Grade 6Al 6V 2Sn Titanium Alloy (UNS 56620)

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 alloys are divided into three types, namely, alpha-phase, beta-phase, and alpha-beta-phase. Alpha-phase titanium alloys are known to be stronger and less ductile. Beta-phase titanium alloys are more ductile. The third category of alpha-beta-phase titanium alloys strikes a balance between the other two categories with its mechanical properties.

Grade 6Al 6V 2Sn titanium alloy is an alpha-beta alloy that can be heat treated to higher strengths and heavier section sizes than titanium alloy 6AL-4V. This alloy possesses excellent strength, good corrosion resistance, and medium fabricability.

The following sections will discuss in detail about grade 6Al 6V 2Sn titanium alloy.

Chemical Composition

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

Element Content (%)
Titanium, Ti 82.89 - 87.8
Aluminum, Al 5-6
Vanadium, V 5-6
Tin, Sn 1.5 - 2.5
Iron, Fe 0.35 - 1
Copper, Cu 0.35 - 1
Oxygen, O ≤ 0.20
Carbon, C ≤ 0.050
Nitrogen, N ≤ 0.040
Hydrogen, H ≤ 0.015
Other, each ≤ 0.10
Other, total ≤ 0.30

Physical Properties

The physical properties of grade 6Al 6V 2Sn titanium alloy are tabulated below.

Properties Metric Imperial
Density 4.54 g/cm3 0.164 lb/in3
Melting point 1627 - 1649°C 2961 - 3000°F

Mechanical Properties

The following table shows mechanical properties of grade 6Al 6V 2Sn titanium alloy.

Properties Metric Imperial
Tensile strength 1280 MPa 186000 psi
Yield strength 1210 MPa 175000 psi
Poisson’s ratio 0.32 0.32
Elastic modulus 117 GPa 117 GPa
Shear modulus 45 GPa 6530 ksi
Elongation at break 10 % 10 %
Hardness, Brinell 411 411
Hardness, Knoop 450 450
Hardness, Rockwell C 44 44
Hardness, Vickers 430 430

Thermal Properties

The thermal properties of grade 6Al 6V 2Sn titanium alloy are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@20-100°C/68-212°F) 8.60 µm/m°C 4.78 µin/in°F
Thermal conductivity 6.60 W/mK 45.8 BTU in/hr.ft².°F

Other Designations

Equivalent materials to grade 6Al 6V 2Sn titanium alloy are as follows:

AMS 4918 AMS 4936 AMS 4971 AMS 4978
DMS 1870 DMS 1887 MIL F-83142 MIL T-81556
MIL T-9047 AMS 4979 MIL T-9046  

Fabrication and Heat Treatment

Machinability

Grade 6Al 6V 2Sn 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 6V 2Sn titanium alloy can be hot or cold formed. Forming techniques include hydropress, stretch or drop-hammer.

Welding

Welding of grade 6Al 6V 2Sn titanium alloy should be performed at beta transus (F +/- 25) 1735.

Heat Treatment

The material can be solution treated at 843-913°C (1550-1675°F) for 1 h, and then water cooled.

Annealing

For annealing grade 6Al 6V 2Sn titanium alloy, the material has to be held at 704°C (1300°F) for 2 h, and air cooled. If stress relieving is required, the material has to be held at 593°C (1100°F) for 2 h and air cooled.

Forging

Rough forging can be performed at 932°C (1710°F), and completed at 843°C (1550°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 6V 2Sn titanium alloy can be performed at 538-621°C (1000-1150°F) for 4-8 h and air cooled.

Applications

Grade 6Al 6V 2Sn titanium alloy is chiefly used in plate and forging applications for rocket cases, airframe sections, and ordnance parts.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Submit