Titanium Grade 7 (Ti-0.15Pd) – UNS R52400
CP titanium with palladium, for reducing media and crevice corrosion
Equivalent to Gr 2 with an addition of 0.12 – 0.25% palladium, which extends passivity in reducing acids (dilute HCl, H2SO4) and greatly increases crevice corrosion resistance in hot brines. Mechanical and physical properties identical to Gr 2.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | R52400 |
| W.Nr./EN | 3.7235 (Ti 2 Pd) |
| DIN | DIN 17851 Ti 2 Pd |
| JIS | JIS H 4600 Class 12 (TP340Pd) |
| Trade names | Ti-0.15Pd, Ti Gr 7 |
| Others | GB TA9; ASME SB-348/SB-265/SB-338 Gr 7 |
Standards by product form
| Form | Standard |
|---|---|
| Bar | ASTM B348 Gr 7 |
| Plate | ASTM B265 Gr 7 |
| Forging/flange | ASTM B381 F-7 |
| Tube | ASTM B338 Gr 7 (exchanger) / B861 / B862 |
| Fittings | ASTM B363 WPT7 |
Tolerances and HS codes
- Forged bars (round and square): machining allowance from 2 mm (Ø 6–16 mm) to 24 mm (Ø 400–500 mm) on the diameter. E.g. Ø 100–125 mm finished: +7 mm, tolerance +6 / −0 (length up to 3,500 mm).
- Forged discs: allowance of 4 to 9 mm on the diameter and 3 to 11 mm on the height, plus-only tolerance.
- Cutting and machining: band saw −0 / +5 to +15 mm on length; waterjet +10 % of thickness on the diameter (min. 2 mm); machined parts −0 / +2 to +5 mm on the diameter. See the full tables (INF 002 and INF 003, the same for every alloy).
| Form | NCM (Brazil, 8 digits) | HS (international, 6 digits) | HTS (USA, 10 digits)* | CN (European Union, 8 digits)* |
|---|---|---|---|---|
| Forged bar | 8108.90.00 | 8108.90 | 8108.90.6031 | 8108 90 30 |
| Hot-rolled bar | 8108.90.00 | 8108.90 | 8108.90.6031 | 8108 90 30 |
| Plate (> 10 mm, width ≥ 600 mm) | 8108.90.00 | 8108.90 | 8108.90.6045 | 8108 90 50 |
| Seamless pipe | 8108.90.00 | 8108.90 | 8108.90.6060 | 8108 90 60 |
| Welded pipe | 8108.90.00 | 8108.90 | 8108.90.6060 | 8108 90 60 |
| Flange and fitting | 8108.90.00 | 8108.90 | 8108.90.3060 | 8108 90 90 |
Tariff class: titanium (by chemical composition, under the Chapter 72 Notes and Section XV Note 5).
*: US and EU codes for reference. NCM per current legislation (General Rules of Interpretation, Notes to Chapters 72, 74 and 75 and Section XV Note 5). Confirm the final code with your customs broker according to the item size and finish. HS = first 6 digits of the NCM.
Chemical composition (%)
ASTM B348 Gr 7 (% by mass)
| Element | Range (%) |
|---|---|
| Pd | 0.12 – 0.25 |
| N | ≤ 0.03 |
| C | ≤ 0.08 |
| H | ≤ 0.015 |
| Fe | ≤ 0.30 |
| O | ≤ 0.25 |
| Residuals (each / total) | ≤ 0.10 / ≤ 0.40 |
| Ti | balance |
Mechanical properties
annealed (ASTM B348, room temperature)
| Property | Value |
|---|---|
| Yield strength (0.2%) | ≥ 275 MPa |
| Tensile strength | ≥ 345 MPa |
| Elongation (4D) | ≥ 20% |
| Reduction of area | ≥ 30% |
| Hardness | ≈ 160 – 200 HV (typical) |
Typical physical properties
| Property | Value |
|---|---|
| Density | 4.51 g/cm³ |
| Melting range | ≈ 1,660 – 1,670 °C |
| Modulus of elasticity | ≈ 103 – 105 GPa |
| Thermal conductivity (20 °C) | ≈ 16 – 22 W/m·K (typical) |
| Thermal expansion (20–100 °C) | ≈ 8.6 µm/m·K |
| Beta transus | ≈ 900 – 925 °C |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | Same as Gr 2: ASME Section VIII up to 316 °C. Resists crevice corrosion in brines and chlorides up to ~250 °C, where Gr 2 fails above ~70 – 80 °C. |
| Heat treatment | Supplied annealed. Annealing 650 – 760 °C, air; stress relief 480 – 595 °C. Does not harden by heat treatment. |
| Welding | Excellent weldability by TIG with AWS A5.16 ERTi-7 filler (keeps the Pd in the bead; do not use ERTi-2 in corrosive service). Argon shielding of the pool, trailing shield and root purge until < ~430 °C. |
| Machining | Same as CP Ti Gr 2: sharp tools, low speed, constant feed and abundant coolant. |
Typical applications
- Equipment in hot dilute HCl and H2SO4
- Hot brines and wet chlorine (chlor-alkali, chlorate)
- Heat exchangers subject to crevice corrosion
- Acid leaching in hydrometallurgy
- Chemical and petrochemical processing
- Pulp bleaching
Alternatives: Gr 16 (Ti-0.05Pd) performs similarly at lower cost; Gr 12 (Ti-0.3Mo-0.8Ni) is cheaper and mechanically stronger, for crevices in brine; Gr 2 when there is no reducing medium. No titanium grade resists fluorides/HF.
