CN102371285A - Technology for preparing gradient material by swinging extrusion - Google Patents

Abstract

The invention relates to swinging extrusion. The swinging extrusion is local shearing extrusion. In the extrusion process, the shearing stresses which are different in heights and vertical to the direction of an extrusion shaft are applied to a metal of a deformation area in the extruding deformation process, so that the metal polycrystal produces swinging shearing deformation using the extrusion shaft as a center in the deformation process. By combining the positive and negative drastic plastic shearing actions borne by a material when being fed into and discharged out of a mold, the purposes of thinning polycrystal grains and improving the microstructure of the material are fulfilled. Because the geometric shape of the material before and after deformation is not changed, the microstructure can be continuously thinned by repeated deformation accumulation and plastic stress till the average grain diameter reaches a saturation value, and finally, the material forms a performance gradient along the thickness direction, for example, the strength is continuously improved along the thickness direction.

Description

Swing extruding preparation functionally gradient material (FGM) technology

Technical field

The invention belongs to the technical field for preparing the property metal material through mechanical means, is a kind ofly to utilize partial cut to push violent Plastic Forming metal grain is carried out refinement, prepares the technology of function-graded material in conjunction with extruding passage and mould structure.

Background technology

Function-graded material (Functionally Gradient Materials; Be called for short FGM) be the new ideas that propose along with development of aviation and aerospace technology; Be in the material preparation process; Key elements such as composition, structure and porosity are changed or stepped change on certain direction of material continuously, thereby make the character of material and a kind of heterogeneous body composite that function also is continuous variation or stepped change.Be the most advanced and sophisticated and high temperature more than the engine combustion chamber interior walls 2100K of head that causes for suitable space shuttle in atmosphere, flies for a long time the earliest, thereby design can be born the special material of huge high temperature and the abominable Service Environment of interior external pressure.

1984, Japanese scholar Masyuhi NINO, Toshio HIRA; With people such as Ryuzo WATANBE the notion of FGM has been proposed at first; Its design philosophy is to adopt the ceramic material of hear resistance and thermal insulation to adapt to the environment of several thousand degree high-temperature gases, adopts heat conduction and the high metal material of mechanical strength simultaneously, through composition, tissue and the micro-porosity of control material; Make it to change continuously, obtain ceramet FGM along thickness direction.

The method for preparing at present FGM is a lot, such as powder metallurgy, the plasma shower nozzle; Vapor phase deposition, centrifugal casting etc., complicated but these methods are production process mostly; Cost is high, and power consumption is big, and contaminated environment; Be not suitable for industrialized production in enormous quantities, also do not meet the requirement of human green production.Given this, the applicant has put forward a kind of new simple possible and has had the machining process of the preparation FGM of practicality, swing extruding preparation functionally gradient material (FGM) technology.

Summary of the invention

The swing extruding is a kind of partial cut extruding, and its mold sections structure is as shown in Figure 1.In extrusion process, be the swing shearing distortion at center perpendicular to pushing axial shear stress, impelling metal polycrystal in deformation process, to form with the extrusion axis through what deformed area metal in the extrusion process used for forming is applied differing heights.Bond material turnover positive and negative twice violent plasticity shear action that mould bore is to reach the purpose that refinement polycrystal crystal grain improves the heterogeneous microstructure of material.

Because the geometry of material does not change before and after the distortion; Can be through the continuous refinement microstructure of repeated deformation accumulation plastic strain until average crystal grain diameter to saturation value; Finally make material form a kind of capability gradient, improve constantly along thickness direction like intensity along thickness direction.

Can realize the control of shear deformation zone simultaneously through control, realize local organization control, form the function-graded material of different tissues gradient and capability gradient swing shearing deformed area height and control of position and extruding passage.For example the mould of Fig. 1 a can be made the function-graded material that portion reduces to center intensity gradually along the limit through the swing extruding, and the mould structure of Fig. 1 b can be processed the function-graded material that intensity is reduced by middle mind-set limit portion gradually.

The present invention can directly apply to conventional extruded equipment through die assembly, need not extras investments, is fit to very much technological transformation and upgrading that medium and small extrusion production enterprise relies on existing equipment to carry out.

