Spheroidal graphite cast iron and preparation method thereof

Abstract

The invention provides spheroidal graphite cast iron. The spheroidal graphite cast iron comprises, by mass, 3.35%-3.7% of C, 2.3%-2.7% of Si, 0.35%-0.55% of Mn, 0-0.035% of P, 0-0.015% of S, 0.016%-0.018% of Re, 0.02%-0.04% of Mg and 0.55%-0.85% of Nb, and the total amount of trace elements including Cu, Zn, Sn, Mo, Al and Zr is smaller than or equal to 0.22%. The tensile strength of the spheroidal graphite cast iron is larger than 750 MPa, the yield strength is about 560 MPa, and the percentage elongation after fracture is 7.5% or above. The invention further discloses a preparation method of the spheroidal graphite cast iron. According to the preparation method of the spheroidal graphite cast iron, the processes of normalizing as well as hardening and tempering heat treatment are omitted, and the prepared spheroidal graphite cast iron has high strength and high plasticity at the same time.

Description

technical field [0001] The invention relates to the field of research and development and production of cast iron, in particular to a nodular cast iron and a preparation method thereof. Background technique [0002] Ductile iron is one of the most important materials in my country's national economy and even the world's manufacturing industry. It is widely used in machinery manufacturing, mining metallurgy, petrochemical and national defense industries. However, with the rapid development of modern industrial technology in the fields of oil drilling, automobile manufacturing and engines, the requirements for the strength and plasticity of ductile iron are getting higher and higher. For example, the crosshead of oil drilling requires mechanical properties of tensile strength ≥ 689MPa, yield strength ≥ 483MPa, elongation ≥ 3.0; spindles of lathes, gear shafts of ball mills, spindles of small water turbines, etc., require a tensile strength of over 700MPa, yield strength of ove...

AI Technical Summary

Problems solved by technology

In the prior art, the method of increasing the amount of Mn, Sn, and Cr is usually used to increase the pearlite content, thereby obtaining higher tensile strength and yield strength, but the elongation of the obtained ductile iron will decrease accordingly, so it cannot Obtain high-strength and high-plasticity ductile iron

On the contrary, in the prior art, when the pearlite content is reduced by reducing the amount of Mn, Sn and Cr, higher elongation can be obtained, but the tensile strength and yield strength of ductile iron will be reduced, and the same Nodular cast iron with high strength and plasticity can not be obtained

Images