Fragmentation-type ferrite pearlitic structure high strength and toughness nodular cast iron and production method thereof

A technology of nodular cast iron and ferrite, which is applied in the field of high-strength nodular cast iron and its production, can solve the problems of complex production process and high cost, and achieve the effects of high elongation, high impact toughness and high tensile strength

Inactive Publication Date: 2017-12-05
DALIAN UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Austenitic and bainitic ductile iron has good comprehensive performance, the tensile strength can reach more than 900MPa, and the elongation can exceed 10%. Usually, it needs to undergo austempering heat treatment, the production process is relatively complicated, and the cost is relatively high
Pearlitic ductile iron is the most widely used, because its pearlite content is generally more than 80%, and the "bull's eye" ferrite surrounds spherical graphite, which makes it exhibit high tensile strength (600-800MPa), but its The elongation is only 2-3%, and the impact toughness is only 20-30J / cm 2

Method used

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  • Fragmentation-type ferrite pearlitic structure high strength and toughness nodular cast iron and production method thereof
  • Fragmentation-type ferrite pearlitic structure high strength and toughness nodular cast iron and production method thereof

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Experimental program
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Effect test

Embodiment 1

[0017] Embodiment 1 The production process of broken type ferrite plus pearlite high-strength and tough ductile iron crankshaft is as follows:

[0018] (1) Composition ratio: by weight percentage, C: 3.5-3.9%, Si: 1.7-2.1%, Mg: 0.03-0.05%, Cu: 0.4-0.8%, Mn: 0.3-0.6%, Sb: 0.006 -0.02%, S≤0.025%, P≤0.06%, Re: 0.012-0.015%, total content of other impurities≤0.02-0.05%, the balance is Fe;

[0019] (2) Charge selection: 5% of low-P and low-S scrap steel and 10% of iron filings are used, 35% of the return charge, and the rest are high-purity pig iron, which is used as the charge according to the composition ratio of step (1);

[0020] (3) Smelting and refining: use the intermediate frequency induction furnace to melt the charge to obtain molten iron, add industrial ferromanganese 0.6%, industrial ferrosilicon 1.0% and electrolytic copper 0.5% according to the composition ratio of step (1) for uniform smelting, and release after desulfurization and refining. The furnace temperature ...

Embodiment 2

[0029] (1) Composition ratio: by weight percentage, C: 3.5-3.9%, Si: 1.7-2.1%, Mg: 0.03-0.05%, Cu: 0.4-0.8%, Mn: 0.3-0.6%, Sb: 0.006 -0.02%, S<0.025%, P<0.06%, Re: 0.012-0.015%, the total content of other impurities is ≤0.02-0.05%, and the balance is Fe;

[0030] (2) Charge selection: 5% of low-P and low-S scrap steel and 10% of iron filings are used, 35% of the return charge, and the rest are high-purity pig iron, which is used as the charge according to the composition ratio of step (1);

[0031] (3) Smelting and refining: use the intermediate frequency induction furnace to melt the charge to obtain molten iron, add industrial ferromanganese 0.6%, industrial ferrosilicon 1.0% and electrolytic copper 0.5% according to the composition ratio of step (1) for uniform smelting, and release after desulfurization and refining. The furnace temperature is: 1480℃;

[0032] (4) Spheroidizing treatment: Z6S spheroidizing agent is selected, and the addition ratio is 0.9%;

[0033] (5) I...

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Abstract

The invention provides a fragmentation-type ferrite pearlitic structure high strength and toughness nodular cast iron and a production method thereof. During melting and casting processes of the nodular cast iron, the casted nodular cast iron is placed in a normalizing furnace for insulation, the holding temperature is 810-860 DEG C, the insulation is carried out for 1-1.5 hours, after air cooling, the fragmentation-type ferrite pearlitic structure high strength and toughness nodular cast iron is obtained. The fragmentation dispersion-type ferrite tissue can be obtained through the production method, the fragmentation-type ferrite content can be controlled at 1-10%, so that the high intensity of the pearlite nodular cast iron is embodied, and the high plasticity and high toughness of the ferrite nodular cast iron are obtained. The fragmentation-type ferrite pearlitic structure high strength and toughness nodular cast iron has the performance characteristics that the tensile strength is 830-920 Mpa, the percentage elongation is 6-9%, the impact toughness is 50-70 J/cm<2>, and the Brinell hardness is 250-270 HBW. The nodular cast iron has high tensile strength, high percentage elongation and high impact toughness, and can generally suitable for parts such as automobile crankshafts, camshafts and hydraulic cylinders.

Description

technical field [0001] The invention belongs to the technical field of metal metallurgy, and relates to a high-strength and tough ductile iron with a crushed ferrite and pearlite structure and a production method thereof. Background technique [0002] Ductile iron is a high-strength cast iron material, and its comprehensive performance is close to that of steel. It has been widely used in various power machinery crankshafts, camshafts, connecting shafts, connecting rods, gears, clutch plates, hydraulic cylinders and other components. According to its matrix structure, ductile iron can be divided into ferritic ductile iron, austenitic bainitic ductile iron and pearlitic ductile iron. The matrix of ferritic ductile iron is almost completely ferrite, and its tensile strength is low (200-400MPa), but its elongation is high (20-30%). Austenite plus bainitic ductile iron has better comprehensive properties, tensile strength can reach more than 900MPa, elongation can exceed 10%, u...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C37/04C22C37/10C22C33/08C21D1/28C21D5/00
CPCC22C37/04C21D1/28C21D5/00C21D2211/005C21D2211/006C21D2211/009C22C33/08C22C37/10
Inventor 孟令刚蔡勇张兴国刘恒乐周秉文孟宪军亚斌张国辉房灿峰张宝昌
Owner DALIAN UNIV OF TECH
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