All About Titanium Metal

Titanium is considered an invaluable metal in contemporary engineering and technology. In light of its peculiar features, such as its ability to deliver high strength, low density, and excellent corrosion resistance, it is a vital material for various industries. Everything from airplane wings to hip replacements, titanium is used in different parts of many things that make up our daily lives. The uses of titanium range from making aircraft endure longer, to improving the performance of sporting equipment or strengthening life-supporting medical equipment. In this article, we will understand why titanium has become so crucial. Looking into its characteristics, uses, production methods, and the most widely used grades in the market at present.

What is Titanium?

Titanium Metal Sheets

Titanium(a non-magnetic alloy) is highly rigid, weightless, and does not corrode easily. However, it’s comparatively more expensive than aluminum, and steel. In the periodic table, titanium belongs to group 4 and period 5 of elements having an atomic number of 22 and the symbol “Ti”. Titanium metal has a lustrous shining surface which can be of grey or white color. Titanium can be colored in various shades by a process known as anodizing. The fundamental principle is done by varying the voltage.

Moreover, it’s important to know that titanium is the ninth most abundant metal on the Earth. It is soluble in rocks, minerals, clay, and sand. But, it doesn’t exist in its original state in nature. Rather, titanium combines with oxygen to protect components by providing a shielding layer of titanium dioxide (TiO₂).

Primarily, titanium is often found in its ore forms. So, pure titanium can be extracted from two minerals: rutile, which is dark and crystal-like, and ilmenite, which is grayish-black in color. In addition, there are more minerals for producing titanium including anatase, perovskite, brookite, and titanite.

As mentioned before, titanium is costlier/more expensive than steel or aluminum, and despite this, it usually finds its extensive use in several applications. Commercially pure titanium is available for roughly $18 and $20 per kilogram. Normally, titanium alloys cost more. These costs can range from 70 to 80 US dollars/kilogram mass.

Key Properties of Titanium

The properties of titanium are divided into chemical, physical, and mechanical categories, highlighting its unique characteristics for various applications.

Table: Physical, Chemical & mechanical properties of titanium.

Physical Properties	Chemical Properties	Mechanical Properties
Density: 4.54 g/cm³	Carbon Content: ≤ 0.08%	Tensile Strength: 200-1,400 MPa
Melting Point: 1,668°C	Iron Content: ≤ 0.5%	Yield Strength: 200-1,200 MPa
Electrical Conductivity: 2.38 x 10^6 S/m	Oxygen Content: ≤ 0.25%	Hardness (Brinell): 150-400 HB
Thermal Conductivity: 21.9 W/m·K	Nitrogen Content: ≤ 0.03%	Elongation (Ductility): 10-30%
Magnetic Properties: Non-magnetic	Hydrogen Content: ≤ 0.015%	Modulus of Elasticity: 105-120 GPa

How is Titanium Made?

The production of titanium involves several key steps: Let’s describe the process of titanium production in the following manner below:

• Extraction of Titanium Ore: Among all the ores of titanium the two most commonly used types are ilmenite (FeTiO₃) and rutile (TiO₂). The following ores are mined and processed with the view of obtaining titanium dioxide.
• Conversion to Titanium Tetrachloride (TiCl₄): The major steps in the manufacturing of titanium compounds involve the chlorination of titanium dioxide. Further, it’s transformed into titanium tetrachloride. The respective process involves the use of titanium dioxide and chlorine gas and the two are treated through heat.
• Reduction to Titanium Metal: Titanium tetrachloride is then reduced to titanium metal using the Kroll, and Hunter processes. In these processes, the titanium tetrachloride is made to react with magnesium at high temperatures to produce titanium and magnesium chloride (MgCl).
• Purification and Alloying: Remember, that the material titanium metal is pure and must be alloyed with other components to obtain desired characteristics. Some of the widely used constituents of alloying are aluminum, vanadium, and molybdenum.
• Processing and Fabrication: These forms include sheet forms, rod forms, and tube forms among other forms depending on the users’ requirements. Further, it is taken through various processes to produce finished products by using turning, welding, and casting among others.

