CN116855792A - Zinc-white copper alloy and preparation method thereof - Google Patents
Zinc-white copper alloy and preparation method thereof Download PDFInfo
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- 239000000956 alloy Substances 0.000 title claims abstract description 163
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 159
- 229910000570 Cupronickel Inorganic materials 0.000 title claims abstract description 69
- 235000014692 zinc oxide Nutrition 0.000 title claims abstract description 69
- 239000011787 zinc oxide Substances 0.000 title claims abstract description 69
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 title claims abstract description 68
- 238000002360 preparation method Methods 0.000 title description 7
- 239000013078 crystal Substances 0.000 claims abstract description 41
- 238000005452 bending Methods 0.000 claims abstract description 29
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 8
- 239000011701 zinc Substances 0.000 claims abstract description 8
- 239000010949 copper Substances 0.000 claims abstract description 7
- 229910052802 copper Inorganic materials 0.000 claims abstract description 6
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 6
- 229910052745 lead Inorganic materials 0.000 claims abstract description 4
- 229910052742 iron Inorganic materials 0.000 claims abstract description 3
- 238000000137 annealing Methods 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 11
- 238000005096 rolling process Methods 0.000 claims description 10
- 238000001192 hot extrusion Methods 0.000 claims description 9
- 238000005266 casting Methods 0.000 claims description 8
- 238000001125 extrusion Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 229910052718 tin Inorganic materials 0.000 claims description 4
- 230000007797 corrosion Effects 0.000 abstract description 26
- 238000005260 corrosion Methods 0.000 abstract description 26
- 238000012545 processing Methods 0.000 abstract description 25
- 238000012360 testing method Methods 0.000 abstract description 16
- 230000004580 weight loss Effects 0.000 abstract description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 16
- 239000000047 product Substances 0.000 description 14
- 230000000694 effects Effects 0.000 description 11
- 230000008569 process Effects 0.000 description 9
- 238000005728 strengthening Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 5
- 238000005336 cracking Methods 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 239000006104 solid solution Substances 0.000 description 5
- 238000009713 electroplating Methods 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 229910016897 MnNi Inorganic materials 0.000 description 3
- 238000003723 Smelting Methods 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000009749 continuous casting Methods 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 239000007769 metal material Substances 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 230000035882 stress Effects 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 230000004888 barrier function Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 229910018605 Ni—Zn Inorganic materials 0.000 description 1
- 238000007545 Vickers hardness test Methods 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000006355 external stress Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- QELJHCBNGDEXLD-UHFFFAOYSA-N nickel zinc Chemical compound [Ni].[Zn] QELJHCBNGDEXLD-UHFFFAOYSA-N 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C9/00—Alloys based on copper
- C22C9/04—Alloys based on copper with zinc as the next major constituent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C23/00—Extruding metal; Impact extrusion
- B21C23/002—Extruding materials of special alloys so far as the composition of the alloy requires or permits special extruding methods of sequences
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
- B22D11/004—Copper alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C30/00—Alloys containing less than 50% by weight of each constituent
- C22C30/02—Alloys containing less than 50% by weight of each constituent containing copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C30/00—Alloys containing less than 50% by weight of each constituent
- C22C30/04—Alloys containing less than 50% by weight of each constituent containing tin or lead
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C30/00—Alloys containing less than 50% by weight of each constituent
- C22C30/06—Alloys containing less than 50% by weight of each constituent containing zinc
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Conductive Materials (AREA)
Abstract
The invention discloses a zinc white copper alloy, which comprises the following components in percentage by weight: 48.0 to 53.2 weight percent of Cu,5.8 to 8.0 weight percent of Ni,1.0 to 3.0 weight percent of Mn,1.0 to 2.8 weight percent of Pb,0.0001 to 0.3 weight percent of Fe, and the balance of Zn and unavoidable impurities; the microstructure of the cross section of the zinc-white copper alloy contains twin crystals, and the average width of the twin crystals is 0.5-5 mu m. The invention can realize that the yield strength of the zinc white copper is more than or equal to 520MPa, the tensile strength is more than or equal to 580MPa, the hardness HV is more than or equal to 155, the elongation is 8-15%, the weight loss rate is less than or equal to 0.02 percent after corrosion for 48 hours, the zinc white copper is repeatedly bent for 180 degrees, the zinc white copper is not broken within 6 times of bending, and the processing and use requirements are met, namely, after the alloy is stamped into a sample blank, the surface of the sample blank has no crack, the dimensional tolerance is less than or equal to +/-0.02 mm, the zinc white copper is loaded with a load of 1.0Nm, the deformation angle is less than 5 degrees, and the drop test requirement is met.
