CN1004260B - Compound alloying technique on metal surface for sealed vacuum components - Google Patents

Abstract

The present invention relates to a compound alloying technique on a metal surface for components formed by vacuum sealing. Dry and powdery alloy powder is laid on the surface of a casting mold; steel, iron and nonferrous metal components of which the surfaces have special performance can be cast. The present invention has the advantages of simple technology, stable and reliable alloying, high composite strength of materials and excellent special service performance and comprehensive performance.

Description

Vacuum sealed molding metal surface combination process

The invention belongs to the metallic composite field.

Casting surface alloying is to produce the more satisfactory a kind of process of wear resistance castings.A.D.Morris has applied for the patent (U.S.Patent of this process in 1913, № .1,072,026), this patent is at casting mold die cavity bottom surface layer overlay antifriction metal (AFM) powder, the powder loam cake is with sheet metal, uses the molten metal with the same material of sheet metal to pour into die cavity, just can obtain the foundry goods that the surface has anti-wear performance.Because sheet metal every between metal powder grain and molten metal, has absorbed the part heat during fusing, cause alloying process to be difficult for stable carrying out, and this method only limit to the foundry goods of simple shape.People had done a large amount of effort and had solved the stable problem of alloying afterwards, but because poor practicability does not obtain extensive practicality so far.(The Transactions of American Foundryman Society such as Canadian K.G.Davis in 1981, Vo1,90,1981～82, PP.385～402) use the principle of vacuum seal system type, the process that cast(ing) surface is carried out alloying pushes away and goes a step further.K.S.Davis adopts the technology of vacuum seal metal surface alloyization to be, scrape off one deck sand on the sand mold surface, or on sand mold, put the annular metal silk, in ring, spread the antifriction metal (AFM) powder of 2～3 millimeters thick, plastic sheeting of powder loam cake, sand mold is communicated with vacuum tube by filter, the sand mold consolidation.The mo(u)ld top half that closes is then poured into a mould.This method directly contacts powder with molten metal after cast, improved the surface-active of dusty material greatly, it and molten metal is cast under the diffusion conditions of cleaning oozed, diffusion and alloying.But the KGDavis method is only limited to the surface alloying of die joint foundry goods, promptly can not carry out surface alloying to the perpendicular side of inside and outside side of foundry goods and complex-shaped foundry goods, thereby its application is restricted.Nineteen eighty-three J.S.Hansen(The Transact ons of American Foundryrman Society, Vo1,91,1983, PP.65～70) the vacuum seal full mold die cast that the is adopted process of carrying out casting surface alloying has had new progress again.Though the J.S.Hansen method is not limited to that some are simple, the surface alloying of plane foundry goods is because this method is to use vinyl acetate, celluloid and alcohol binding agent mix with alloy powder particle, be coated on the full mold mould, utilize vacuum sealed molding then, water out the foundry goods of surface abrasion resistance.So binding agent, the particularly volatilization gas of full mold mould cause the gas of alloying process to increase, although the effect of vacuum suction is arranged, yet the foundry goods alloy-layer relatively is easy to generate pore and slag inclusion, has influenced the quality of alloying.

The objective of the invention is that to only limit to a kind of technology that simple flat surface foundry goods or surface alloying quality instability proposed simple in order to solve prior art, surface alloying is good, and can make the process of various difform part and component surface alloyings.

Accompanying drawing is a vacuum sealed molding metal surface combination technological method embodiment schematic diagram.(1) is the casting mold of vacuum condition among the figure, and (2), (5) are film, and (3) are the needle plate acanthopore, and (4) are alloy powder particle, and (6) are metal powder formable layer device, and (7) are mo(u)ld top half, and the arrow direction is to vacuumize direction among the figure.

Main points of the present invention are: utilize the principle of vacuum sealed molding, alloying process is finished under the condition of vacuum seal and bone dry and purification.During molten metal filling casting mold under vacuum and directed flow condition, between alloy powder particle, cast and ooze, and the thermal capacitance of molten metal is dispersed in the casting mold by alloy-layer, heat is concentrated and is passed alloy-layer, help heating alloy powder particle, strengthen powder alloying element thermal diffusion and improve the alloying result of metallurgical binding.And surface alloying is not subjected to the restriction of foundry goods shape.

