A lecture given by Andrew Rose at the Adventures in the Physical Metallurgy of Steels (APMS) conference held in Cambridge University. The talk describes the pioneering technology for the mass production of the world's first bulk nanostructured metal, the so-called superbainite that consists of slender platelets of bainitic ferrite separated by thinner films of retained austenite. Tata Steel have undertaken work to demonstrate the feasibility of superbainite for application as armour steel. The challenge was to adapt the composition to the demands of a tonnage production route, while still attaining the property advantages of superbainite. The Tata production route involves oxygen steelmaking, continuous casting and hot strip rolling, followed by downstream processing to a final form as armour plate. Each of these stages presents challenges to the production of high-strength steels. Tata Steel Research have reviewed the requirements for production of superbainite, and undertaken experimental work, including optical and electron metallography, studies of transformation behaviour, and mechanical testing, to justify the final choice of production parameters. As a result a composition and process route have been formulated which enable production of commercial casts of superbainite without danger to the process. Further development work has supported the downstream processing steps culminating in heat treatment of the material, and enabled the optimisation of the parameters involved. Metallurgical examination and testing have confirmed that this processing gives the superbainite microstructure with the expected properties. Ballistic testing has shown that superbainite armour is comparable with other armour steels competing in the same area.