Description
Technical Field
The invention belongs to the field of copper alloy, and particularly relates to a zinc white copper alloy and a preparation method thereof.
Background
The zinc white copper has excellent strength and hardness, good plasticity, good corrosion resistance and certain processability, and is widely applied to precise instrument parts. With the rapid development of science and technology in recent years, the requirements for the use of products are improved, and the performance requirements for the zinc-white copper alloy are also higher and higher. In particular, in the case of products having complicated and small shapes such as mechanical keys, it is generally required to perform multi-pass deep drawing, stamping, plating, etc., and zinc-white copper alloy is required to have not only excellent stamping performance but also excellent corrosion resistance and excellent plastic workability.
In addition, due to the use characteristics of the product, the product can be frequently plugged and unplugged, twisted and easily fallen in the use process, and the requirements on the strength and bending resistance of the alloy are extremely high, so that high nickel zinc white copper alloy materials are mostly adopted, but the cost is high, the dependence on noble metal resources is strong, and the development of the product processing industry is severely restricted. Meanwhile, the surface quality and the dimensional tolerance of the stamped sample blank are higher, burrs on the surface of the alloy blank are required to be neat, the flatness is high, the dimensional tolerance is small, and during stamping, as the alloy material is required to have good ductility to meet the stamping requirement, certain plastic deformation can be caused along the stamping direction, and the appearance of redundant burrs on the edge of a part is macroscopic, so that the use requirement is difficult to meet.
According to the above-mentioned demands, there is a strong demand for substitution of an alloy material having a low noble metal content, high strength, bending resistance, corrosion resistance, dimensional accuracy, and excellent press workability. At present, the production cost of materials is reduced simply by replacing nickel with copper in the market, but other aspects of the materials are not considered much, and particularly the bending resistance, stamping processability and the like of the materials are not considered. Therefore, research on alloy materials is needed again, and alloys meeting the use requirements of products such as mechanical keys and the like are developed.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the zinc-white copper alloy and the preparation method thereof, wherein the alloy has the comprehensive properties of excellent strength, corrosion resistance, bending resistance, excellent stamping processability and the like, can be processed into the forms of bars, wires, flat wires and the like, and is suitable for the industries of mechanical keys and the like.
The technical scheme adopted for solving the technical problems is as follows: the zinc white copper alloy comprises the following components in percentage by weight: 48.0 to 53.2 weight percent of Cu,5.8 to 8.0 weight percent of Ni,1.0 to 3.0 weight percent of Mn,1.0 to 2.8 weight percent of Pb,0.0001 to 0.3 weight percent of Fe, and the balance of Zn and unavoidable impurities; the microstructure of the cross section of the zinc-white copper alloy contains twin crystals, and the average width of the twin crystals is 0.5-5 mu m.
The weight percentage of Ni element in the zinc white copper alloy is 5.8-8.0 wt%. Ni is used as a main alloy element, forms a continuous solid solution with Cu, has a solid solution strengthening effect, and improves the strength, hardness and corrosion resistance of the alloy. When the content of Ni element in the alloy is less than 5.8wt%, the strength, hardness and corrosion resistance of the alloy are low, the elongation is improved, and the strength, bending resistance and electroplating processing cannot meet the requirements. When the Ni content exceeds 8.0wt%, ni is used as a noble metal, and too high Ni content increases the alloy manufacturing cost and significantly deteriorates the workability thereof. Therefore, the Ni element content in the zinc white copper alloy is controlled to be 5.8-8.0 wt%.
