A kind of method of large-area laser cladding high rigidity nickel-bass alloy material
Technical field:
The invention belongs to the material surface engineering field, particularly relate to a kind of method of using laser melting and coating technique big area cladding high hardness wear-resisting ni-resist base alloy material on metallic matrix.
Background technology:
It is the important means of material surface modifying and novel material preparation that material surface is handled, and countries in the world are all attached great importance to this.Development of modern industry improves day by day to the requirement of material surface modifying and optimization.Country's 863 high-tech programs are handled new technology to the development material surface as a key areas of future development from the beginning.In numerous process for treating surface, laser melting and coating technique is an emerging advanced person's surface treatment technology of material, and along with constantly improving of this technology developed, be widely used in further in the modern processing manufacturing industry, especially broad further in the application of key areas such as space flight, metallurgy, electric power, petrochemical industry, automobile, military project, in the manufacturing of product and brought into play vital role in the manufacturing processed again.Compare with conventional surface treatment technology such as flame (plasma) spraying, built-up welding, plating etc., laser melting and coating technique has coating structure refinement densification, matrix heat affected zone and is out of shape little, coating and matrix can be realized firm metallurgical binding, easily be automated control, the coating advantage such as controlled attractive in appearance that is shaped.Laser melting and coating technique relates to the content of laser processing technology, metallic substance science, programming simulation, mechanical workout and processing control method aspects such as (as processing sequence, thermal treatments etc.), related all respects must be unified scientific and reasonable, in order in phase just can reach desirable cladding effect, not so just can cause cladding layer cracking, pore, be mingled with, the generation of mass defect such as undercut, even workpiece is scrapped, stop production, serious consequence such as security incident.
For guarantee the nuclear power facility continuously, safety, steady running, each parts related material property, working method and treatment process in the processing and manufacturing process proposed the requirement of stricter harshness.As for nuclear power water pump axle sleeve, its material is 1Cr18Ni9Ti, is of a size of ¢ 240 * 200mm, wall thickness 25mm, though matrix has certain corrosion resisting property, hardness is very low, wears no resistance, and can not directly use.People such as Chen Qiang, You Qingzhao has carried out studying that { 2000Vol.12 No.2 P.33-35} to see " steel research journal " to the hardness and the wear resistance that strengthen the high-density alloy surface, it selects Ni60A and the superhard powder of WC, WC-Co for use, adopt two kinds for the treatment of processs of plasma spraying and vacuum sintering, obtained the wear-resistant coating of high rigidity at metal base surface.But all there is very big defective in the coating of above-mentioned two kinds of methods preparation, easily peels off, exists crackle etc. as porosity height, non-metallurgical binding, coating.Appoint the patriotic people of grade that the laser melting coating crack arrest technique has been carried out studying { seeing " sufacing " the 35th volume second phase }, seven kinds of basic materials and different cladding powdered materials such as 1Cr18Ni9Ti, 45 steel, 40Cr are selected in test for use, the result shows, when cladding material is Ni60, Ni45, Ni35, the cladding layer crackle is difficult to control, and particularly Ni60 cladding powder crackle is uncontrollable.Even to this day, the cracking problem of high hardness wear-resisting nickel-base alloy laser melting coating is still a stubborn problem, especially big area cladding, thickness when 1mm is above and do not crack, defect problem such as pore yet there are no report so far.
Summary of the invention:
The object of the present invention is to provide a kind of method of large-area laser cladding high hardness wear-resisting nickel-bass alloy material, in order to solve the cracking problem of the existing a series of problems of conventional surface treatment technology and existing laser melting coating high rigidity nickel-base alloy, especially at big area cladding, thickness when 1mm is above, very easily crack, defect problem such as pore.
