The matrix structure of three grades of gray cast iron samples is shown in the figure.
It can be seen from the figure that the matrix structure of the three grades of gray cast iron samples is composed of pearlite + ferrite + eutectic phosphorus, and the pearlite content of the three grades of gray cast iron matrix.
The pearlite content of the three grades of gray cast iron samples is more than 90%, indicating that the matrix of the three grades of gray cast iron samples is pearlite matrix, in which the pearlite content of low alloy HT250 and HT300 added with trace alloying elements is more than 95%. Pearlite is a lamellar interphase structure composed of ferrite and cementite, with properties between ferrite and cementite and good strength and toughness, The increase of pearlite content can weaken the splitting effect of flake graphite tip on the matrix and enhance the tensile and fatigue properties of gray cast iron.