Zn in the zinc-white copper alloy is taken as a main element, can be largely dissolved in a copper matrix, forms a wide single-phase alpha solid solution area, has the solid solution strengthening effect, and improves the strength, the hardness and the corrosion resistance of the alloy. When the Ni content is unchanged, along with the increase of the Zn content, the alloy changes from alpha single phase to alpha+beta double-phase structure, on one hand, the corrosion resistance of the alloy is obviously increased, and the electroplating processing requirement of the alloy is met; on the other hand, the hot workability of the alloy can be improved. Therefore, the alloy has alpha+beta double-phase structure by controlling Zn content, and improves the processing performance of the alloy while improving the strength, hardness and corrosion resistance of the alloy. In zinc white copper alloy with too low Zn element content, the beta phase structure content is reduced or even does not exist, when the alloy is hot extruded at high temperature, the cracking phenomenon is easy to occur, the processing difficulty is increased, the strength, the hardness and the corrosion resistance are not easy to strengthen, and the bending resistance test, the drop test and the electroplating requirement are difficult to meet; however, if the Zn content is too high, the beta phase structure content is increased, the plastic deformation capacity of the alloy is reduced, the hard and brittle beta phase increases the stamping difficulty of the alloy at room temperature, the formation of deformed twin crystals is reduced, and the twin crystal strengthening effect is reduced.
Mn has larger solid solubility in Cu-Ni-Zn system alloy, and the strength of the alloy is further improved through solid solution strengthening; on the other hand, the Mn element obviously reduces the stacking fault energy of the alloy, is beneficial to the formation of twin crystals in crystal grains, and improves the twin crystal strengthening effect of the alloy. When a certain amount of Mn is added into the alloy, mn and Ni can form a MnNi compound, so that the alloy has the effects of refining grains and strengthening precipitation, and the strength, bending resistance and corrosion resistance of the alloy are further improved. The Mn content in the zinc white copper alloy is controlled to be 1.0-3.0wt%. On one hand, too high Mn content can lead to the formation of a large amount of MnNi compounds in the alloy, so that the alloy is too hard, the alloy is difficult to process and punch in multiple passes, the risk of cracking in the alloy processing process is increased, and the processing performance is reduced; on the other hand, the high Mn content can increase the beta phase content in the alloy, reduce the plastic deformation capability, and has higher cold working difficulty and is easy to generate cracks. And when the Mn content is too low, its effect on improving alloy properties is limited.
The invention improves the alloy processability by adding a small amount of Pb element. Pb is hardly dissolved in copper in a solid state, and is mainly in a granular form and uniformly distributed in a zinc-white copper alloy. Since Pb is mainly distributed in the form of particles on the grain boundaries and the surface tension of liquid Pb is small, the Pb content in the alloy is not so high. On one hand, the zinc-white copper alloy with high Pb content has large longitudinal cracking tendency during annealing, and on the other hand, the high Pb content has increased aggregation tendency, and large-area Pb particles can reduce the corrosion resistance of the alloy, so that the corrosion resistance of the alloy is difficult to reach the expected level, and the electroplating process of the alloy is difficult to finish. Pb with the content of less than 1.0 weight percent is not obvious for improving the processing performance of the alloy, burrs of a stamped sample blank are increased, the purposes of improving the processing efficiency and the processing quality of the part are difficult to achieve, and the dimensional tolerance of the part is larger. Therefore, the Pb content in the zinc-white copper alloy is controlled to be 1.0-2.8 wt%, which is favorable for effectively controlling the dimensional tolerance of the punched product and meets the processing and application requirements of the alloy.
The solid solubility of Fe element in the zinc-white copper alloy is small, so that the corrosion resistance and mechanical property of the alloy are improved, and the corrosion resistance of the alloy is improved particularly; secondly, the addition of Fe element greatly reduces the stacking fault energy of the alpha-phase matrix, can generate twin crystals at low temperature, has lower corresponding required deformation energy storage, and is favorable for forming twin crystals in the alpha-phase. The content of Fe element in the alloy is not more than 0.3wt%, otherwise, the alloy has stress corrosion cracking tendency, and the corrosion is aggravated; and the proper amount of Fe element improves the corrosion resistance of the zinc white copper in the corrosive liquid.