The present invention mainly comprises following content:

The first step: the preparation of blank and the manufacturing of mould.To the requirement of the physical dimension and the structure property of required graded metal material, the corresponding blank of designing and preparing.Because swing extruding does not change the cross sectional shape of material, can repeated deformation, so the blank physical dimension can be identical with final required physical dimension, only stays a small amount of allowance to get final product.Simultaneously to final functionally gradient material (FGM) physical dimension and structure property require processing and manufacturing swing accordingly extrusion die one or more sets.

Second step: based on requirement design extrusion-processing technology and the passes of organizing gradient.Every time swing extruding all causes the local violent plastic deformation of material, causes the refinement of local microcosmic crystal grain, therefore based on finally the requirement of organizing gradient being designed concrete extruding scheme, and the built-up sequence of especially different swing extrusion dies.

The 3rd step: the violent Plastic Forming of swing extruding.Blank is placed recipient, swing the violent plastic deformation of extruding based on the processing technology that is designed through corresponding extrusion equipment.Relying in the extrusion process with the extrusion axis is the violent asymmetric detrusion at center; Under the condition that does not change the blank cross-sectional geometry, become to making metal grain that strong partial cut distortion takes place; Strenuous exercise through dislocation forms dislocation born of the same parents and subgrain fast; Grain size is changed along thickness direction continuously, realize organizing gradient and then the control of functionally gradient.

The specific embodiment

Relate to the preparation of alloy blank, the selection of extrusion equipment, the manufacturing of swing extrusion die, design construction, the swing violent Plastic Forming of extruding and the materials microstructure after the swing extruding and the test analysis of performance of swing extrusion process in this patent practical implementation process, mainly comprise:

One: the manufacturing of the preparation of blank, lectotype selection and mould.Physical dimension Design and Machining corresponding metal blank according to final formed parts.Because extruding does not change the cross sectional shape of material, can repeated deformation, so the blank physical dimension can be identical with final required physical dimension, only stays a small amount of allowance to get final product.Accomplish simultaneously the type selecting of calculating extrusion pressure and extrusion equipment according to the structure of final formed parts, and processing and manufacturing cross section corresponding swing extrusion die as shown in Figure 1 one or more sets.

Two: violent plastic forming process design construction.Grand microstructure and the corresponding violent plastic forming process of tissue characteristic's design construction according to material; Mainly refer to the passes of violent Plastic Forming and the arrangement of many molds extrusion process; Because it is saturated that the grain refinement of single violent Plastic Forming exists, therefore push passage and do not advise above four times as far as possible.

Three: the violent Plastic Forming of swing extruding.Blank is placed recipient; Swing the violent plastic deformation of extruding through corresponding extrusion equipment according to the processing technology that is designed; Under the condition that does not change the blank cross-sectional geometry, become to making metal grain that strong partial cut distortion takes place, realize organizing the control of gradient and then functionally gradient.It should be noted that at this violent plastic forming process needs the lubricated of no-float, can select molybdenum bisuphide or high-performance nano lubricant for use.

Four: the material structure performance test analysis.The material of accomplishing process is carried out macroscopic material performance and microstructure test, analyze final material property and tissue characteristic, carry out further repeating above-mentioned processing technology for the section bar of unmet designing requirement and process again.

Five: the surface treatment of final drip molding, block and follow-up processing.Material for through test analysis carries out surface treatment, and blocks and follow-up processing according to accessory size.

The high 10mm of embodiment 1 thick 5mm like figure along z to reducing in gradient to center intensity by single side portion, tissue is by the red copper thick plate of thin crystal orientation coarse-grain Gradient distribution

At first prepare 5mm * 10mm slab billot as blank, can stay allowance 1mm.Lead the r=1mm fillet, length can be confirmed according to the actual requirements.Next calculates extruding force, selects extrusion equipment and processing and manufacturing to reverse extrusion die accordingly according to extruding force and working condition, and under the requirement of satisfying the extruding tonnage, extrusion equipment both can have been selected for use and vertically also can select horizontal extruder for use.

