GR7 Titanium Plate (Ti-0.2Pd) — Maximum Corrosion Resistance for the Most Aggressive Environments
The highest corrosion resistance of all commercially pure titanium grades. Palladium alloying enables exceptional performance in reducing acids, hot chlorides, and severe crevice environments where GR2 and even GR12 cannot survive. ASTM B265 in stock, 1.0–13 mm.
ISO 9001:2015 Certified | Rm ≥ 345 MPa | Pd 0.12–0.25 wt% | EN 10204 3.1 MTC | ASME SB-265 | Ready to Ship Worldwide
Available Dimensions & Stock
GR7 is a specialty grade stocked in focused quantities. The table below reflects current warehouse availability from ProX Metal. We can also produce custom dimensions from 1.0 mm up to 25 mm by coil-to-sheet processing and up to 75 mm by single-plate rolling, with full EN 10204 3.1 MTC documentation.
Current Stock Inventory
| Thickness | Width (mm) | Length (mm) | Weight (kg) | Surface | Availability |
|---|---|---|---|---|---|
| 1.0 mm | 1000 | 2000 | 44.0 | Bright / Pickled | In Stock |
| 1.5 mm | 1000 | 2000 | 27.0 | Bright / Pickled | In Stock |
| 2.0 mm | 1000 | 1850–2000 | 55.6 | Bright / Pickled | In Stock |
| 2.0 mm | 1000 | 2000 | 16.0 | Bright / Pickled | In Stock |
| 3.0 mm | 1000 | 2000 | 80.9 | Hot-Rolled Pickled | In Stock |
| 13.0 mm | 1010 | 1600 | 103.0 | Hot-Rolled Pickled | In Stock |
Why GR7 from ProX Metal
GR2 is the standard choice for most corrosion-resistant applications. GR12 adds Mo+Ni to resist hot chloride crevice corrosion. But when the process contains strong reducing acids — hot hydrochloric acid, dilute sulfuric acid, chloride brines at high temperature, or severe crevice conditions — only GR7 provides the necessary safety margin.
Palladium Catalytic Protection
The 0.12–0.25% Pd addition forms a catalytic surface that promotes hydrogen evolution, maintaining a low corrosion potential and keeping the titanium oxide film stable even in strongly reducing conditions.
Reducing Acid Resistance
GR7 withstands hot HCl, dilute H2SO4, and phosphoric acid environments where GR2 would corrode rapidly and GR12 would show limited lifetime.
Highest Crevice Threshold
GR7 pushes the crevice corrosion temperature threshold above 150°C in chloride brines — well beyond GR2 (~82°C) and GR12 (~120°C).
Same Fabrication as GR2
Mechanical properties match GR2, so forming, welding, and machining parameters are identical. No special equipment or procedures are needed beyond Pd-bearing filler wire.
ASME SB-265 Listed
GR7 is approved for pressure vessel construction under ASME Section VIII. Design stresses are the same as GR2, so substitution is straightforward when corrosion demands it.
Traceability per Heat
Every GR7 shipment includes an EN 10204 3.1 MTC with actual Pd content, full chemistry, and mechanical test results for the specific heat supplied.
Technical Specifications
GR7 (ASTM Grade 7, UNS R52400, Chinese designation TA9) is a commercially pure titanium grade with a small but critical palladium addition. The chemistry and mechanical properties are specified to deliver maximum corrosion resistance while retaining the formability and weldability of CP grades.
Chemical Composition (ASTM B265 GR7)
| Element | Specification (wt%) | Metallurgical Role |
|---|---|---|
| Pd | 0.12 – 0.25 | Cathodic surface catalyst — maintains low corrosion potential in reducing acids |
| Fe | ≤ 0.30 | Controlled impurity |
| O | ≤ 0.25 | Interstitial strengthener |
| C | ≤ 0.08 | Controlled impurity |
| N | ≤ 0.03 | Controlled impurity |
| H | ≤ 0.015 | Strictly limited to prevent hydride embrittlement |
| Ti | Balance | Matrix metal |
Mechanical Properties (Room Temperature, Annealed)
| Property | GR7 | GR2 | GR12 |
|---|---|---|---|
| Tensile Strength Rm (MPa) | ≥ 345 | ≥ 345 | ≥ 483 |
| Yield Strength Rp0.2 (MPa) | ≥ 275 | ≥ 275 | ≥ 345 |
| Elongation A (%) | ≥ 20 | ≥ 20 | ≥ 18 |
| Hardness (HB) | ~160 | ~160 | ~200 |
| Density (g/cm³) | 4.51 | 4.51 | 4.51 |
| Max Service Temp. | ~150°C | ~150°C | ~300°C |
Welding Essentials
- Filler metal: Use ERTi-7 (AWS A5.16) to preserve Pd corrosion resistance in the weld metal. ERTi-2 filler is acceptable only for non-critical joints to GR2; the weld will behave like GR2.