The microstructure of the cross section of the zinc-white copper alloy contains twin crystals, and the average width of the twin crystals is 0.5-5 mu m. Because the grain boundary of the twin crystal is a special low-energy-state grain boundary, dislocation movement can be effectively prevented, particularly, when the width of the twin crystal sheet layer is thinned to a lower level, the strengthening effect of the twin crystal sheet layer begins to appear, and a large number of twin crystals can greatly improve the strength of the alloy without sacrificing the plasticity and the toughness; however, as the twin boundary layer width is reduced, the tensile plasticity and fracture toughness of the alloy are both increased, and the softening capability of the alloy is particularly shown, so that the bending resistance of the alloy is not improved, excessive burrs are generated on the stamped sample blank, the dimensional tolerance is increased, and the stamping forming is poor. Therefore, the zinc-white copper alloy introduces a twin crystal fault structure, and by controlling the width of twin crystals, dislocation movement is effectively hindered, and the work hardening capacity of the alloy is reduced on the premise of further improving the strength, the hardness and the bending resistance of the alloy, so that the alloy has certain tensile plasticity, and the processing stamping performance of the alloy is improved. When the average width of the twin crystals is lower than 0.5 mu m, as the width size of the twin crystals becomes smaller, a plastic deformation mechanism is transformed from dislocation twin crystal boundary interaction dominance to dislocation movement dominance in a twin crystal lamellar structure, the alloy is in a softened state, and the strength and the stamping formability are reduced, so that the use requirement of products cannot be met; in addition, the twin boundary forms a stronger barrier to the crossing of single dislocation, when the twin wafer layer is wider, dislocation plug products can be formed at the twin boundary, and stress concentration is generated, so that the dislocation can pass through the twin boundary under relatively lower external stress, and the strengthening effect of the performance is reduced. A certain width of twinning is thus necessary to achieve high strength and a certain plasticity.
Preferably, the contents of Ni and Mn in the weight percentage composition of the zinc white copper alloy are respectively recorded as [ Ni ] and [ Mn ], and X=0.5 [ Ni ] +2.0[ Mn ], so that X is more than or equal to 5.5 and less than or equal to 9.0. The Ni and Mn contents in the zinc white copper alloy can influence the strength, corrosion resistance and bending resistance of the alloy to a certain extent. When the X value is lower than 5.5, the strength, corrosion resistance and bending resistance of the alloy are obviously lower; when the X value is higher than 9.0, a large amount of MnNi compounds can be formed, the hardening rate of the alloy is higher, cracks are easy to appear in the processing process of a sample blank and in the drop test, and the yield is poor; on the other hand, when the Ni content is too high, the manufacturing cost of the alloy increases.
Preferably, the zinc white copper alloy of the present invention may further comprise one or more elements of Sn, mg, al, co, bi, S, si in a total amount of 0.001 to 1.0 wt%. The addition of a small amount of Sn, mg, al, co, bi, S, si can reduce the alloy stacking fault energy, is beneficial to the formation of twin crystals and improves the strength and bending resistance of the zinc-white copper alloy. The Sn, mg, al, co, bi, S, si content does not have a significant negative effect on the workability and corrosion resistance of the alloy while improving the strength of the alloy. If the total amount of these elements exceeds 1.0wt%, the overall properties of the alloy are deteriorated.
Preferably, in the microstructure of the cross section of the zinc-white copper alloy, the number of twin crystals is more than or equal to 1 multiplied by 10 4 Individual/mm 2 . The zinc-white copper alloy introduces a large amount of twin crystal layer fault tissues to further strengthen the alloy. Along with the decrease of the twin crystal quantity and the increase of twin crystal intervals in crystal grains, the blocking effect of the twin crystal grains as a special crystal boundary on dislocation movement is weakened, the dislocation movement is easier to grow, and the strength and bending resistance of the alloy are reduced, so the twin crystal quantity is controlled to be more than or equal to 1 multiplied by 10 4 Individual/mm 2 。
Preferably, the beta phase quantity in the microstructure of the cross section of the zinc white copper alloy is more than or equal to 2 multiplied by 10 4 Individual/mm 2 The beta phase is distributed at the grain boundary and in the alpha phase, wherein the grain size of the beta phase at the grain boundary is less than or equal to 50 mu m, and the grain size of the beta phase in the alpha phase is less than or equal to 20 mu m. The beta phase in the zinc white copper alloy is distributed at the grain boundary and in the alpha phase, so that the pinning effect is achieved on grains and dislocation, and the stamping processability of the alloy can be enhanced under the condition of effectively improving the strength and bending resistance of the alloy. The invention is thatThe size of the beta phase in the alpha phase of the zinc-white copper alloy is smaller, and the smaller the particle size of the beta phase is, the better the alloy strength is; secondly, the beta phase is a hard phase, the dislocation is difficult to cut during movement, and the movement is performed in a way of bypassing the beta phase to generate dislocation loops, so that the external energy is absorbed, the toughness of the alloy is ensured, and meanwhile, the bending resistance of the alloy is enhanced. The grain size of beta phase at the grain boundary of the zinc-white copper alloy is relatively larger, which is beneficial to breaking the continuity of a matrix during punching and improving the punching processability and the processing toughness of the alloy.
