Difference Between Titanium Grade 1 and Grade 2: Properties and Applications
Nov 26, 2025
Introduction
Grade 1 (Gr1) and Grade 2 (Gr2) are the two most frequently specified commercially pure (CP) titanium grades. They share the same corrosion resistance family and welding behavior, but differ in impurity limits, strength, and ductility. These small differences decide whether a part deep-draws cleanly or carries a pressure load for twenty years. This article compares both grades on the basis of ASTM B265, the governing specification for titanium sheet, strip, and plate.
Composition and Purity Limits
CP titanium grades are defined by maximum impurity limits rather than by a nominal titanium percentage. The controlling elements are iron and oxygen, both of which raise strength and reduce ductility.
| Element (max %) | Grade 1 | Grade 2 |
|---|---|---|
| Iron | 0.20 | 0.30 |
| Oxygen | 0.18 | 0.25 |
| Carbon | 0.08 | 0.08 |
| Nitrogen | 0.03 | 0.03 |
| Hydrogen | 0.015 | 0.015 |
Lower iron and oxygen limits make Grade 1 the higher-purity material, with slightly better corrosion resistance in extreme environments and markedly better ductility.
Mechanical Properties
| Property (min) | Grade 1 | Grade 2 |
|---|---|---|
| Tensile strength | 240 MPa | 345 MPa |
| Yield strength | 170 MPa | 275 MPa |
| Elongation | 24% | 20% |
| Hardness (typical HV) | 120-150 | 150-200 |
The practical reading: Grade 2 carries roughly 40 percent more load at the same section size, while Grade 1 bends, stretches, and deep-draws with greater margin before cracking.
Formability and Fabrication
Grade 1 is the preferred material for severe forming: deep drawing of bellows and expansion joints, spinning of domes, and rolling of thin foil down to a few hundredths of a millimeter. Its lower yield strength also reduces springback in press forming. Grade 2 remains readily formable and is the more common choice where strength must survive the forming operation. Both grades weld easily with GTAW under argon shielding; Grade 1 welds show slightly better ductility, which matters for thin-wall components subject to cyclic loading.
Corrosion Resistance
Both grades form the same self-healing TiO₂ passive film and resist seawater, chlorides, oxidizing acids, and most organic media. In most marine and chemical service the corrosion performance of the two grades is equivalent. Grade 1 holds a small advantage in highly reducing, low-pH media where lower impurity content delays the onset of attack, but for the majority of applications this difference is not the deciding factor.
Typical Applications
| Grade 1 | Grade 2 |
|---|---|
| Chemical equipment linings | Heat exchangers and piping |
| Electrolytic cell components | Marine engineering and desalination |
| Titanium foil, bellows, expansion joints | Medical implants and surgical instruments |
| Architectural cladding and roofing | Pressure vessels and structural parts |
| Deep-drawn consumer products | Process equipment in chemical plants |
Selection Guidance
Choose Grade 1 when the design demands extreme formability, maximum ductility, or the highest available purity for demanding corrosion service. Choose Grade 2 when the part must carry load in a corrosive environment and will be fabricated by conventional welding and bending; Grade 2 covers the large majority of industrial CP titanium demand. If in doubt, evaluate the forming operation first: parts that crack in Grade 2 trial forming should be re-specified in Grade 1, and parts that yield under load in Grade 1 should move up to Grade 2.
Frequently Asked Questions
Is Grade 1 titanium stronger than Grade 2?
No. Grade 2 has higher minimum tensile strength (345 MPa versus 240 MPa per ASTM B265). Grade 1 is softer and more ductile.
Which grade is better for deep drawing?
Grade 1. Its lower yield strength and higher elongation (24 percent minimum) allow deeper draws and tighter radii without cracking, which is why bellows and foil are typically Grade 1.
Do Grade 1 and Grade 2 cost differently?
Grade 1 is usually priced close to Grade 2 and occasionally higher because the tighter impurity control constrains melting. The price gap is normally small and rarely drives the grade decision.
Can both grades be used for medical implants?
Yes. CP titanium Grades 1 to 4 are covered by ASTM F67 and ISO 5832-2 for implantable devices. Both grades are biocompatible; the implant design determines which is chosen.
Which grade should I use for a seawater heat exchanger?
Grade 2 is the standard choice for seawater service, including condenser tubes and heat-exchanger plate/tube forms. Grade 1 may be specified for thin-wall tubes where maximum formability is required.
Are the two grades interchangeable?
Not without checking the design. Where load capacity or pressure rating governs, Grade 2 is required; where forming severity governs, Grade 1 is required. Substituting one for the other should always follow a re-evaluation of both strength and formability.
