Detroit Steel is a human-piloted mech suit created by Hammer Industries to be sold with the goal of protecting corporate interests. The Hammer girls Sasha Hammer and Justine Hammer use Detroit Steel to fill in the gap in the military industry left by the demise of Stark Industries. He is deployed in a fake terrorist attack in Tokyo organised by the Hammer girls to come out victorious and show up Iron Man and War Machine who arrive later at the attack site.
Detroit Steel was created by Matt Fraction and Salvador Larroca in 2010 and first appeared in Invincible Iron Man # 25.
Mayor Story Arcs
Detroit Steel would assist Iron Man during his fight with Mokk, Breaker of Faith in Paris. Starks tells Johnson to leave but the hotheaded mech-pilot pours on the assault with artillery fire. Mokk gets close enough to rip through Detroit Steel's armor and turn Johnson into stone. His death allowed Iron Man the opportunity to get in close and slice off the top portion of Mokk's head with an energy saber.
Through he died from this transformation, Odin's powers allowed all those who died to the Serpent's avatars to be resurrected, which brought back Johnson in turn, through no one at the time was any wiser of his status.
Dead Man Walking
Johnson, stranded in Paris after his revival, was considered KIA by the military and the general public, and as such, a new Detroit Steel was required to replace him: Sasha Hammer was selected as his replacement, and modified the Detroit Steel suit in conjunction to her biological upgrades given by Ezekiel Stane.
Through difficult, Johnson was eventually able to return to the US covertly, and stalked Sasha for days on end, recording her movements and remaining unseen. After a while, he assaulted and took her as a hostage, angrily stating he was no longer Doug Johnson, but rather, the one and only Detroit Steel, and demanded that the suit be given to himself in exchange for Sasha's freedom.
Sasha agreed with this deal, and managed to obtain the Detroit Steel for Johnson to use. However, as she had been in control of the suit for weeks on end, she also understood the internal controls of it, and planned to use the self destruct command to destroy the suit and Johnson at the same time when he went inside the mech. Of course, Johnson had foreseen this, and had hacked the interface of the suit days before the encounter which meant that this plan failed.
With this plan going unsuccessful, Johnson now had full control of the Detroit Steel suit again, and started to fight Sasha and her Hammer reinforcements in a prolonged fight while within the suit, but was finally killed after Sasha sliced the head off the suit while Johnson was within the suit, decapitating him instantly.
In general, the Detroit Steel suit was highly customisable, able to switch between multiple different weapons and even paint jobs (as it was hired out to different countries, it would be repainted to match the colours of their flag) and as such was able to adapt to different situations.
The Detroit Steel suit was highly armored, immune to both small and large arms fire, as well as being physically strong enough to carry multiple large military grade weapons, such as mobile cannons, machine guns, a gatling gun and even a massive industrial chainsaw, which was powerful enough to rip through the Bleeding Edge variant of the Iron Man armor, through it was unsuccessful in permanently damaging it.
Through far more heavy and clunky compared to the Bleeding Edge suit, it was surprisingly fast and mobile, capable of catching up with the armor using powerful thrusters contained within the bottom of the feet. As well as this, Detroit also had reinforced plates within the feet of the suit, which allowed it to crush through steel simply by landing on it. This was also used to attack Iron Man and hold him in place.
While the suit was piloted by a human, it was assisted with a high tech interface, which allowed for easier piloting of the mech in battle, through it was still noted that the suit had the reactions of a trained human regardless, perhaps suggesting that these interfaces weren't very effective.
When Sasha Hammer took over as the new Detroit Steel, the suit was modified and upgraded to match her biological upgrades given, and she piloted the armor for a while before it was hijacked. Afterwards, she would abandon the Detroit Steel mech in favour of her own design, which was significantly slimmer and functioned far differently than it.