Preferably, in the microstructure of the cross section of the zinc-white copper alloy of the invention, the average grain size is less than or equal to 20 mu m, and the number of grains below 1 mu m accounts for more than 20% of the total number of grains. The finer the grain, the higher the strength and hardness. Because finer grains, larger total grain boundary area, more dislocation barriers, more grains with different orientations that need to be coordinated, and higher resistance to plastic deformation of the alloy. In addition, as the grains are smaller, more grains in the alloy structure can frequently collide with the grains when crack growth occurs, thereby enabling control of crack branching and reduction of crack growth rate with change of crack growth direction, and improving bending resistance of the alloy. Meanwhile, the finer the grains are, the more the number of grains in unit volume is, the more the number of grains participating in deformation is, the more uniform the deformation is, and the larger plastic deformation is caused before fracture. Therefore, the present invention improves strength, hardness and bending resistance of the zinc white copper alloy by refining the grains and controlling the grain size and the ratio of small-sized grains.
The zinc-white copper alloy has the yield strength of over 520MPa, the tensile strength of over 580MPa, the Vickers hardness of over 155 and the elongation percentage of 8-15 percent, the weight loss rate after corrosion for 48 hours is less than or equal to 0.02 percent, the zinc-white copper alloy is repeatedly bent for 180 degrees, the zinc-white copper alloy is not broken within 6 times of bending, and the processing and using requirements are met, namely, after the zinc-white copper alloy is stamped into a sample blank, the surface of the sample blank is free from cracks, the dimensional tolerance is less than or equal to +/-0.02 mm, the sample blank is loaded with a load of 1.0Nm, the deformation angle is less than 5 degrees, and the drop test requirements are met.
The preparation method of the zinc white copper alloy comprises the following steps: casting, hot extrusion, stretching, annealing, rolling, annealing and stretching a finished product, wherein the steps are as follows:
(1) And (3) casting: the alloy of the invention adopts a horizontal continuous casting mode to produce casting blanks, the material mixing amount is calculated according to the alloy components of the invention, raw materials are melted in an induction furnace, and the casting blanks are drawn from a heat preservation furnace. Wherein the smelting temperature is 1150-1250 ℃, and the casting is carried out in a crystallizer at 1040-1160 ℃, the quality of the casting blank crystallized at the temperature is better, and the interior of the casting blank has no defects of bubbles, looseness, inclusion and the like.
(2) Hot extrusion: in the hot extrusion process adopted by the alloy, the extrusion temperature is 750-850 ℃, and the extrusion ratio is more than 290. The alloy is subjected to hot extrusion under the extrusion ratio condition of more than 290, so that the hot extrusion process is finished, cracks are prevented from being generated in the hot extrusion and subsequent cold processing processes, and the stamping processing performance is improved; on the other hand, the alloy microstructure can be ensured, the alloy performance requirement can be met, and the required specification can be achieved.
(3) Stretching: the processing rate is 25-35%, the lattice distortion caused under the cold deformation condition is small, the atom dislocation degree is low, deformation twin crystals are easy to generate, and the ideal microstructure is formed in the later stage by stretching, so that the effect of improving the alloy performance is further achieved.