Technical scheme of the present invention is:
A kind of method of large-area laser cladding high rigidity nickel-bass alloy material is used laser melting and coating technique, and the employing powder feed system in metal base surface, forms the nickel-bass alloy material coating of the anti-corrosion nothing shortcoming of high hardness wear-resisting with the cladding of high rigidity powdered material.Wherein:
(1) the laser processing technology parameter is: laser power 2.5-6.0KW, sweep velocity 180-800mm/min, spot diameter 3.0-5.0mm, overlapping rate 30-40%, cladding thickness 1.0-2.0mm;
(2) heat treating method is: 200-300 ℃ of workpiece preheating temperature in early stage, 1-2 hour heat-up time; The heat tracing temperature is 300 ℃ ± 20 ℃ in the laser cladding process; Follow-up 200 ℃ ± 20 ℃ insulations of process finishing 3-5 hour and furnace cooling are to room temperature.
The method of described large-area laser cladding high rigidity nickel-bass alloy material, work flow is as follows:
(1) workpiece surface cleaning: before cladding, with sand paper or polishing machine dirt, the oxide film of workpiece surface are removed, with acetone that the workpiece surface oil removal is clean again;
(2) workpiece thermal pretreatment: after workpiece surface has been cleared up, adopt heating and heat-insulating device that workpiece is carried out thermal pretreatment, preheating temperature 200-300 ℃, 1-2 hour heat-up time;
(3) cladding processing: after the workpiece substrate temperature reaches preheating temperature, it is carried out laser melting coating processing;
(4) heat tracing is handled: in the cladding course of processing, adopt heating and heat-insulating device that workpiece is carried out heat tracing all the time and handle, temperature is controlled at 300 ℃ ± 20 ℃;
(5) follow-up insulation slow cooling is handled: after the workpiece cladding finishes, put it in the resistance furnace of 200 ℃ ± 20 ℃ of furnace temperature insulation immediately 3-5 hour, and furnace cooling is to room temperature.
The method of described large-area laser cladding high rigidity nickel-bass alloy material, the high rigidity powdered material is Ni-based, iron-based or Co-based alloy powder, granularity is at the 80-500 order, and this powdered material coating hardness is up to 58-63HRC behind laser melting coating, and cladding layer does not have the cladding shortcoming.
The method of described large-area laser cladding high rigidity nickel-bass alloy material, the high rigidity powdered material is the Ni60A nickel base self-fluxing alloy powder, the powdered alloy granularity: 140-320 order, fusing point 960-1040 ℃.
The method of described large-area laser cladding high rigidity nickel-bass alloy material, by weight percentage, Ni60A ni-based self-fluxing alloy composition and content are: C1.0%, Si4.0%, B3.5%, Cr17.0%, Fe<5%, Ni surplus.
The method of described large-area laser cladding high rigidity nickel-bass alloy material adopts the bath temperature proofing unit that the laser molten pool temperature is detected in real time, regulates; Adopt heating and heat-insulating device that workpiece is carried out preheating and the processing of cladding process heat tracing.
The method of described large-area laser cladding high rigidity nickel-bass alloy material; powder feed system adopts gas to carry formula powder feeder or scraper plate gravity type boat davit powder feeder; automatic powder feeding system be side direction synchronously, preset powder feeding or coaxial powder-feeding, powder feed system adopts argon gas to carry powder also to protect the molten bath.
The method of described large-area laser cladding high rigidity nickel-bass alloy material, laser equipment is CO
2Gas laser, YAG laser apparatus, semiconductor laser or optical fiber laser.
