Titanium Grades Complete Guide — CP, Alpha, Alpha-Beta, and Beta Alloys Explained

Titanium alloys are classified by their microstructure into four main categories: commercially pure grades, alpha and near-alpha alloys, alpha-beta alloys, and beta alloys. Each category offers a different balance of strength, ductility, corrosion resistance, and machinability. The selection of a specific grade for a component depends on the operating requirements, the manufacturing process, and the cost constraints of the application. This guide provides a systematic comparison of the major titanium grades and the engineering logic behind their selection. Detailed material property data for individual grades is available in the materials section of the site.

• Titanium alloy classification system
• Commercially pure grades — when strength is not the priority
• Alpha and near-alpha alloys — creep resistance at elevated temperatures
• Alpha-beta alloys — the workhorse category
• Beta alloys — high strength for specialized applications
• Grade selection logic by application

Titanium alloy classification system

Titanium alloys are classified by the phases present in their microstructure at room temperature. The alpha phase has a hexagonal close-packed crystal structure and is stable at lower temperatures. The beta phase has a body-centered cubic structure and is stable at higher temperatures. Alloying elements stabilize one phase or the other, and the relative proportions of each phase at room temperature determine the alloy category.

Alpha stabilizers such as aluminum and oxygen increase the temperature at which the alpha phase is stable. These elements are present in nearly all titanium alloys because aluminum improves the strength-to-weight ratio and oxygen provides solid-solution strengthening. Beta stabilizers such as vanadium, molybdenum, chromium, and iron lower the temperature at which the beta phase is stable, allowing some beta phase to be retained at room temperature.

The distinction between alpha, alpha-beta, and beta alloys is not arbitrary — it determines how the material responds to heat treatment, what mechanical properties can be achieved, and how the material behaves during manufacturing operations including machining, forming, and welding. Understanding the classification system is the foundation for grade selection in engineering applications.

Commercially pure titanium is not alloyed in the conventional sense. It contains only trace amounts of other elements, with oxygen being the primary controlled element that determines the grade. CP grades are single-phase alpha materials and cannot be strengthened by heat treatment — they are strengthened only by cold work and solid-solution strengthening from interstitial elements.

Commercially pure grades — when strength is not the priority

Commercially pure titanium is available in grades 1 through 4, distinguished primarily by oxygen content. Grade 1 has the lowest oxygen content, the lowest strength, and the highest ductility and formability. Grade 4 has the highest oxygen content within the CP range, the highest strength, and the lowest ductility. The progression is continuous — each grade increases in strength by approximately 50 to 70 MPa over the previous grade while ductility decreases correspondingly.

CP titanium grades are used where corrosion resistance is the primary requirement and strength requirements are moderate. Grade 1 and Grade 2 are common in chemical processing equipment, heat exchangers, and marine components where the environment is corrosive but the mechanical loads are not severe. Grade 2 is the most widely used CP grade because it offers a practical balance of strength, ductility, and cost.

Grade 3 is less common than Grade 2 or Grade 4. It occupies a middle position in the CP range and is used where slightly higher strength than Grade 2 is needed but the formability of Grade 4 is not acceptable. Grade 4 is used in applications requiring the highest strength among CP grades, such as medical implant components where the higher strength is beneficial but the alloy must remain pure enough to avoid biocompatibility concerns.

All CP grades are easier to form and weld than alloyed titanium grades, but they are more difficult to machine than the alpha-beta alloys in certain respects. CP titanium produces a stringy, ductile chip that is difficult to break, and the built-up edge formation is more severe than with Ti-6Al-4V. Tooling strategies for CP grades should emphasize chip breaking geometry and lower cutting speeds to manage built-up edge formation.

Alpha and near-alpha alloys — creep resistance at elevated temperatures

Alpha alloys contain primarily alpha-stabilizing elements with minimal beta stabilizers. They maintain their strength at elevated temperatures better than alpha-beta alloys but have lower room-temperature strength. Near-alpha alloys contain a small amount of beta-stabilizing elements, typically 2 to 5 percent by weight, which provides a small volume fraction of beta phase that improves hot workability without significantly reducing high-temperature performance.

The primary application for alpha and near-alpha alloys is in components that operate at elevated temperatures. Ti-6Al-2Sn-4Zr-2Mo, known as Ti-6242, is a near-alpha alloy designed for service temperatures up to approximately 540°C. It is used in gas turbine engine components such as compressor casings and blades where creep resistance at temperature is more important than room-temperature strength.

Ti-5Al-2.5Sn is an alpha alloy with excellent weldability and good strength at cryogenic temperatures. It is used in aerospace components for liquid hydrogen and liquid oxygen systems where the material must maintain ductility at extremely low temperatures. The alloy is also used in marine applications where its combination of corrosion resistance and moderate strength is advantageous.

Near-alpha alloys are generally more difficult to machine than Ti-6Al-4V because their higher aluminum content increases hardness and reduces ductility at the cutting interface. Tool wear rates are typically 20 to 40 percent higher than for Ti-6Al-4V at equivalent cutting parameters. Process planning for near-alpha alloys should account for this reduced machinability by specifying lower cutting speeds and more frequent tool changes.

Alpha-beta alloys — the workhorse category

Alpha-beta alloys are the most widely used category of titanium alloys, accounting for the majority of titanium tonnage in aerospace and industrial applications. They contain both alpha-stabilizing and beta-stabilizing elements, and their microstructure consists of a mixture of alpha and beta phases at room temperature. The proportion of each phase can be adjusted by heat treatment, allowing a range of strength and ductility combinations from a single alloy composition.

