What Are GR1 and GR2 Titanium?
GR1 titanium (also known as titanium cp1) is the softest and most ductile of all titanium grades.
GR2 titanium is the workhorse grade – it offers a balance of strength and formability, making it the most widely used commercially pure titanium grade.
Chemical Composition Comparison
| Element | GR1 Titanium (Max %) | GR2 Titanium (Max %) |
|---|---|---|
| Nitrogen (N) | 0.03 | 0.03 |
| Carbon (C) | 0.08 | 0.08 |
| Hydrogen (H) | 0.015 | 0.015 |
| Iron (Fe) | 0.20 | 0.30 |
| Oxygen (O) | 0.18% | 0.25% |
| Titanium (Ti) | Balance | Balance |
The 0.07% higher oxygen in GR2 creates solid solution strengthening – oxygen atoms distort the titanium lattice, making it harder and stronger but less ductile.
Mechanical Properties Comparison
| Property | GR1 Titanium | GR2 Titanium |
|---|---|---|
| Tensile Strength (min) | 240 MPa | 345 MPa |
| Gr1 Titanium Yield Strength (min) | 138 MPa | 275 MPa |
| Elongation (min) | 24% | 20% |
| Grade 1 Titanium Hardness (HRB) | 70-80 | 80-85 |
| Titanium Grade 1 Density | 4.51 g/cm³ | 4.51 g/cm³ |
| Modulus of Elasticity | 103 GPa | 103 GPa |
| Poisson's Ratio | 0.34 | 0.34 |
Gr1 Titanium Yield Strength vs Gr2
Gr1 titanium yield strength (138-275 MPa) vs GR2 yield strength (275-450 MPa) has direct implications for:
| Application Requirement | Winner |
|---|---|
| Deep drawing – needs low yield strength to stretch without tearing | GR1 |
| Flaring and expanding – needs high ductility | GR1 |
| Pressure rating – needs higher yield strength for thin walls | GR2 |
| Structural support – needs strength to carry loads | GR2 |
| Impact resistance – GR1 absorbs more energy before fracture | GR1 |
If you need to form it – choose GR1. If you need to support weight – choose GR2.
Grade 1 Titanium Hardness vs Grade 2
| Aspect | GR1 Titanium | GR2 Titanium |
|---|---|---|
| Hardness (HRB) | 70-80 (softer) | 80-85 (harder) |
| Tool Wear | Lower | Higher |
| Cutting Speed | Can be slightly faster | Slower |
| Surface Finish | Easier to achieve smooth finish | More challenging |
| Galling Tendency | Moderate | Higher |
Gr1 titanium machinability is better than GR2 due to lower hardness and less work hardening. However, both grades require sharp carbide tools and flood coolant due to titanium's low thermal conductivity.
Corrosion Resistance
This is a common question about titanium grade 1 vs grade 2. The answer is: almost identical.
Both GR1 and GR2 offer exceptional corrosion resistance in:
Seawater and brine
Chlorides (no stress corrosion cracking)
Acids (nitric, acetic, dilute sulfuric)
Alkalis
Organic compounds
The only difference: In highly reducing acid environments (e.g., concentrated HCl or H2SO4), the higher iron content in GR2 (0.30% vs 0.20%) may cause slightly lower corrosion resistance. For gr1 titanium heat exchanger and gr1 titanium reactor applications in seawater or chlorides, both grades perform identically.
Weldability Comparison
| Weld Property | GR1 Titanium | GR2 Titanium |
|---|---|---|
| Weld Ductility | Excellent | Good |
| Residual Stress | Lower | Higher |
| Risk of Cracking | Very low | Low |
| Filler Metal | ERTi-1 | ERTi-2 |
Both weld well, but gr1 titanium tube is easier to weld for thin-wall applications due to lower residual stress.
Forming and Bending Comparison
Gr1 titanium forming/bending is significantly easier than GR2 due to lower yield strength and higher elongation.
| Forming Operation | GR1 Titanium | GR2 Titanium |
|---|---|---|
| Minimum Bend Radius (Tube) | 2-3 x OD | 3-4 x OD |
| Springback | 15-20% (less than steel) | 20-25% |
| Deep Drawing Capability | Excellent | Good |
| Maximum Elongation Before Tearing | Higher | Lower |
| Required Forming Force | Lower | Higher |
Best application for GR1: Gr1 titanium for deep drawing – complex shapes like cookware, fuel cell plates, and pump diaphragms. GR2 would crack under the same deformation.
