CN115652136B - Free-cutting copper-nickel-silicon bar and preparation method thereof - Google Patents
Free-cutting copper-nickel-silicon bar and preparation method thereof Download PDFInfo
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- 238000005520 cutting process Methods 0.000 title claims abstract description 46
- ZUPBPXNOBDEWQT-UHFFFAOYSA-N [Si].[Ni].[Cu] Chemical compound [Si].[Ni].[Cu] ZUPBPXNOBDEWQT-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 30
- 239000010949 copper Substances 0.000 claims abstract description 23
- 239000011159 matrix material Substances 0.000 claims abstract description 22
- 239000012535 impurity Substances 0.000 claims abstract description 3
- 238000001125 extrusion Methods 0.000 claims description 38
- 238000005266 casting Methods 0.000 claims description 37
- 238000000034 method Methods 0.000 claims description 30
- 238000012545 processing Methods 0.000 claims description 29
- 239000000463 material Substances 0.000 claims description 23
- 239000006104 solid solution Substances 0.000 claims description 21
- 230000032683 aging Effects 0.000 claims description 20
- 238000001816 cooling Methods 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 9
- 238000004321 preservation Methods 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000003723 Smelting Methods 0.000 claims description 4
- 239000000498 cooling water Substances 0.000 claims description 3
- 238000005728 strengthening Methods 0.000 abstract description 19
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 abstract description 10
- 229910052802 copper Inorganic materials 0.000 abstract description 10
- 229910052759 nickel Inorganic materials 0.000 abstract description 6
- 229910045601 alloy Inorganic materials 0.000 description 39
- 239000000956 alloy Substances 0.000 description 39
- 230000000694 effects Effects 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 10
- 239000000047 product Substances 0.000 description 8
- 230000008023 solidification Effects 0.000 description 8
- 238000001556 precipitation Methods 0.000 description 7
- 238000007711 solidification Methods 0.000 description 7
- 229910017876 Cu—Ni—Si Inorganic materials 0.000 description 6
- PTVDYARBVCBHSL-UHFFFAOYSA-N copper;hydrate Chemical compound O.[Cu] PTVDYARBVCBHSL-UHFFFAOYSA-N 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 229910000881 Cu alloy Inorganic materials 0.000 description 4
- 238000005336 cracking Methods 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000005482 strain hardening Methods 0.000 description 3
- 230000035882 stress Effects 0.000 description 3
- 238000000137 annealing Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 229910052745 lead Inorganic materials 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012805 post-processing Methods 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 229910018030 Cu2Te Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 229910001215 Te alloy Inorganic materials 0.000 description 1
- 238000007545 Vickers hardness test Methods 0.000 description 1
- GFAWQOJYGFJWNJ-UHFFFAOYSA-N [Bi].[Zn].[Cu] Chemical compound [Bi].[Zn].[Cu] GFAWQOJYGFJWNJ-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000001668 ameliorated effect Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000011856 silicon-based particle Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000011895 specific detection Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a free-cutting copper-nickel-silicon bar, which is characterized in that: the copper nickel silicon comprises the following components in percentage by mass: 3.5 to 5.5 percent, si: 0.7-1.5%, te:0.1 to 1.0 percent, P:0.01 to 0.1 percent, mn:0 to 0.2 percent, mg:0.05 to 0.2 percent, and the balance of Cu and unavoidable impurities. Ni, si, te, P, mn, mg is added to copper matrix and the addition amount is controlled, and delta-Ni is contained in matrix 2 Si strengthening phase and NiP strengthening phase, the strength of the matrix is improved, the conductivity of the matrix is not reduced, and Cu is contained in the matrix 2 Te cutting phase, improving cutting property of the matrix, and finally realizing that the tensile strength of the copper-nickel-silicon bar is more than or equal to 750MPa, the yield strength is more than or equal to 700MPa, the elongation is more than or equal to 2%, the conductivity is more than or equal to 25% IACS, the hardness HV is more than or equal to 260, and the cutting index is more than 80% of C36000.
Description
Technical Field
The invention belongs to the technical field of copper alloy, and particularly relates to a free-cutting copper-nickel-silicon bar and a preparation method thereof.