Concrete processing step of the present invention is: casting mold is made with the method for vacuum sealed molding, the capital equipment of vacuum sealed molding be water-ring vacuum pump (when vacuum when-455 millimetress of mercury, the speed of exhaust of SZ-2 type and SZ-3 type vavuum pump is respectively 57 and 240m ²/ time), size, the far-infrared heater that ability and sandbox (with air filter) size matches, inhale film case and vibration molding platform, used template be drilled with inhale 1～1.5 millimeter of φ that film uses aperture several, decide according to mould shapes quantity and position, use during moulding and do, 70/140 order synthetic quartz sand (or aluminium alum sand and film of diffusing shape, but film acetic acid-ethene polymers plastic sheeting), its thickness is 0.05～0.12 millimeter, concrete molding operation operation is as follows: 1. multiple film, plastic sheeting is toasted on far-infrared heater, when film temperature reaches 60～90 ℃, film is buckled on the template, and film is pyroplastic deformation and covers on the template; 2. on template, put sandbox, add sand and little shaking 0.5～1 minute, the unnecessary sand in sandbox top is scraped off, cover thin film; 3. vacuumize, open the conduit air valve that is connected with the sandbox air filter, casting mold and vacuum pump speed are logical, thereby take out the air in the casting mold, make inner vacuum-400～-650 millimetress of mercury that keep of casting mold, and casting mold is by consolidation, and moulding is finished in last molding.On the already made surface that is in the casting mold of vacuum condition, with needle plate (its length can be casting mold die cavity 1/4～1/3), disperse, the film thorn that will be adsorbed on the mo(U)ld face sealing equably is saturating, evidence, the area that is stung is 0.000028 of whole mo(U)ld face area～0.00014 o'clock, casting mold vacuum does not have to change substantially, at this moment do preprepared, the even shakedown of bulk alloy powder is put on this layer film, and then wrap metal powder formable layer device with the film of a same material, the metal powder formable layer device that to wrap film again places fast have been spread on the mo(U)ld face of putting the metal bisque, and the shape of metal powder formable layer device is decided according to the surface configuration of foundry goods needs alloying.The material of bisque shaped device is plastics, metal (as copper coin, steel plate etc.) or other material (as plank etc.).The film and the casting mold that will wrap in then on the metal powder formable layer device are bonding, make metal bisque and casting mold be in the sealing state of original vacuum again.With this layer film good seal after, the bisque shaped device is taken out, use the purpose of this shaped device to be, the thickness of temporary transient fixed film and control bisque.Because the effect of vacuum, the alloyed powder granulosa is adsorbed and is fixed on mo(U)ld face, the sealing of second layer film, make after the upper and lower type mould assembling, base metals liquid waters fashionable (normally used base metals is a cast steel, cast iron and non-ferrous metal etc.), and the molten metal casting is oozed in the alloy powder particle gap, and with powder counterdiffusion mutually, finish the part and component surface alloying.And alloying is stable, and alloy layer thickness is even.Casting mold vacuum is generally-400～-650 millimetress of mercury (mmHg), and wherein-500～-620 millimetres of mercury (mmHg) is best.General foundry goods cuts off vacuum through certain hour cooling back after cast, decide according to foundry goods size and wall thickness cool time, and for example, wall thickness is can cut off vacuum in 20～30 minutes behind 20～30 millimeters the general casting pouring.The composition of the alloy powder particle of doing, loose that is usually adopted and consisting of:

High carbon ferro-chrome: composition is: Cr:65%, C:8.6%, Si:1.2%; Consist of the 100%(percentage by weight), or medium carbon ferrochrome: composition is: Cr:68.25%, C:5.0～6.0%, Si:1.1%; Consist of 100%, or consist of 90～96% medium carbon ferrochrome and 4～10% molybdenum-iron, the molybdenum-iron composition is: Mo:55%, C:0.2%, Si:1%, or the vanadium iron of 90～95% medium carbon ferrochrome and 5～10%, the vanadium iron composition is: V:48%, C:1%, Si:2.09%, or the casting WC of 100% casting WC or 40～50% and 50～60% medium carbon ferrochrome, or the tungsten slag ferroalloy of 50～90% high carbon ferro-chrome and 10～50%, the composition of tungsten slag ferroalloy is: W:4.5～7.5%, Mn:14～20%, Nb:0.5～0.6%, Ta:0.16～0.22%, Ti:0.12～0.16%, C:5.5～6.2%, Si:0.12～0.7%, Fe:65～70%, or the tungsten slag ferroalloy of 50～70% WC and 30～50% or 100% SiC, the granularity of alloy powder particle generally are that the alloy powder particle that fusing point is lower than the molten metal melting temperature is 40～140 orders, the alloy powder particle that 100～200 orders and fusing point are higher than the molten metal melting temperature is 28～40 orders, 40～100 orders.Do, bulk alloy powder normally pass through pre-alloyed after, fragmentation, levigate, also can be in fragmentation, in the levigate process by the ratio mixing of the composition and the composition of above-mentioned alloy.