Titanium Grade 7 (Ti-0.15Pd): complete guide
What titanium Grade 7 is
Grade 7 belongs to the family of titanium and its alloys, in the group of palladium-modified commercially pure grades. The base is Grade 2, with the same limits for oxygen, iron, nitrogen, carbon and hydrogen; the addition of 0.12 to 0.25% palladium shifts the alloy's electrochemical potential into the passive region, so that the TiO2 film is maintained even in dilute reducing acids and in crevices, where Grade 2 depassivates.
Heat treatment, forming and welding
Annealing at 650 – 760 °C and stress relief at 480 – 595 °C, in a clean furnace. Welding is done by TIG or MIG with ERTi-7 consumable and full high-purity argon shielding, with acceptance by bead color; joints with Grade 2 only keep crevice resistance if the consumable is ERTi-7. Machining follows the titanium rules: low speed, positive feed and abundant coolant.
Corrosion and limits of use
Grade 7 resists everything Grade 2 resists, seawater, wet chlorine, chlorides, nitric acid and organic acids, and adds resistance to dilute hydrochloric and sulfuric acids, up to about 10%, to phosphoric acid and to crevices in hot chlorides, up to about 250 °C. It still does not resist hydrofluoric acid and fluorides, hot concentrated reducing acids or dry chlorine. Use under the ASME code goes up to about 315 °C.
Applications and alternatives
Heat exchangers with tubesheets and gaskets in hot chlorides, flanges and fittings, chlor-alkali and desalination equipment, pickling and dilute acid processes, pulp and paper, power generation and pollution control equipment. When the cost of palladium weighs, Grades 16 and 17, with less palladium, or Grade 12, with molybdenum and nickel, are alternatives; for high mechanical strength, Grade 5.
Supply forms and Dustre services
Round bars cut to size on a band saw, with rough or finish machining and hardness and tensile testing. All material is supplied with a 3.1 inspection certificate and heat traceability.
Frequently asked questions
What is the chemical composition of Titanium Grade 7 (Ti-0.15Pd)?
Per ASTM B348 Gr 7 (% by mass): Pd 0.12 – 0.25; N ≤ 0.03; C ≤ 0.08; H ≤ 0.015; Fe ≤ 0.30; O ≤ 0.25.
Which standards cover Titanium Grade 7 (Ti-0.15Pd)?
Bar: ASTM B348 Gr 7. Plate: ASTM B265 Gr 7. Forging/flange: ASTM B381 F-7. Tube: ASTM B338 Gr 7 (exchanger) / B861 / B862. Fittings: ASTM B363 WPT7.
Up to what temperature can Titanium Grade 7 (Ti-0.15Pd) be used?
Same as Gr 2: ASME Section VIII up to 316 °C. Resists crevice corrosion in brines and chlorides up to ~250 °C, where Gr 2 fails above ~70 – 80 °C.
Which materials can replace Titanium Grade 7 (Ti-0.15Pd)?
Gr 16 (Ti-0.05Pd) performs similarly at lower cost; Gr 12 (Ti-0.3Mo-0.8Ni) is cheaper and mechanically stronger, for crevices in brine; Gr 2 when there is no reducing medium. No titanium grade resists fluorides/HF.