(4) Annealing: the annealing temperature is 600-700 ℃, the annealing time is 180-300 min, and after annealing, partial deformation twins disappear, and new annealing twins are formed. On one hand, the alloy is softened, so that the subsequent processing of the alloy is facilitated; on the other hand, the alloy structure is further homogenized, cracks are avoided in the processing process, and the processing performance is improved.
(5) Rolling: the alloy is cold deformed by adopting a rolling mill, and the deformation amount is 40-60%. The alloy is further deformed by low-temperature rolling, which is favorable for generating high-density dislocation and micron-sized deformation twin crystals, and along with the increase of rolling deformation, grains are refined, a greater number of twin crystal lamellar structures are generated, precipitate particles become smaller and smaller, the distribution is more and more uniform, and the comprehensive performance of the alloy is improved.
(6) Annealing: the annealing temperature is 600-700 ℃ and the annealing time is 180-250 min. The purpose of recovering the plasticity of the alloy is achieved, the deformation resistance of the alloy is reduced, and meanwhile, the structure is further optimized, so that the alloy with the required performance is achieved.
(7) And (3) stretching a finished product: the finished product is stretched at 20-35% of stretching rate, so that the sample with the required specification can be obtained, and meanwhile, the strength of the alloy can be slightly improved without affecting other properties of the alloy.
In order to meet the preparation of the samples with the required specification, the preparation method can be used for carrying out multiple stretching and annealing before and after rolling, wherein the processing rate of each stretching is 25-40%, the annealing temperature of each annealing is 600-750 ℃, and the annealing time is 180-280 min.
To remove surface defects and oxides from the material, a clean material surface may be obtained by providing an acid wash step prior to each material stretching step. Because the zinc white copper is easy to oxidize, the existence of defects such as oxides, impurities and the like damages the uniformity and the continuity of the alloy matrix and causes stress concentration, the defects such as the oxides, the impurities and the like are often the source of cracks, the risk of cracking of the alloy can be reduced through an acid washing process, and the yield is improved.
Compared with the prior art, the invention has the advantages that: the invention adds Pb, mn and trace Fe on the basis of the traditional zinc-white copper alloy, promotes the formation of twin crystals, improves the strength and bending resistance of the alloy by controlling the average width of the twin crystals to be 0.5-5 mu m, and has less influence on stamping processability. The invention can realize that the yield strength of the zinc white copper is more than or equal to 520MPa, the tensile strength is more than or equal to 580MPa, the hardness HV is more than or equal to 155, the elongation is 8-15%, the weight loss rate is less than or equal to 0.02 percent after corrosion for 48 hours, the zinc white copper is repeatedly bent for 180 degrees, the zinc white copper is not broken within 6 times of bending, and the processing and use requirements are met, namely, after the alloy is stamped into a sample blank, the surface of the sample blank has no crack, the dimensional tolerance is less than or equal to +/-0.02 mm, the zinc white copper is loaded with a load of 1.0Nm, the deformation angle is less than 5 degrees, and the drop test requirement is met.
Drawings
FIG. 1 is a photograph of a metallographic microstructure of a cross section of a zinc white copper alloy of example 3.
Detailed Description
The invention is described in further detail below with reference to the embodiments of the drawings.
According to the components of 10 example alloys and 1 comparative example alloy (alloy brands: BZn 10-38) in Table 1, raw materials are respectively proportioned and proportioned, smelting is carried out at 1180 ℃, continuous casting is carried out at 1050 ℃ continuous casting temperature after smelting to form cast ingots, then hot extrusion is carried out at 775 ℃ and 305 extrusion ratio to form wires with the diameter of 8.3mm, then acid washing and peeling are carried out on the products to remove surface impurities and oxides, and stretching, annealing and rolling treatment are carried out on extrusion blanks: firstly, stretching at a processing rate of 27%, then annealing at 670 ℃ for 210min, pickling to remove surface impurities, further rolling at a deformation of 50%, annealing at 650 ℃ for 200min, and finally pickling a sample to remove surface impurities, and stretching a finished product to obtain a flat wire with a 1.76 multiplied by 7.76mm, wherein the stretching rate is 26%.
For the obtained samples, property evaluation was performed under the following conditions, and test results are shown in tables 2 and 3.
