A metallic body of carbon steel covered with an adhesive layer capable of adhering to a rubber matrix based on diene elastomer. The carbon content of the steel is between 0.35 and 1.2% by weight. The adhesive layer is formed of a metallic layer bearing aluminum oxides or hydroxides, which itself is covered with an organosilane film which is at least bifunctional, capable of ensuring, as coupling agent, the bond between the aluminum oxides or hydroxides on one hand, and the rubber matrix on the other hand.