← Back to Resources
Material Guide · Titanium · Aerospace & Medical
Ti-6Al-4V vs CP Grade 2 vs Grade 23 ELI —
Properties, Specifications, and How to Choose
Links
Related article
Spec / standard
Process / treatment
Titanium is specified when you need the best strength-to-weight ratio available in a structural metal, combined with excellent corrosion resistance. It costs significantly more than stainless or aluminum and is dramatically harder to machine, so getting the grade right matters. This guide covers the three titanium grades most commonly encountered in precision machining: Ti-6Al-4V (Grade 5), commercially pure Grade 2, and Ti-6Al-4V ELI (Grade 23). We machine all three here at C&W Manufacturing, along with reference materials like
17-4 PH stainless and
7075 aluminum that often compete for the same applications.
Understanding Titanium Grade Designations
Titanium grades are designated by ASTM Grade numbers (Grade 1 through 38+) and by their alloy composition. The three grades covered here represent the three most important categories: commercially pure (CP), the standard structural alloy, and the medical/cryogenic variant.[1]
What does "ELI" mean?
ELI stands for Extra Low Interstitials. Grade 23 has the same 6Al-4V base composition as Grade 5, but with tighter limits on oxygen, nitrogen, hydrogen, and iron. These interstitial elements increase strength but decrease fracture toughness and ductility. By reducing them, Grade 23 achieves better fracture toughness and fatigue crack growth resistance at a modest cost in peak strength. This is why Grade 23 is specified for medical implants (where a fatigue fracture inside a patient is catastrophic) and for cryogenic applications (where fracture toughness at low temperature is critical).[2]
At a Glance — All Three Grades
Grade 2 is the corrosion and formability grade. Grade 5 is the structural strength grade. Grade 23 is Grade 5 with better fracture toughness for medical and cryogenic use. All values for annealed bar unless noted.[1][3]
Grade 2 (CP Ti)
UNS R50400 · AMS 4902 · ASTM B348
"The corrosion grade" — pure titanium, most formable
Density
0.163 lb/in³ / 4.51 g/cm³
Max service temp.
~600°F / 315°C
Corrosion resistance
Exceptional
Grade 5 (Ti-6Al-4V)
UNS R56400 · AMS 4928 (bar) · AMS 4911 (sheet)
"The workhorse" — accounts for ~50% of all titanium usage
Tensile strength
130 ksi
895 MPa (min annealed)
Yield strength
120 ksi
827 MPa (min annealed)
Density
0.160 lb/in³ / 4.43 g/cm³
Max service temp.
~600°F / 315°C
Weldability
Good (inert atmosphere required)
Corrosion resistance
Excellent
Grade 23 (Ti-6Al-4V ELI)
UNS R56401 · AMS 4930 · ASTM F136
"The medical/cryo grade" — same as Grade 5 with better fracture toughness
Density
0.160 lb/in³ / 4.43 g/cm³
Max service temp.
~600°F / 315°C
Weldability
Good (inert atmosphere required)
Corrosion resistance
Excellent
Fracture toughness
Superior to Grade 5
Strength Comparison
CP Grade 250 ksi / 345 MPa
7075-T6 Aluminum (ref)83 ksi / 572 MPa
Grade 23 ELI (Ti-6Al-4V ELI)120 ksi / 827 MPa
Grade 5 (Ti-6Al-4V)130 ksi / 895 MPa
17-4 PH H900 (ref)190 ksi / 1310 MPa
In plain terms: titanium vs the alternatives
Ti-6Al-4V (Grade 5) has roughly the same tensile strength as
17-4 PH stainless at H1025 (~155 ksi) but at 56% of the weight. That strength-to-weight advantage is why aerospace specifies titanium. If weight isn't governing your design,
17-4 PH delivers comparable or higher strength at a fraction of the material and machining cost. If you need light weight but can accept lower strength,
7075-T6 aluminum is lighter than titanium (2.81 g/cm³ vs 4.43 g/cm³) and dramatically cheaper, but its strength and corrosion resistance are both lower.
Property Comparison Chart
Toggle between properties to compare all three titanium grades with 17-4 PH and 7075-T6 as reference.
[1][3][4]
Titanium grade comparison
CP Grade 2, Grade 5 (Ti-6Al-4V), Grade 23 (ELI), with 17-4 PH H900 and 7075-T6 as reference.
Tensile strength
Yield strength
Elongation %
Density (g/cm³)
Grade-by-Grade Breakdown
CP Grade 2 is commercially pure titanium (99.2% Ti) with no intentional alloying additions. It is the most commonly specified commercially pure grade, offering a balance of moderate strength, excellent formability, and the best corrosion resistance of any titanium grade. It resists seawater, chlorides, and most acids, and is biocompatible for medical applications.
[1]
Grade 2 is significantly weaker than Ti-6Al-4V (50 ksi vs 130 ksi tensile), but that's not the point. It's specified when corrosion resistance, formability, or biocompatibility is the primary requirement and the loads are moderate. It welds easily and doesn't require
solution treatment or aging.
Typical components
Chemical processing equipment, heat exchangers, marine hardware, desalination plant components, medical implants and instruments, dental components, architectural cladding, and any application where corrosion resistance in aggressive environments is the primary driver and structural loads are moderate.
When to specify Grade 2
Specify
AMS 4902 (bar) or
ASTM B265 (plate) when the design is driven by corrosion resistance, biocompatibility, or weight savings in a moderately loaded structure. Grade 2 is the titanium equivalent of
304 stainless: the default for corrosion applications. If your stress analysis shows the loads require more than 40 ksi yield, step up to Grade 5.
