CN110756748A

CN110756748A - Preparation process of semi-solid rheoforming slurry

Info

Publication number: CN110756748A
Application number: CN201911108500.6A
Authority: CN
Inventors: 陶诚; 徐光周
Original assignee: Jiangsu Leader Technology Co Ltd
Current assignee: Jiangsu Leader Technology Co Ltd
Priority date: 2019-11-13
Filing date: 2019-11-13
Publication date: 2020-02-07

Abstract

The invention provides a preparation process of semi-solid rheoforming slurry, which comprises the following steps: s1, adding the metal particles into the molten metal liquid to prepare alloy liquid; s2, transferring the alloy liquid into a heat preservation furnace through a flow guider; s3, primary inoculation, namely keeping the alloy liquid at a first preset temperature, adding a self-inoculant into the alloy liquid, and stirring the alloy liquid to dissolve the self-inoculant; s4, secondary inoculation, namely keeping the alloy liquid at a second preset temperature, adding a self-inoculant into the alloy liquid again, stirring the alloy liquid to dissolve the self-inoculant to obtain semi-solid rheoforming slurry, introducing new high-melting-point particles into the liquid metal after the self-inoculant is melted and stably existing by means of adding metal particles into the molten metal liquid and stirring by means of two-time inoculation and electromagnetic pulse, so that more nucleation bases are provided for subsequent nucleation, the nucleation rate is improved, and the problems of the change of the volume fraction of the solid phase of the primary alpha-Al crystal particles and the change of the morphology are solved.

Description

Preparation process of semi-solid rheoforming slurry

Technical Field

The invention relates to the technical field of metal semi-solid rheoforming, in particular to a preparation process of semi-solid rheoforming slurry.

Background

The semi-solid forming technology belongs to the leading metal processing technology of the 21 st century, and is rapidly developed in recent years. The semi-solid rheo-die casting technology makes the traditional die casting mode deeply changed, the semi-solid forming technology breaks through the traditional dendritic crystal solidification mode, the granular crystal structure improves the density of the casting, and the comprehensive performance of the casting is improved.

In the process of metal semi-solid rheological production, the semi-solid slurry is difficult to store and convey, and the semi-solid slurry produced in batches is bound to be temporarily stored due to the time interval of the pouring process. In the isothermal preservation process, the mutual diffusion between the solid-phase primary a-Al crystal grains and the residual liquid phase of the slurry can occur along with the prolonging of time, so that the difference of the structure and the components is caused. When the slurry is stored at room temperature, the temperature of the slurry is reduced along with the prolonging of the storage time, so that the solid-phase volume fraction and the morphology of the primary alpha-Al crystal grains are changed.

Disclosure of Invention

The invention provides a preparation process of semisolid rheoforming slurry, which aims to solve the technical problem that in the isothermal preservation process of semisolid slurry, the temperature of the slurry is reduced along with the prolonging of the preservation time, so that the volume fraction and the shape of a solid phase of primary alpha-Al crystal grains are changed.

The technical scheme adopted by the invention for solving the technical problems is as follows: a preparation process of semi-solid rheoforming slurry comprises the following steps: s1, adding the metal particles into the molten metal liquid to prepare alloy liquid; s2, transferring the alloy liquid into a heat preservation furnace through a flow guider; s3, primary inoculation, namely keeping the alloy liquid at a first preset temperature, adding a self-inoculant into the alloy liquid, and stirring the alloy liquid to dissolve the self-inoculant; and S4, secondary inoculation, namely keeping the alloy liquid at a second preset temperature, adding the self-inoculant into the alloy liquid again, and stirring the alloy liquid to dissolve the self-inoculant to obtain semi-solid rheoforming slurry.

Further: the inclination angle of the flow guider is 20-40 degrees.

Further: the first predetermined temperature in S3 is 700 ℃ -740 ℃.

Further: the first predetermined temperature in S4 is 640 ℃ -680 ℃.

Further: and in the stirring in S3 and S4, electromagnetic pulse stirring is adopted, and inert protective gas is introduced below the alloy liquid during stirring.

Further: the self-inoculant used in the S3 and the S4 is alloy composite inoculant and consists of three elements of Al, Zr and Ti.

Further: the electromagnetic pulse stirring speed is 800-900 rpm, and the stirring time is 40-60 s.

The preparation process of the semi-solid rheoforming slurry has the beneficial effects that a large amount of alloy liquid is nucleated by adding metal particles into molten metal liquid, so that the alloy liquid with a round and pure microstructure is prepared, meanwhile, through twice inoculation, a self-inoculant is added into the alloy liquid, and through electromagnetic pulse stirring and stirring of protective gas introduced below the self-inoculant, the self-inoculant plays a role of internal cooling, so that local supercooling in the liquid alloy is promoted to be formed, and a large amount of crystal nuclei or large-size atomic clusters are generated in a local area.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a process schematic of a semi-solid rheoforming slurry manufacturing process of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention. On the contrary, the embodiments of the invention include all changes, modifications and equivalents coming within the spirit and terms of the claims appended hereto.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", and the like, indicate orientations and positional relationships based on the orientations and positional relationships shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be considered as limiting the present invention.

Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.

As shown in fig. 1, the present invention provides a process for preparing a semi-solid rheoforming slurry, comprising the steps of: s1, adding the metal particles into the molten metal liquid to prepare alloy liquid; s2, transferring the alloy liquid into a heat preservation furnace through a flow guider; s3, primary inoculation, namely keeping the alloy liquid at a first preset temperature, adding a self-inoculant into the alloy liquid, and stirring the alloy liquid to dissolve the self-inoculant; and S4, secondary inoculation, namely keeping the alloy liquid at a second preset temperature, adding the self-inoculant into the alloy liquid again, and stirring the alloy liquid to dissolve the self-inoculant to obtain semi-solid rheoforming slurry.

S1, adding metal particles into the molten metal liquid to nucleate a large amount of alloy liquid and prepare the alloy liquid with round and pure microstructure; in S3 and S4, after the self-inoculating agent is melted, new high-melting points are introduced into the liquid metal and exist stably, so that more nucleation bases are provided for subsequent nucleation, and the nucleation rate is further improved. The self-inoculant is added into the liquid alloy to be melted, and partial heat of the liquid alloy is absorbed, so that the temperature of the alloy slurry is rapidly reduced. Then the casting is carried out, which is equivalent to the reduction of the casting temperature. The self-inoculant is used as an artificial nucleating agent, and the composition of the self-inoculant is the same as that of a matrix alloy, so that the wetting angle theta used as a heterogeneous nucleation substrate tends to be 0 degrees, the nucleation work is greatly reduced, and the crystal nucleus is easier to form. The comprehensive effects of several aspects finally achieve the purpose of refining the tissue.

The inclination angle of the flow guider is 20-40 degrees. The metal samples are compared in experiments to obtain that the angle of the fluid director has certain influence on the self-inoculated casting structure, and when the mixed slurry flows through the fluid director with the inclination angle of 20-40 degrees, the obtained sample has the best effect.

The first predetermined temperature in S3 is 700 ℃ -740 ℃; the first preset temperature in S4 is 640-680 ℃, the stirring in S3 and S4 adopts electromagnetic pulse stirring, protective gas is introduced below the alloy liquid during stirring, the protective gas is inert gas, the electromagnetic pulse stirring speed is 800-.

The self-inoculant used in the S3 and the S4 is an alloy composite inoculant and consists of three elements of Al, Zr and Ti, the elements of Ti and Zr can form Al3Ti particles and Al3Zr particles with Al, and the two particles can serve as nucleation cores of a matrix, so that certain grain refinement effect can be generated on the alloy liquid.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic representation of the term does not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A preparation process of semi-solid rheoforming slurry is characterized in that: the method comprises the following steps:

s1, adding the metal particles into the molten metal liquid to prepare alloy liquid;

s2, transferring the alloy liquid into a heat preservation furnace through a flow guider;

s3, primary inoculation, namely keeping the alloy liquid at a first preset temperature, adding a self-inoculant into the alloy liquid, and stirring the alloy liquid to dissolve the self-inoculant;

and S4, secondary inoculation, namely keeping the alloy liquid at a second preset temperature, adding the self-inoculant into the alloy liquid again, and stirring the alloy liquid to dissolve the self-inoculant to obtain semi-solid rheoforming slurry.

2. A process for preparing a semi-solid rheoforming slurry according to claim 1, wherein: the inclination angle of the flow guider is 20-40 degrees.

3. A process for preparing a semi-solid rheoforming slurry according to claim 1, wherein: the first predetermined temperature in S3 is 700 ℃ -740 ℃.

4. A process for preparing a semi-solid rheoforming slurry according to claim 1, wherein: the first predetermined temperature in S4 is 640 ℃ -680 ℃.

5. A process for preparing a semi-solid rheoforming slurry according to claim 1, wherein: and in the stirring in S3 and S4, electromagnetic pulse stirring is adopted, and inert protective gas is introduced below the alloy liquid during stirring.

6. A process for preparing a semi-solid rheoforming slurry according to claim 1, wherein: the self-inoculant used in the S3 and the S4 is alloy composite inoculant and consists of three elements of Al, Zr and Ti.

7. A process for preparing a semi-solid rheoforming slurry according to claim 5, wherein: the electromagnetic pulse stirring speed is 800-900 rpm, and the stirring time is 40-60 s.