Background
The high-strength high-conductivity copper alloy is an important material applied to the high and new fields in the future, and the basic principle of the design of the high-strength high-conductivity copper alloy is that the alloy element with low solid solubility is added into a copper matrix, and the alloy element forms supersaturated solid solution in the copper matrix through high-temperature solution treatment. After the subsequent aging treatment, the supersaturated solid solution is decomposed, and the alloy elements in solid solution are separated out from the copper matrix in the form of a precipitation phase, so that the strength and the conductivity of the alloy are improved.
Wherein Cu-Ni-Si series is used as a precipitation strengthening alloy, and dispersed delta-Ni 2 Si particles can be dissolved in solutionThe alloy is effectively separated out from the heat treatment matrix, the strength of the material is greatly improved, and the alloy has good conductivity. At present, the main brands of Cu-Ni-Si series alloys are C70250, C70260, C19010, C19005 and the like, wherein the contents of Ni and Si in the C70250 series are higher, and the mass ratio of Ni to Si is controlled to be about 4:1, so that delta-Ni is precipitated in the C70250 series under the same process condition 2 The number of the Si strengthening phases is more than that of other brands, and the highest tensile strength of the material can reach more than 800MPa stably.
However, the Cu-Ni-Si alloy bars have the problem of poor cutting performance, and especially the strength of the material is further improved after work hardening and aging strengthening. Because no free cutting phase exists in the alloy tissue, the cutting resistance of the material is extremely high, the cutter is seriously damaged, and the service life of the cutter is seriously reduced, so that the cutting processing rate is required to be set very slowly, and the production efficiency is influenced. In order to improve the cutting performance of the material, a certain amount of free-cutting elements must be added, but the negative effect is that the cold and hot workability of the alloy is reduced and the mechanical property is reduced. If the prior conventional process is adopted, the negative effects are particularly remarkable, and the high strength and the free cutting performance cannot be achieved at the same time. Therefore, to achieve high strength and free cutting properties, the alloy composition must be optimized and the processing technique adjusted to minimize the above negative effects.
Aiming at the problems, the free-cutting alloy copper-nickel-silicon bar is developed on the basis of Cu-Ni-Si series components, the formation of a free-cutting phase is promoted on the premise of not remarkably reducing the alloy strength and the conductivity by optimizing the alloy element components, and meanwhile, the cold-hot processing and the heat treatment process are optimized, so that the free-cutting alloy copper-nickel-silicon bar has the Cu-Ni-Si series high-strength high-conductivity and good cutting processing performance.
Disclosure of Invention
The invention aims to provide a free-cutting copper-nickel-silicon bar with the advantages of strength, conductivity and cold-hot processability.
The second technical problem to be solved by the invention is to provide a preparation method of a free-cutting copper-nickel-silicon bar.
The invention solves the first technical problem by adopting the technical scheme that: the utility model provides a free-cutting copper nickel silicon rod which characterized in that: the copper nickel silicon comprises the following components in percentage by mass: 3.5 to 5.5 percent, si: 0.7-1.5%, te:0.1 to 1.0 percent, P:0.01 to 0.1 percent, mn:0 to 0.2 percent, mg:0.05 to 0.2 percent, and the balance of Cu and unavoidable impurities.
The invention is based on Cu-Ni-Si alloy series, wherein Ni element and Si element are used as main additive elements to promote delta-Ni 2 The formation of Si precipitation strengthening phase ensures that the material has high strength and high conductivity. The lower limit of Ni content is controlled to be more than 3.5%, on one hand, ni element can be dissolved in Cu matrix in a solid solution manner, thereby realizing good solid solution strengthening effect, and on the other hand, delta-Ni is ensured 2 The quantity of the Si precipitation strengthening phase is formed, and a good precipitation strengthening effect is achieved. The upper limit of Ni element is controlled to be more than 5.5%, so as to avoid deteriorating the processing performance of the alloy, if the Ni content is too high, the required extrusion force is greatly improved, and the extruded blank is easy to generate transverse cracks. Meanwhile, the difficulty of the alloy solid solution process is increased, the blank after solid solution treatment has high hardness and low plasticity, and the subsequent cold processing treatment cannot be normally performed. The addition amount of Si element is related to the Ni content, and the mass ratio of Ni/Si is controlled within the range of 4-5 so as to obtain the optimal mechanical property and conductivity. If the Si content is too high, on one hand, the brittleness of the material is increased, the post-processing plasticity is reduced, and on the other hand, the conductivity of the alloy is reduced.
