Grade Ti 7AI 4Mo Alloy (UNS R56740)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
     Machinability
     Forming
     Hot Working
     Cold Working
Applications

Introduction

Titanium alloys possess excellent corrosion resistance, very high tensile strength and toughness. Another added advantage is that they are light weight.

Grade Ti 7AI 4Mo alloy is an alpha-beta alloy that has high strength and good creep resistance.The following sections will discuss in detail about grade Ti 7AI 4Mo alloy.

Chemical Composition

The chemical composition of grade Ti 7AI 4Mo alloy is outlined in the following table.

Element Content (%)
Titanium, Ti 89
Aluminum, Al 7
Molybdenum, Mo 4
Iron, Fe ≤ 0.30
Oxygen, O ≤ 0.20
Carbon, C ≤ 0.10
Nitrogen, N ≤ 0.050
Hydrogen, H ≤ 0.013

Physical Properties

The physical properties of grade Ti 7AI 4Mo alloy are tabulated below.

Properties Metric Imperial
Density 4.48 g/cm3 0.162 lb/in3
Melting point ≤ 1650°C ≤ 3000°F

Mechanical Properties

The following table shows mechanical properties of grade Ti 7AI 4Mo alloy.

Properties Metric Imperial
Tensile strength 1030 MPa 149000 psi
Yield strength 970 MPa 141000 psi
Poisson’s ratio 0.32 0.32
Elastic modulus 111 GPa 16100 ksi
Shear modulus 42 GPa 6090 ksi
Hardness, Brinell 318 318
Hardness, Knoop 346 346
Hardness, Rockwell C 34 34
Hardness, Vickers 333 333

Thermal Properties

The thermal properties of grade Ti 7AI 4Mo alloy are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@0.000-100°C/32-212°F) 9 µm/m°C 5 µin/in°F
Thermal conductivity 6.10 W/mK 42.3 BTU in/hr.ft².°F

Fabrication and Heat Treatment

Machinability

Grade Ti 7AI 4Mo alloy is hard to machine but can be successfully done using slow speeds, high coolant flow, and high feed rates. Tooling should be performed using tungsten carbide designations C1-C4 or cobalt type high speed tools.

Forming

Grade Ti 7AI 4Mo alloy can be hot or cold formed using power brake, hydropress, stretch or drop hammer methods.

Hot Working

Hot working enhances the overall ductility of the material.

Cold Working

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

Applications

Grade Ti 7AI 4Mo alloy is used in the following application areas:

  • Structural components in aerospace
  • Jet engine disks
  • Compressor blades and spacers
  • Sonic horns

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