Titanium 6Al-4V ELI

Aging Procedure

Age at 538 C (1000 F) for 4 hours, air cool.

Annealing Procedure

Hold at 732 C(1350 F) between 1/4 and 4 hours, Furnace cool to 566 C(1050 F) then air cool. Furnace cooling is not required for forgings and bars.

Applications

Typically found in surgical implants of all shapes and sizes and in a variety of salt water applications. Also used in high pressure cryogenic vessels down to -320 C. The material is capable of high fracture toughness by using special mill processing and heat treatment.

Cold Workability

The cold working characteristics of this material are similar to those of austenitic stainless steels. In multiple forming operations, intermediate stress relieving is recommended to offset the alloy's tendency to work harden. Post-work annealing is required to re-attain optimum performance characteristics.

Forgeability

Rough forge at 982 C(1800 F), finish at @ 968 C (1750 C).

Formability

This alloy may be hot or cold formed. Popular methods include hydropress, stretch or drop-hammer. This material responds similarly to 300 series stainless steels.

Heat Treatability

Solution treat at 904-954 C(1660-1750 F) for 2 hours followed by water quench.

Hot Workability

Hot forming will reduce both the springback and required forming forces, and will increase the overall ductility of the material.

Machinability

As a family, titanium and its alloys have developed a mystique as a nightmare to machine. This is simply not the case. Experienced operators have compared its characteristics to those found in 316 stainless steel. Recommended practice includes high coolant flow(to offset the material's low thermal conductivity), slow speeds and relatively high feed rates. Tooling should be tungsten carbide designations C1-C4 or cobalt type high speed tools.

Principle Design Features

ELI stands for "extra low interstitial". Essentially, this is a controlled chemistry version of the standard 6-4 product with lower oxygen content. To qualify as a true ELI product, it should be produced as such at the mill. Some suppliers, however, have been known to check the chemical test report and "re-certify" the product themselves. Be sure to ask your supplier if the material you are buying has been produced and certified properly.

Weldability

Rated as "fair" in terms of weldability.