Tin-zinc bronze alloy and preparation method thereof

Abstract

The invention discloses a tin-zinc bronze alloy and a preparation method thereof, the tin-zinc bronze alloy comprises the following elements in percentage by mass: 3-5wt% of Sn, 2-4wt% of Zn, 2-4wt% of Cu, 0.005-0.03 wt% of X and the balance of unavoidable impurities, the sum of the mass percentages of all the elements is 100%, the X element comprises 0.005-0.03 wt% of P, the balance of Cu and inevitable impurities, and the sum of the mass percentages of all the elements is 100%. The structure texture of the tin-zinc bronze alloy is as follows: 1t; 100 gt; direction texture and lt; 111gt, 111gt; a directional texture composition, where lt; 100 gt; the area ratio of the directional texture is 55-70%, lt; 111gt, 111gt; and the area ratio of the directional texture is 30-45%. The tin-zinc bronze alloy has a proper yield ratio, and the tin-zinc bronze alloy provided by the invention has a relatively large elastic deformation range and can bear severe conditions such as high temperature, high pressure and strong corrosion.

Description

Technical Field

[0001] The present invention belongs to the technical field of copper alloys, and particularly relates to a tin-zinc bronze alloy and a preparation method thereof. Background Art

[0002] Tin-zinc bronze is a bronze with Sn and Zn as the main alloying elements, and the representative alloy grade is CuSn4Zn3 (QSn4-3). Due to its unique physical and chemical properties, the components made of tin-zinc bronze alloy can withstand high-strength and heavy-load working environments while maintaining their stability and reliability, and have a wide range of applications in the fields of electronic information, aerospace, chemical equipment, etc. Tin-zinc bronze has good thermal conductivity and electrical conductivity and is used to manufacture components such as electronic connectors, radiators, and electrical contact pieces; the anti-magnetic property and good elasticity of tin-zinc bronze make it an ideal material for manufacturing high-precision electronic components. For example, when manufacturing high-sensitivity sensors and micro relays, tin-zinc bronze can ensure the stability and reliability of the components and improve the overall performance of electronic equipment. In the aerospace field, the wear resistance and good hot working performance of tin-zinc bronze make it an important material for manufacturing key components.

[0003] Tin-zinc bronze is not suitable for hot working. The QSn4-3 bar and wire in the market are usually produced by the method of "horizontal continuous casting - stretching". Due to the existence of many casting defects such as porosity, gas holes, and segregation in the as-cast structure during the billet opening of the horizontal continuous casting method, these defects cannot be well eliminated in conventional cold working and annealing. Since tin-zinc bronze belongs to a solid solution strengthening and strain strengthening type alloy, the existence of casting defects limits the improvement of the mechanical properties of the alloy by large deformation, and at the same time affects the reliability of the components processed by it, making the components prepared by this method unable to be applied in the aerospace field.

[0004] The invention patent application with the publication number of CN119177373A discloses a tin bronze bar and wire and a preparation method thereof. The tin bronze bar and wire are composed of the following components in weight percentages: Sn: 10-14wt%, P: 0.05-0.3wt%, Zn: 0.01-0.5wt%, and the balance is Cu and inevitable impurities; the structure of the tin bronze bar and wire includes an α+δ+Cu 3 P ternary eutectic, and the area ratio of the α+δ+Cu 3 P ternary eutectic is ≤0.5%. The tin bronze bar and wire have good mechanical properties. Although the invention patent application makes the tin bronze bar and wire have a high tensile strength by controlling the area ratio of the ternary eutectic, the yield ratio of the tin bronze bar and wire disclosed in this patent application is relatively high, which is not conducive to application in the aerospace field.

[0005] In view of the problems of low mechanical properties and poor reliability of QSn4-3 tin-zinc bronze products in the current market, the present invention develops a tin-lead bronze alloy suitable for aerospace applications and its preparation method, breaking through the technical bottleneck that the tin-zinc bronze prepared by the prior art is prone to deformation and fracture, obtaining a tin-zinc bronze alloy with high strength and good toughness, which can withstand harsh conditions such as high temperature, high pressure and strong corrosion in extreme working environments, meet the high requirements of the aerospace field for the mechanical properties and reliability of alloys, ensure the safe and stable operation of aerospace vehicles, and fill the gaps in domestic and foreign products and technologies. Summary of the Invention

[0006] The present invention provides a tin-zinc bronze alloy, which has a suitable yield ratio. The tin-zinc bronze alloy provided by the present invention has a large elastic deformation range and can withstand harsh conditions such as high temperature, high pressure and strong corrosion.

[0007] The present invention provides a tin-zinc bronze alloy, including Sn, Zn, Cu, X element and inevitable impurities, and the sum of the mass percentages of all elements is 100%. Among them, Sn: 3-5 wt%, Zn: 2-4 wt%, and the X element includes P: 0.005-0.03 wt%.

