I. Classification by Chemical Composition (the Core Classification Method)

Based on the content and type of alloying elements in titanium, it is classified as: Pure titanium 、 Titanium alloy The two major categories serve as the primary basis for selecting grades in production.

1. Pure titanium (industrial pure titanium)

It contains only trace amounts of impurities (such as Fe, C, N, O, and H) and does not include intentionally added alloying elements. It exhibits excellent ductility and outstanding corrosion resistance, with moderate strength, making it suitable for manufacturing components that do not require high strength but demand superior corrosion resistance—for example, the base material for joint prostheses in medical implants and chemical pipelines.

Press Oxygen content (Affecting strength and plasticity) is divided into several levels. The correspondence between the international standard (ISO) and the Chinese standard (GB/T) is as follows:

2. Titanium alloys (classified by main alloying elements)

By adding elements such as Al, V, Mo, Zr, and Nb to enhance strength, heat resistance, corrosion resistance, or biocompatibility, these materials are commonly used in high-end applications (such as aerospace and medical fields). Based on the type of alloying elements, they can be categorized into four major systems:

(1) Alpha-type titanium alloy (low-temperature stable, excellent corrosion resistance)

• Alloying elements Primarily add α-stabilizing elements (such as Al, Sn, and Zr), and do not add or add only small amounts of β-stabilizing elements.

• Feature At room temperature, it exhibits an α single-phase microstructure, has good weldability, nearly the same corrosion resistance as pure titanium, and higher strength than pure titanium; however, its high-temperature strength is relatively low (≤500℃).

• Typical grade ：

• • Grade 5 (Ti-6Al-4V ELI): A commonly used grade of medical titanium alloy (ELI stands for “Extra Low Interstitial,” meaning lower levels of C, O, and N, resulting in better biocompatibility). It is used in artificial joints and spinal internal fixators.

• • Grade 9 (Ti-3Al-2.5V): High strength and high ductility, used for aerospace tubing and medical interventional devices (such as stents);

• • Grade 23 (Ti-6Al-4V ELI): Building on Grade 5, this grade further reduces the levels of interstitial elements, making it suitable for components intended for long-term implantation in the human body.

(2) Beta-type titanium alloy (high-temperature stability, high strength)

• Alloying elements Primarily add β-stabilizing elements (such as Mo, Nb, Ta, and V) at relatively high concentrations (≥10%).

• Feature At room temperature, a β single-phase or α+β duplex microstructure can be obtained through quenching and aging treatment. This microstructure exhibits high strength (tensile strength ≥ 1100 MPa), good cold-workability, and excellent biocompatibility (free of toxic elements).

• Typical grade (Medical-related grades):

• • Ti-13Nb-13Zr: Contains no V or Al, thereby avoiding the toxicity associated with metal ion leaching; used for dental implants and artificial joints.

• • Ti-29Nb-13Ta-4.6Zr (TNZT alloy): Its elastic modulus is close to that of human bone (approximately 60 GPa, lower than the 110 GPa of Ti-6Al-4V), which helps reduce the “stress shielding” effect and makes it one of the promising directions for the development of medical titanium alloys.

• • Ti-15Mo: Has strong corrosion resistance and is used for corrosion-resistant components in the chemical industry and orthopedic medical devices.

(3) α+β titanium alloy (with relatively good overall performance)

• Alloying elements Simultaneously adding α-stabilizing elements (Al) and β-stabilizing elements (V, Mo) results in an α+β duplex microstructure at room temperature.

• Feature Its microstructure can be adjusted through heat treatment (such as annealing, solid-solution aging) to strike a balance among strength (higher than that of α alloys), ductility (superior to that of β alloys), and high-temperature performance (up to 600℃). It is a widely used alloy type in the aerospace and medical fields.

• Typical grade ：

• • TC4 (Grade 5, Ti-6Al-4V): The non-ELI version—beyond its use in aerospace structural components such as aircraft landing gear, fuselage frames, and engine blades, as well as industrial molds and double-blade impellers for energy and power equipment—can also be used in the medical field to fabricate customized orthopedic implants via 3D printing technology (e.g., total cervical artificial vertebral bodies). Its sheet and foil materials can further serve as cladding materials for aerospace electronic components.

