Titanium OT4-SR (Stress relieved)
Heat-treated state
Applied after forming, welding or heavy machining to remove residual stress with almost no loss of strength.
Values for the SR condition
Other OT4 tempers and conditions
OT4 is listed in 5 conditions; see the grade overview at OT4.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
MDefault Thermomechanically controlled processed | Standard stocked condition for sheet and plate; best balance of strength, ductility and formability. | 640 | 780 | 16 | 22 HRC | 1.1 % IACS |
As-welded deposit | Reference condition for welded sheet assemblies; joint efficiency is high but ductility drops in the fusion zone. | 640 | 760 | 9 | 23 HRC | 1.1 % IACS |
SRThis page Stress relieved | Applied after forming, welding or heavy machining to remove residual stress with almost no loss of strength. | 670 | 800 | 15 | 23 HRC | 1.1 % IACS |
Hot rolled | Cheapest mill condition for thick plate and forging stock that will be machined and annealed later. | 690 | 820 | 13 | 25 HRC | 1.1 % IACS |
Cold-rolled, work-hardened sheet | Use only where higher strength and flatness matter more than bend ductility; limited cold-work capacity in Ti. | 820 | 900 | 8 | 29 HRC | 1.1 % IACS |
What is OT4-SR?
OT4-SR is OT4 heat treated to SR — applied after forming, welding or heavy machining to remove residual stress with almost no loss of strength. OT4-SR has a yield strength of 670 MPa (97.2 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 52% of titanium grades. Elongation at break is 15% and the elastic modulus is 115 GPa (16.7 Msi). OT4-SR has a density of 4.55 g/cm³ (0.164 lb/in³), heavier than 84% of titanium grades. It melts at 1,620°C (2,948 °F). M is the default condition FabDigit quotes; SR is available on request or by drawing note.
OT4-SR properties
Typical room-temperature values for OT4-SR; 23 are specific to this condition. Other listed values are OT4 reference data and may not represent this condition. Bars are the position among titanium grades.
Physical3
OT4-SR has a density of 4.55 g/cm³ (0.164 lb/in³), heavier than 84% of titanium grades. It melts at 1,620°C (2,948 °F).
Mechanical17
OT4-SR has a yield strength of 670 MPa (97.2 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 52% of titanium grades. Elongation at break is 15% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
OT4-SR is rated for continuous service to 350°C (662 °F). It conducts heat at 9.5 W/m·K (5.49 BTU/hr·ft·°F), better than 56% of titanium grades. Thermal expansion is 8.6 µm/m·K (4.78 µin/in·°F).
Electrical3
OT4-SR conducts electricity at 1.1 % IACS, worse than 67% of titanium grades.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), worse than 77% of titanium grades.
Sustainability4
Producing a kilogram of OT4-SR takes about 620 MJ of energy and emits 38 kg of CO₂ — less than 97% of titanium grades. Typical recycled content is 25%.
Manufacturability7
OT4-SR's machinability is poor (27/100, better than 57% of titanium grades); weldability very good (70/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with OT4-SR
Is OT4 easy to machine?
Machine like other titanium: rigid setup, sharp uncoated-carbide or coated tools, low surface speed (25–45 m/min), heavy positive feed and flood coolant to avoid work-hardening, galling and chip fires.
Can OT4 be welded?
Good fusion weldability by GTAW, plasma or EBW with full argon/vacuum shielding and trailing gas; keep interstitials low, clean thoroughly, and stress-relieve rather than post-weld solution treat.
Can OT4 be formed, bent or molded?
Annealed sheet cold-bends to moderate radii (~3–4 t) but springs back strongly; warm forming at 300–500 °C markedly improves formability and dimensional control.
What surface finishes work on OT4?
Pickle in HNO3/HF (short times, then bake to avoid hydrogen pickup), then anodise or apply plasma-electrolytic oxide for colour/wear; can be bead-blasted, brushed or polished, and takes primer/paint well after conversion coating.
OT4 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 | 3.5 – 5 | 4.2 |
| Mnlow-cost beta stabiliser | 0.8 – 2 | 1.5 |
| Zrimpurity limit | ≤ 0.3 | — |
| Si | ≤ 0.15 | — |
| Fe | ≤ 0.3 | — |
| C | ≤ 0.1 | — |
| O | ≤ 0.15 | — |
| N | ≤ 0.05 | — |
| Hhydrogen embrittlement control | ≤ 0.01 | — |
| other impurities (total) | ≤ 0.3 | — |
| Ti | balance | — |
OT4-SR — frequently asked
What is OT4-SR used for?
OT4-SR is typically used for sheet metal parts and panels, forged fittings, welded sheet assemblies, formed brackets and stiffeners, ducting and tube components and moderately loaded structural covers. In short: manganese-stabilised low-cost alpha; formable weldable sheet grade; 350 °C service ceiling.
What is the yield strength of OT4-SR?
OT4-SR has a typical yield strength of 670 MPa (97.2 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 52% of titanium grades. Strength varies by condition: see the 5 listed tempers.
Is OT4-SR easy to machine?
Not especially — machinability is rated poor (27/100, better than 57% of titanium grades). Machine like other titanium: rigid setup, sharp uncoated-carbide or coated tools, low surface speed (25–45 m/min), heavy positive feed and flood coolant to avoid work-hardening, galling and chip fires.
Can OT4-SR be welded?
Yes — weldability is rated very good (70/100). Good fusion weldability by GTAW, plasma or EBW with full argon/vacuum shielding and trailing gas; keep interstitials low, clean thoroughly, and stress-relieve rather than post-weld solution treat.
What surface finishes work on OT4-SR?
Pickle in HNO3/HF (short times, then bake to avoid hydrogen pickup), then anodise or apply plasma-electrolytic oxide for colour/wear; can be bead-blasted, brushed or polished, and takes primer/paint well after conversion coating.
Can OT4-SR be formed, bent or molded?
Annealed sheet cold-bends to moderate radii (~3–4 t) but springs back strongly; warm forming at 300–500 °C markedly improves formability and dimensional control.
What is the maximum service temperature of OT4-SR?
OT4-SR is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between OT4-M and OT4 CR-H?
M is the default condition — standard stocked condition for sheet and plate; best balance of strength, ductility and formability. CR-H: use only where higher strength and flatness matter more than bend ductility; limited cold-work capacity in Ti. Yield strength is 640 MPa in M versus 820 MPa in CR-H.
Sources
- GOST 19807 — Titanium and titanium alloys, grades — Gosstandart (1991)
- GOST 22178 — Titanium alloy sheets, technical requirements — Gosstandart (1976)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (titanium section) — ASM International (1990)
- Titanium Alloys of the CIS — physical and mechanical property tables (VIAM data compilations) — VIAM / Metallurgiya (2000)
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.