Best application for GR2: Simple bends and rolls – where strength is needed and forming is minimal.
When to Choose GR1 vs GR2
Choose GR1 Titanium When:
| Application | Why GR1 |
|---|---|
| Gr1 titanium heat exchanger | Thin walls need ductility for tube expansion into tubesheets |
| Gr1 titanium reactor with complex heads | Deep drawing requires high elongation |
| Gr1 titanium for deep drawing (cookware, cutting boards) | 24% elongation prevents tearing |
| Grade 1 titanium anode/cathode | Pure surface for MMO coating |
| Medical grade 1 titanium (ASTM F67) | Biocompatibility and formability for implants |
| Gr1 titanium cutting board | Soft surface won't dull knives |
Choose GR2 Titanium When:
| Application | Why GR2 |
|---|---|
| Pressure vessels | Higher yield strength (275 MPa) allows thinner walls |
| Structural pipes | Needs strength to support loads |
| Seawater piping systems | Higher strength for same corrosion resistance |
| Fasteners and fittings | Hardness provides thread strength |
| Heat exchanger shells (not tubes) | Shell needs pressure rating, tubes need ductility |
GR1 vs GR2 Cost
Gr1 titanium price per kg vs GR2 price – which is more expensive?
| Factor | GR1 Titanium | GR2 Titanium |
|---|---|---|
| Raw Material Cost | Slightly higher | Lower |
| Manufacturing Cost | Similar | Similar |
| Final Price per kg (wholesale) | $25-40 USD/kg FOB | $22-35 USD/kg FOB |
GR1 requires higher purity titanium sponge (lower oxygen content). This is more expensive to produce than the standard sponge used for GR2. The price difference is typically $3-5 USD/kg.
Inspection Module
Both GR1 and GR2 titanium products undergo the same rigorous inspection:
| Test | Standard | Requirement |
|---|---|---|
| Chemical Analysis | ASTM E2371 | Verify gr1 titanium chemical composition or GR2 |
| Tensile Test | ASTM E8 | Confirm gr1 titanium yield strength or GR2 |
| Hardness Test | ASTM E18 | Verify grade 1 titanium hardness or GR2 |
| Hydrostatic Test | ASTM B338 | 100% of gr1 titanium pipe |
| Eddy Current Test | ASTM E215 | 100% of gr1 titanium tube |
| Ultrasonic Test | ASTM E213 | Upon request |
| Dimensional Check | Laser micrometer | OD, WT, length |
Packaging
All gr1 titanium pipe and gr2 titanium pipe are packaged to prevent damage:
| Step | Method |
|---|---|
| 1 | Plastic end caps on both ends |
| 2 | Bubble wrap or kraft paper wrapping |
| 3 | Wooden crates (ISPM-15 fumigated) |
| 4 | Steel strapping to secure bundles |
| 5 | Color-coded labels (blue for GR1, yellow for GR2) |
| 6 | Waterproof plastic lining inside crate |
Factory & Equipment
As professional gr1 titanium tube manufacturers and a direct gr1 titanium tube factory, our facility includes:
| Equipment | Function |
|---|---|
| Cold Pilger Mills (8 units) | Precision tube reduction |
| Annealing Furnaces (4 units) | Vacuum stress relief |
| Ultrasonic Testing Line (2 units) | Automated flaw detection |
| Eddy Current Testers (3 units) | Surface defect detection |
| Optical Emission Spectrometer (2 units) | In-house chemical verification |
| Universal Testing Machine (2 units) | Gr1 titanium yield strength verification |
FAQ
Q1: What is the main difference in chemical composition between ASTM B338 Grade 1 and ASTM B338 Grade 2 titanium tube?
A: The main difference between ASTM B338 Grade 1 and ASTM B338 Grade 2 is oxygen content. Grade 1 has 0.18% oxygen max. Grade 2 has 0.25% oxygen max. This small difference makes Grade 1 softer and more ductile, while Grade 2 is stronger. Both have the same titanium grade 1 density (4.51 g/cm³).
Q2: Which grade is better for a gr1 titanium heat exchanger – GR1 or GR2?
A: For gr1 titanium heat exchanger tubes, GR1 is preferred. The tubes need to be expanded into tubesheets, which requires high ductility and low yield strength. Gr1 titanium yield strength (138 MPa) is ideal for expansion. For the shell (not tubes), GR2 may be used for higher pressure rating. Never use GR2 for tubes that require rolling or expansion.
