Titanium – the casing material of the Apple iPhone 15 Pro under the microscope

A big deal is currently being made of the fact that Apple has chosen titanium for the casing of its new Pro smartphones. In recent years, several patents awarded to Apple have shown that developments are heading in this direction. The Apple Watch Series 5 also paved the way for titanium casings on Apple devices in 2019. Or should it be better to mention the PowerBook G4 from 2001? You see, there's a lot to be said about Apple's use of Titan. Below you will find everything organized and explained, from material information to Apple patents to information about the sustainability of titanium.

The Basics: What is Titanium?

Let's start with the basics: Titanium is a chemical element with atomic number 22. It is at the top of the 4th subgroup in the periodic table, which is also called the “titanium group”. Titanium also belongs to the transition elements or transition metals, which also extend across other groups and some of which are used in titanium alloys. But this is all small-scale theory that you can read through on Wikipedia or in a chemistry textbook. That's why I'll stop right here.

What is much more important for this consideration is the fact that titanium is a robust metal that is resistant to corrosion and some chemicals. It is also relatively light, especially compared to steel. However, not as light as aluminum. Even small amounts of titanium in alloys provide greater stability and protection. Steel becomes tougher and stronger with a titanium concentration of 0,01% to 0,1%. It prevents intercrystalline corrosion in stainless steel alloys.

Above all, titanium ensures a lower weight of the object made with it (compared to stainless steel and its alloys) as well as the pure use of the other advantages of titanium. It achieves high strength with a relatively low density and is corrosion-resistant. However, it is also ductile, meaning it can deform before it breaks. This is possibly the reason for the aluminum substructure that appears in the iPhone 15 Pro (Max) is used. This could further stiffen the housing and protect it from deformation.

Density comparison of titanium, stainless steel and aluminum

Even though titanium has a significantly lower density than steel and the substructure in the iPhone 15 Pro (Max) is made of the even lighter aluminum, the Pro models of the iPhone 15 series only 19 grams lighter than its predecessors. But this can also be due to additional hardware inside the devices. If you look at the density and therefore weight comparison of different starting materials, you can see a considerable difference:

• Iron: 7,87 g/cm³
• Steel: 7,85 to 7,87 g/cm³
• Stainless steel: 7,7 to 8,2 g/cm³
• Titanium: 4,5 g/cm³
• Aluminum: 2,7 g/cm³

What is Grade 5 Titanium?

As obvious as the comparison may be, Apple does not make it any easier for laypeople to understand and use titanium when it speaks of “Grade 5” titanium. This was in the Presentation of the new devices highlighted and, in addition to the iPhone 15 Pro, also mentioned as the source material used for Mars rovers. According to the titanium supplier Titanium Processing Center, the more technical name is Ti 6AI-4V. 

Ti 6AI-4V (Grade 5) is the most commonly used titanium alloy and is accordingly referred to as the “workhorse” of titanium alloys. Grade 5 titanium is believed to account for half of the world's titanium usage. In addition to aircraft turbines, engines, aerospace and shipping, it is also used in sports equipment, electronic devices and other consumer products. Without going into the exact additions for Grade 5 titanium, it is stated that titanium alloys in general may contain trace amounts of aluminum, molybdenum, vanadium, niobium, tantalum, zirconium, manganese, iron, chromium, cobalt, nickel and copper.

What makes titanium so special as a case material?

So the titanium alloy used for the iPhone is the most commonly used. Also and especially because it offers the highest strength-to-weight ratio among titanium alloys. Due to the numerous uses and the resulting large-scale production, the comparatively stable cost of the material certainly also plays a role. Titanium as a material for the iPhone casing as well as the casings of various Apple Watch models offers the best from different areas.

However, titanium is not really special as a housing material. As already shown, the material used can be found quite often on the market and has been used by Apple for a long time. It is used not only in space travel and in industrial forms, but also in consumer technology - such as wristwatches, loudspeakers, sports equipment, etc. The only special thing is that Apple has secured some patents for the processing of Grade 5 titanium in order to make its surface and appearance more attractive.

Apple's patents surrounding titanium as an embellished material for device casings

Apple was already able to secure a patent in 2021, thanks to which the iPhone manufacturer was granted the rights to process titanium material into a semi-glossy surface. But it wasn't just about the iPhone, but also about the iPad, the Apple Watch and the MacBook. However, it is not yet clear whether these devices will also have the brushed and polished titanium outer shell.

In 2022, Apple was awarded another patent that once again deals with the processing of metal surfaces. This is specifically about strong and stable metals whose original surface is not very attractive and needs to be spruced up for sale. The patent describes the creation of a textured surface. This would be matt, but can be made shinier with additional coatings.