Design philosophy of the present invention is:
The present invention and is equipped with scientific and reasonable technology, material and method on the basis of the laser melting and coating technique of application of advanced, on the basis of repetition test, analysis, invented a kind of large-area laser and do not had the method for splitting cladding high rigidity nickel-bass alloy material.Laser processing technology parameter of the present invention is: laser power 2.5-6.0KW, and sweep velocity 180-800mm/min, about spot diameter 3.0-5.0mm, about overlapping rate 30-40%, cladding thickness 1.0-2.0mm; Heat treating method of the present invention is: preheating, insulation and follow-up insulation slow cooling measure, namely earlier workpiece is carried out 200-300 ℃ thermal pretreatment, carry out cladding processing then, in cladding process, by heating and heat-insulating device workpiece temperature is controlled all the time in 300 ℃ ± 20 ℃ that set, after the course of processing finishes, immediately workpiece is sent into furnace temperature and is in 200 ℃ ± 20 ℃ the resistance furnace insulation 3-5 hour and furnace cooling to room temperature.The laser technical parameters of optimizing and to the regulation and control of bath temperature, can guarantee the stable, consistent of cladding quality, avoid cladding generation of defects such as crackle, pore, and farthest reduce body material to the diluting effect of coated material, thereby guarantee the performance of coated material composition and high rigidity and wear-and corrosion-resistant.Being worked into last follow-up insulation slow cooling from workpiece preheating, cladding handles, to the monitoring of workpiece substrate temperature and regulate and control most important, and temperature will so also can fundamentally prevent workpiece and crack in cladding process or in the cladding process end process of cooling in the scope that technology allows.Adopt the present invention, can the big area cladding have extreme hardness, the nickel-base alloy powder powder material wear-resisting, that corrosion resisting property is good, obtain the firmly cladding layer of metallurgical binding of low dilution rate (below 10%), and it is worth noting, cladding layer and matrix flawless, pore, be mingled with, mass defect such as undercut.These all be conventional surface treatment technology and common laser melting and coating technique can not reach or all reach.
The present invention can bring following beneficial effect:
1) the cladding layer hardness of the present invention's preparation can reach 58-63HRC, and wear and corrosion behavior is good;
2) the present invention can obtain large-area cladding thickness at flawless, the pore of 1-2mm, be mingled with, the cladding layer of mass defect such as undercut, the area of cladding layer reaches 1500cm
2About, and cladding layer dense structure, grain refining, performance gains such as anti-corrosion strengthens;
3) the present invention can realize the metallurgical binding that coating and matrix are firm, and coating can not peeled off, and can effectively reduce the thinning ratio of matrix, generally below 10%;
4) the present invention can significantly improve the work-ing life of workpiece, society, remarkable in economical benefits.After adopting the present invention that the nuclear power axle sleeve is handled use, the life-span has improved more than 2 times, and so far still in good operation;
5) operation is simple for each unit of the present invention, and technology and method applicability are strong, can realize automatic control;
6) method of the present invention has epitaxy and extendability widely, and expansion, the application in other field has certain reference that instructs to laser melting and coating technique.
Description of drawings:
Fig. 1 is laser melting coating flow process chart of the present invention.
Fig. 2 is laser melting coating processing unit (plant) synoptic diagram of the present invention.Among the figure, 1 laser equipment; 2 bath temperature proofing units; 3 powder feed systems; 4 chucks; 5 heating and heat-insulating devices; 6 workpiece; 7 cladding layers; 8 resistance furnaces; 9 side direction powder-feeding heads.
Fig. 3 is the metallograph of embodiment 1.
Fig. 4 is the metallograph of embodiment 2.
Embodiment:
As shown in Figure 1, the present invention uses laser melting and coating technique, adopt powder feed system with the cladding of high rigidity powdered material big area in metal base surface, form the anti-corrosion Ni-based alloy coating material of high hardness wear-resisting, realize cladding layer and matrix metallurgical binding firm, low dilution rate, and can guarantee cladding layer flawless, pore, mass defect such as be mingled with.Workpiece laser cladding work flow, concrete steps are as follows:
1, workpiece surface cleaning: before cladding, with removals such as the dirt of workpiece surface, oxide films, workpiece surface greasy dirt etc. is removed clean with acetone with sand paper or polishing machine again;
2, workpiece thermal pretreatment: after workpiece surface has been cleared up, adopt heating and heat-insulating device that workpiece is carried out thermal pretreatment, preheating temperature 200-300 ℃, reduce the temperature difference between matrix and cladding layer 1-2 hour heat-up time, prevent cracking;
3, cladding processing: after the workpiece substrate temperature reaches preheating temperature, it is carried out laser melting coating processing:
(1) processing parameter of laser melting coating processing is: laser power 2.5-6.0KW, sweep velocity 180-800mm/min, spot diameter 3.0-5.0mm, overlapping rate 30-40%, cladding thickness 1.0-2.0mm.