[0008] The texture of the tin-zinc bronze alloy is composed of <100>-direction texture and <111>-direction texture. Among them, the area ratio of the <100>-direction texture is 55-70%, and the area ratio of the <111>-direction texture is 30-45%.

[0009] Since the <100>-direction texture has a low stored energy of deformation, and the stored energy of deformation increases slowly with the increase of the amount of deformation, showing a low work hardening rate, it can limit the rising rate of the yield strength of the material. Therefore, the present invention controls the area ratio of the <100>-direction texture at a relatively high level, and its purpose is to be able to inhibit the rapid increase of the yield strength.

[0010] Since the <111>-direction texture has a high stored energy of deformation, and the stored energy of deformation increases significantly with the increase of the amount of deformation, the local strain generated inside the grains of the <111>-direction texture becomes larger and the work hardening rate is high, thus increasing the rising rate of the yield strength of the material. Therefore, the present invention needs to control the upper limit of the area ratio of the <111>-direction texture to avoid the too fast rising rate of the yield strength affecting the yield ratio. However, the <111>-direction texture can limit the dislocation slip and grain boundary slip of the material and can improve the tensile strength of the material. Therefore, the present invention sets the lower limit of the area ratio of the <111>-direction texture, so that the tin-zinc bronze alloy has a suitable yield ratio while having a high tensile strength.

[0011] The functions of other elements of the tin-zinc bronze alloy provided by the present invention are as follows:

[0012] Sn: Sn has a strong solid solution strengthening effect in Cu. As the Sn content increases, the strength of the alloy also increases. When the Sn content is less than 3%, the degree of alloying is low and the solid solution strengthening effect is not ideal, and the strength of the alloy cannot meet the high-strength requirements of the present invention. However, when the Sn content exceeds 5 wt%, brittle δ phase is formed between Cu and Sn, which has a negative impact on the strength improvement of the alloy. Therefore, the Sn content range of the tin-zinc bronze alloy of the present invention is controlled at 3-5 wt%.

[0013] Zn: Zn can be largely dissolved in Cu, improving the mechanical properties of the alloy with little effect on the alloy structure. The addition of Zn can narrow the crystallization temperature range of the alloy, improve the fluidity of the liquid alloy, and reduce the dendritic segregation of Sn element. However, since Zn is more active than Sn and preferentially combines with Cu to form CuZn solid solution, the solid solution strengthening effect of Zn is much weaker than that of Sn. Excessive Zn content will reduce the solid solution strengthening effect of Sn, and when the Zn content exceeds 4 wt%, the corrosion resistance of the alloy will decrease significantly. Therefore, the Zn content in the tin-zinc bronze of the present invention should be controlled at 2-4 wt%.

[0014] P: P is a good deoxidizer, which can improve the casting properties of tin bronze and also enhance the mechanical properties such as the strength, elastic modulus, and fatigue strength of the alloy. However, P has a great impact on the electrical conductivity of the alloy. Therefore, the P content in the tin bronze of the present invention should be controlled at 0.005-0.03 wt%.

[0015] Preferably, the yield ratio Rp 0.2 / Rm of the tin-zinc bronze alloy is 0.78-0.90, where Rp 0.2 is the yield strength and Rm is the tensile strength.

[0016] By controlling an appropriate yield ratio, the present invention enables a larger elastic deformation range of the part before yielding, which is particularly important for occasions where precise deformation control is required, such as in precision instruments, aerospace, etc. fields. Because a larger elastic deformation range can not only better absorb and buffer external force impacts, but also give more warning time in case of slight overload to prevent catastrophic failure. At the same time, it can also endow the material with higher strength, making the material prepared from the tin-zinc bronze alloy provided by the present invention not easily undergo plastic deformation under external forces.

[0017] Further preferably, the tensile strength Rm of the tin-zinc bronze alloy ≥ 550 Mpa, and the yield strength Rp 0.2 ≥ 430 Mpa.

[0018] Preferably, the elongation A of the tin-zinc bronze alloy 50 ≥ 10%, and the electrical conductivity ≥ 18% IACS.

[0019] Preferably, the area ratio of twins in the structure of the tin-zinc bronze alloy is 40-60%. By controlling the appropriate ratio of twins, the tin-zinc bronze alloy of the present invention has high strength and ductility.

[0020] Preferably, the average grain size of the tin-zinc bronze alloy is 10-25 μm. The size of the average grain size has a great influence on the mechanical properties and processing properties of metals. Generally, at room temperature, the finer and more uniform the grains, the better the comprehensive properties of the material. The present invention provides an appropriate grain size to obtain a tin-zinc bronze alloy with better comprehensive properties, while reducing the resistance to plastic deformation of the metal and increasing the processing rate during cold working.