- Process: Standard GTAW (TIG) with 100% argon shielding, interpass temperature below 150°C.
- Post-weld: Pickle to remove heat tint and surface contamination. Silver or straw color = acceptable; blue/grey = reject and re-pickle.
Grade Comparison: GR2 vs. GR12 vs. GR7
Choosing the right titanium grade is a balance between corrosion severity, mechanical requirements, and cost. GR7 is the premium corrosion solution; it is not always the necessary one. Use this comparison to identify when GR7 is justified.
Corrosion Resistance
| Environment | GR2 | GR12 | GR7 |
|---|---|---|---|
| Seawater (ambient) | Excellent | Excellent | Excellent |
| Seawater (>80°C) | Crevice risk | Excellent | Excellent |
| Hot chloride brines | High risk | Good–Excellent | Excellent |
| Dilute HCl / H2SO4 | Poor | Moderate | Excellent |
| Hot HCl / strong reducing acids | Not suitable | Limited | Excellent |
| Crevice corrosion threshold | ~82°C | ~120°C | >150°C |
Mechanical Properties
| Property | GR2 | GR12 | GR7 |
|---|---|---|---|
| Tensile Strength Rm (MPa) | ≥ 345 | ≥ 483 | ≥ 345 |
| Yield Strength Rp0.2 (MPa) | ≥ 275 | ≥ 345 | ≥ 275 |
| Elongation A (%) | ≥ 20 | ≥ 18 | ≥ 20 |
| Hardness (HB) | ~160 | ~200 | ~160 |
Cost & Selection Guidance
| Factor | GR2 | GR12 | GR7 |
|---|---|---|---|
| Material Cost | $ — Lowest | $$ — Moderate | $$$ — Premium |
| Best Used When | Oxidizing or neutral environments; ambient seawater | Hot chlorides, crevice corrosion risk, moderate reducing acids | Strong reducing acids, hot HCl, severe crevice, highest reliability |
| Welding Filler | ERTi-2 | ERTi-12 | ERTi-7 |
Decision rule: Start with GR2 for oxidizing/neutral service. Move to GR12 when hot chloride crevice corrosion is the primary risk. Specify GR7 only when the process chemistry includes reducing acids or when the cost of corrosion failure justifies the palladium premium.
Industrial Applications
GR7 is specified where the failure mode is chemical attack rather than mechanical overload. Its applications are process-driven — typically in chemical processing, hydrometallurgy, and desalination systems where even a small corrosion rate is unacceptable.
Chemical Reactors & Pressure Vessels
Processes involving hot hydrochloric acid, chlorinated intermediates, or sulfuric acid streams require a material that remains passive through oxidation-reduction cycling. GR7 provides that safety margin. ASME SB-265 listed for pressure vessels; design rules identical to GR2.
- Resists hot HCl and dilute H2SO4 where GR2 fails
- Remains passive through redox cycling in chlorinated organics
- Direct design substitution for GR2 under ASME Section VIII
- Full traceability with EN 10204 3.1 MTC per heat
PTA & Brominated Chemical Plants
Purified terephthalic acid (PTA) plants use bromide-promoted oxidation catalysts. Bromide and hot acetic acid create an extremely aggressive environment for lower grades. GR7 is the standard material of construction for the most critical reactors, crystallizers, and slurry piping in PTA units.
- Standard material for bromide-promoted PTA oxidation reactors
- Resists hot acetic acid + bromide mixtures
- Long service life in crystallizers and filter systems
- Reduces unplanned shutdowns from corrosion leaks
Hydrometallurgical Leaching
High-pressure acid leaching (HPAL) and pressure oxidation (POX) circuits use sulfuric acid at elevated temperature and pressure. GR7 is specified for autoclave internals, flash vessels, and downstream piping where acid concentration and temperature exceed the safe range for GR2 and GR12.
- HPAL autoclave components exposed to hot H2SO4
- POX vessels and flash tanks
- Acid-resistant piping and valve components
- Lower corrosion rate than GR12 in concentrated hot acid
Pharmaceutical & Fine Chemical
Pharmaceutical batch reactors often see a wide range of acids, halides, and organic solvents across campaign changes. GR7's broad corrosion resistance simplifies material selection and reduces the risk of cross-campaign corrosion incidents. Meets biocompatibility and cleanliness requirements.