Grades of Titanium Commonly Employed for Parts’ Manufacturing

Titanium is available in various grades depending on the intended application and material specification. These grades are normally classified depending on the chemical composition and the mechanical characteristics. The common grades of titanium are as follows:

1. Grade 1

Description: Commonly known as commercial titanium, it has the highest ductility and the lowest strength of all the grades of titanium.

Chemical Composition: 99.5% titanium.

Mechanical Properties:

• Tensile Strength:240MPa or 35 ksi
• Yield Strength: 170 MPa (25 ksi)
• Elongation:24%

2. Grade 2

Description: This grade is characterized by good strength and good ductility.

Chemical Composition: Approximately 98.9 percent titanium compound, and the rest is iron and oxygen.

Mechanical Properties:

• Tensile Strength:350 MPa (50 ksi).
• Yield Strength: The tensile strength is up to 275 MPa (40 ksi).
• Elongation: 20%

3. Grade 3

Description: The intended grade is stronger than Grades 1 and 2 but has lower ductility as compared to the two grades.

Chemical Composition: Around 97.5% titanium with iron and oxygen as major alloying elements.

Mechanical Properties:

• Tensile Strength: The yield strength of the material is 450 MPa (65 ksi).
• Yield Strength: Typically, the density of the material is 380 MPa (55 ksi).
• Elongation: 15%

4. Grade 4

Description: Grade 4, has high strength and relatively moderate ductility, Normally, applied where high strength is desired.

Chemical Composition: It has about 90% titanium and traces of elements such as iron, oxygen, and others.

Mechanical Properties:

• Tensile Strength: 550 MPa (80 ksi).
• Yield Strength:480 MPa (70 ksi)
• Elongation: 10%

5. Grade 5 (Ti-6Al-4V)

Description: Most popular of all titanium alloys due to its high strength and good weldability. Grade 5 has aluminum and vanadium as the alloying constituents. Relatively, used in 3D printing applications for prototype manufacturing.

Chemical Composition: It contains 90% of titanium, 6% of aluminum, and 4% of vanadium.

Mechanical Properties:

• Tensile Strength: 900 MPa (130 ksi).
• Yield Strength: 830 MPa (120 ksi)
• Elongation: 14%

6. Grade 7

Description: Grade 7 has enhanced corrosion characteristics that have been made possible by the incorporation of palladium. It usually lies among BETA grades.

Chemical Composition: About 90 percent titanium with a small amount of palladium.

Mechanical Properties:

• Tensile Strength: The yield strength of the material is 370 MPa or 54 ksi.
• Yield Strength: Typically, 275 MPa (40 ksi).
• Elongation: 20%

7. Grade 9 (Ti-3Al-2. 5V)  

Description: A lightweight grade that has higher strength and better fatigue properties, used in aerospace and sports equipment.

Chemical Composition: 90% Titanium, 3% Aluminum, 2.5% vanadium.

Mechanical Properties:

• Tensile Strength:620 MPa or 90 ksi
• Yield Strength: The material properties of the steel used in the construction of the offshore platform are 480 MPa (70 ksi) tensile strength.
• Elongation:15%

8. Grade 23 (Ti-6Al-4V ELI)

Description: This is a low-interstitial variant of Grade 5, which usually improves fracture toughness. Commonly employed in medical implants.

Chemical Composition: 90% titanium, 6% aluminum, 4% vanadium with less amount of oxygen content.

Mechanical Properties:

• Tensile Strength:860 MPa (125 ksi)
• Yield Strength:795 MPa (115 ksi).
• Elongation:14%

The different grades of titanium have unique features which makes it appropriate in many uses in areas such as aerospace, medical, and industrial uses.