The Te element is added to improve the cutting performance of the material, and has extremely low solubility in Cu, namely Cu 2 The Te phase is dispersed in the grain boundary, and the stress field strength is low, so that the alloy maintains good conductivity. Compared with other free-cutting Pb, bi, S and other elements, the addition of Te element does not obviously reduce the mechanical property and the processing plasticity of the alloy. Although the Pb, bi and S elements can improve the cutting performance of the material to a certain extent, the brittleness of the material is remarkably increased, good cold and hot working plasticity cannot be obtained, and the strength of the material is greatly reduced along with the increase of the addition amount of the elements. In order to obtain good mechanical conductivity comprehensive performance and cutting performance, the addition amount of Te element is controlled within the range of 0.1-1.0%.
The addition of the P element mainly promotes the formation of a NiP compound, and the NiP compound can further improve the material strength as a precipitated phase. Meanwhile, the content range of P needs to be strictly controlled, if the content of P is too high, the conductivity and the processing plasticity of the material are obviously reduced, and therefore, the addition amount of the P element is controlled within the range of 0.01-0.1%.
The Mn element is added to improve the fatigue strength of the material so as to further improve the service life of the material. If the Mn element is added too high, the viscosity of the copper water is increased in the smelting process, the fluidity is poor, and copper oxide slag is easy to form. Therefore, the addition amount of Mn element in the present invention is controlled to be in the range of 0 to 0.2%, preferably 0.01 to 0.2%.
The Mg element is added to improve the quality of cast ingot, and because the alloy disclosed by the invention is high in casting temperature, copper water is easy to suck in the solidification process to form defects such as looseness and air holes. The above problems can be effectively ameliorated by the addition of Mg element. Meanwhile, trace Mg element is added, so that the cutting processability of the material is improved, and the addition amount of the Mg element is controlled to be in the range of 0.05-0.2%.
Preferably, the microstructure of the copper-nickel-silicon contains a matrix phase and a second phase, the second phase comprising delta-Ni 2 Si phase, niP phase and Cu 2 Te phase, delta-Ni 2 Average size range of Si phase: 0.01-0.5 mu m, the area ratio is 0.5-5%, and the average size range of the NiP phase is: 0.05-1 mu m, the area ratio is 0.1-2%, cu 2 Average size range of Te phase: 5-10 mu m, and the area ratio is 5-20%. On the premise of a certain content of the added element, the smaller the size of the precipitated phase, the more the distribution quantity of the precipitated phase, and the more remarkable the improvement of the mechanical property, the conductivity and the cutting effect. Conversely, the larger the size of the precipitated phase, the smaller the distribution amount, and the improvement in the performance is not remarkable. delta-Ni 2 Si phase and NiP are both reinforcing phases, if the area ratio is small, the reinforcing effect is not obvious, if the area is increased, the cold deformation plasticity of the alloy is poor, the alloy is easy to generate tensile deformation cracking, and normal processing cannot be performed. Cu (Cu) 2 The Te phase belongs to the free cutting phase, and if the area ratio is small, the cutting performance cannot meet the requirements. If the area ratio is too large, the alloy has poor hot working plasticity, and cannot be prepared by a normal extrusion processing technology.
The invention solves the second technical problem by adopting the technical proposal that: a preparation method of a free-cutting copper-nickel-silicon bar is characterized by comprising the following steps: the process flow comprises smelting, casting, extruding, intermediate stretching, aging and finished product stretching; the casting temperature: 1200-1300 ℃, and the casting speed is: the temperature of the ingot casting crystallizer is 600-800 ℃ at 20-50 mm/min.