(2) high rigidity cladding powdered material adopts Ni-based, iron-based or Co-based alloy powder, and granularity is at the 80-500 order, and this powdered material coating hardness is up to 58-63HRC behind laser melting coating, and coating does not have the cladding shortcoming.
(3) powder feed system adopts gas to carry formula powder feeder or scraper plate gravity type boat davit powder feeder, automatic powder feeding system be side direction synchronously, preset powder feeding or coaxial powder-feeding, powder feed system adopts argon gas to carry powder also to protect the molten bath.
(4) laser equipment is CO
2Gas laser, YAG laser apparatus, semiconductor laser or optical fiber laser.
4, heat tracing is handled: in cladding process, adopt heating and heat-insulating device that workpiece is carried out heat tracing all the time and handle, temperature is controlled at 300 ℃ ± 20 ℃.
5, follow-up insulation slow cooling is handled: after cladding finishes, immediately workpiece is put into resistance furnace insulation 3-5 hour of 200 ℃ ± 20 ℃ of furnace temperature, and furnace cooling eliminates stress to room temperature, prevent distortion and cracking.
As shown in Figure 2, the laser melting coating processing unit (plant) mainly comprises: laser equipment 1, bath temperature proofing unit 2, powder feed system 3, chuck 4, heating and heat-insulating device 5, workpiece 6, side direction powder-feeding head 9 etc.The side direction powder-feeding head 9 of powder feed system 3 is corresponding with workpiece 6, and the laser output of laser equipment 1 and bath temperature proofing unit 2 are corresponding with workpiece 6 respectively, and workpiece 6 is installed on the chuck 4, and heating and heat-insulating device 5 is arranged at workpiece 6 bottoms.
Course of processing concrete steps of the present invention are described as follows:
(1) enables 5 pairs of workpiece of heating and heat-insulating device 6 and carry out thermal pretreatment;
(2) enable laser equipment 1 and powder feed system 3, the high rigidity powdered material is from side direction powder-feeding head 9 output of powder feed system 3 and send into the laser molten pool on workpiece 6 surfaces, finishes the big area cladding processing to workpiece 6 on the chuck 4, forms cladding layer 7;
(3) enabling 2 pairs of bath temperatures of bath temperature proofing unit detects, regulates; Adopt 5 pairs of workpiece of heating and heat-insulating device 6 to carry out heat tracing and handle, temperature is controlled in specialized range;
(4) after the cladding process finishing, utilize 8 pairs of workpiece 6 of chamber type electric resistance furnace to carry out follow-up insulation slow cooling immediately and handle.
Among the present invention, heating and heat-insulating device 5 has following characteristics:
1) can heat workpiece, and Heating temperature can reach 600 ℃;
2) device has thermal insulating warm-keeping layers such as refractory brick, asbestos, and workpiece is had heat insulation function;
3) this heating unit has the temperature control regulatory function, can set, detect, regulate temperature.
Embodiment 1:
For solving certain Nuclear power plants pump shaft cover (material 1Cr18Ni9Ti, be of a size of ¢ 240 * 200mm, wall thickness 25mm) erosion corrosion problem determine to adopt the present invention to carry out the processing treatment of the anti-corrosion ni base alloy coating of high hardness wear-resisting in the sleeve outer circle perimeter surface, and is specific as follows:
1) laser processing technology is: laser power 2.5KW, and sweep velocity 180mm/min, spot diameter 3.0mm, overlapping rate 40%, cladding thickness 2.0mm, cladding powdered material are Ni60A.
2) heat treating method is: 300 ℃ of workpiece preheating temperatures, 2 hours heat-up times, the resistance furnace that 300 ℃ ± 20 ℃ of heat tracing temperature, process finishing are put into 200 ℃ ± 20 ℃ of furnace temperature at once in the cladding process carries out insulation in 5 hours and furnace cooling to room temperature.
