Spheroidal graphite cast iron and preparation method thereof

A technology for ductile iron and molten iron, applied in the field of ductile iron and its preparation, can solve the problems of low tensile strength and yield strength of ductile iron, failure to obtain high-strength and high-plastic ductile iron, and reduced elongation of ductile iron, and achieve stability Spheroidization rate, eliminating the need for normalizing and tempering heat treatment, and improving the effect of mechanical properties

Inactive Publication Date: 2017-02-22
长沙金龙铸造实业有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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 duct

Method used

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  • Spheroidal graphite cast iron and preparation method thereof
  • Spheroidal graphite cast iron and preparation method thereof
  • Spheroidal graphite cast iron and preparation method thereof

Examples

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[0030] Example 1

[0031] A method for preparing as-cast nodular cast iron includes the following steps:

[0032] 1) Smelting: The molten iron is smelted by an intermediate frequency induction electric furnace. The electric furnace adds 55-65% by weight of pig iron, 25-35% of ductile iron recycle material, and 5-10% of scrap steel. The electric furnace is heated to 1450-1550℃ , Smelting the mixture of pig iron, ductile iron recycle material and scrap steel into molten iron;

[0033] 2) Adjust the content of molten iron composition: Adjust the weight percentage of the chemical composition in the molten iron obtained in step 1) to the following ranges: C: 3.35%-3.7%, Si: 2.3%-2.7%, Mn: 0.35%- 0.55%, P≤0.035%, S≤0.015%, Re: 0.016%-0.018%, Mg: 0.02%-0.04%, Nb: 0.55%-0.85%;

[0034] 3) Spheroidizing treatment: Add the molten iron obtained in step 2) to the spheroidizing agent ladle containing trace alloy elements Cu, Zn, Sn, and perform spheroidizing treatment;

[0035] 4) Inoculation trea...

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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...

Claims

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Application Information

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IPC IPC(8): C22C37/04C22C37/10C22C33/08C21C1/10
CPCC22C37/04C21C1/10C22C33/08C22C37/10
Inventor 常应祥许晓嫦黄为王威明
Owner 长沙金龙铸造实业有限公司
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