The alloy is added with Ni, si, mn, te, P and other elements simultaneously on the basis of a copper matrix, the heat conduction performance is general, the solidification and crystallization rate of the alloy is slower in the solidification process, after the outer layer of an ingot is solidified, the central part is still likely to be liquid, and the addition amount of Ni and Si elements is larger, so that the alloy is extremely easy to generate casting stress in the casting process, transverse central epitaxial cracks are easily generated in the ingot, after Te elements are added on the basis of Ni and Si components, brittle phases are formed and easily aggregated to form a large-area brittle area, the brittle cracking tendency of the material is increased, the cracking of the ingot is caused, the probability of cold separation phenomenon is greatly increased, after Mn elements are additionally increased, the heat conduction performance of the alloy is further reduced, the crystallization rate is further reduced in the solidification process, the outer solidification center is still likely to be liquid, the phenomenon is easy to cause the alloy to form stress cracks, the casting performance is further deteriorated, and the casting difficulty is greatly increased.
The casting temperature is 1200-1300 ℃, the casting temperature is lower than 1200 ℃, the copper water heat loss is accompanied in the casting process, the phenomenon of solidification and blockage of the copper water of the drainage tube is easy to occur, and the normal casting cannot be performed. If the casting temperature is higher than 1300 ℃, the defects of air holes, shrinkage porosity and the like of cast ingots obtained by casting are easy to cause the suction of molten copper.
Drawing and casting speed: if the drawing and casting speed is too high, copper leakage phenomenon is easily caused by insufficient solidification of copper water, the production efficiency is affected if the drawing and casting speed is too low, and meanwhile, the solidification section in the crystallizer moves upwards if the drawing and casting speed is too low, so that the friction resistance between the cast ingot and the crystallizer is increased, and the surface quality of the cast ingot is reduced.
The temperature of the ingot casting crystallizer is 600-800 ℃, and if the extraction temperature is lower than 600 ℃, the section of the ingot casting is easy to generate the transverse crack extending from the core part. If the extraction temperature is higher than 800 ℃, the copper water is not sufficiently solidified, and the phenomenon of leakage is easy to occur.
Preferably, during the casting process, the cooling water pressure of the crystallizer: 0.4-1.0 MPa, water inlet temperature: 10-30 ℃, and the water outlet temperature is: 20-45 ℃.
Preferably, the extrusion process is as follows: the heating temperature of the cast ingot is 850-950 ℃, the heat preservation time is 1-4 hours, the extrusion ratio is 30-100, and the extrusion speed is as follows: 5-15 mm/s, the extrusion billet is in on-line solid solution, the solid solution temperature is 750-950 ℃, and the cooling speed is 200-600 ℃/s.
The cast ingot after casting has a brittle phase containing Te, is obviously brittle under high temperature conditions, and has more severe extrusion conditions.
If the heating temperature of the cast ingot is 850-950 ℃, and is lower than 850 ℃, the high-temperature extrusion deformation resistance of the alloy is large, and the extrusion force exceeds the limit, so that the alloy cannot be extruded and discharged smoothly. The upper limit of the extrusion heating temperature is controlled at 950 ℃, so that the growth of alpha crystal grains and precipitated phases caused by the over-high heating temperature is avoided, and if the precipitated phases of nickel and silicon grow (more than 5 mu m) and are aggregated, the plasticity of an extrusion blank is rapidly deteriorated, and the blank is easy to crack and break during the subsequent stretch plastic processing.
If the extrusion ratio is less than 30, the extrusion specification is increased, and one-pass stretching to the required finished product specification cannot be realized, and a two-pass or multi-pass stretching and high-temperature softening annealing process is adopted. The adoption of the high-temperature softening annealing process can cause the growth of crystal grains, and the delta-Ni cannot be effectively realized 2 Average size range of Si phase: 0.01-0.5 mu m, the area ratio is 0.5-5%, and the average size range of the NiP phase is: 0.05-1 mu m, the area ratio is 0.1-2%, cu 2 Average size range of Te phase: 5-10 mu m, and the area accounts for 5-20% of ideal tissue characteristics. If the extrusion ratio is greater than 100, the extrusion specification is reduced, the extrusion force is greatly increased, on one hand, the material cannot be extruded normally, and on the other hand, annular cracks are easy to appear on the surface of the blank.
