The importance of titanium, or any other material for that matter, can be no greater
than the use to which it is put. In selecting titanium and its alloys for any
particular application, the engineer must consider both the economic and
technological justification for the utilization of this metal in specific
Even at the current premium price of titanium, many items for civilian and military
uses are justifiable in titanium. In many items the initial high cost of the
material is compensated for either by the advantages of weight reduction due
to the low density of the metal or by the increased life of the component due
to high corrosion resistance of the metal.
Since it is generally anticipated that the price of this metal will no doubt decrease
with increasing production and improvement in processing, it is not intended here
to treat fully, by any means, the economic considerations. Rather, it is intended
to consider the technological justification required in utilization of titanium
for the various components desired.
Two basic considerations must be appreciated: one stemming from the specifications
of the component and the other from design. Specifications usually require the
meeting of certain mechanical properties desirable in the end item. Such properties
may include one or several of the following: yield strength, tensile strength,
elongation, reduction in area, bend ductility, impact strength, hardness, fatigue
strength, creep, and elevated temperature properties.
Upon selection of a material by the materials engineer which meets the basic minimum
requirements specified, it then becomes the product engineer’s responsibility to
consider the fabrication problems which are peculiar to the design. Here the
capabilities of the materials to undergo the required fabrication methods to produce
the desired end-product must be evaluated.
Selection of Materials
Good purity unalloyed titanium is cast, formed, joined, and machined with relative
ease as compared with the alloy grades. In view of this, wherever the properties
desired in the end item can be satisfied by the employment of unalloyed titanium
grades, the selection should be made on this basis.
There is considerable variation in the properties offered by the unalloyed grades
of commercial producers. Even with the same producer, variation has been noticed
among heats of the same grade. As melting techniques are continually improved,
greater homogeneity can be expected. Significant improvement has been made in this
direction in the last few decades.
To insure the ease of fabricability, consistent with that of unalloyed titanium,
the materials engineer should acquaint himself with the contaminating interstitial
content of the metal in order that the material used will not exceed the maximum
tolerable limits of these elements.
Where higher strengths are required or where special applications necessitate
specific alloying elements, an alloy grade of titanium must be considered. Increasing
the alloy content will increase, to a point, the strength, usually with an
accompanying loss of ductility. This lowering of ductility indicates a lessening
in the ease of formability.
In selecting an alloy, therefore, it is generally desirable to choose that alloy
which offers the maximum formability for the strength level desired whether the
strength requirement be tensile, fatigue, or creep strength. Where high strength
and hardness are prime requirements, it may be desirable to select an alloy which
exhibits a good response to heat-treatment. In this way the material can be
heat-treated to obtain maximum ductility, rendering ease of formability.
Subsequently, formed products can be heat-treated to the required strength or
Manganese and chromium binaries have generally not been found desirable as casting
materials. Aluminum additions to these binary alloys improve the quality of the
casting produced. Multicomponent alloys containing aluminum as the major addition
have been found to offer better elevated temperature properties. It appears now
that aluminum ternary alloys with either manganese, chromium, or vanadium will
become the most useful titanium materials.
As a general guideline, employ unalloyed titanium wherever possible. Where alloy
grades are required, the material which offers the best formability at the required
strength level should be selected. Where possible, heat-treatment should be employed
either to obtain the best ductility for ease of forming or to obtain maximum strength
in the end product.
For adequate commercial utilization of titanium, it is necessary that the particular
component be justifiable both from the standpoint of economics and technology.
Designers and engineers have already found wide utilization for this lightweight,
high strength, corrosion resistant metal encompassing many diversified
Aeronautical design engineers find in titanium and its alloys a metal whose light
weight and high strength, particularly at elevated temperatures, render it a highly
desirable material in aircraft construction.
Titanium is finding increasingly greater preference over aluminum and stainless
steel in aircraft utilization. Aluminum loses its strength rapidly at elevated
temperatures. Titanium, on the other hand, has a distinct high temperature strength
advantage at temperatures up to 800°F (426°C); such elevated temperatures
occur at high speeds due to aerodynamic heating.
The advantage of titanium substitution for steel in aircraft stems from its
accompanying weight reduction with no loss in strength. The overall reduction of
weight and the increased elevated temperature performance allowed by the utilization
of titanium permit increased pay loads, as well as an increase in range and
maneuverability. In view of this, effort is being applied to utilize this metal in
aircraft construction from engines and airframes to skins and fasteners.
