It can be seen that under the condition that the basic composition of gray cast iron is basically the same, different inoculants are used for inoculation treatment, and there are great differences in the mechanical properties of gray cast iron. The tensile strength, Brinell hardness and matrix microhardness of experimental gray cast iron a inoculated with 75 ferrosilicon inoculant, which is the most widely used in China, are the lowest, while the average tensile strength of experimental gray cast iron D inoculated with silicon zirconium manganese inoculant is the highest, which can reach 400MPa, The average tensile strength of gray cast iron a sample inoculated with 75 ferrosilicon inoculant is 17 MPa higher than that of experimental gray cast iron a sample inoculated with 75 ferrosilicon inoculant.
Combined with the analysis of the effects of different inoculation treatments on the graphite structure, pearlite matrix and primary austenite structure of the experimental gray cast iron sample, from the aspect of graphite, the graphite in the experimental gray cast iron sample D is curved, fine, densely distributed and uniform; From the aspect of pearlite matrix, the pearlite flake spacing is the smallest in the D sample of gray cast iron; From the analysis of the microstructure of primary austenite in four kinds of experimental gray cast iron, the primary austenite network framework structure of experimental gray cast iron D sample is the most complex, the dendrite is also the most developed, and there are many secondary dendrites. In terms of mechanical properties, the tensile strength and matrix microhardness of experimental gray cast iron sample D are significantly higher than those of experimental gray cast iron samples a, B and C, and the hardness is slightly higher than that of experimental gray cast iron samples a, B and C. It can be seen that the mechanical properties of high-strength gray cast iron are determined by its microstructure characteristics. The finer the graphite and the more uniform the distribution, the higher the material strength and the better the mechanical properties; The smaller the distance between pearlite sheets, the greater the microhardness of the matrix; The more complex the primary austenite network frame structure is, the more refined and developed the secondary dendrites are, the more conducive to obtain high-strength gray cast iron.