4.6 Titanium Alloys

Titanium alloys are selected for applications requiring high strength, low weight, high operating temperature or high corrosion resistance. Specific strength is high compared with steel. Densities are approximately 55% those of steel and 60% greater than aluminum alloys. The properties and cost of titanium alloys make them the choice in applications where a premium can be justified for high performance, such as aerospace, chemical processing and prosthetic devices.

The designation system indicates the type and amount of the major alloying constituents. For example Ti-6Al-4V contains 6% aluminum and 4% vanadium.

As with other forging alloys, the mechanical properties of titanium alloys are affected by forging and thermal processes as well as alloy content. However, when die filling is optimized, there is only a moderate change in tensile properties with grain direction, and comparable strengths and ductilities are obtainable in both thick and thin sections. The processing of titanium alloys through the forging and subsequent thermal processes is a highly developed technology.

Titanium alloys are more difficult to forge than most steels. The metallurgical behavior of the alloys imposes some limitations and controls on forging operations, and influences all of the steps in the manufacturing operation. Special care is exercised throughout all processing steps to minimize surface contamination by oxygen, carbon or nitrogen. These contaminants can severely impair ductility, impact toughness, and the overall quality of a titanium forging if left on the surfaces.

Hydrogen can also be absorbed by titanium alloys and can cause problems if levels exceed specified amounts. Hydrogen absorption, unlike that of oxygen, is not always confined to the surface.

Titanium alloys can be forged to precision tolerances. However, excessive die wear, the need for expensive tooling, and problems with microstructure control and contamination may make the cost of close tolerance (not machined) forging prohibitive except for simple shapes like compressor fan blades for turbo-fan engines.

Close tolerance forgings in moderately large sizes are currently being developed using hot die and isothermal forging techniques. Hot die and conventional forging of the Ti-10V-2Fe-3Al alloy, which has a relatively low forging temperature, has been demonstrated to be very successful with dies made from heat resistant alloys and heat treated to over 650°C (1200°F).

Glass coatings are commonly used to protect the titanium forgings from excessive oxidation and to provide some lubrication as well as serving as a release compound to prevent die galling (pressure welding).

There are three basic types of titanium forging alloys: alpha alloys, alpha-beta alloys, and beta alloys. The alpha alloys are designed for resistance to creep at elevated temperatures, exceeding 535°C (1000°F) in some cases. They are not heat treatable in the conventional sense but they are annealed after forging to relieve stresses. The microstructure of alpha is essentially all alpha phase.

The alpha-beta alloys are those that include a mixture of alpha and transformed beta microstructures at room temperatures. They are heat treatable to very high strengths with a solution treatment and an age cycle. The widely used Ti-6Al-4V alloy is also the most common forging alloy.

The beta alloys are those containing sufficient alloy content to retain the beta phase to room temperature. Alloys include the more common Ti-10V2Fe3Al as well as some more highly alloyed grades such as Ti-13V-11Cr-3Al. These alloys are treatable to high strengths exceeding those achievable with Ti-6Al-4V. Ti-13V-11Cr-3Al has been largely superseded by the 10-2-3 grade for forgings.

In all three groups, the forging practices have a profound influence on the resulting properties. Forging suppliers should be contacted for their experiences in forging and heat treating these families of titanium alloys. Commonly forged titanium alloys are:

Unalloyed Grades
            ASTM Grade ASTM-B-381
  ASTM Grade 2 ASTM-B-381
  ASTM Grade 3 ASTM-B-381
  ASTM Grade 4 ASTM-B-381
  ASTM Grade 7 ASTM-B-381
Alpha and Near-Alpha Alloys
  Ti-5Al-2.5Sn AMS 4966
  Ti-8Al-1Mo-1V AMS 4973
  Ti-6Al-2Sn-4Zr-2Mo AMS 4976
  Ti-5Al-3Sn-3Zr-1Nb (IMI 829)
  Ti-5Al-4Sn-4Zr-1Nb (IMI 834)
  Ti-6Al-3Sn-4Zr-0.5Si (Ti-1100)
Alpha-Beta Alloys
  Ti-6Al-4V AMS 4928
  Ti-6Al-4V ELI AMS 4930
  Ti-6Al-6V-2Sn AMS 4971
  Ti-6Al-2Sn-4Zr-6Mo AMS 4981
Beta and Near-Beta Alloys
  Ti-10V2Fe3Al AMS 4983
  Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti-17)

The specifications listed are one of many such that might be applied to each grade. Details of properties obtainable from these and many other titanium alloys are presented in ASM Metals Handbook.