• • Grade 22 (Ti-6Al-4V ELI): Higher purity than Grade 5 ELI, used for high-demand medical implants;

• • Ti-6Al-2Sn-4Zr-2Mo: Offers higher high-temperature strength than Ti-6Al-4V and is used for aeroengine blades (up to 550℃).

(4) Near-α titanium alloy (excellent high-temperature strength)

• Alloying elements Primarily composed of α-stabilizing elements, with a small addition of β-stabilizing elements (≤2%).

• Feature The microstructure is dominated by the α phase with a small amount of β phase. It exhibits high strength at elevated temperatures (up to 650℃) and excellent oxidation resistance, making it suitable for high-temperature environments.

• Typical grade ：

• • Ti-8Al-1Mo-1V: Used for aero-engine combustion chambers and high-temperature fasteners;

• • Ti-6Al-2Sn-4Zr-6Mo: Exhibits high strength at elevated temperatures and is used in aerospace vehicle components.

II. Classification by Processing State (Impact on Mechanical Properties)

For titanium materials of the same grade, mechanical properties (strength and ductility) can vary significantly depending on differences in rolling, forging, and heat treatment processes. Therefore, these differences must be clearly indicated during production. Common processing states are as follows:

III. Classification by Application Field (Select Grades Based on Specific Needs)

Performance requirements for titanium materials vary significantly across different fields. Below is a matching of grades for core application areas:

IV. Table of Correspondence Between International Standards and Chinese Standard Grades (Commonly Used for Production Coordination)

In production, it is often necessary to align international orders (such as ASTM and ISO standards) with domestic procurement (GB standards). The following is the correspondence for key grades:

V. Special Requirements for Medical Titanium Grades (Items to Pay Attention To)

For the production of medical titanium materials, the following two points require extra attention:

1. Interstitial Element Control Medical-grade alloys (such as Grade 5 ELI and TNZT) require C ≤ 0.08%, O ≤ 0.13%, N ≤ 0.05%, and H ≤ 0.015%. These requirements are stricter than those for industrial-grade alloys and necessitate rigorous control during the melting process (in a vacuum self-consuming arc furnace).

2. Biocompatibility certification It must pass the ISO 10993-1 (Biological Evaluation of Medical Devices) test to ensure that it is non-cytotoxic and non-sensitizing. The grade selection must comply with the YY/T 0640 standard (Medical Titanium and Titanium Alloy Processing Materials).

Source of the article

1. Chinese national standards: GB/T 3620.1-2016 "Designations and Chemical Composition of Titanium and Titanium Alloys"; GB/T 2965-2023 "Titanium and Titanium Alloy Bars"; GB/T 13810-2017 "Processed Materials of Titanium and Titanium Alloys for Surgical Implants."

2. International standards: ISO 5832-2 “Implants for surgery — Titanium and titanium alloys — Part 2: Wrought titanium”; ASTM B265 “Standard Specification for Titanium and Titanium Alloy Strip, Sheet, and Plate”;

3. Industry Materials: “Analysis of GB/T 2965-2023 Standard ‘Titanium and Titanium Alloy Bars’” (Baoji Kehui Titanium Industry Co., Ltd.), “Total Materia Material Database – Standards for Titanium Materials,” and “Analysis of Methods for Querying Titanium Material Grades and Chemical Compositions as Well as the Corresponding Standard System.”

4. Enterprise and Industry News: Sichuan News Broadcast—“Pangang Successfully Rolls the First TC4 Titanium Alloy Coil in Southwest China”; Guangming Net—“Filling a Domestic Gap: Chongqing Achieves Major Technological Breakthrough in New Materials R&D”; China Nonferrous Metals Network—“Nanjing Baotai Successfully Develops a Double-Layer Blade Impeller for TC4 Titanium Alloy Castings”; Securities Daily—“Tiangong Shares Releases Third-Quarter Report, Paving the Way for High-End Titanium Alloy Products and Unlocking Long-Term Growth Potential”; The Paper—“World’s First: Changzheng Hospital Uses 3D Printing to Replace a Patient’s Entire Cervical Vertebrae with Titanium Alloy”; National Medical Products Administration—“Bio-Type Knee Joint Prosthesis System Approved for Market Launch.”