Martensite

is an Ignition Ability used by Iron that allows him to strengthen his body and attacks.

Usage
Martensite uses a similar process as flame hardening, a metalworking technique that utilizes heat to harden the surface of a metal object. By using his Third-Generation abilities to heat his body in much the same way, specifically the iron content in his body, Iron is able to increase the durability of his skin to the point of being able to shrug off gunfire.

A notable weakness of this ability is that Iron is unable to harden his joints, leaving them particularly vulnerable compared to the rest of his body when using Martensite. An observant opponent is able to exploit this weakness and target the soft parts of Iron's body to defeat him.

Trivia

 * Iron's Ignition Ability is named after martensite, an extremely hard form of steel crystalline structure.
 * Martensite's inability to harden some parts of Iron's body might be a reference to the real-life process of flame hardening, which is prone to creating an extremely brittle zone between the heat-hardened metal and the unheated metal.