A light metal is a metal that has a relatively low density; the first seven metals in the periodic table, which include lithium, beryllium, sodium, magnesium, aluminum, potassium, and calcium, are collectively known as the “lightest metals.” In this regard, aluminum and magnesium are commonly used to reduce the weight of components and structures. Titanium, although not one of the seven lightest metals, has a relatively lower density than heavy metals; therefore, it also qualifies as a light metal and has specific industry applications.
Below, we discuss the unique properties of the most commonly used lightweight metals and their specific industry applications.
Unique Properties and Applications of Lightweight Metals
Lightweight metals are commonly used in many industrial applications because of their unique chemical, physical, and mechanical properties. Let’s take a look at some of the most commercially-utilized lightweight metals.
Lithium is the lightest of all metals, with an atomic mass of 6.941 u and the lowest density of 0.534 g/cm³. It has a shiny appearance and is easy to cut, even with a simple knife when sufficient force is applied. It rapidly gets oxidized in free air at room temperature but behaves the opposite at higher temperatures above 572°F.
Lithium is commonly used in:
- Ion batteries.
- Continuous casting powder.
- Industrial air conditioning.
- Lubricating greases.
Lithium-aluminum alloys are also extensively used for aerospace applications.
Aluminum has a low density of 2.7 g/cm³ and is thus lightweight. It is three times lighter than steel yet has a much higher strength-to-weight ratio. Aluminum is highly corrosion-resistant, as it forms a thin layer of oxide around its surface that prevents further air and water contact. Aluminum conductors weigh only 30% of copper conductors but have double the electrical conductivity for the same electrical resistance.
Different alloying elements such zinc, copper, and magnesium are added to pure aluminum to further enhance its strength. Aluminum alloys are available in seven different series, engineered to meet unique application requirements.
|Al Series||Primary Alloying element(s)||Properties||Applications|
|1xxx series||99% pure aluminum||High corrosion resistance, workability, and thermal and electrical conductivity||Electrical transmission lines|
|2xxx series||Copper||Strength and toughness||Aerospace applications|
|3xxx series||Manganese||Good weldability and machinability||General purpose, beverage cans|
|4xxx series||Silicon||Low melting point, high ductility||Welding wire, brazing fillers|
|5xxx series||Magnesium||High strength, high corrosion resistance, and excellent formability, machinability, and weldability||Pressure vessels, marine applications|
|6xxx series||Magnesium and silicon||Heat treatable, highly formable, good machinability||Aircraft, marine frames, semiconductor assemblies|
|7xxx series||Zinc||Strongest of all of the series, heat treatable||Aircraft, aerospace, sporting equipment|
Magnesium has the lowest mass among the alloys used for die casting. The addition of different elements improves the mechanical properties and corrosion resistance of magnesium without compromising the lightweight property. Magnesium alloys are 30% less dense compared to aluminum, with a density of 1.7-2.0 g/cm³. Magnesium excels as the lightest metallic construction material and comes with a low cost of production because of its abundant supply in nature. Therefore, modern aerospace and automotive industries extensively use magnesium alloys to achieve low-cost, lightweight designs.
Magnesium is commonly used in:
- Sporting goods.
- Household products.
- Office equipment.
- Automotive applications.
- The biomedical industry.
- Aircraft engine and gearbox casings.
Next to aluminum, titanium offers an excellent strength-to-weight ratio. Titanium has a higher density than aluminum but requires less material to achieve the same strength. The tensile strength of titanium alloys can go up to 160 ksi, twice that of aluminum alloys. It is as strong as steel but weighs only 56% as much. When alloyed with varying traces of other metals, titanium achieves even greater strength and workability.
Titanium alloys can be classified into several commercially pure grades and alloy grades in terms of strength, corrosion resistance, and high-temperature service. For example, titanium bronze metal powders are used in resin casting (cold casting), decorative coatings, and powder metallurgy to achieve excellent stress relaxation resistance. Also, certain titanium alloys retain their strength and ductility even at cryogenic temperatures. For instance, Al25Zn alloys with titanium additives display excellent gamma-ray and neutron shielding properties. However, titanium alloys also come with a high price tag, which can be difficult for those who must adhere to strict budgets.
As a highly reactive metal, titanium spontaneously forms a protective hard oxide layer when it comes into contact with oxygen underwater or in free air. It offers excellent corrosion resistance to acids, alkali, and polluted water. It is the only metal completely immune to microbiological-induced corrosion in seawater.
Titanium is commonly used in:
- Jet engines.
- Medical implants.
- Sports equipment.
- Bicycle frames.
- Powerplant pipes.
Challenges with Lightweight Metals
Although there are many advantages to using lightweight metals, there are some downfalls as well. Below, we discuss some of the challenges of using lightweight metals, including machining difficulties and high material costs.
Parts deformation is a great concern when machining lightweight metals. It is imperative to maintain a distortion-free workholding that gives rigidity to fragile and delicate materials. Metals like titanium require a lower cutting resistance through pulse cutting technology to avoid distortion due to high thermal loads.
High Material Cost
Using lightweight alloys in the manufacturing process increases project costs, as many of these alloys can be quite expensive. To offset these costs, it’s worth considering utilizing verified metal remnants to obtain the desired characteristics of your end product but at a lower manufacturing cost.
A lack of experience and high-end cutting tools can lead to generating metal waste while machining lightweight metals. This, in turn, will lead to overpurchasing and exceeding your production budget in the long run.
In the absence of expertise and state-of-the-art cutting equipment, it is better to partner with a local metal supplier to get your lightweight metals cut to size on time.
Precision-Cut Lightweight Metals in the Bay Area and Beyond
Industrial Metal Service has been serving as a trusted metal supplier and recycler of lightweight metals and a wide range of other metal alloys in the San Francisco Bay Area for more than two decades. Our wide inventory includes aluminum, steel, titanium, and copper as well as specialty metals such as Invar. We supply new metals sourced straight from U.S. mills as well as verified metal remnants for those looking to lower their costs while maintaining high quality for their production runs. Our other services include precision metal sawing, machine teardown, and warehouse cleanup.