- Multi-purpose reactors handling acids and halides
- Corrosion-resistant linings and internals
- High-purity process compatibility
- Easy to clean and passivate between batches
Desalination Critical Components
For large thermal desalination plants, GR7 is used selectively in the hottest, most concentrated brine zones — typically brine heater tubes, tube sheets, and high-temperature pump components where GR2 and GR12 corrosion rates are not acceptable for 30-year design life.
- Brine heater tubes and tube sheets in high-temperature zones
- High-temperature brine pump casings and impellers
- Selected for maximum reliability in mega-desalination projects
- Field-proven in Middle East and North African plants
Value-Added Processing — Ready for Your Production Line
We offer custom cut-to-size processing for GR7 plate and sheet — tailored to your exact dimensions and drawing requirements. Whether you need rectangular blanks, irregular shapes, or finished components, we deliver material ready for your production line.
Manufacturing Quality & Factory Direct Supply
Stock & Production Capability
Focused GR7 Inventory — 6 Batches, ~326.5 kg
ProX Metal maintains a targeted inventory of GR7 sheet and plate in 1.0–13 mm thickness, with widths around 1000–1010 mm and lengths from 1600–2000 mm. For larger or custom requirements, we produce to order using coil-to-sheet processing or single-plate rolling, fully certified to ASTM B265 / ASME SB-265.
Quality Infrastructure
| Capability | Details |
|---|---|
| Certifications | ISO 9001:2015 • ASTM B265 • ASME SB-265 |
| MTC Standard | EN 10204 3.1 (standard) • 3.2 by TUV/SGS/BV/Lloyd's (on request) |
| NDT | 100% Ultrasonic Testing for plates ≥10mm per ASTM B265 • PMI on request |
| Surface Finish | Annealed + Pickled (standard) • Cold Rolled Bright • Sandblasted • Polished |
| Condition | Mill Annealed (standard) • Stress Relieved (on request) |
| Packaging | Seaworthy plywood cases with VCI interleaving • Vacuum sealing for marine shipments |
Strategic Location: Baoji Titanium Valley
ProX Metal is headquartered in Baoji, Shaanxi Province — "China's Titanium Valley." Over 60% of China's titanium production capacity sits within a 50 km radius. This gives us direct access to high-quality titanium sponge, ingot, rolling mills, and specialized corrosion-testing laboratories. From melt to finished plate, your GR7 order is produced within the world's most concentrated titanium supply chain.
Frequently Asked Questions
Q: What is GR7 titanium plate?
A: GR7 (ASTM Grade 7, Ti-0.2Pd, UNS R52400, Chinese designation TA9) is a commercially pure titanium grade alloyed with 0.12–0.25% palladium. The Pd addition dramatically improves corrosion resistance in reducing acids and hot chloride environments, making it the most corrosion-resistant of all CP titanium grades.
Q: How does GR7 differ from GR2 and GR12?
A: GR2 is unalloyed CP titanium — excellent in oxidizing environments but vulnerable to crevice corrosion above ~80°C and to reducing acids. GR12 adds Mo+Ni to resist hot chloride crevice corrosion at moderate cost. GR7 adds palladium, which provides a catalytic surface that maintains low corrosion rates even in strongly reducing acids and the most aggressive crevice conditions. GR7 is the premium choice when corrosion failure is unacceptable.
Q: Why is GR7 more expensive than GR2 and GR12?
A: Palladium is a precious metal. Even at 0.2 wt%, the Pd content drives a significant raw-material premium compared to CP grades. GR7 is typically specified only when the process environment justifies the cost — for example, hot hydrochloric acid, sulfuric acid, or high-temperature chloride brines where GR2 and GR12 would fail.
Q: Can GR7 be welded to GR2 or GR12?
A: Yes. GR7 is metallurgically compatible with GR2 and GR12. For welding GR7 to itself, use ERTi-7 (Pd-bearing) filler. For dissimilar joints to GR2, ERTi-2 is sometimes used for cost reasons, but ERTi-7 or ERTi-12 preserves the corrosion-resistant overlay at the joint. GTAW with 100% argon shielding is standard.
Q: What is the Chinese standard equivalent of GR7?
A: GR7 corresponds to TA9 under GB/T 3621. ProX Metal supplies GR7/TA9 with dual-standard certification when required, enabling use in projects that reference either ASTM or GB/T specifications.
Q: Is GR7 plate available from stock?
A: GR7 is a specialty grade with limited standard stock. ProX Metal carries a focused inventory of common sheet/plate sizes (1.0–13 mm thickness) and can produce custom dimensions on short lead times. Contact us with your required thickness, width, length, and quantity for current availability and pricing.
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