For three generations, Apple wrapped the Pro line in a titanium frame. Titanium looks premium. Titanium resists corrosion. Titanium is lighter than steel. And — compared to aluminium — titanium is a conspicuously poor conductor of heat.
The third-party metallurgy is public:
Source: LVMA CNC, Titanium Supplier — cited in our internal iPhone research report. Ranges reflect alloy variation.
Plainly: the titanium frame on the 15 Pro, 15 Pro Max, 16 Pro and 16 Pro Max moves heat to the chassis roughly an order of magnitude slower than the older aluminium Pros. Heat from the A-series SoC has a harder time reaching the rail; once it does, it has a harder time leaving.
At launch, Apple publicly denied that titanium was related to thermal complaints. By 2025, Apple shipped a unibody aluminium iPhone 17 Pro and listed thermal performance among the design reasons.
We're not telling you your phone is broken. We're telling you the engineering reality your 15 Pro, 16 Pro and 16 Pro Max still has to live with — and why, on this generation, an external cooler isn't a luxury. It's the headroom Apple took back and never gave you.