[0021] Preferably, the X element further includes Mg: 0.001-0.01 wt%, Fe ≤ 0.03%, Ni ≤ 0.02 wt%, Pb ≤ 0.01%.

[0022] The functions of each X element are as follows:

[0023] By controlling the content of Mg, on the one hand, the stress relaxation resistance of the processed parts of the tin-zinc bronze alloy is improved, and on the other hand, it assists P in deoxidation, improves the casting properties of the tin-zinc bronze, and minimizes the influence on the electrical conductivity.

[0024] By controlling the content of Fe, the Fe existing as an independent phase is reduced. The Fe existing as an independent phase makes the copper alloy exhibit a certain magnetism, thereby controlling the magnetism of the copper alloy and avoiding interference with signals caused by high magnetism.

[0025] Ni can be infinitely soluble in Cu. By controlling the content of Ni, the strength of the alloy can be increased, and at the same time, the magnetic display of the copper alloy under the magnetic field caused by Ni can be reduced. High magnetism will interfere with signals.

[0026] The solubility of Pb in the α phase is extremely low, and the melting point of Pb is only 327°C. By controlling the content of Pb, the presence of hot brittleness of Pb on the grain boundaries during hot working, which leads to hot working cracking, is minimized.

[0027] On the other hand, the present invention also provides a preparation method of the tin-zinc bronze alloy. The technological process of this preparation method includes: melting → semi-continuous casting → extrusion → intermediate drawing and annealing → finished product drawing → low-temperature annealing;

[0028] Weigh and melt according to the mass percentages of each component of the tin-zinc bronze alloy;

[0029] The temperature of the extrusion is 740-860°C, the extrusion ratio is 10-60, and the extrusion speed is 2-6 mm / s.

[0030] Compared with the "horizontal continuous casting - stretching" method for preparing QSn4-3 rod and wire materials disclosed in the prior art, the present invention obtains billets by hot extrusion, which greatly reduces the casting defects inside the casting structure. However, since tin-zinc bronze is a single-phase α alloy and the α phase has poor hot plasticity, the deformation resistance during hot extrusion of tin-zinc bronze alloy is very large, and it often occurs that extrusion cannot be carried out. Therefore, the present invention adopts a process of small extrusion ratio, medium temperature and low-speed extrusion to obtain billets with appropriate grain size and specifications and fewer defects. While controlling the extrusion temperature to improve the metal fluidity, the present invention avoids cracking of a small amount of low-melting ternary eutectics inside the tin-zinc bronze, and at the same time controls the extrusion ratio and extrusion speed.

[0031] By controlling the extrusion ratio, the present invention avoids the situation of extrusion failure, and at the same time makes the recrystallized structure of the hot deformation more uniform, and minimizes the remaining as-cast structure; by controlling the extrusion speed, the present invention makes the surface layer of the extruded billet receive an appropriate additional tensile stress, avoids the generation of cracks, and at the same time avoids excessive temperature drop in the extrusion cylinder resulting in incomplete extrusion of the ingot.

[0032] Preferably, the process flow of the intermediate stretching and annealing includes: first stretching → first annealing → second stretching → second annealing;

[0033] The temperature of the first annealing is 500 - 580 °C, the processing rate of the second stretching is 35 - 50%, and the temperature of the second annealing is 420 - 480 °C.

[0034] Since the extrusion deformation resistance of tin-zinc bronze alloy is very large, the extrusion deformation resistance is reduced by reducing the extrusion ratio, that is, increasing the billet specification. Therefore, the specification of the billet after extrusion is still relatively large. Therefore, through two stretches and two annealings, the present invention can not only make the specification of the billet reach the required specification, but also achieve uniform structure, obtain appropriate grain size, appropriate area ratios of <100> and <111> texture directions and the proportion of twins.

[0035] By controlling the first annealing temperature at a relatively high level, the blank can be fully recrystallized, improving the problem of uneven texture distribution in the middle and tail parts of the extruded blank head, so that the bar blank can obtain a relatively uniform and consistent recrystallized texture distribution after the first stretching and annealing at a relatively high temperature. By controlling the processing rate of the second stretching and the temperature of the second annealing, on the basis of the relatively uniform and consistent recrystallized texture distribution obtained after the first annealing, the area ratios and twin ratios of the appropriate <100> - direction texture and <111> - direction texture are further regulated. That is, a medium processing rate is beneficial to increasing the twin area ratio, and annealing at a lower temperature for the second time is beneficial to obtaining a <100> - direction texture with a medium - upper area ratio, avoiding the situation where the area ratio of the <100> - direction texture is too high due to annealing at a relatively high temperature or excessive strain hardening due to a large processing rate. At the same time, the control of the grain size is also achieved, avoiding grain growth.

