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Manufacturing method for nodular cast iron used for crankshaft

A ductile iron and crankshaft technology, which is applied in the field of ductile iron preparation, can solve the problems of wear resistance and heat resistance limiting the performance of crankshafts, and achieve the effects of increasing wear resistance, ensuring toughness and improving recovery rate.

Inactive Publication Date: 2015-11-11
HEFEI CITY TENVER PRECISION CASTING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The power source crankshaft is a part that bears continuously changing bending, torsional and shearing loads, and in its service life, it needs to cycle one billion times. Now most of the gasoline engine cars in the world are equipped with ductile iron crankshafts instead of forged steel crankshafts. However, the limitations of its wear resistance and heat resistance limit the improvement of crankshaft performance, so it is necessary to improve the wear resistance and heat resistance of ductile iron to improve the performance of crankshaft

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] In this embodiment, the contents of the components of a ductile iron used for the crankshaft are: C: 4.256%, Si: 2.680%, Mn: 0.035%, P: 0.1%, S: 0.036%, Cu: 0.008%, Cr : 0.015%, Mo: 0.385%, Ni: 0.012%, Nb: 0.056%, Ti: 0.03%, Mg: 0.02%, Ce: 0.05%, Ta: 0.092%, V: 0.001%, and the balance is iron.

[0020] The preparation method specifically comprises the following steps:

[0021] (1) Raw material smelting, using low-sulfur, low-manganese, low-silicon, and low-phosphorus steel scrap, low-sulfur, low-phosphorus pig iron, low-sulfur coke, recycled scrap iron, tin furnace slag, and iron slag as raw materials. The weight ratio of 1:5.8:0.8:1.5:0.6:0.3 is packaged and molded, and melted through the circuit. After all the raw materials are melted, take a sample for composition testing, and add the corresponding raw materials to adjust the composition to the above requirements;

[0022] (2) Spheroidizing treatment, when the temperature of the molten iron rises to 1450-1550°C, add...

Embodiment 2

[0031] In this embodiment, the contents of the components of a ductile iron used for the crankshaft are: C: 3.726%, Si: 2.68%, Mn: 0.035%, P: 0.118%, S: 0.026%, Cu: 0.008%, Mo : 0.36%, Ni: 0.008%, Nb: 0.08%, Ti: 0.04%, Mg: 0.018%, Ce: 0.06%, Ta: 0.094%, V: 0.002%, and the balance is iron.

[0032] The preparation method is specifically the same as in Example 1.

[0033] Wherein, the mass percent of the nodulizer composition is: Si: 43%, Sb: 0.75%, Ti: 0.5%, Mg: 6%, Al: 0.2%, Re: 0.72%, Ca: 4%, and the balance For iron and unavoidable trace elements.

[0034] Wherein, the mass percentage of the composition of the slag collector is: Si: 66%, Al: 10%, Ca: 0.6%, K: 3.2%, and the balance is iron and unavoidable trace elements.

[0035] Wherein, the addition amount of the slag collecting agent in step (2) is: 0.09%, and the addition amount in step (2) is: 0.07%.

[0036] Wherein, the mass percentage of the composition of the first inoculant is: Si: 50%, Ba: 2.6%, and the balance ...

Embodiment 4

[0044] Among the present invention, nodular cast iron is used in the crankshaft. The nodular cast iron commonly used in the crankshaft on the market is the nodular cast iron produced by Shanghai Tingxi Industrial Co., Ltd. with the grade of QT700-2, and it is used as a control group. According to the above-mentioned multiple embodiments The obtained nodular cast iron was used as the experimental group, and ingots of the same size were taken as the experimental objects for testing. All the indicators met the standards, and the elongation and impact resistance values ​​were significantly improved. The specific values ​​are as follows:

[0045] project Tensile strength (MPa) Yield strength (MPa) Elongation (%) -40℃ impact value (J) Brinell hardness Spheroidization rate (%) Example 1 775 457 2 14.5 316 95 Example 2 773 463 2 15.2 307 96 Example 3 776 468 2 14.8 302 95 Comparative example 720 425 2 11.8 245 91

[0...

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Abstract

The invention discloses a manufacturing method for nodular cast iron used for a crankshaft. Waste steel, pig iron, coke, melted-down waste iron, tin slag and iron-ore slag are selected as raw materials. The manufacturing method includes the five steps of raw material melting, spheroidizing, primary inoculation, secondary inoculation and pouring. Compared with the prior art, the manufacturing method has the beneficial effects that the silicon content is reduced, the recovery rate can be increased, and the production cost can be reduced; as Sb elements and Re elements are additionally arranged in the nodular cast iron, the abrasion resistance, the corrosion resistance and the tensile strength of the nodular cast iron are improved on the original basis; timely slag raking is carried out after spheroidizing to remove impurities in molten iron, slag raking is carried out again after two times of inoculation are carried out under the corresponding conditions, impurities are reduced, the quality of materials is improved accordingly, and the tenacity of the nodular cast iron is guaranteed; and the content of Nb elements and the content of Mo elements are increased, and as the thermal expansion coefficient of the Nb elements and the thermal expansion coefficient of the Mo elements are small, the heat resistance and the abrasion resistance of the nodular cast iron are improved.

Description

technical field [0001] The invention relates to a preparation method of nodular cast iron, in particular to a preparation method of nodular cast iron used for crankshafts. Background technique [0002] Spheroidal graphite cast iron is obtained through spheroidization and inoculation treatment, which effectively improves the mechanical properties of cast iron, especially improves plasticity and toughness, thereby obtaining higher strength than carbon steel. Ductile iron is a high-strength cast iron material developed in the 1950s. Its comprehensive performance is close to that of steel. It is based on its excellent performance that it has been successfully used to cast some complex stress, strength, toughness, and durability. Parts with high abrasiveness requirements. Ductile iron has rapidly developed into a cast iron material that is second only to gray cast iron and is widely used. The so-called "substituting iron for steel" mainly refers to ductile iron. [0003] The p...

Claims

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Application Information

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IPC IPC(8): C22C37/10C22C37/08C22C37/04C22C33/08
Inventor 孙爱琴
Owner HEFEI CITY TENVER PRECISION CASTING
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