Since require red copper thick plate tissue and intensity gradient for by limit portion to the monolateral gradual change in center, so the mould geometry can be as shown in Figure 2, plastic deformation does not take place in assurance bottom material in the swing extrusion process.Be that assurance tissue and intensity gradient can be processed the different many molds of deformed area shown in Figure 2 height simultaneously, organize gradient and intensity gradient through combined deformation control.

Combine horizontal on this basis or vertical extruder is swung extrusion process.Can at first carry out 2 passages swing extruding through Fig. 2 b cross-section mold; After this carry out 2 passages swing extruding through Fig. 2 c cross-section mold; Cooperate Fig. 2 d cross-section mold to carry out the extruding of two passages at last; Realize desired along z to reducing in gradient to center intensity by single side portion, tissue is by the processing of the red copper thick plate of thin crystal orientation coarse-grain Gradient distribution.

To being increased in gradient to center intensity by two side portion, tissue is by the titanium alloy thick plate of coarse-grain to thin brilliant Gradient distribution along Z for embodiment 2 as the thick 5mm of the high 20mm of figure

At first prepare 20mm * 10mm slab billot as blank, can stay allowance 1mm.Lead the r=1mm fillet, length can be confirmed according to the actual requirements.Next calculates extruding force, selects extrusion equipment and processing and manufacturing to reverse extrusion die accordingly according to extruding force and working condition, and under the requirement of satisfying the extruding tonnage, extrusion equipment both can have been selected for use and vertically also can select horizontal extruder for use.

Owing to require titanium alloy thick plate tissue and intensity gradient for to be symmetrical distribution to the center bilateral by limit portion; Therefore the mould geometry can be as shown in Figure 3; The plastic deformation total deformation that guarantees centre material in the swing extrusion process is greater than limit portion; Realizing along Z to increasing in gradient to center intensity by two side portion, tissue by coarse-grain to thin brilliant Gradient distribution.

Combine horizontal on this basis or vertical extruder is swung extrusion process.Can at first pass through Fig. 2 d cross-section mold; In conjunction with the detection of being out of shape the back microstructure being carried out 2～4 passages swing extruding; Process as scheme the thick 5mm of high 20mm along Z to increasing in gradient to center intensity by two side portion, tissue is by the titanium alloy thick plate of coarse-grain to thin brilliant Gradient distribution.

Description of drawings: Fig. 1 is a swing extrusion die cross section structure sketch map

Fig. 2 obtains the mold sections sketch map to the red copper thick plate that is reduced in gradient to center intensity by single side portion along z by swing extruding

[0034] Fig. 3 has the swing extruding to obtain along Z to the titanium alloy thick plate mold sections sketch map that is increased in gradient to center intensity by two side portion.

Claims (1)

1. swing extruding preparation functionally gradient material (FGM) is characterised in that:

The first step: the preparation of blank and the manufacturing of mould.To the requirement of the physical dimension and the structure property of required graded metal material, the corresponding blank of designing and preparing.Because swing extruding does not change the cross sectional shape of material, can repeated deformation, so the blank physical dimension can be identical with final required physical dimension, only stays a small amount of allowance to get final product.Simultaneously to final functionally gradient material (FGM) physical dimension and structure property require processing and manufacturing swing accordingly extrusion die one or more sets.

Second step: based on requirement design extrusion-processing technology and the passes of organizing gradient.Every time swing extruding all causes the local violent plastic deformation of material, causes the refinement of local microcosmic crystal grain, therefore based on finally the requirement of organizing gradient being designed concrete extruding scheme, and the built-up sequence of especially different swing extrusion dies.

The 3rd step: the violent Plastic Forming of swing extruding.Blank is placed recipient, swing the violent plastic deformation of extruding based on the processing technology that is designed through corresponding extrusion equipment.Relying in the extrusion process with the extrusion axis is the violent asymmetric detrusion at center; Under the condition that does not change the blank cross-sectional geometry, become to making metal grain that strong partial cut distortion takes place; Strenuous exercise through dislocation forms dislocation born of the same parents and subgrain fast; Grain size is changed along thickness direction continuously, realize organizing gradient and then the control of functionally gradient.

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