Titanium and titanium alloys are non-ferrous metals with excellent corrosion resistance, fatigue properties, and high strength-to-weight ratios. Pure titanium is a silver colored metal that has a low density and is strong, lustrous, and corrosion-resistant. Pure titanium has been used for orthopedic and dental implants, however it is mostly applied as an alloy with iron, aluminum, vanadium, and/or molybdenum among others.

Titanium alloys are generally categorized into four main types: alpha alloys, near-alpha alloys, alpha & beta alloys, and beta alloys.

Alpha alloys are those that contain neutral alloying elements (tin) and/or alpha stabilizers (aluminum or oxygen) only. They have good weldability and good strength and oxidation resistance at elevated temperatures as a result of aluminum content. These alloys cannot be heat treated to enhance their mechanical properties because they are single-phase alloys.

Near-alpha alloys are those that contain small amounts of beta-phase to increase ductility. Besides alpha-phase stabilizers, near-alpha alloys are alloyed with 1-2% of beta phase stabilizers such as molybdenum, silicon, or vanadium.

Alpha & beta alloys are metastable and generally include some combination of both alpha and beta stabilizers. These two-phase alloys can be heat treated and quenched to significantly strengthen the material; however their ductility lowers proportionally to strength increases after treatment.

Beta alloys are metastable and contain sufficient beta stabilizers (molybdenum, silicon, and vanadium). They can be solution treated and aged to improve strength, and the metastable beta can be strengthened considerably by heat treatment.

Specifications

Selecting metal alloys requires an analysis of the desired dimensions and specifications. Dimensions to consider include:

• Outer diameter (OD)
• Inner diameter (ID)
• Overall length
• Overall thickness

Other specifications of importance (based on application) include product shape, tensile strength, yield strength, melting point, conductivity, corrosion resistance, ductility, and malleability. These properties differ based on the forming method and alloy composition.

Applications

Titanium and titanium alloys are used in corrosive environments or in applications that require light weight, high strength-to-weight ratio, and nonmagnetic properties. They are used most notably in the aerospace and automotive industries as lightweight parts, the medical industry as implants, and the chemical and petroleum industries as equipment alternatives to higher cost or shorter lifespan metals.

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PLANSEE SE