In jet engines titanium is chiefly used in compressor blades, turbine disks, and
many other forged parts. The materials replaced in these applications are stainless
and heat-treated alloy steels.
The corrosion resistance of titanium and its alloys makes this metal a prime
consideration for use in marine environments. The Navy is thoroughly investigating
titanium’s corrosion resistance to stack gases, steam, and oil as well as sea water.
Of almost equal importance in these applications is the high strength-weight
The light weight of the metal, in conjunction with the corrosion resistance, offers
in naval vessels improved maneuverability, increased range, less preventative
maintenance, and reduced power cost.
Naval investigations cover applications such as wet exhaust mufflers for submarine
diesel engines, meter disks, and thin wall condenser and heat exchanger tubes. In
the case of the exhaust mufflers, titanium may offer greater service life than is
offered by most materials. Titanium as applied to meter disks should offer improved
service in salt water, gasoline, or oil where present materials are inferior in one
or more of these environments.
Also being investigated for possible utilization are heat exchanger tubes which must
be resistant to corrosion by sea water on the outer walls and at the same time give
equal resistance to exhaust condensate on the inner walls. Items such as antennas
and exposed radar components, which require resistance to stack gases as well as
to marine atmospheres, are also being considered.
Perhaps the largest potential military consumer of titanium products will be the
Army Ordnance Corps. Much of the sponsorship of the early research and development
on titanium stemmed from Army Ordnance. Many prototype components are currently being
investigated by ordnance engineers. However, few production applications of the metal
are standardized. The vast amount of development work and the few production items
are indicative of the great interest shown by Ordnance and the limits imposed on
production items by high cost.
Early investigation of titanium and its alloys indicated that the metal had promising
armor plate applications. Tests on early titanium armor permitted a 25% weight saving
by substitution of titanium for steel armor with equal resistance to ballistic
attack. This was accomplished by replacing 1/2-inch armor plate with 5/8-inch
titanium armor. With improved alloys an inch-for-inch substitution does not seem
unreasonable. This would allow up to a 44% weight saving.
Employment of titanium on a production basis would allow greater maneuverability,
wider traveling range, and greater useful life. For airborne transportation, the
advantage of lightweight vehicles fabricated from titanium is obvious. The first
standard application of titanium by Ordnance has been in the manufacture of a
titanium alloy gas piston for use in some automatic weapons.
Many of the advantages indicated for armored vehicles also apply to the
Decreased fuel consumption or increased pay load and better fatigue strength in
piston rods and transmissions are possible advantages offered by the substitution
of titanium for materials used in transportation industries today. In railway
equipment applications, dead weight considerations are of utmost importance. Where
the overall weight of a railway car can be substantially decreased by the application
of titanium, it follows that the horsepower required to pull this lighter car will
be markedly reduced, as will be the size required for the journals and the journal
Another application where load is a major consideration is in trailer trucks. Here,
also, increased pay load can be achieved by the replacement of steel with titanium
in such items as axles and wheels.
In the chemical industry the corrosion resistance of a metal plays the most important
part. However, light weight and strength are desirable. The advantages described
there indicate utilization in many industries once the price is reduced to a
Production equipment which facilitates transportation of corrosive materials such
as acid, alkali, and inorganic salts are logical applications for titanium.
Manufacturing equipment such as vats, reflux towers, filters, and pressure vessels
give additional opportunities for the utilization of titanium.
Titanium tubing can improve the performance of heating coils in laboratory
autoclaves and heat exchangers.
The food, petroleum and electrical industries, as well as the field of surgical
instruments and surgery itself, are representative of the diverse fields in which
application of titanium has been found desirable.
Food processing tables as well as steam tables, where titanium has been substitute
for stainless steel, have been evaluated and results indicate superior performance
and potential utilization.
In oil and gas drilling applications, the corrosion problem is serious, and titanium
substitution will permit less frequent replacement of corroding underground shafts.
In catalytic processing applications and fuel pipe lines, titanium’s high temperature
properties and corrosion resistance are desirable. Increased utilization is again
dependent upon increased supply of the metal at reduced prices.
The electrical industry is equally desirous of taking advantage of the metal’s
high strength-lightweight ratio and, in addition, its high electrical resistance and
nonmagnetic properties for utilization as cable armor material.
Most industries employ fasteners in some form or other, and the production of
titanium fasteners on a commercial basis has not been lacking over the conventional