Steamhammer was a sadistic killer even before the war, when he knew Prowl and Jazz, so when the Decepticon recruiters showed up promising action, excitement, and destruction he jumped at the chance. Instead he got stuck pulling guard duty at Fort Scyk in Stanix, the most boring post in the Decepticon army.
Steamhammer is a Triple Changer, transforming from a jet to a tank to a robot. In robot mode Steamhammer is equipped with a pair of piston hammers driven from his forearms that can smash the ground, knocking his opponents over with deadly shockwaves. He also carries a concussion blaster and a particle accelerator cannon. Steamhammer's face is entirely covered by a protective grille.
Steamhammer revels in the violence of the battlefield, taking a sadistic glee in the destruction of defenseless Autobot targets. His passion for battle can prove a liability however; when enraged Steamhammer may refuse to retreat even when there are compelling tactical reasons to do so.
Marvel Comics UK continuity
Steamhammer led a Decepticon strike team consisting of him himself, Pounder, Claw, Switchblade and Ripsnorter to dislodge a group of neutralists from the nearby town of Yuss. His team was ambushed by the Magnificent Six, an Autobot infiltration team, and completely destroyed, leaving Steamhammer a choice to fight or flee. He chose to fight, and was killed when he was shot in the chest by three Autobots simultaneously.
The same 3 Autobots that killed Steamhammer also killed Pounder.