Sustainability: Titanium is said to be better in many areas

In addition to hardware upgrades and housings, the big topics for the new Apple products in 2023 are sustainability and environmental friendliness. Here too, titanium is convincing compared to other materials. According to some sources, there are several advantages that, in addition to environmental compatibility, also concern the ethical aspect of the recovery and processing of the raw materials. The following arguments are mentioned, among others:

• Longevity of the material: The iPhone can be used longer because it wears less during everyday use. If the device is replaced more frequently, there will theoretically be less electronic waste. However, this assumes that iPhones are only replaced because of their appearance and not because of the annual chip and camera upgrades.
• Promotion of raw material: Compared to mining aluminum, mining titanium from the earth's crust is said to use less energy. This means that the current Pro models of the iPhone have a lower carbon footprint. However, it is important to note the aluminum substructure, the influence of which cannot be masked by the titanium shell. The titanium alloy also contains other metals.
• ethical concerns: Titanium appears to be primarily mined in safe and regulated parts of the world. This can reduce concerns about dangerous working conditions, child labor and the like. As mentioned in the last point, when it comes to grade 5 titanium, attention must go beyond the namesake to the alloy metals.
• Recycling options: Titanium can be recycled very well. This means that the large-scale use of the material as an alternative to less reusable materials results in less electronic waste.
• Falling price: Apparently the price of titanium and alloys will continue to fall, so that there will be a good ratio of weight, strength and price, somewhere between aluminum and steel.

When did Apple first use a titanium case?

As already mentioned at the beginning, Apple dared to experiment with offering a device with a titanium case in January 2001. This is the first generation of the Apple PowerBook G4, which was sold until 2003. From January 2003, the different sizes (12 inches, 15 inches, 17 inches) were replaced by devices with aluminum housings. Today, Apple still uses aluminum as the housing material for the MacBook (although this could change again in the future according to the patents mentioned above).

Apple's first foray into using titanium, after plastic cases for the PowerBook G3, was short-lived as it brought with it several problems. For example, the hinges of the display were made of titanium, which was stable but not designed for long-term use. Even when these components were used regularly without overexertion, they often broke. In addition, the display cables that ran past the titanium hinges were often damaged. There were even third-party manufacturers that made sturdier components to fix the problems.

Plastic parts that were connected to the titanium housing could also be damaged because they could not withstand the stress that titanium could withstand and transfer to it. In addition, the plastic cutouts for the WLAN antennas were not sufficient, so the radio connection to the Internet router was poor due to the metal shielding. And the paint on the edges of the titanium base wore, peeled and bubbled - especially where the palms of the hands rested when using the laptop.

These current Apple devices have a titanium casing

• Some models of Apple Watch Series 5 (2019)
• Some models of Apple Watch Series 6 (2020)
• Some models of Apple Watch Series 7 (2021)
• apple watch ultra (2022)
• Apple Watch Ultra 2 (2023)
• iPhone 15 Pro (2023)
• iPhone 15 Pro Max (2023)

Will Apple completely switch from stainless steel and aluminum to titanium?

The above-mentioned patents from 2021 and 2022 indicate that not only the Pro models of the iPhone, but also the iPad, the MacBook and again the Apple Watch will see a change to titanium as the housing material. However, you should keep the same thing in mind here as with all other patents: Apple operates according to the motto “You are better off than you are.” The patent specifications say nothing about future developments and, like many others, could languish in the company's poison cupboard over the years.

Further information in the article sources

In this post I have listed a wide variety of information and data for you. Of course, I don't have all of these in my head and I didn't even determine them all myself. Or to put it another way: I used a lot of sources. If you would like to use this for your own research, please use the following list:

• Information about individual metals: Wikipedia pages of elements and alloys
• Density range of different stainless steel variants: World steel
• Information about Grade 5 Titanium (Ti 6AI-4V): Titanium Processing Center
• Information about Apple patents relating to titanium surfaces: 9to5Mac
• Information about sustainability and other advantages of titanium on the iPhone: Medium contribution
• Details about the Apple Titan PowerBook G4: Apple website from 2001 / MacTracker / Wikipedia
• Information on current devices with titanium housings: sir appleot / MacTracker

Johannes Domke

After graduating from high school, Johannes completed an apprenticeship as a business assistant specializing in foreign languages. But then he decided to research and write, which resulted in his independence. For several years he has been working for Sir Apfelot, among others. His articles include product introductions, news, manuals, video games, consoles, and more. He follows Apple keynotes live via stream.