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Titanium alloys are selected for applications requiring high strength, low weight, high operating temperature or high corrosion resistance. Specific strength is high compared with steel. Densities are approximately 55% those of steel and 60% greater than aluminum alloys. The properties and cost of titanium alloys make them the choice in applications where a premium can be justified for high performance, such as aerospace, chemical processing and prosthetic devices.

The designation system indicates the type and amount of the major alloying constituents. For example Ti-6Al-4V contains 6% aluminum and 4% vanadium.

As with other forging alloys, the mechanical properties of titanium alloys are affected by forging and thermal processes as well as alloy content. However, when die filling is optimized, there is only a moderate change in tensile properties with grain direction, and comparable strengths and ductilities are obtainable in both thick and thin sections. The processing of titanium alloys through the forging and subsequent thermal processes is a highly developed technology.

Titanium alloys are more difficult to forge than most steels. The metallurgical behavior of the alloys imposes some limitations and controls on forging operations, and influences all of the steps in the manufacturing operation. Special care is exercised throughout all processing steps to minimize surface contamination by oxygen, carbon or nitrogen. These contaminants can severely impair ductility, impact toughness, and the overall quality of a titanium forging if left on the surfaces.

Hydrogen can also be absorbed by titanium alloys and can cause problems if levels exceed specified amounts. Hydrogen absorption, unlike that of oxygen, is not always confined to the surface.

Titanium alloys can be forged to precision tolerances. However, excessive die wear, the need for expensive tooling, and problems with microstructure control and contamination may make the cost of close tolerance (not machined) forging prohibitive except for simple shapes like compressor fan blades for turbo-fan engines.

Close tolerance forgings in moderately large sizes are currently being developed using hot die and isothermal forging techniques. Hot die and conventional forging of the Ti-10V-2Fe-3Al alloy, which has a relatively low forging temperature, has been demonstrated to be very successful with dies made from heat resistant alloys and heat treated to over 650°C (1200°F).

Glass coatings are commonly used to protect the titanium forgings from excessive oxidation and to provide some lubrication as well as serving as a release compound to prevent die galling (pressure welding).

There are three basic types of titanium forging alloys: alpha alloys, alpha-beta alloys, and beta alloys. The alpha alloys are designed for resistance to creep at elevated temperatures, exceeding 535°C (1000°F) in some cases. They are not heat treatable in the conventional sense but they are annealed after forging to relieve stresses. The microstructure of alpha is essentially all alpha phase.

The alpha-beta alloys are those that include a mixture of alpha and transformed beta microstructures at room temperatures. They are heat treatable to very high strengths with a solution treatment and an age cycle. The widely used Ti-6Al-4V alloy is also the most common forging alloy.

The beta alloys are those containing sufficient alloy content to retain the beta phase to room temperature. Alloys include the more common Ti-10V2Fe3Al as well as some more highly alloyed grades such as Ti-13V-11Cr-3Al. These alloys are treatable to high strengths exceeding those achievable with Ti-6Al-4V. Ti-13V-11Cr-3Al has been largely superseded by the 10-2-3 grade for forgings.

In all three groups, the forging practices have a profound influence on the resulting properties. Forging suppliers should be contacted for their experiences in forging and heat treating these families of titanium alloys. Commonly forged titanium alloys are:

Unalloyed Grades
            ASTM Grade ASTM-B-381
  ASTM Grade 2 ASTM-B-381
  ASTM Grade 3 ASTM-B-381
  ASTM Grade 4 ASTM-B-381
  ASTM Grade 7 ASTM-B-381
Alpha and Near-Alpha Alloys
  Ti-5Al-2.5Sn AMS 4966
  Ti-8Al-1Mo-1V AMS 4973
  Ti-6Al-2Sn-4Zr-2Mo AMS 4976
  Ti-5Al-3Sn-3Zr-1Nb (IMI 829)
  Ti-5Al-4Sn-4Zr-1Nb (IMI 834)
  Ti-6Al-3Sn-4Zr-0.5Si (Ti-1100)
Alpha-Beta Alloys
  Ti-6Al-4V AMS 4928
  Ti-6Al-4V ELI AMS 4930
  Ti-6Al-6V-2Sn AMS 4971
  Ti-6Al-2Sn-4Zr-6Mo AMS 4981
Beta and Near-Beta Alloys
  Ti-10V2Fe3Al AMS 4983
  Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti-17)

The specifications listed are one of many such that might be applied to each grade. Details of properties obtainable from these and many other titanium alloys are presented in ASM Metals Handbook.


