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Preparation method of precision investment casting nodular cast iron QT450-10L

A technology of investment precision casting and nodular cast iron, which is applied in the direction of casting molding equipment, casting molds, and casting mold components. It can solve the problems of slow cooling speed, unstable matrix structure, and reduced performance indicators of castings, and achieve low-temperature impact toughness improvement. Effect

Active Publication Date: 2020-02-21
DONGFENG PRECISION CASTING CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The investment casting process is used to prepare nodular cast iron, the cooling rate is uncontrollable, and the casting is hot shell pouring, which leads to slow cooling rate in the early stage of investment casting and fast later stage, resulting in poor quality of investment casting graphite spheroidization, unstable matrix structure, and castings. The performance indicators of the
Therefore, it is more difficult to produce high-strength low-temperature impact ductile iron by investment casting process

Method used

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  • Preparation method of precision investment casting nodular cast iron QT450-10L
  • Preparation method of precision investment casting nodular cast iron QT450-10L
  • Preparation method of precision investment casting nodular cast iron QT450-10L

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Embodiment 1

[0033] This embodiment discloses a preparation method of investment casting nodular cast iron QT450-10L, which includes the following steps:

[0034] Shell making and firing of investment casting shells: the mixture of silica sol and quartz sand is used as the surface coating of the shell, wherein the mass ratio of silica sol:quartz sand is 1:1.9, and the mixture of silica sol and mullite is used as the coating. The back layer coating of the shell, in which the mass ratio of silica sol: mullite is 1:1.8, the surface layer is sanded with quartz sand, and the back layer is sanded with mullite sand, and the shell is roasted in a through-type natural gas roasting furnace , The firing temperature is controlled at 900-950°C, and the firing time is 2.5h.

[0035] Melting of molten iron: The molten iron is smelted by an intermediate frequency induction circuit, and the furnace materials are 200kg of Q10 pig iron, 200kg of recycled materials, 100kg of scrap steel and 3.5kg of low-sulfu...

Embodiment 2

[0041] This embodiment discloses a preparation method of investment casting nodular cast iron QT450-10L, which includes the following steps:

[0042] Shell making and firing of investment casting shells: a mixture of silica sol and quartz sand is used as the surface coating of the shell, wherein the mass ratio of silica sol:quartz sand is 1:2.1, and a mixture of silica sol and mullite is used as the coating. The back layer coating of the shell, in which the mass ratio of silica sol: mullite is 1:2.3, the surface layer is sanded with quartz sand, and the back layer is sanded with mullite sand, and the shell is roasted in a through-type natural gas roasting furnace , The firing temperature is controlled at 900-950°C, and the firing time is 3.5h.

[0043] Molten iron smelting: use medium frequency induction circuit to smelt molten iron, and select 300kg Q10 pig iron, 100kg recycled material, 100kg scrap steel and 4.5kg low-sulfur graphite recarburizer as the charge.

[0044] Sph...

Embodiment 3

[0049] This embodiment discloses a preparation method of investment casting nodular cast iron QT450-10L, which includes the following steps:

[0050] Shell making and firing of investment casting shell: the mixture of silica sol and quartz sand is used as the surface coating of the shell, the mass ratio of silica sol:quartz sand is 1:2, and the mixture of silica sol and mullite is used as the coating. The back layer coating of the mold shell, in which the mass ratio of silica sol: mullite is 1:2, the surface layer is sanded with quartz sand, and the back layer is sanded with mullite sand, and the mold shell is roasted in a through-type natural gas roasting furnace , The firing temperature is controlled at 900-950°C, and the firing time is 3h.

[0051] Melting of molten iron: use medium frequency induction circuit to smelt molten iron, and select 250kg of Q10 pig iron, 200kg of recycled material, 50kg of scrap steel and 3.8kg of low-sulfur graphite recarburizer as the charge. ...

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Abstract

The invention provides a preparation method of precision investment casting nodular cast iron QT450-10L. The preparation method mainly comprises the steps of housing making and roasting of an investment casting housing, molten iron smelting, spheroidizing, inoculation, mold housing pouring and heat treatment. By combining with a precision investment casting process, the silicon content in a material is reduced to a certain extent, so that the problem of poor low-temperature impact toughness of the material is solved; and meanwhile, the preparation process is improved, so that the tensile strength is greater than or equal to 450Mpa, and the elongation percentage is greater than or equal to 10% while the low-temperature impact energy of a V-shaped notch of the nodular cast iron is greater than or equal to 5J under the condition of -40 DEG C.

Description

technical field [0001] The invention relates to the technical field of casting of special ductile iron materials, in particular to a preparation method of investment precision casting ductile iron QT450-10L. Background technique [0002] In the national standard of ductile iron, the grades of ductile iron with low temperature impact toughness requirements are QT350-22L and QT400-18L, and their yield strengths are 220MPa and 240Mpa respectively. The yield strength is low and does not meet the requirements for the use of auto parts. [0003] The yield strength of QT450-10 can reach 310MPa, and it has high toughness, making it one of the most frequently used materials for ductile iron. With the substantial improvement in the performance of automobiles, OEMs have higher and higher requirements on the performance of castings, especially the impact toughness of materials has attracted more and more attention. In the existing research, the low temperature impact performance of QT45...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22C9/04B22D1/00C21C1/10B22C3/00C21D9/00C22C33/08C22C37/04C22C37/10
CPCB22C3/00B22C9/04B22D1/00C21C1/105C21D9/0068C22C33/08C22C37/04C22C37/10Y02P10/143Y02P10/20
Inventor 陈娟马波陈礼年
Owner DONGFENG PRECISION CASTING CO LTD
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