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A vast variety of industries today are looking for innovative ways to maximize their profit. These innovative ways are expected at a reduced cost of production, reduce their products’ weight, and lower their overall energy consumption. Consequently, lightweight metal including titanium and aluminum is considered increasingly to steel. Therefore, to obtain the perfect material solution in light of this, it is important to have a glimpse of information on their strength. This article provides the most important information by drawing a comparison between each metal using varieties of characteristics.
In the manufacturing space, when you think of a dream team of material properties for parts, strength and lightweight come to mind. In essence, titanium and aluminum naturally come to the mind of designers in this case. Interestingly, both titanium and aluminum tick off other important boxes such as excellent tolerance for heat and resistance to corrosion. To help obtain the perfect choice for your project, we will be using a variety of properties to draw a comparison between aluminum and titanium. They include:
In a bid to differentiate titanium from aluminum, the elemental composition is very important. This is because some components may not be required because of their reactivity with the environment or because of added characteristics they may add to the metal at large. Examples of such characteristics may include corrosion resistance, weight, and many more. In comparison, titanium is known to contain a variety of elements including nitrogen, hydrogen, oxygen, carbon, iron, and nickel. With titanium as the major elemental composition, other constituents may vary in composition between 0.013 and 0.5%.
On the other hand, aluminum is composed of a variety of constituents including aluminum as its major composition, silicon, zinc, magnesium, manganese, copper, iron, titanium, chromium, zirconium, and many more.
Corrosion resistance is another property that can be used to draw comparisons between titanium and aluminum. Both titanium and aluminum feature excellent corrosion resistance properties. However, one is more resistant than the other and as a result, it is more preferable when corrosion resistance is one of the major considerations in a project.
Titanium is inert and as result, it is highly corrosion-resistant. Because of its inert nature, titanium is the most biocompatible metal with impressive application in the medical industry. This application may be found in the production of surgical applications while Ti 6-4 alloys hold up well in a salty environment with great application in the marine industry. On the other hand, alloys of aluminum form a layer of oxides that makes the material non-reactive with corrosive elements. However, the corrosion of such alloy now depends on the aqueous/atmospheric conditions such as temperature, airborne chemicals, and chemical composition.
Electrical conductivity is the ability of a material to allow the flow of electrons due to a drop in potential. To determine the electrical conductivity of a material, copper is used as the standard for rating electrical conductivity.
When titanium is compared with copper’s conductivity it exhibited about 3.1% of copper’s conductivity. As a result, it follows that titanium is a good conductor of electricity and it cannot be used where good conductivity is a prime factor. While titanium is not a good conductor, it can be used as a good resistor. On the other hand aluminum exhibit 64% of copper’s conductivity. This means that in a situation where electrical conductivity is required, then aluminum is preferred over titanium.
The thermal conductivity of a material is its ability to transfer or conduct heat. For a material to be a good radiator it must have a high rate of conductivity while a material with low thermal conductivity is a good insulator. This phenomenon is referred to as the time rate of transfer by conduction through the unit thickness, across a unit of material for a unit temperature gradient.
In comparison, aluminum has a high thermal conductivity of 1460 BTU-in/hr-ft²-°F (210 W/m-K) compared to titanium 118 BTU-in/hr-ft²-°Fm (17.0 W/m-K). This is why it is given preferential treatment when it involves applications including heat exchangers, cookware, and heatsinks.
A metal’s melting temperature known as the melting point is the temperature at which such metal begins to transit from a solid phase into a liquid phase. At this temperature, the solid phase of the metal and the liquid phase of such metal exist in equilibrium. Once the material reaches this temperature level, it can be easily formed and it can be used for thermal applications.
In comparison, titanium has a higher melting point of 1650 – 1670 °C (3000 – 3040 °F) which is why it is used as a refractory metal. On the other hand, aluminum exhibit a lower melting point compared to titanium 660.37 °C (1220.7 °F). Therefore, in a heat resistance application titanium is more applicable.
A metal’s hardness is its comparative value which helps to describe its response to etching, denting, deformation, or scratching along its surface. This can be mostly done with a tool called an indenter machine. As a result, the indenter machine or tools brings out the value of the metal to determine the strength of such metal. While the Brinell’s hardness of titanium 70 HB is greater than pure aluminum 15 HB, some alloys of aluminum exhibited higher hardness than titanium. Examples include AA7075 temper T7 & T6, AA6082 temper T5 & T6, and more.
On the other hand, titanium deforms easily when scratched or indented. This can be corrected because titanium forms an exceptionally hard surface by forming an oxide layer to form a titanium oxide layer that resists most penetration forces. In an application where hardness is one of the major requirements, then, titanium is the best choice.
In measurement, titanium and aluminum are both light but for specific reasons. In terms of comparisons aluminum density (2712 kg/m3) is lower than the density of titanium (4500 kg/m3). Aluminum’s density is considerably lighter, although titanium is about two-thirds heavier than aluminum. This means that users of either metal will need less titanium. Only a fraction of titanium is needed to obtain the physical strength of aluminum. This is why titanium is used in aircraft jet engines and space crafts. It is known that its lightweight and strength reduce the cost of fuel.
Therefore, depending on application, titanium or aluminum are either a perfect choice. For example, in a situation where the strength to weight ratio is a thing of concern, titanium is used and where lightweight is only needed, then aluminum is used.
In order to compare the price of titanium and aluminum, a basic piece of a quarter-inch round, on foot long of both metals are compared together. When compared, the aluminum rod cost less than the titanium rod, therefore, this shows that there is a cost difference between both metals. In addition to cost, more from the outset, titanium is very difficult to work with compared to aluminum and as a result, it makes the manufacturing process more expensive.
