If you are sourcing titanium tubing for a heat exchanger, condenser, or marine cooling system, you have likely seen both ASTM B338 GR1 and GR2 on supplier quotes. They look similar. The price difference is usually small. So which one do you actually need?
Higher tensile strength does not always mean better performance. Specifying the wrong grade can lead to cracked tubes during fabrication or premature failure in service.
This guide compares GR1 and GR2 side by side so you can make the right call for your specific application.
View our full technical specifications for [ASTM B338 GR1 titanium tube] here.
What is the real difference between GR1 and GR2?
The difference comes down to one element: oxygen.
| Element | GR1 (max) | GR2 (max) | Why It Matters |
|---|---|---|---|
| Oxygen | 0.18% | 0.25% | Higher oxygen increases strength but reduces ductility |
| Iron | 0.20% | 0.30% | GR2 allows slightly more iron |
| Nitrogen | 0.03% | 0.03% | Same |
| Carbon | 0.08% | 0.08% | Same |
| Hydrogen | 0.015% | 0.015% | Same |
| Titanium | Balance | Balance | - |
GR1 has 0.18% oxygen maximum. GR2 has 0.25% maximum. That 0.07% difference changes the mechanical properties significantly.
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How do the mechanical properties compare side by side?
| Property | GR1 | GR2 | What This Means For You |
|---|---|---|---|
| Tensile Strength (min) | 240 MPa (35 ksi) | 345 MPa (50 ksi) | GR2 is 44% stronger in tension |
| Yield Strength (min) | 138 MPa (20 ksi) | 275 MPa (40 ksi) | GR2 requires nearly double the force to bend permanently |
| Elongation (min) | 24% | 20% | GR1 stretches more before breaking |
| Hardness (HRB max) | 70 | 80 | GR1 is softer - easier on tooling |
| Cold formability | Excellent | Good | GR1 can bend tighter without cracking |
Which grade handles bending and rolling better?
Rolling tubes into tube sheets: GR1 expands more easily and seals tighter. The lower yield strength means you use less rolling force, and the tube is less likely to crack at the tube sheet joint. For thin-wall tubes (under 1.5 mm), this difference matters.
U-bending: GR1 can be bent to a centerline radius of 1.5x OD without annealing. GR2 typically requires annealing below 2.5x OD. If your heat exchanger design calls for tight U-bends, GR1 is the correct grade.
Deep drawing: GR1 is the standard grade for deep drawn titanium parts. GR2 will often crack on multi-stage draws without intermediate annealing.
Machining: GR1 is softer, so tool wear is lower. The difference is not huge, but on high-volume production, GR1 will save you tooling costs.
Does corrosion resistance differ between GR1 and GR2?
No. In seawater, chemical service, and most industrial environments, GR1 and GR2 perform identically. The oxygen difference does not affect corrosion resistance. If corrosion is your only concern, either grade works.
Both grades are suitable for continuous service from cryogenic (-200°C) up to about 300°C. Above 300°C, oxidation accelerates. GR2 has no advantage here.
When should I specify GR1 instead of GR2?
Choose ASTM B338 GR1 titanium tube in these situations:
U-bend heat exchanger tubes with bend radius under 3x OD
Thin-wall tubes (under 1.2 mm) that will be rolled into tube sheets
Deep drawn or hydroformed components
Coiled tubes for immersion heaters or chillers
Any fabrication involving severe cold forming without intermediate annealing
Applications where the fabricator has limited titanium experience - GR1 is more forgiving
If your tube will be bent, rolled, or formed after delivery, GR1 is the safer bet.
When should I specify GR2 instead?
Choose GR2 when:
Straight tubes with no cold forming after delivery
Higher operating pressure (above 500 psi) where the 44% strength difference matters
Abrasive service where slightly higher hardness helps (though titanium is not truly wear-resistant)
General-purpose tubing where GR2 is more commonly stocked
Cost is identical - often GR2 is the same price or cheaper due to higher production volume
If your tube goes from the box straight into service with no bending or rolling, GR2 is fine.
1. Is GR1 always more expensive than GR2?
Not necessarily. GR2 is produced in larger volumes, so it is often the same price or slightly cheaper. GR1 can be more expensive from some mills because it requires tighter oxygen control. Always compare prices for both grades on your specific size.
2. Can GR1 and GR2 be welded together?
Yes. They are fully compatible. Use GR2 filler metal or straight titanium filler. The weld will have properties between the two grades.
3. Does GR1 have better corrosion resistance than GR2?
No. Corrosion resistance is identical in seawater, chlorides, and most chemicals. The oxygen difference does not affect corrosion performance.
4. Which grade is more commonly stocked by suppliers?
GR2 is more widely available. Many suppliers stock GR2 as their standard grade. GR1 may require a mill order for certain sizes. Check availability before specifying GR1 for a tight delivery schedule.
5. Can I substitute GR2 if GR1 is not available?
Only if your application does not involve tight bending or aggressive cold forming. For U-bends under 2.5x OD or rolling thin-wall tubes, substitution is risky. Get approval from your engineer first.
6. Does the price difference justify switching from GR1 to GR2?
If your fabrication requires GR1's ductility, the cost of cracked tubes and rework will far exceed any material savings. Do not switch grades to save a few percent on material cost if it risks fabrication yield.
7. How can I tell GR1 from GR2 after delivery?
You cannot by visual inspection. The markings on the tube or the mill certificate are the only reliable methods. Always maintain traceability from the heat number to the installed tube.
8. Which grade is better for seawater cooling systems?
Both perform the same. Base your decision on fabrication requirements. If the tubes will be rolled into a tube sheet, GR1 is preferred. If they are straight tubes with no forming, GR2 works fine.
9. Does GR1 require different welding parameters than GR2?
No. The same TIG welding parameters work for both grades. Use pure argon shielding on front and back. No filler is required for butt welds on thin wall tubes.
10. What happens if I accidentally buy GR2 but need GR1?
Depending on the application, you may be able to anneal the tubes before forming. Annealing softens GR2 but does not change the oxygen content. Consult a titanium welding engineer before proceeding. For tight U-bends, annealing may not be enough.
Packaging
Packaging
ASTM B338 titanium tubes are packed in export-grade wooden cases or steel-framed bundles, with each tube end capped to prevent moisture ingress and debris contamination. Tubes are separated by foam or cardboard dividers to avoid surface scratching during transit. For U-bend tubes, individual plastic wrapping and layer separation are provided to maintain bend geometry. All packaging complies with ISPM-15 for international shipping, and heat numbers are clearly marked on each bundle or case for full traceability upon receipt.
Our Factory & Equipment
Our facility is equipped with dedicated titanium tube production lines, including cold pilger mills, draw benches, and argon-filled annealing furnaces specifically calibrated for commercially pure titanium. For welded tubes, we use automatic TIG welding stations with online eddy current monitoring to detect weld seam defects in real time. Inspection equipment includes a full-spectrum spectrometer for chemical verification, an ultrasonic flaw detector for seamless tubes, and a hydrostatic pressure tester rated to 10,000 psi. All finished tubes pass through a laser micrometer for OD and wall thickness measurement. Our quality lab maintains independent cross-checks on every heat lot, and all inspection equipment is calibrated annually to NIST-traceable standards. This setup allows us to produce ASTM B338 tubes that consistently meet or exceed the required mechanical and corrosion performance.