Extrusion speed: 5-15 mm/s, and particularly, the control of the extrusion speed is critical on the premise of determining the extrusion temperature. If the extrusion speed is too high, continuous transverse cracks are likely to occur in the extruded wire blank. If the extrusion speed is low, the extrusion time is increased, the extrusion process is accompanied with ingot temperature loss, and the extrusion force is greatly increased when the ingot is extruded to the tail stage, so that the extrusion efficiency and quality are affected.
The extrusion blank is subjected to on-line solid solution, the solid solution temperature is 750-950 ℃, the cooling speed is 200-600 ℃/s, the temperature of the extrusion blank is controlled at 750-950 ℃ before cooling, and reasonable cooling conditions are controlled, so that the aim of achieving a good solid solution effect is achieved, and the precipitation of a precipitated phase is avoided before an aging process, thereby greatly reducing cold working plasticity of the blank. If the temperature of the extrusion billet before cooling is lower than 750 ℃, a certain amount of precipitated phases are generated, the number of the precipitated phases is increased along with the reduction of the temperature (above the aging temperature), the solid solution temperature is higher than 950 ℃, alpha grains and other phases are further grown, the structural uniformity is reduced, and Cu distributed in the grain boundary is distributed at the same time 2 The Te phase brittleness is further increased, and the extrusion is extremely easy to form cracking. The cooling rate is lower than 200 ℃/s, the solid solution effect of the blank is not ideal, part of precipitated phases cannot be effectively dissolved in a copper matrix, the post-processing plasticity of the alloy is poor, the drawing cold deformation processing with large processing rate cannot be realized, the problem of lower strength of a finished product is indirectly caused, the cooling rate is higher than 600 ℃/s, the solid solution cooling is faster and better in general, and the practical solid solution effect has the cooling limit.
Extrusion billet performance: hardness: 80-100 HV, tensile strength: 320-360 MPa, yield strength: 120-160 MPa, elongation: 25-40%, conductivity: 10-12% IACS, average grain size of matrix phase (alpha phase): 40-80 mu m.
Preferably, the intermediate stretching process is as follows: the stretching is carried out in multiple passes, the stretching processing rate of each pass is controlled to be 5-30%, and the total stretching processing rate is 50-80%.
The total processing rate of stretching is controlled to be 50-80%, so as to realize good deformation strengthening effect. When the elongation of the extrusion blank reaches the ideal range of 25-40%, the cold working plastic working rate of the material can reach 80%, and if the working rate is lower than 50%, the deformation strengthening effect is not obvious, meanwhile, alpha-phase crystal grains are not fully crushed, fine grain strengthening cannot be realized, and the process is processed until the specification strength of the finished product cannot meet the requirement. The single-pass processing rate is controlled to be in the range of 5-30%, if the single-pass processing rate is more than 30%, the risk of breakage of a stretching chuck is easy to occur, meanwhile, the surface of a rod is seriously scalded after stretching, on one hand, the subsequent stretching processing is influenced, on the other hand, the surface temperature of the rod is increased, part of precipitated phases are precipitated from a solid solution state, the plasticity of the material is reduced, and the uniformity of the structure is poor.
Preferably, the aging process is as follows: adopting a reducing atmosphere for protection, wherein the aging temperature is 380-450 ℃, the time from room temperature to aging temperature is 60-120 min, and the heat preservation time is 100-250 min.
The aging temperature is 380-450 ℃, and the aim is to precipitate more delta-Ni 2 Si and NiP precipitate as strengthening phase. If the temperature is low, delta-Ni 2 The precipitation amount of Si phase and NiP compound is less, and the strength of the alloy is not obviously improved. If the temperature is too high, delta-Ni 2 The Si phase and NiP compound gather and grow up, the strengthening effect is weakened, and the alloy strength is reduced.
The time from room temperature to aging temperature is 60-120 min, the production efficiency is affected by too slow temperature rise, and the NiP compound and delta-Ni are heated too fast 2 Si phase is easy to fully grow up and aggregate, ageing strengthening effect is weakened, and simultaneously the size and distribution uniformity of precipitated phase are poor.
