Chemical vapor deposition (CVD) using gaseous hydrocarbon sources has shown great promise for large-scale graphene growth, but high growth temperatures (typically 1000 °C) require sophisticated and expensive equipment, which increases graphene production costs. Here, we demonstrate a new approach to produce graphene at low cost from scrap steel sheets treated by thermal evaporation of copper plating, which is a derivative of traditional CVD technology. Without additional carbon sources, graphene film was successfully prepared on copper-coated scrap steel sheets at 820 °C. The resulting graphene has few defects and uniform morphology, comparable to CVD graphene grown at 1000 °C. Finally, the obtained graphene film is used in combination with an interdigital electrode to detect NO₂ successfully, showing excellent performance. This technology expands the application of graphene in the manufacture of gas sensing devices and is compatible with traditional microelectronics technology.