AmerTek is the weapons manufacturer that employed John Henry Irons, the hero known as Steel. There are several billboards around Gotham City for AmerTek, and the actual AmerTek Plant was at the Industrial District.
During the Batman: Arkham Origins Trailer, there was a lingering close up of Deadshot's spent shell casing with a stamp that reads AmerTek. In addition, the Penguin also intended to raid a boat enclave at Pier 4 of what was presumably an AmerTek owned shipyard at 10 PM on a Thursday, with one of his henchmen named Barret who was assigned to open the door at the warehouse during the heist, was based on a list in his office that also included targets such as LexCorp (a truck convoy) and Queen Industries (presumably at an airport due to references to a Hangar 18 and Flight 132).
During the Arkham Knight Incident, a building on Founders' Island that belonged to AmerTek, was utilized as a front for North Refrigeration, a front company that belonged to Penguin and his criminal empire for laundering guns and assorted illicit weaponry. Batman went over to that location, both to put an end to Penguin's gunrunning, and to rescue Nightwing, as the latter had recklessly attempted to bring it down by himself and was captured in the process. That was also the site where Penguin, in a last ditch effort to stop Batman from destroying his illicit weapons, held Nightwing hostage, and his arrest at the hands of Batman and Nightwing.