Titanium specifications define the properties of pure titanium and titanium alloys, providing the framework engineers use to select and qualify materials for demanding applications.
Thanks to the allotropic behavior of titanium, which allows diverse changes in its microstructure, a broad range of properties and applications can be served with a relatively limited number of titanium alloy grades.
Many titanium alloys are produced to meet specifications established by the American Society for Testing and Materials (ASTM), aerospace titanium specifications (SAE-AMS), military specifications for titanium alloys (MIL-T), and titanium specifications developed by the American Society of Mechanical Engineers (ASME). These diverse US systems of titanium specifications are harmonized through the Unified Numbering System (UNS), which assigns metals and alloys a lettered prefix and a five-digit number. Titanium and its alloys fall within the UNS R5 category and carry designations such as UNS R50400.
Table 1. Overview of Major Titanium Specification Systems
Standard / Specification
Organization
Primary Scope
Typical Use
ASTM
ASTM International
Material specifications and test methods
General industrial titanium products
SAE AMS
SAE International
Aerospace material specifications
Aerospace components
MIL-T
U.S. Department of Defense
Military material specifications
Defense and military applications
ASME
Pressure equipment and mechanical engineering standards
Boilers, pressure vessels, piping
UNS
Unified Numbering System
Unified alloy designation system
Cross-referencing titanium alloys
ISO
International Organization for Standardization
International standards
Global engineering applications
EN (Euronorm)
European Committee for Standardization (CEN)
European material standards
European manufacturing
JIS
Japanese Industrial Standards
National material standards
Japanese industry
GOST
Russian standards system
Russian industry
Important international titanium specifications include ISO, Euronorm, the Russian GOST, and the Japanese JIS. Although these standard specifications overlap in many areas, they are not interchangeable. In an effort to achieve a more global approach, the Japanese Titanium Society has proposed unified systems of titanium specifications.
The primary challenge with titanium specifications is not a shortage of standard specifications defined by standards development organizations (SDOs). Instead, it is the proliferation of detailed, individual titanium specifications developed by aerospace companies, which often involve relatively limited production runs. Each aerospace company maintains its own specifications for titanium alloys, and these frequently require specific, proprietary process routes. As a result, many titanium specifications are in circulation that are relevant to, and understood by, only a select group of participants. In other words, a large number of titanium specs are not standardized.
This article explains the specification systems used to define titanium and its alloys. The related guides in the Titanium series cover the topics you will need alongside it. Titanium Grades classifies commercially pure titanium and its alloys into families, and Titanium Properties details the strength, low density, and corrosion resistance that those specifications ultimately describe. Titanium Standards sets out the broader frameworks that govern these specification systems, a closely linked topic worth reading alongside this one. Together, they connect the specification framework with the grades, properties, and standards behind it.
Titanium specifications are standards that define the properties, chemical composition, and processing requirements of pure titanium and titanium alloys. They help engineers select and qualify materials for specific applications.
In the United States, titanium specifications are developed by the ASTM, SAE (aerospace AMS specifications), the military (MIL-T), and the ASME. Internationally, key bodies include ISO, Euronorm, the Russian GOST, and the Japanese JIS.
The UNS harmonizes the various US titanium specifications by assigning each metal or alloy a lettered prefix and a five-digit number. Titanium and its alloys belong to the UNS R5 category, with designations such as UNS R50400.
No. Although there is considerable overlap between US and international titanium specifications, they are not interchangeable and should be cross-referenced carefully.
Many aerospace companies develop their own detailed titanium specifications for limited production runs, often requiring proprietary process routes. This creates a large number of specifications that are understood by only a select group of participants.