Q3: What is the difference between pure titanium gr1 and gr2 for a titanium reactor vessel?
A: Difference between pure titanium gr1 and gr2 for gr1 titanium reactor applications: GR1 is used when the reactor head requires deep drawing (complex shape). GR2 is used when the reactor needs a higher pressure rating (thinner walls for same pressure). Both offer identical corrosion resistance in chemical processing environments.
Q4: Why is grade 1 titanium hardness lower than grade 2, and does it affect machinability?
A: Grade 1 titanium hardness (70-80 HRB) is lower than Grade 2 (80-85 HRB) because GR1 has less oxygen (0.18% vs 0.25%). Lower hardness means gr1 titanium machinability is slightly better – less tool wear and lower cutting forces. However, both grades require sharp carbide tools and flood coolant due to titanium's low thermal conductivity.
Q5: Can I substitute GR2 for GR1 in a deep drawing application?
A: No. Gr1 titanium for deep drawing is specifically chosen for its 24% minimum elongation and low yield strength (138 MPa) . GR2 has only 20% elongation and 275 MPa yield strength. Substituting GR2 will likely cause cracking or tearing during deep drawing. Always use GR1 titanium for deep drawn components like cookware, fuel cell plates, and diaphragms.
Q6: Which grade has better corrosion resistance in seawater – GR1 or GR2?
A: Both GR1 and GR2 offer identical corrosion resistance in seawater. Titanium's corrosion resistance comes from its stable oxide layer (TiO2), which is the same for both grades. For gr1 titanium pipe in marine applications, GR1 is preferred for tubes (due to expansion needs), but GR2 can be used for piping systems where higher strength is required. Neither will corrode in seawater.
Q7: How does gr1 titanium yield strength at elevated temperatures compare to GR2?
A: Gr1 titanium yield strength decreases faster than GR2 above 200°C. At room temperature: GR1 138 MPa vs GR2 275 MPa. At 200°C: GR1 ~100 MPa vs GR2 ~180 MPa. At 300°C: GR1 ~60 MPa vs GR2 ~110 MPa. For gr1 titanium heat exchanger operating below 150°C, both are acceptable. For service above 200°C, GR2 is required.
Q8: What is the Chinese equivalent grade for GR1 and GR2 titanium?
A: GR1 titanium = TA1 per GB/T 3620-2007. GR2 titanium = TA2. TA1 has the same oxygen limit (0.18%) and mechanical properties as ASTM Grade 1. TA2 has 0.25% oxygen max.
Q9: Can ASTM F67 Grade 1 (medical) and ASTM F67 Grade 2 be used interchangeably?
A: No. ASTM F67 Grade 1 (medical grade 1 titanium) is used for implants requiring high formability (e.g., bone plates, skull mesh). ASTM F67 Grade 2 is used for implants requiring higher strength (e.g., hip stems, dental implants). They have different oxygen limits (0.18% vs 0.25%) and different gr1 titanium yield strength requirements. Do not substitute one for the other without regulatory approval.
Q10: Is gr1 titanium pipe more expensive than GR2 pipe? Why?
A: Yes. Gr1 titanium price per kg is typically $3-5 USD/kg higher than GR2. The reason: GR1 requires higher-purity titanium sponge with oxygen content below 0.18%. This sponge is more expensive to produce than the standard sponge (0.25% oxygen) used for GR2. For wholesale grade 1 titanium orders (500kg+), the price difference narrows. Contact us for current gr1 titanium price.
Q11: Which grade should I choose for a gr1 titanium MMO anode – GR1 or GR2?
A: For gr1 titanium MMO anode (mixed metal oxide coating), GR1 is preferred but GR2 can also be used. Grade 1 titanium anode/cathode applications typically specify GR1 because its purer surface oxide layer provides better adhesion for the MMO coating.
Q12: Do you stock both gr1 titanium tube and gr2 titanium tube for fast delivery?
A: Yes. As professional gr1 titanium tube suppliers, we maintain gr1 titanium tube in stock and GR2 tube in stock. Gr1 titanium tube for sale includes sizes from 6mm to 219mm OD. Fast delivery gr1 titanium (7-15 days for standard sizes). Gr1 titanium ready to ship for urgent orders. Both grades available with ASTM B338, ASTM B861, or ASTM B862 certification. Request a quote with your size and quantity.