In the present embodiment, adopting gas to carry the formula synchronous side and carries powder to automatic powder feeding system, is carrier gas with the argon gas, with powder continuously, stable, send into laser molten pool equably, used argon gas also plays the certain protection effect to the molten bath;
In the present embodiment, adopt the high-power crossing current CO of 6KW
2Laser equipment is as source for cladding, and the output laser beam mode is multimode, in the cladding process laser molten pool temperature is monitored in real time, and keeps the stability of bath temperature by the adjusting laser power;
In the present embodiment, adopt Ni-based high hardness wear-resisting non-corrosive metal powder Ni60A as the laser melting coating material, as shown in Figure 3, cladding layer is that proeutectic tissue (strengthening phase) is grown with the dentrite form, organize mainly by FeNi3, Ni2Si and γ phase composites such as (Fe-Ni), also contain Cr6.5Ni2.5Si in the coating, intermetallic compound and Ni3Si2CrB2 such as Cr2Ni3B6Cr3Ni2, compounds such as Cr3C2CrB, these compound hardness very high diffusive are distributed on the coating, this tissue characteristic makes coating have good wear and corrosion behavior, can satisfy the working condition requirement of axle sleeve well;
In the present embodiment, the laser melting coating material is the Ni60A nickel base self-fluxing alloy powder, and it has following characteristics:
1) this self-melting alloy wear and corrosion behavior is good, and extreme hardness can reach HRC58-63;
2) this powdered alloy granularity: 140-320 order; Fusing point 960-1040 ℃;
3) alloying constituent and content (weight percent) are:
Composition |
C |
Si |
B |
Cr |
Fe |
Ni |
Content |
1.0% |
4.0% |
3.5% |
17.0% |
<5% |
Bal |
As shown in Figure 3, the Nuclear power plants pump shaft cover of present embodiment has obtained good cladding effect, defectives such as flawless, pore, and axle sleeve use properties and life-span significantly improve, and hardness reaches 59-63HRC, improves 2 times and still in good operation work-ing life.
Embodiment 2:
Difference from Example 1 is:
Certain drift material is the H13 steel, for improving high temperature resistance wearing and tearing and the cold and hot fatigue property of drift, adopts the present invention that the laser melting coating intensive treatment is carried out on its surface:
1) laser power 6.0KW, sweep velocity 800mm/min, spot diameter 5.0mm, overlapping rate 30%, cladding thickness 1.0mm, cladding powdered material are Ni60A;
2) the workpiece preheating temperature is 200 ℃, 1 hour heat-up time; Heat tracing is 300 ℃ ± 20 ℃ in the cladding process; Process finishing at once workpiece is put into 200 ℃ ± 20 ℃ furnace temperature carry out 3 hours the insulation and furnace cooling to room temperature.
As shown in Figure 4, coating structure is typical rapid solidification tissue, the tiny densification of crystal grain, cladding layer has formed excellent metallurgical with matrix and has been combined, the tissue of cladding layer mainly by FeNi3, Ni2Si and γ phase composites such as (Fe-Ni), exists a large amount of cocrystalization compounds between dentrite, black region contains a large amount of intermetallic compounds such as alloyed cementite, by the acting in conjunction of solution strengthening, hard phases strengthening, dispersion-strengthened and refined crystalline strengthening, make coating structure obtain good strengthening effect.The drift of present embodiment effect after the laser melting coating intensive treatment is fine, claddings such as coating and matrix flawless, pore shortcoming, and hardness reaches 58-62HRC, uses on the machine the life-span raising more than 1 times.
The result shows, adopt the method for the invention, can fundamentally guarantee stability, the consistence of laser melting coating, generation of defects such as avoid crackle, pore and be mingled with, reduce the matrix heat affected zone, reduce thinning ratio, obtain the high abrasion of the grain refining densification of firm metallurgical binding, anti-corrosion ni base alloy coating tissue, hardness reaches 58-63HRC, and workpiece can improve more than 1-2 times after treatment work-ing life.