High Corrosion Resistance, High Strength and High Toughness Titanium Alloy – Ti 6Al-4V ELI

Ti 6Al-4V is an alpha-beta titanium-based alloy consisting of 6% Al and 4% V. It is the most widely used of all titanium-based alloys, exhibiting superior strength, toughness, and corrosion resistance. Fracture toughness and ductility is improved by carefully controlling the interstitial elements of oxygen and iron. Controlled interstitial element levels are called extra low interstitials or ELI, thus giving this alloy the name, Ti 6Al-4V ELI.

Chemistry and Properties

The chemistry of the Ti 6Al-4V ELI alloy as specified by ASTM F136 and Fort Wayne Metals is given in Table 1.

Table 1. Typical chemistry

  ASTM F136 FWM Avg. Wt. %
Nitrogen, max. 0.05 0.011
Carbon, max. 0.08 0.015
Hydrogen, max. 0.012 (a) 0.0058
Iron, max. 0.25 0.12
Oxygen, max. 0.13 0.11
Aluminum 5.5-6.50 6.06
Vandium 3.5-4.50 3.97
Titanium Balance Balance

The mechanical properties of Ti 6Al-4V ELI as per ASTM F136 are listed in Table 2.

Table 2. Mechanical Properties as per ASTM F136

Size in. (mm) U.T.S. min., ksi (MPa) Y.S. min. (0.2% offset) ksi (MPa) % Elongation, min.
Under 0.187 (4.75) 125 (860) 115 (795) 10% (2 in. gage length)
0.187 to 0.250 (4.75) to (6.35) 125 (860) 115 (795) 10% (4D)

The approximate mechanical properties of the FWM alloy when subjected to conditions, such as annealed, cold worked, and cold worked/stress relieved are provided in Table 3.

Table 3. Approximate FWM mechanical properties

Condition U.T.S. ksi (MPa) % Elongation (2 in. gage length)
Cold Worked 190-210 (1310-1448) 3%-7%
Cold Worked / Stress Relieved 170-190 (1172-1310) 5%-10%
Annealed 145-170 (1000-1172) 10% min.

Table 4 lists the physical properties of Ti 6Al-4V ELI.

Table 4. Physical Properties

Density 0.160 lbs/in3
Modulus Of Elasticity 16.5 psi x 106
Electrical Resistivity 1.71 µohms-m
Thermal Conductivity
6.6-6.8 W/mK

Diameter Tolerances

Fort Wayne Metals supplies materials with tighter tolerances thanks to its improved processing techniques and surface treatment capabilities. Standard diameter tolerances for wire and coil forms of Ti 6Al-4V ELI are given in Table 5.

Table 5. Diameter Tolerances

Including Under Standard Tolerance
0.0010 (0.0254) 0.0048 (0.1219) ±0.0001 (0.0025)
0.0048 (0.1219) 0.0080 (0.2032) ±0.0002 (0.0051)
0.0080 (0.2032) 0.0120 (0.3048) ±0.0003 (0.0076)
0.0120 (0.3048) 0.0240 (0.6096) ±0.0004 (0.0102)
0.0240 (0.6096) 0.0330 (0.8382) ±0.0005 (0.0127)
0.0330 (0.8382) 0.0440 (1.1176) ±0.0008 (0.0203)
0.0440 (1.1176) 0.2510 (6.3754) ±0.0010 (0.0254)

Surface Conditions

During processing, Ti 6Al-4V ELI is prone to cold welding, fretting, or sticking to drawing dies. This problem is generally addressed by using heavy pickling or etching at finish size, but producing a coarse or highly textured surface. Only minimal etching is required at finish size in case of the processing techniques and surface treatments developed at Fort Wayne Metals, removing most of the residual oxide and producing a surface that is clean and smooth.

Products

Fort Wayne Metals produces precision drawn Ti 6Al-4V ELI using advanced equipment and processing techniques. The company typically supplies the wire form of the alloy on standard FWM spools and will consider bespoke spools or packaging depending on its equipment capabilities. The diameter of the wires ranges from 0.001" (0.0254mm) to 0.062" (1.5748mm).

Fort Wayne Metals’ precision loose wound coils are used in a myriad of critical applications. The weight range varies from nominal 50 pound to a maximum of 100 pounds based on the diameter. The diameter of coils ranges from 0.040" (1.016mm) to 0.500" (12.70mm). Cut and straightened bar products are supplied in centerless and precision ground conditions. The typical length of the product ranges from 10' (3048mm) to 12' (3657mm), with tighter tolerances for most diameters. Discrete lengths are also available upon request.

Applications

Ti 6Al-4V ELI is used in pressure vessels, aerospace applications, and medical implants and devices. Well controlled microstructures and absence of melt-related defects are crucial to meet the rigorous user specifications of medical applications. Fort Wayne Metals offers Ti 6Al-4V ELI in many different forms, including wires, flat wires, cables, strands, coils, cut bars, and straightened bars, for use in many different industrial and medical applications:

  • Ligature clips
  • Orthodontic appliances
  • Surgical staples
  • Orthopaedic cables
  • Springs
  • Orthopaedic pins and screws

About Fort Wayne Metals

Fort Wayne Metals is a recognized leader in the research, development and production of fine grade medical wire. Our expertise lies in stainless steel, titanium and titanium alloys and specialty alloys such as Nitinol.

Our headquarters are in Fort Wayne, Indiana. We also have a production facility in Ireland as well as warehouse and sales facilities in Castlebar, Ireland to serve the European market.

Fort Wayne Metals is taking an active role in ASM International, a society dedicated to the exchange of material information. We are also active in ASTM, specifically the F-4 committee, which has authored many standards for medical wire.

Fort Wayne Metals

This information has been sourced, reviewed and adapted from materials provided by Fort Wayne Metals.

For more information on this source, please visit Fort Wayne Metals.

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