The heat preservation time is 100-250 min, if the heat preservation time is too short, the aging is insufficient, the precipitated phases can not be completely precipitated, and the strengthening effect is weakened. Overaging occurs when the heat preservation time is too long, the alloy is softened, and the strength is reduced.
Preferably, the finished product has a tensile processing rate of 5 to 20%. The processing rate is lower than 5%, the deformation strengthening effect is not obvious, and the alloy strength cannot be further increased. The processing rate is higher than 20%, the plasticity of the finished bar is easy to become low, the elongation is less than 2%, the subsequent straightening plasticity is poor, and the straightness of the finished bar is affected. Poor straightness and influences the cutting performance of the material.
Compared with the prior art, the invention has the advantages that: ni, si, te, P, mn, mg is added to copper matrix and the addition amount is controlled, and delta-Ni is contained in matrix 2 Si strengthening phase and NiP strengthening phase, the strength of the matrix is improved, the conductivity of the matrix is not reduced, and Cu is contained in the matrix 2 Te cutting phase, improving the cutting property of the matrix and finally realizing that the tensile strength of the copper-nickel-silicon bar is more than or equal to 750MPa, the yield strength is more than or equal to 700MPa and the elongation is more than or equal to 2 percentThe conductivity is more than or equal to 25 percent IACS, the hardness HV is more than or equal to 260, and the cutting index is more than 80 percent of C36000.
Drawings
FIG. 1 is a photograph showing a metallographic structure of example 1 of the present invention.
FIG. 2 is a photograph showing the metallographic structure of a comparative example of the present invention.
Detailed Description
The invention is described in further detail below with reference to the embodiments of the drawings.
The invention provides 10 examples and 5 comparative examples, the specific compositions are shown in Table 1.
The examples include the following preparation steps:
1) Smelting: proportioning according to the requirements of the required components.
2) Casting: casting ingot by using a semi-continuous casting mode, wherein the casting temperature is as follows: 1200-1300 ℃, cooling water pressure: 0.4-1.0 MPa, water inlet temperature: 10-30 ℃, and the water outlet temperature is: 20-45 ℃, and the casting speed is: the temperature of the ingot casting crystallizer is 600-800 ℃ at 20-50 mm/min, and the ingot casting with the specification phi of 180-200 mm is obtained.
3) Extruding: the heating temperature of the cast ingot is 850-950 ℃, the heat preservation time is 1-4 h, and the extrusion ratio is 30-100: 1, extrusion speed: 5-15 mm/s, the extrusion billet is in on-line solid solution, the solid solution temperature is 750-950 ℃, and the cooling speed is 200-600 ℃/s.
4) Intermediate stretching: the stretching is carried out in multiple passes, the stretching processing rate of each pass is controlled to be 5-30%, and the total stretching processing rate is 50-80%.
5) Aging: adopting a reducing atmosphere to protect and introducing ammonia gas, heating the temperature from room temperature to aging temperature for 60-120 min at the aging temperature of 380-450 ℃, and keeping the temperature for 100-250 min.
6) And (3) stretching a finished product: the finished product tensile processing rate is 5-20%, and key technological parameters are shown in tables 2 and 3.
Comparative example 1 is a commercially available C70250 alloy bar.
Comparative example 2 is different from example 1 in that: the temperature of the ingot casting crystallizer is below 100 ℃.
Comparative example 3 is different from example 1 in that: the casting speed is 60mm/min.
Comparative example 4 differs from example 1 in that: the extruded billet was cooled directly to room temperature, i.e. without on-line solution treatment.
Comparative example 5 is different from example 1 in that: the ageing temperature is 500 ℃.
The mechanical properties and/or microstructure of the obtained examples and comparative examples are detected, and specific detection indexes and detection standards are as follows:
1) Hardness HV5: GB/T4340.1-2009 Vickers hardness test section 1: test methods.
2) Tensile strength, elongation: GB/T228.1-2010 Metal tensile test part 1: room temperature tensile test method.
3) Metallographic microscopic test: YS/T449-2002 copper and copper alloy casting and processing product microstructure inspection method.
Fig. 1 is a photograph of a metallographic structure of example 1, white crystal grains are alpha phase, fine crystal grains and uniformly distributed. The black particles are Cu2Te phase and distributed in the grain boundary.