Return to Table of Contents

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Titanium alloys are selected for applications requiring high strength, low weight, high operating temperature or high corrosion resistance. Specific strength is high compared with steel. Densities are approximately 55% those of steel and 60% greater than aluminum alloys. The properties and cost of titanium alloys make them the choice in applications where a premium can be justified for high performance, such as aerospace, chemical processing and prosthetic devices.

The designation system indicates the type and amount of the major alloying constituents. For example Ti-6Al-4V contains 6% aluminum and 4% vanadium.

As with other forging alloys, the mechanical properties of titanium alloys are affected by forging and thermal processes as well as alloy content. However, when die filling is optimized, there is only a moderate change in tensile properties with grain direction, and comparable strengths and ductilities are obtainable in both thick and thin sections. The processing of titanium alloys through the forging and subsequent thermal processes is a highly developed technology.

Titanium alloys are more difficult to forge than most steels. The metallurgical behavior of the alloys imposes some limitations and controls on forging operations, and influences all of the steps in the manufacturing operation. Special care is exercised throughout all processing steps to minimize surface contamination by oxygen, carbon or nitrogen. These contaminants can severely impair ductility, impact toughness, and the overall quality of a titanium forging if left on the surfaces.

Hydrogen can also be absorbed by titanium alloys and can cause problems if levels exceed specified amounts. Hydrogen absorption, unlike that of oxygen, is not always confined to the surface.

Titanium alloys can be forged to precision tolerances. However, excessive die wear, the need for expensive tooling, and problems with microstructure control and contamination may make the cost of close tolerance (not machined) forging prohibitive except for simple shapes like compressor fan blades for turbo-fan engines.

Close tolerance forgings in moderately large sizes are currently being developed using hot die and isothermal forging techniques. Hot die and conventional forging of the Ti-10V-2Fe-3Al alloy, which has a relatively low forging temperature, has been demonstrated to be very successful with dies made from heat resistant alloys and heat treated to over 650°C (1200°F).

Glass coatings are commonly used to protect the titanium forgings from excessive oxidation and to provide some lubrication as well as serving as a release compound to prevent die galling (pressure welding).

There are three basic types of titanium forging alloys: alpha alloys, alpha-beta alloys, and beta alloys. The alpha alloys are designed for resistance to creep at elevated temperatures, exceeding 535°C (1000°F) in some cases. They are not heat treatable in the conventional sense but they are annealed after forging to relieve stresses. The microstructure of alpha is essentially all alpha phase.

The alpha-beta alloys are those that include a mixture of alpha and transformed beta microstructures at room temperatures. They are heat treatable to very high strengths with a solution treatment and an age cycle. The widely used Ti-6Al-4V alloy is also the most common forging alloy.

The beta alloys are those containing sufficient alloy content to retain the beta phase to room temperature. Alloys include the more common Ti-10V2Fe3Al as well as some more highly alloyed grades such as Ti-13V-11Cr-3Al. These alloys are treatable to high strengths exceeding those achievable with Ti-6Al-4V. Ti-13V-11Cr-3Al has been largely superseded by the 10-2-3 grade for forgings.

In all three groups, the forging practices have a profound influence on the resulting properties. Forging suppliers should be contacted for their experiences in forging and heat treating these families of titanium alloys. Commonly forged titanium alloys are:

Unalloyed Grades
            ASTM Grade ASTM-B-381
  ASTM Grade 2 ASTM-B-381
  ASTM Grade 3 ASTM-B-381
  ASTM Grade 4 ASTM-B-381
  ASTM Grade 7 ASTM-B-381
Alpha and Near-Alpha Alloys
  Ti-5Al-2.5Sn AMS 4966
  Ti-8Al-1Mo-1V AMS 4973
  Ti-6Al-2Sn-4Zr-2Mo AMS 4976
  Ti-5Al-3Sn-3Zr-1Nb (IMI 829)
  Ti-5Al-4Sn-4Zr-1Nb (IMI 834)
  Ti-6Al-3Sn-4Zr-0.5Si (Ti-1100)
Alpha-Beta Alloys
  Ti-6Al-4V AMS 4928
  Ti-6Al-4V ELI AMS 4930
  Ti-6Al-6V-2Sn AMS 4971
  Ti-6Al-2Sn-4Zr-6Mo AMS 4981
Beta and Near-Beta Alloys
  Ti-10V2Fe3Al AMS 4983
  Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti-17)

The specifications listed are one of many such that might be applied to each grade. Details of properties obtainable from these and many other titanium alloys are presented in ASM Metals Handbook.


Return to Table of Contents

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