For part and component with the ferrochrome surface alloying, can heat-treat, the heat treatment heating-up temperature is 920 ℃～980 ℃, temperature retention time 2～4 hours, air cooling then.Can reach 60～67 through heat treated part and component HRC.

Alloying technology of the present invention is stable, and operation is simple and reliable, not only can be used for casting surface alloying, also is used for the surface alloying of some members, and be not subjected to the restriction of part and component shape.Owing to adopt the compound aurification technology of vacuum seal, the consumption that can save precious metal improves combined strength bination and surperficial serviceability between mother metal and the alloy powder particle, makes foundry goods have good comprehensive performances.The part and component of surface alloying under a stable condition, can replace large and medium-sized powder metallurgy part and component, as rolling mill carbide alloy composite roll etc.

Embodiment 1, medium carbon ferrochrome carry out tabular steel casting surface alloying

Casting section thickness: 35 millimeters (comprising alloy powder layer thickness);

Alloy powder particle is formed: medium carbon ferrochrome is 100%, and its composition is: Cr:68.25%, C:5.9%, Si:1.1%;

Granularity: levigate through fragmentation, granularity is 70～140 orders;

Alloy powder layer thickness: 5 millimeters;

Alloy power layer shaping device: five-ply board;

Mother metal cast steel, C content are 0.30%;

Pouring temperature is: 1580 ℃～1600 ℃;

It with thickness 0.075 millimeter the multiple film of vinyl acetate polymer plastic sheeting, with granularity is that the dried shape synthetic quartz of 140/70 purpose sand causes vacuum seal casting mold 1, casting mold vacuum is-580 millimetress of mercury, sting the film 2 of casting mold bottom surface with needle plate, pin hole is 20 millimeters apart from 3, then, spread above-mentioned medium carbon ferrochrome powder 4 on this layer film, the thickness of alloyed powder granulosa is 5 millimeters.At last, with a vinyl acetate polymer film 5 and metal powder formable layer device 6 alloy is spread bisque again and cover and seal, then shaped device is taken out.As nowel, after upper and lower case mould assembling, be 1580 ℃～1600 ℃ with temperature, the molten steel of C content 0.3% pours into casting mold.Heat-treat after the foundry goods cooling, be heated to 950 ℃, be incubated 2 hours, air cooling.

Foundry goods alloying case hardness can reach HRC65.

Embodiment 2, high carbon ferro-chrome and tungsten slag alloy powder carry out tabular steel casting surface alloying.

Casting dimension: 180 * 100 * 40 millimeters (comprising alloy powder layer thickness);

The alloy powder particle composition, form: high carbon ferro-chrome (Cr:65%, C:8.6%, Si:1.2%): 60%, tungsten slag ferroalloy (W:4.5～7.5%, Mn:14～20%, Nb:0.5～0.6%, Ta:0.16～0.22%, Ti:0.12～0.16%, C:5.5～6.2%, Si:0.12～0.7%, Fe:65～70%): 40%.

Alloy powder particle granularity: 70/140 order;

Alloy powder layer thickness: 5 millimeters;

Mother metal: ZG45;

Pouring temperature: 1580 ℃～1600 ℃;

Acetic acid-ethene polymers plastic sheeting with 0.075 millimeter of thickness, with granularity is that the dried shape synthetic quartz of 140/70 purpose sand causes the vacuum seal casting mold, casting mold vacuum is-570 millimetress of mercury, sting the film of casting mold bottom surface with needle plate, the true footpath of pin hole is 0.15 millimeter of φ, the pin hole distance is 20 millimeters, then, the alloy powder particle of forming with mentioned component on this layer film upper berth, the thickness of powder particle layer is 5 millimeters, uses a vinyl acetate polymer film (thick is 0.075 millimeter) at last, alloy powder layer is covered, place a wooden alloy power layer shaping device above again, cling sealing with around the film with gummed paper then, as mo(u)ld bottom half.Behind upper and lower type mould assembly, be that 1580 ℃～1600 ℃ ZG45 molten steel pours into casting mold with temperature.Pour into a mould and cut off the casting mold vacuum in back 20 minutes, unpack after 4 hours, after the foundry goods cooling, the cutting dead head is heat-treated, and is heated to 960 ℃, is incubated 2 hours, air cooling.