Machining Operations for Titanium

Titanium Machining

Titanium is a bit difficult to work with. Because it’s highly rigid and strong. So, the material properties demand specific processes to be carried out. Some of the common operations employed in machining are CNC turning, milling, drilling, and tapping. Titanium alloys are normally machined at low speeds to minimize heat and wear on the cutter. Carbide-cutting tools are used since they are more protective of the titanium from wearing out. In high-precision work, the tolerances could be as tight as ±0.005″. Moreover, Some other techniques can also be carried out including Electrical Discharge Machining (EDM), and laser cutting for the geometries and hard-to-machine areas by conventional means.

Industry Applications of Titanium

Let’s figure out common applications of titanium across several sectors:

Aerospace Industry

Aerospace sectors are heavier consumers of titanium. Titanium and its alloys are usually employed for parts of aircraft including jet engine parts, landing gears, airframe structures, and exhaust systems. These materials are particularly well suited to these high-stress areas due to their high strength-to-weight ratio and corrosion resistance abilities.

Medical Industry

In the medical industry, titanium is applied in the fabrication of surgical appliances, and dental, and prosthetic equipment. This makes it compatible with human tissue so that when implanted it does not elicit any adverse reactions.

Automotive Industry

The auto industry is one of the biggest consumers of titanium. Titanium helps manufacture products like race cars and high-end luxury cars. They are used in the manufacturing of exhaust systems, valve parts, and suspension systems which facilitate the lightweight and high strength of vehicles.

Chemical Processing Industry

As discussed earlier, titanium material is not easily corroded by the environment. So, it can be used in the manufacture of pump valves, heat exchangers, and piping systems for chemical plants. Further, it added the benefit of being able to handle very aggressive chemicals and therefore, increases the lifespan of the equipment.

Marine Industry

Titanium has high corrosion resistance characteristics. So, It’s extensively used in the manufacturing of ship components and accessories such as propeller shafts, hull fittings, and seawater systems, and offers high durability and low maintenance in maritime environments.

Conclusion

To conclude, because of the distinct properties of titanium material, it is possible to machine it to the required tolerance. Its diverse grades can be applied in aerospace, medical, and industrial fields. However, titanium has poor machinability, it can be machined with great accuracy if proper tools and techniques are employed during the process. This makes titanium valuable in any application where strength and accuracy are critical.

FAQs

Q1. What are the Main Categories of Titanium Alloys?

Titanium alloys are categorized into three main types: which include alpha alloys, beta alloys, and alpha-beta alloys. Alpha alloys are those that possess high strength and an acceptable degree of ductility. Beta alloys provide improved mechanical properties, advanced strength, and enhanced machinability. Alpha-beta alloys contain both alpha and beta phases and therefore the properties associated with both phases are exhibited.

Q2. How does Titanium Stand With Other Metals in Terms of Corrosion?

Titanium has a natural oxide layer which makes it resistant to rust and corrosion; therefore, it can be used in seawater, acid, and other corrosive environments.   

Q3. Why is Titanium Used in Aerospace Applications?

Titanium material is extremely lightweight, yet very strong, which makes it ideal for aerospace uses. It offers high strength, but it is about 50% lighter than steel. Therefore, it significantly improves fuel efficiency and performance in aircraft and spacecraft components. 

Q4. What Makes Titanium Biocompatible?

Titanium does not elicit any negative response when used in the human body. After all, it can easily bond with human tissue. Owing to its non-adherent and chemically inactive surface, it does not cause inflammation when used in surgical implants and artificial limbs.

Q5. How is Titanium Machined and Fabricated?

Titanium like many other metals. It can be machined in the traditional ways. But it is a very hard and strong metal, thus needing specialized tools and methods of machining. These include high-speed machining, precision grinding as well as electrical discharge machining (EDM). Other processes involved in fabrication may be welding, casting, forging, and the like depending on the requirement.