FIG. 2 is a photograph of a metallographic structure of comparative example 1, in which alpha-phase grains are coarse and the size and distribution uniformity are general.
4) Cutting index: the cutting performance was evaluated according to the method for measuring cutting performance in appendix B of YS-T647-2007 copper zinc bismuth tellurium alloy rod, and the cutting index of C36000 (HPb 63-3) was set to 100%.
5) Conductivity of: GB/T351-2019 metal material resistivity measurement method.
6) The size and area ratio of the second phase were photographed and measured by a scanning electron microscope.
TABLE 1 Components/wt% of the examples of the invention
TABLE 2 Key process parameter control for embodiments of the invention
TABLE 3 Key process parameter control for embodiments of the invention
TABLE 4 microstructure of examples of the invention
TABLE 5 Properties of examples and comparative examples of the invention
Claims (7)
1. The utility model provides a free-cutting copper nickel silicon rod which characterized in that: the copper nickel silicon comprises the following components in percentage by mass: 3.5 to 5.5 percent, si: 0.7-1.5%, te:0.1 to 1.0 percent, P:0.01 to 0.1 percent, mn:0 to 0.2 percent, mg:0.05 to 0.2 percent, and the balance of Cu and unavoidable impurities;
the microstructure of the copper-nickel-silicon contains a matrix phase and a second phase, wherein the second phase comprises delta-Ni 2 Si phase, niP phase and Cu 2 Te phase, delta-Ni 2 Average size range of Si phase: 0.01-0.5 mu m, the area ratio is 0.5-5%, and the average size range of the NiP phase is: 0.05-1 mu m, the area ratio is 0.1-2%, cu 2 Average size range of Te phase: 5-10 mu m, and the area ratio is 5-20%.
2. A method for preparing the free-cutting copper-nickel-silicon bar material according to claim 1, which is characterized in that: the process flow comprises smelting, casting, extruding, intermediate stretching, aging and finished product stretching; the casting temperature: 1200-1300 ℃, and the casting speed is: the temperature of the ingot casting crystallizer is 600-800 ℃ at 20-50 mm/min.
3. The method for preparing the free-cutting copper-nickel-silicon bar according to claim 2, which is characterized in that: during the casting process, the cooling water pressure of the crystallizer is as follows: 0.4-1.0 MPa, water inlet temperature: 10-30 ℃, and the water outlet temperature is: 20-45 ℃.
4. The method for preparing the free-cutting copper-nickel-silicon bar according to claim 2, which is characterized in that: the extrusion process comprises the following steps: the heating temperature of the cast ingot is 850-950 ℃, the heat preservation time is 1-4 hours, the extrusion ratio is 30-100, and the extrusion speed is as follows: 5-15 mm/s, the extrusion billet is in on-line solid solution, the solid solution temperature is 750-950 ℃, and the cooling speed is 200-600 ℃/s.
5. The method for preparing the free-cutting copper-nickel-silicon bar according to claim 2, which is characterized in that: the intermediate stretching process comprises the following steps: the stretching is carried out in multiple passes, the stretching processing rate of each pass is controlled to be 5-30%, and the total stretching processing rate is 50-80%.
6. The method for preparing the free-cutting copper-nickel-silicon bar according to claim 2, which is characterized in that: the aging process comprises the following steps: adopting a reducing atmosphere for protection, wherein the aging temperature is 380-450 ℃, the time from room temperature to aging temperature is 60-120 min, and the heat preservation time is 100-250 min.
7. The method for preparing the free-cutting copper-nickel-silicon bar according to claim 2, which is characterized in that: the finished product stretching processing rate is 5-20%.
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| CN111778427A (en) * | 2020-06-16 | 2020-10-16 | 陕西斯瑞新材料股份有限公司 | Preparation method of CuNiSi alloy wire for electric connector |
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| GB1358055A (en) * | 1971-09-22 | 1974-06-26 | Langley Alloys Ltd | Copper-based alloys |
| CN101605917A (en) * | 2007-02-16 | 2009-12-16 | 株式会社神户制钢所 | Intensity and the copper alloy plate for electric and electronic parts that has excellent formability |
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