The case hardness of foundry goods alloying reaches HRC62, and the alloy-layer degree of depth is 8～9 millimeters, and has reduced alloy powder particle cost about 20%.

Embodiment 3, φ 10 round steel rolling mill guide plate surface alloyings

Add the molybdenum-iron powder with medium carbon ferrochrome and carry out surface alloying, replace former WC-8%Co carbide alloy to insert.

The guide plate size: it is 60 * 30 millimeters places that 280 * 90 * 25 millimeters guide plate point planes amass, originally being YG8(WC-8%Co) carbide alloy inserts, bear high temperature wear and chilling and shock heating during work, life-span is short, the present invention adds the molybdenum-iron powder with medium carbon ferrochrome and carries out surface alloying at this position and replace former carbide alloy and insert, improve 3～5 times service life, shop, most advanced and sophisticated position powder thickness is 5 millimeters.

The alloy powder particle composition, form:

Medium carbon ferrochrome (Cr content is 68.25%, and C content is 5.9%, and Si content is 1.1%): 90%;

Molybdenum-iron (Mo content is 55%, and C content is 0.2%, and Si content is 1%): 10%;

Alloy powder particle granularity: 70/140 order;

Guide plate mother metal: ZG25;

After operation sequence has been made guide plate mo(u)ld bottom half (casting mold vacuum is-580 millimetress of mercury) with aforementioned vacuum sealed molding method, on the acetic acid-ethylene polymer film at 60 * 30 millimeters positions, the most advanced and sophisticated position of guide plate, use the needle plate acanthopore, the aperture is 1.15 millimeters of φ, pitch-row is 15 millimeters, behind the acanthopore, with above-mentioned medium carbon ferrochrome and molybdenum-iron powder, put on the film of acanthopore the shop, thickness is 5 millimeters, with another piece area is 80 * 50 millimeters, thickness is that 0.075 millimeter vinyl acetate polymer film cover is on powder, place one on the film with the wooden bisque shaped device identical with guide plate tip end surface shape, push down gently, then with around gummed paper or the binding agent sealing film, make it become sealant, take out the deposited bisque of putting of bisque shaped device inspection and after sealing, consolidation hardness should be arranged, so far mo(u)ld bottom half is made, the top box that closes at last is that 1580 ℃ ZG25 molten steel pours into die cavity with temperature, cuts off the vacuum of casting mold after 20 minutes, unpack after 4 hours, cutting dead head in cooling back is heat-treated, and guide plate is heated to 950 ℃ of insulations 2 hours, air cooling, case hardness can reach HRC66.

The cylindrical mold inner surface alloying of embodiment 4, compacting SiC emery wheel base

The mould outside diameter is 283 millimeters of φ, and inner diameter is 253 millimeters of φ, and the mould height is 120 millimeters.

Mold base material material: ZG45;

Alloy powder particle becomes to be grouped into: high carbon ferro-chrome (Cr content is 65%, and C content is 8.6%, and Si content is 1.2%): 100%;

Alloy powder particle granularity: 70/140 order;

Alloy powder particle shop powder thickness: 3 millimeters.

