Grade of ductile iron with reinforced ferritic matrix

A ductile cast iron with a strengthened ferritic matrix structure, wherein the strengthened ferritic matrix structure comprises more than 70% of ferrite, the ductile cast iron has a tensile strength (Rm) equal to or greater than 700 MPa, an elongation at break equal to or greater than 11%, a yield strength (Rp0.2) equal to or greater than 532 MPa and a minimum ratio of yield strength (Rp0.2) to tensile strength (Rm) of 76% in a tensile test performed on a specimen taken from a tensile bar in accordance with standard EN 1563 and having a diameter of 25 mm and a length of 200 mm, and in that the ductile cast iron is formed by the following elements, in percentage by weight:

• carbon, between 2.8% and 4.5%;
• silicon, between 3% and 5%;
• manganese, between 0.1% and 0.8%;
• sulfur, less than 0.01%;
• phosphorus, between 0.001% and 0.05%;
• copper, between 0.1% and 1%;
• magnesium, less than 0.1%;
• nickel, between 0% and 1%;
• chromium, between 0% and 1%;
• impurities, less than 0.2%;
• and
• iron, making up 100%.