In order to improve the tensile strength of gray cast iron, lower carbon equivalent should be adopted. Most of the carbon content in gray cast iron is 2.6% - 3.6%, and silicon content is 1.2% - 33.0%. According to the casting wall thickness, the lower limit should be taken as far as possible, and the manganese content should be appropriately increased. Generally, the manganese content of gray cast iron is 0.4% - 1.2%, and the upper limit should be taken as far as possible when there is no white cast iron.

In addition, the tensile strength of the cast iron can also be improved by adding trace elements such as Fe, Cr, and so on.