Grade 6Al 2Sn 4Zr 6Mo Titanium Alloy (UNS R56260)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
     Machinability
     Forming
     Welding
     Heat Treatment
     Annealing
     Forging
     Hot Working
     Cold Working
     Aging
Applications

Introduction

Titanium mixed with other chemical elements such as aluminum, molybdenum and zirconium produces a wide range of titanium alloys.

Grade 6Al 2Sn 4Zr 6Mo titanium alloy possesses high strength at elevated temperatures, good hardenability and good weldability. It is heat-treatable alpha-beta alloy.

The following sections will discuss grade 6Al 2Sn 4Zr 6Mo titanium alloy in detail.

Chemical Composition

The chemical composition of grade 6Al 2Sn 4Zr 6Mo titanium alloy is outlined in the following table.

Element Content (%)
Molybdenum, Mo 6
Aluminum, Al 6
Zirconium, Zr 4
Tin, Sn 2
Titanium, Ti Balance

Physical Properties

The physical properties of grade 6Al 2Sn 4Zr 6Mo titanium alloy are tabulated below.

Properties Metric Imperial
Density 4.65 g/cm3 0.168 lb/in3
Melting point 1595-1675°C 2903-3047°F

Mechanical Properties

The following table shows mechanical properties of grade 6Al 2Sn 4Zr 6Mo titanium alloy.

Properties Metric Imperial
Tensile strength 1210 MPa 175000 psi
Yield strength 1120 MPa 162000 psi
Poisson’s ratio 0.33 0.33
Elastic modulus 114 GPa 16500 ksi
Shear modulus 42.9 GPa 6220 ksi
Elongation at break 13 % 13 %
Hardness, Brinell 360 360
Hardness, Knoop 392 392
Hardness, Rockwell C 39 39
Hardness, Vickers 376 376

Thermal Properties

The thermal properties of grade 6Al 2Sn 4Zr 6Mo titanium alloy are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@0.000-100°C/32-212°F) 8.60 µm/m°C 4.78 µin/in°F
Thermal conductivity 7.70 W/mK 53.4 BTU in/hr.ft².°F

Other Designations

Equivalent materials to grade 6Al 2Sn 4Zr 6Mo titanium alloy are as follows:

  • AMS 4981
  • DIN 3.7164
  • MIL T-9046
  • PWA 1222
  • PWA 1223
  • PWA 1224
  • PWA 1225

Fabrication and Heat Treatment

Machinability

Grade 6Al 2Sn 4Zr 6Mo titanium alloy can be machined using slow speeds, right quantity of coolant flow and high feed rates. High-speed tools should be used for tooling this alloy and the recommended tool types are tungsten carbide designations C1-C4 or cobalt based.

Forming

Grade 6Al 2Sn 4Zr 6Mo titanium alloy can be hot or cold formed.

Welding

Weldabilty of grade 6Al 2Sn 4Zr 6Mo titanium alloy is rated as limited.

Heat Treatment

The material can be solution treated at 843-913°C (1550-1675°F), and then air, oil or water quenched.

Annealing

For annealing grade 6Al 2Sn 4Zr 6Mo titanium alloy, the following process is used. Triplex-Beta minus 14°C (25°F), 1-2 h, air cool; 801-857°C (1490-1595°F), 1-4 h, air cool; 593°C (1100°F), 4-8 h, and air cool. To perform stress relief, heat the material to 482-649°C (900-1200°F), hold for 1-4 h and air cool.

Forging

In case of bar and billet, forge at 843-927°C (1565-1725°F)

Hot Working

Hot working enhances the overall ductility of the material.

Cold Working

Cold working features of this material is same as that of austenitic stainless steel. Post-work annealing is recommended to re-attain favorable performance properties.

Aging

Aging of grade 6Al 2Sn 4Zr 6Mo titanium alloy can be performed by holding the material at 579-607°C (1075-1125°F) for 8 h and then air cooling.

Applications

Grade 6Al 2Sn 4Zr 6Mo titanium alloy is used in the following application areas:

  • Intermediate-temperature jet engine components
  • Blades, discs, spacers and seals
  • In gas turbine discs and impellers
  • In deep sour well components.

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