Operation sequence is with the moulding of aforementioned vacuum sealed molding method, casting technique is taked two-part mo(u)lding, top box constitutes the external form of mould, the cylindrical close-over of nowel constitutes the inwall of mould, (diameter is 253 millimeters of φ at the cylindrical close-over of mo(u)ld bottom half, height is 120 millimeters) acetic acid-ethene polymers plastic sheeting on, with the aperture of needle plate thorn with 0.15 millimeter of diameter phi, 25 millimeters of pitch-rows, (diameter is 259 millimeters of φ with prefabricated cylindrical shape, length is 160 millimeters) acetic acid-ethene polymers plastic sheeting (thickness is 0.075 millimeter), (external diameter is 269 millimeters to overcoat with plastic alloy power layer shaping device, internal diameter is 259 millimeters, height is 120 millimeters), be enclosed within cylindrical close-over film outside together, 20 millimeters of reel like film lower ends are bonded on the casting mold with gummed paper or plastic sheeting, cling sealing, then, in the middle of double-layer films, fill 70/140 purpose high carbon ferro-chrome powder from the upper end, to use diameter be the steel wire tamping alloy powder particle gently of 2 millimeters of φ while filling out, after filling up 120 millimeters high toroidal cavities, 20 millimeters the film envelope that rapidly upper end is grown close-over is tightly on close-over end face film, simultaneously, film is bondd, good seal, because the alloy powder particle between the double-layer films is in sealing state, the acanthopore of internal layer membrane is communicated with negative pressure (580 millimetres of mercury) in the casting mold, so bisque is consolidation and certain surface hardness is arranged immediately, take out alloy powder particle cylindrical shape shaped device, check integrated degree and the case hardness that put the bisque shop.So far, made mo(u)ld bottom half, with the mo(u)ld top half mould assembling of making, after adding foundary weight, water the molten steel with ZG45, the in advance necessary deoxidation of molten steel is good, spread slag, pour into a mould the vacuum of cutting off the casting mold conduit in back 20 minutes, unpack after 4 hours, dead head is removed in the cooling back, heat-treats, and foundry goods is heated to 950 ℃, be incubated 2 hours, air cooling, pressing mold inner surface hardness can reach HRC67, inner surface is bright and clean, only needs grinding, can reach the requirement size.

Claims (8)

1, a kind of vacuum sealed molding metal surface combination technological method, promptly (vacuum is in the type :-400～-650 millimetress of mercury at the vacuum condition that is in that uses the vacuum seal method to be made, on the surface of casting mold mmHg) (1), certain thickness doing put in the shop, diffusing shape contains bronze grain (4), to go up, the mo(u)ld bottom half mould assembling, pour into base metals liquid, it is characterized in that this alloy powder particle (4) shop puts on the sealing film (2) that has stung equably disperseing with needle plate, then, the metal powder formable layer device (6) that also will have controlled alloyage powder layer thickness function at another film of covering (5) on the described alloy powder layer fast places on the film (5), with described film and casting mold adhering and sealing, make the metal bisque be in original vacuum again, take out this metal powder formable layer device.

2,, it is characterized in that casting mold pressure the best of described vacuum condition is :-500～-620 millimetress of mercury (mmHg) according to the described process of claim 1.

3,, it is characterized in that described film is acetic acid-ethene polymers plastic sheeting according to claim 1,2 described processes.

4, according to claim 1,2 described processes, it is characterized in that described doing, consisting of of bulk alloy powder: high carbon ferro-chrome (the Cr:65% 100%(percentage by weight), C:8.6%, Si:1.2%), or 100% medium carbon ferrochrome (Cr:68.25%, C:5.0～6.0%, Si:1.1%), or the molybdenum-iron (Mo:55% of 90～96% medium carbon ferrochrome and 4～10%, C:0.2%, Si:1%), or the vanadium iron (V:48% of 90～95% medium carbon ferrochrome and 5～10%, C:1%, Si:2.09%), or 100% casting WC, or 40～50% casting WC and 50～60% medium carbon ferrochromes, or tungsten slag ferroalloy (W:4.5～7.5% of 50～90% high carbon ferro-chrome and 10～50%, Mn:14～20%, Nb:0.5～0.6%, Ta:0.16～0.22%, Ti:0.12～0.16%, C:5.5～6.2%, Si:0.12～0.7%, Fe:65～7(%), or the tungsten slag ferroalloy of 50～70% WC and 30～50%, or 100% SiC.

5, according to the described process of claim 1, it is characterized in that described alloy powder particle is through after pre-alloyed, fragmentation, levigate or in fragmentation, by its composition, proportion of composing mixes in the levigate process.

6, according to the described process of claim 4, it is characterized in that its granularity of alloy powder particle that fusing point is lower than the molten metal fusing point is: 40～140 orders and 100～200 orders, fusing point is higher than the alloy powder particle of molten metal fusing point, as WC etc., its granularity is: 28～40 orders, 40～100 orders.

7, according to the described process of claim 1, it is characterized in that its shape of described alloy power layer shaping device decides according to the shape of foundry goods alloy surface, use plastic material, metal material or other material are manufactured.

8, according to the described process of claim 1, it is characterized in that heat-treating with the part and component behind the ferrochrome surface alloying, heating-up temperature is 920～980 ℃, temperature retention time is 2～3 hours, then air cooling.

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