Ti-6Al-4V, commonly referred to as Grade 5, is the dominant alpha-beta alloy. It accounts for approximately 50 percent of all titanium used worldwide. The alloy contains 6 percent aluminum as an alpha stabilizer and 4 percent vanadium as a beta stabilizer. In the annealed condition, it has a tensile strength of approximately 900 to 1000 MPa, with good ductility and fracture toughness. In the solution-treated and aged condition, strength can be increased to approximately 1100 to 1200 MPa.

The widespread use of Ti-6Al-4V is not because it is the best titanium alloy for any single property — it is because it offers the best combination of properties across the full range of engineering requirements. It has good strength, acceptable ductility, excellent corrosion resistance, and reasonable machinability. It can be forged, rolled, heat treated, welded, and machined using standard processes. For applications that do not require the specialized properties of other alloy categories, Ti-6Al-4V is typically the first choice.

Ti-6Al-4V ELI, or Grade 23, is a version of Ti-6Al-4V with lower interstitial element content — reduced oxygen, iron, and carbon. The lower interstitial content improves ductility and fracture toughness at the cost of a small reduction in strength. Grade 23 is the standard material for medical implant applications and for aerospace components requiring enhanced damage tolerance.

Other alpha-beta alloys serve specific niches within the category. Ti-6Al-7Nb was developed as a niobium-stabilized alternative to Ti-6Al-4V for medical applications where vanadium biocompatibility concerns were raised, though in practice both alloys have extensive clinical history. Ti-6Al-2Sn-4Zr-6Mo provides higher strength than Ti-6Al-4V at elevated temperatures and is used in gas turbine engine applications where the operating temperature exceeds the capability of Ti-6Al-4V.

The machinability of alpha-beta alloys varies with their heat treatment condition. Annealed material machines more easily than solution-treated and aged material, which has higher hardness and produces higher cutting forces. For components that will be heat treated after roughing, the roughing should be performed in the annealed condition and the finishing after heat treatment, with appropriate adjustments to cutting parameters. The machining challenges article provides a detailed analysis of how these properties affect cutting behavior across the major titanium alloy categories.

Beta alloys — high strength for specialized applications

Beta alloys contain a sufficient concentration of beta-stabilizing elements that the beta phase is retained at room temperature after cooling. They can be heat treated to very high strength levels — tensile strengths of 1200 to 1400 MPa are achievable — but at the cost of reduced ductility and increased difficulty in manufacturing.

Ti-10V-2Fe-3Al, known as Ti-1023, is a beta alloy developed for high-strength aerospace applications. It can be heat treated to tensile strengths above 1200 MPa, comparable to high-strength steels, with the weight advantage of titanium. It is used in landing gear components, structural forgings, and other applications where high strength is required and the component geometry is amenable to forging.

Ti-15V-3Cr-3Sn-3Al, or Ti-15-3, is a beta alloy available in strip and sheet form. It can be cold rolled and then heat treated to high strength, making it suitable for sheet metal components that require high strength-to-weight ratios. It is used in aerospace ducting, brackets, and honeycomb panel skins.

Beta alloys are the most difficult to machine of the titanium categories. Their higher strength and hardness produce higher cutting forces, and their lower thermal conductivity — already low for titanium — concentrates even more heat at the cutting edge. Tool life in beta alloys is typically 30 to 50 percent lower than in Ti-6Al-4V at equivalent cutting speeds. Process planning for beta alloys requires lower cutting speeds, higher coolant pressure, and more conservative tool change intervals.

The higher material cost of beta alloys, combined with their manufacturing difficulty, limits their use to applications where the strength requirement cannot be met by alpha-beta alloys. For most titanium components, Ti-6Al-4V in the annealed or solution-treated and aged condition provides adequate strength at lower material and manufacturing cost.

Grade selection logic by application

For aerospace structural components, Ti-6Al-4V in the annealed or solution-treated and aged condition is the standard choice. The alloy provides the strength-to-weight ratio required for airframe structures, landing gear components, and engine mounts. For components operating above 400°C, near-alpha alloys such as Ti-6242 are specified for their creep resistance. For high-strength applications such as landing gear, beta alloys such as Ti-1023 are used where the weight savings justify the higher cost.

For medical implant components, Grade 23 Ti-6Al-4V ELI is the standard material. The reduced interstitial content provides the fracture toughness required for fatigue-loaded implants such as hip stems and bone plates. CP titanium grades 2 and 4 are used for implant components where the loads are lower and the priority is on biocompatibility and bone integration. Dental implants are typically Grade 23 or CP Grade 4, depending on the implant design and loading conditions.

For chemical processing and marine applications, CP titanium grades 2 and 7 are the primary choices. Grade 2 provides adequate strength for pressure vessels and piping systems, with excellent corrosion resistance in seawater and most chemical environments. Grade 7 contains 0.15 percent palladium, which improves corrosion resistance in reducing acid environments where CP titanium alone may be attacked.

For industrial and consumer applications, the selection depends on the specific requirements of each application. CP Grade 2 is common for heat exchangers and piping. Ti-6Al-4V is used for high-performance bicycle components, automotive exhaust systems, and consumer electronics where the combination of strength, weight, and aesthetic appearance is valued. Beta alloys are used in specialty consumer products such as high-end watch cases where the material’s response to surface finishing produces a distinctive appearance.

For applications where machinability is a primary selection criterion — such as high-volume precision components — Ti-6Al-4V offers the best combination of mechanical properties and manufacturing efficiency among the structural titanium alloys. The established tooling knowledge, parameter databases, and process experience available for Ti-6Al-4V make it the lowest-risk choice for new titanium component development.

Table 1: Titanium grade categories and key characteristics

Table 2: Grade selection by industry application

To apply these grade selection criteria interactively to your application, use the titanium grade finder.