Grade 5 (Ti-6Al-4V): The aerospace structural standard
Ti-6Al-4V is the most widely used titanium alloy in the world, accounting for roughly half of all titanium produced by weight. The 6% aluminum and 4% vanadium additions create an alpha-beta microstructure that delivers 130 ksi tensile strength at 56% of the density of steel. It is heat treatable, can be
solution treated and aged
(STA) to reach even higher strength levels (~165 ksi), and maintains useful strength to approximately 600°F (315°C).
[1][3]
Grade 5 is notoriously difficult to machine. It has low thermal conductivity (similar to
Inconel), generates intense heat at the cutting interface, and work-hardens. Cycle times are 3 to 5 times longer than equivalent
6061 aluminum
operations. Tooling cost is also significantly higher. These factors drive the machining cost premium that engineers need to budget for when specifying titanium.
Typical components
Aerospace structural frames, bulkheads, and fittings. Jet engine compressor blades and discs (up to ~600°F). High-performance fasteners. Defense hardware. Automotive connecting rods and valve springs in racing applications. Sporting goods (bicycle frames, golf club heads). Medical implants where Grade 23 isn't required. Any application where the strength-to-weight ratio justifies the cost.
When to specify Grade 5
Specify
AMS 4928 (bar, annealed) or
AMS 4911 (sheet) when the design requires high strength at low weight and the operating temperature stays below approximately 600°F (315°C). For STA condition, specify
AMS 4965. Grade 5 is the default titanium alloy; if someone says "titanium" without a grade, they almost always mean Ti-6Al-4V. We machine Grade 5 bar and plate regularly at C&W for aerospace and defense programs.
Grade 23 (Ti-6Al-4V ELI): Medical implants and cryogenic
Grade 23 is the same 6Al-4V chemistry as Grade 5 but with tighter limits on interstitial elements: oxygen ≤0.13% (vs 0.20% in Grade 5), nitrogen ≤0.03% (vs 0.05%), and iron ≤0.25% (vs 0.30%). These reductions improve fracture toughness, fatigue crack growth resistance, and ductility at the expense of approximately 10 ksi in peak tensile strength.
[2]
The "ELI" designation is critical for two application families: medical implants (where
ASTM F136
governs and a fatigue fracture inside a patient would be catastrophic) and cryogenic structures (where fracture toughness at low temperature is the governing property). Grade 23 machines identically to Grade 5, with the same difficulty and cost profile.
Typical components
Orthopedic implants (hip and knee replacements, spinal cages, bone screws, and plates per
ASTM F136). Dental implants. Cryogenic pressure vessels and tankage (liquid oxygen, liquid hydrogen). Surgical instruments. Any structural component where fracture toughness and fatigue crack growth resistance are the governing design criteria.
When to specify Grade 23
Specify
AMS 4930 (bar) or
ASTM F136
(medical implant grade) when the application is a medical implant, when the part operates at cryogenic temperatures, or when fracture toughness is explicitly a governing criterion. If the part is a standard aerospace structure at ambient temperature, Grade 5 provides higher strength at lower cost and Grade 23 offers no advantage.
Full Property Comparison
All values for standard annealed bar at room temperature unless noted.
17-4 PH H900
and
7075-T6
included as reference materials that often compete for the same applications.
[1][3][4]
Cost Guidance for Engineers
⚠ Before specifying titanium: do you actually need it?
Titanium's strength-to-weight ratio is exceptional, but if weight isn't a governing design criterion, you may be paying a substantial premium for a property you don't need.
17-4 PH stainless at H1025
provides 155 ksi tensile at a fraction of the material and machining cost. If the part is a static structure at room temperature that doesn't fly, float, or go inside a patient, stainless or
alloy steel should be evaluated first. We machine both titanium and stainless at C&W and can advise on the most cost-effective material for your application.
Grade 2 saves significant cost over Grade 5
If your application is corrosion-driven (chemical processing, marine, desalination) and the structural loads are moderate, CP Grade 2 at 50 ksi tensile may be more than adequate. Grade 2 bar is less expensive than Ti-6Al-4V, more widely stocked, and somewhat easier to machine. Don't default to Grade 5 because "titanium should be strong." Specify the grade that matches your actual requirement.
Grade 23 costs more and is weaker than Grade 5
Grade 23 has approximately 10 ksi lower tensile strength than Grade 5 and costs more due to tighter chemistry control. Specify it only when fracture toughness,
ASTM F136
compliance (medical implants), or cryogenic service is actually required. For standard aerospace structural work at ambient temperature, Grade 5 is both stronger and cheaper.
Which Grade Is Right for Your Part?
CP Grade 2
Best for: Corrosion, formability, and moderate loads
Best corrosion resistance of any titanium grade. Most formable and weldable. Moderate strength only. The default for chemical processing and marine applications.
Chemical processing
Heat exchangers
Marine hardware
Desalination
Dental
Architecture
Grade 5 (Ti-6Al-4V)
Best for: Aerospace structural strength at low weight
The default titanium alloy. Highest strength of the three. Heat treatable for even higher strength (STA). The workhorse for airframe, defense, and high-performance structural applications.
Airframe structure
Compressor blades
Fasteners
Defense
Racing
Sporting goods
Grade 23 (ELI)
Best for: Medical implants and cryogenic service
Same 6Al-4V base with better fracture toughness. Required for ASTM F136 implant applications. Specified for cryogenic pressure vessels. Slightly weaker and more expensive than Grade 5.
Hip/knee implants
Spinal cages
Bone screws
Cryo vessels
Surgical instruments
Need titanium components machined?
Our team at C&W machines CP Grade 2, Ti-6Al-4V (Grade 5), and Grade 23 ELI regularly for aerospace, defense, and medical programs. We can advise on grade selection, coordinate with material suppliers, and provide full cert packages including mill certs and material test reports.
