive feed to avoid work-hardening and never dwell.
Can Ti-4Al-4Mo-2Sn be welded?
Not readily — weldability is rated poor (28/100). GTAW/EBW/plasma in full inert shielding is possible but the aged microstructure is destroyed — post-weld solution + age (or at minimum stress relief) is required and weld ductility remains low, so welding is avoided on rotating parts.
What surface finishes work on Ti-4Al-4Mo-2Sn?
Grit blast plus chemical (HF/HNO3) pickle to remove alpha case, then Type II anodize, ion nitriding or dry-film lube for galling/fretting control; polishes well but never leave scale from hot working.
Can Ti-4Al-4Mo-2Sn be formed, bent or molded?
Essentially a hot-work alloy: forge/roll just below the ~975 °C β transus and hot form at 700–850 °C; cold forming is limited to very gentle bends on annealed thin stock.
What is the maximum service temperature of Ti-4Al-4Mo-2Sn?
Ti-4Al-4Mo-2Sn 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 Ti-4Al-4Mo-2Sn-STA and Ti-4Al-4Mo-2Sn-ANN?
STA is the default condition — standard supply condition for aero-engine discs, shafts and high-strength forgings up to ~425 °C; use for peak strength in sections under ~50–75 mm. ANN: pick for stock bar/forgings that will be machined and heat treated later, or where maximum ductility and stability matter more than peak strength. Yield strength is 1,030 MPa in STA versus 900 MPa in ANN.
How much does Ti-4Al-4Mo-2Sn cost?
Ti-4Al-4Mo-2Sn is a high-cost titanium ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- IMI 550 (Ti-4Al-4Mo-2Sn-0.5Si) alloy data sheet — IMI Titanium / Timet (2000)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- Materials Properties Handbook: Titanium Alloys — ASM International (1994)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
- DIN 17851 / Werkstoff-Nr. 3.7185 titanium alloy designation — DIN (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.