Room temperature tensile test according to GB/T228.1-2010 metal material tensile test part 1: room temperature test method the strength and elongation are tested on an electronic universal mechanical property tester.
Microhardness HV values according to GB-T4340.1-2009 section 1 Vickers hardness test of metallic materials: test methods were tested on a digital vickers hardness tester.
Corrosion resistance according to NSS experiment of GB/T10125-2021 salt spray test for artificial atmosphere corrosion test, the test is carried out in neutral salt spray with pH value of 7 for 48 h.
Grain size, beta phase, twin crystal size and number measurement the sample structure was observed with a metallographic microscope, and the average grain size, number and duty ratio of the phases were calculated from the results, the calculation results being shown in table 3. The photograph of the metallographic microstructure of the cross section of the zinc-white copper alloy of example 3 is shown in FIG. 1.
Deformation angle: after an alloy having a dimension of 1.76×7.76mm was punched into a sample, a load of 1.0Nm was applied thereto, and then a permanent deformation angle was measured, and the deformation angle was determined to be acceptable as < 5 °.
Drop test: after an alloy with the size of 1.76 x 7.76mm is punched into a sample blank, the alloy is judged to be qualified when the sample blank is dropped for 100 times or more at the height of 1m, and the normal use functions are not affected by fracture, bending and the like, and the alloy is indicated by O; otherwise, the test is determined to be failed, and indicated by "X".
Bending test according to GB/T238-2013 method for repeated bending test of metal material wire rod, 180-degree repeated bending is carried out on a motorized bending test machine until the bending test is broken, and the bending times during breaking are determined.
TABLE 1
TABLE 2
TABLE 3 Table 3
Note that: the B value is the percentage of the number of grains with the grain size below 1 μm to the total number of grains.
Claims (9)
1. The zinc white copper alloy is characterized by comprising the following components in percentage by weight: 48.0 to 53.2 weight percent of Cu,5.8 to 8.0 weight percent of Ni,1.0 to 3.0 weight percent of Mn,1.0 to 2.8 weight percent of Pb,0.0001 to 0.3 weight percent of Fe, and the balance of Zn and unavoidable impurities; the microstructure of the cross section of the zinc-white copper alloy contains twin crystals, and the average width of the twin crystals is 0.5-5 mu m.
2. The zinc-white copper alloy according to claim 1, wherein the contents of Ni and Mn in the zinc-white copper alloy are respectively represented by [ Ni ], [ Mn ], and X=0.5 [ Ni ] +2.0[ Mn ], and X is not less than 5.5 and not more than 9.0.
3. A zinc-white copper alloy according to claim 1, characterized in that the zinc-white copper alloy further comprises one or more elements of Sn, mg, al, co, bi, S, si in a total amount of 0.001-1.0 wt%.
4. A zinc-white copper alloy according to claim 1, characterized in that the number of twin crystals in the microstructure of the cross section of the zinc-white copper alloy is not less than 1 x 10 4 Individual/mm 2 。
5. A zinc-white copper alloy according to claim 1, characterized in that the beta phase is present in a microstructure of the cross section of the zinc-white copper alloy in an amount of not less than 2 x 10 4 Individual/mm 2 The beta phase is distributed at the grain boundary and in the alpha phase, wherein the grain size of the beta phase at the grain boundary is less than or equal to 50 mu m, and the grain size of the beta phase in the alpha phase is less than or equal to 20 mu m.
6. A zinc-white copper alloy according to claim 1, characterized in that the average grain size is not more than 20 μm and the number of grains of 1 μm or less is 20% or more of the total number of grains in the microstructure of the cross section of the zinc-white copper alloy.
7. The zinc-white copper alloy according to any one of claims 1 to 6, wherein the zinc-white copper alloy is repeatedly bent 180 ° and does not break within 6 times of bending.
8. The method for producing a zinc-white copper alloy according to any one of claims 1 to 7, comprising the steps of: casting, hot extrusion, stretching, annealing, rolling, annealing and stretching a finished product, wherein the deformation of the rolling is 40-60%.
9. The method for preparing a zinc-white copper alloy according to claim 8, wherein the hot extrusion temperature is 750-850 ℃, and the extrusion ratio is not less than 290.
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