Another thing is that the grinding, bending, and welding of titanium is delicate to perform as it requires excellent professionalism. On the other hand, aluminum is easy to work with, so it is less expensive and cost-effective for most applications.
The durability of material remains its ability to be functional without the use of excessive repairs or maintenance when the material is acted upon by challenges of normal operations. No doubt, both titanium and aluminum are durable and can be used for a longer period. Titanium is very rigid and durable and its frames can last for decades without any sign of wear and tear when is properly cared for.
Also, titanium provides reasonable flex to help deaden the vibration of the road and can feel whippy when exposed to a heavy load like touring panniers. On the other hand, aluminum also proves its durability in extreme transportation environments especially when strength, safety, and durability are critical.
Machinability is a comparative score of a metal to determine how well they react to machining stress including stamping, turning, milling, and many more. The machinability score of such metal is used to determine the type of machining method to be used. Interestingly, CNC turning and milling are time-tested methods of producing titanium and aluminum parts. They can be produced in less than a day with adherence to tolerances of +/-0.005 inches (0.13mm). When the production of parts is required quickly, aluminum is a perfect choice since it is cost-effective with high quality.
However, machining may be somewhat limited when it comes o geometrics because extremely complex designs require a different solution irrespective of the chosen material. Another factor to consider when choosing material for machining is machining waste. Hence, milling away excess material is fine for inexpensive aluminum but not ideal for costly titanium. As a result, manufacturers often prefer to produce prototypes using aluminum, then later switch to titanium for parts production.
In terms of formability, aluminum is more formable than titanium. All forms of aluminum are readily fabricated into finished parts using a wide variety of methods. Aluminum can be cut using many processes depending on the form and shape of the material.
It can also be cut with different types of saw while laser, plasma, or water jet produce finished sizes that can have intricate forms and shapes. While titanium is formable and not as formable as aluminum, aluminum is the perfect choice when formability is critical for the success of a project.
When it comes to welding which is the ability of a material to welded, both metals can be welded and they can also be welded or joined together. However, either titanium or aluminum is more weldable than the other.
In comparison, titanium welding requires more professionalism as it is always regarded as a specialty within a specialty. On the other hand, aluminum is highly weldable and it is used for a wide range of applications. So, if weldability is one of the major requirements for material selection, aluminum will be a perfect choice.
The yield strength of a material is the maximum stress at which a material begins to permanently deform. This property can be used to differentiate titanium from aluminum. When compared, it is evident that commercially pure titanium (> 99% Ti) is a low-to-moderate strength metal that is not well suited for structures or engines of aircraft. It exhibits the yield strength of high-purity titanium ranging from 170 MPa up o about 480 MPa which is regarded low for heavily loaded aerostructures.
On the other hand, pure aluminum exhibits a yield strength ranging from 7 MPa up to about 11 MPa while alloys of aluminum exhibit a yield strength ranging from 200 MPa up to 600 MPa.
The tensile strength of a metal is the highest (ultimate) on the curve of engineering stress-strain. This is termed the highest stress that may be sustained when a material is exposed to tension. The ultimate tensile strength at an ambient temperature of titanium and its alloys ranges from 230 MPa for the softest grade of commercially pure titanium to 1400 MPa for high strength alloys.
Also, the proof strengths of titanium vary from around 170 MPa to 1100 MPa based on grade and condition. On the other hand, alloys of aluminum exhibit far greater strength than pure aluminum. Pure aluminum exhibit a tensile strength of 90 MPa and can be increased to over 690 MPa for some heat-treatable alloys of aluminum.
The resistant properties of metal against the shear load before the component fail in shear is referred to as shear strength. This majorly occurs normally on a plane in a parallel direction to the direction of the force acting. Titanium shear stress is rated between 40 to 45 MPa depending on alloy properties while the shear strength of aluminum is rated between 85 to about 435 MPa. Therefore, if shear strength constitutes one of the major reasons for material selection, some grades of aluminum may be preferable over titanium.
In differentiating or telling a difference between titanium and aluminum, the color of the material is important. This will help to recognize the material to avoid using the wrong metal for your project. To differentiate, aluminum has a silvery-white appearance that varies in color from silver to dull grey depending on the material’s surface. This appearance is normally towards silver for smooth surfaces. On the other hand, titanium has a silver appearance which is darker when viewed under the light.
Titanium and aluminum are both used in a vast varieties of applications. These applicable constitutes possible way to differentiate both metals from one another. The application of titanium and alumium is as stated below:
Titanium is applicable in various ways out of which include as an alloying element in steel, reduces grain size, and as a deoxidizer and in stainless steel to reduce carbon content. It is found almost everywhere in the industrial space including:
Aluminum is generally used in different industries due to the impressive corrosion resistance it offers. Aluminum exists in varieties of alloys which markedly improves its mechanical properties, especially when tempered. For example, the most common aluminum alloy in form of foils and beverage cans arranges from 92% to about 99% aluminum. The major application of aluminum include:
We have been able to draw reasonable comparisons using about 17 properties to enable obtain a professional insight into using the right materials for your project. For easy access, below are tables showing a summary of the previous section.
We have done a direct comparison of electrical, physical, thermal, and many more properties of titanium with aluminum. However, there are vast varieties of elements that can be used to pick the final choice of material for an application. As a result, we have been able to differentiate using about 17 properties to help you gain an understanding of the two metals.
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