The present disclosure provides an array substrate, including multiple metallic pattern layers which are insulated and spaced from each other. Each metallic pattern layer comprises a metallic piece made of a metallic material. An oxide film is formed on a lateral face of the metallic piece in at least one of the multiple metallic pattern layers and made of an oxide of the metallic material forming the metallic piece. The present disclosure further provides a display device and a method for manufacturing an array substrate.