[0036] Further preferably, the processing rate of the first stretching is 40 - 60%. By controlling the processing rate of the first stretching, the texture in the middle and tail parts of the extrusion batch head is made more uniform, and at the same time, the additional tensile stress on the surface metal of the bar blank is prevented from exceeding the strength limit and generating cracks.

[0037] Further preferably, the heating - up time of the first annealing is 60 - 120 min, and the holding time is 120 - 300 min.

[0038] Further preferably, the heating - up time of the second annealing is 30 - 90 min, and the holding time is 180 - 360 min.

[0039] Preferably, the melting temperature is 1100 - 1300 °C, and the raw materials for melting are electrolytic copper, tin ingots, Cu - P master alloy, and Cu - Mg master alloy.

[0040] Preferably, the casting temperature for semi - continuous casting is 1170 - 1250 °C, the cooling water temperature is 20 - 38 °C, the cooling water pressure is 1 - 3 bar, the primary cooling water flow rate is 10 - 18 m 3 / h, and the casting speed is 40 - 90 mm / min.

[0041] Specifically, the processes of melting and casting are as follows: proportioning according to the required components of the alloy, adding electrolytic copper, tin ingots, Cu - P master alloy, and Cu - Mg master alloy into the electric furnace in sequence, with a melting temperature of 1100 - 1300 °C, then tilting the furnace head, and casting ingots using the vertical semi - continuous casting method, with a casting temperature of 1170 - 1250 °C, a cooling water temperature of 20 - 38 °C, a cooling water pressure of 1 - 3 bar, a primary cooling water flow rate of 10 - 18 m 3 / h, and the casting speed is 40 - 90 mm / min.

[0042] Preferably, the processing rate of the finished product stretching is 20-70%. The present invention improves the mechanical properties of the blank through deformation strengthening by controlling the processing rate of the finished product stretching.

[0043] Preferably, the temperature of the low-temperature annealing is 180-240° C. The present invention reduces the number of movable dislocations in the material and the effect of Sn atoms segregating and orderly strengthening on the stacking fault plane by controlling the temperature of the low-temperature annealing, thereby improving the yield strength and regulating the yield strength ratio, while avoiding the recrystallization of the blank and reducing the strength of the blank. Further preferably, the time from room temperature to the temperature is 30-60 minutes, and the holding time is 120-300 minutes.

[0044] Preferably, when the tin-zinc bronze alloy is a rod, it is straightened after low-temperature annealing, and the straightness of the rod after straightening is ≤0.5 mm / m.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The present invention increases <100> The area ratio of directional texture is reduced <111> The area ratio of the directional texture can slow down the deformation energy storage during the deformation process, reduce the work hardening rate, limit the rate of increase of the yield strength, and control <111> The lower limit of the area ratio of the directional texture makes the tin-zinc bronze alloy provided by the present invention have a higher tensile strength, thereby obtaining a tin-zinc bronze alloy with a suitable yield ratio and higher tensile strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a metallographic structure photograph of the tin-zinc bronze alloy prepared in Example 1 of the present invention;

[0048] Figure 2 This is a metallographic photograph of the tin-zinc bronze alloy prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0049] The present invention provides 7 embodiments and 2 comparative examples, and the specific components are shown in Table 1.

[0050] Embodiment 1 of the present invention provides a specification of The preparation method of tin-zinc bronze rods includes the following specific steps:

[0051] 1) Melting and casting: According to the required alloy ingredients, electrolytic copper, tin ingots, Cu-P master alloy, Cu-Mg master alloy are added to the electric furnace in sequence. The melting temperature is 1100-1300℃, the casting temperature is 1190-1220℃, the cooling water temperature is 29℃, the cooling water pressure is 1.4bar, and the primary cooling water flow is 13m 3 / h, the casting speed is 65mm / min, and the ingot specifications are

[0052] 2) Extrusion: The extrusion specifications are The extrusion ratio is 23.9, the extrusion temperature is 810 °C, and the extrusion speed is 5 mm / s.

[0053] 3) Intermediate stretching and annealing: After the extruded blank is pickled to remove the surface scale, it is first stretched to with a 42.9% processing rate, and then the bar blank is softened and annealed. The annealing temperature is 540 °C, the heating-up time is 90 min, the holding time is 240 min, and after annealing, it is stretched to with a 36.9% processing rate, and then softened and annealed again. The annealing temperature is 460 °C, the heating-up time is 60 min, and the holding time is 300 min.

[0054] 4) Finished product stretching: First stretch to Skin-pass to Eliminate surface defects, and then continue to stretch to the finished product specifications The processing rate is about 32%.

[0055] 5) Low-temperature annealing: The low-temperature annealing temperature of the bar is 210 °C. The time from room temperature to this temperature is 40 min, and the holding time is 150 min.

[0056] 6) Straightening: After low-temperature annealing The bar is straightened on a precision straightening machine, and the straightness ≤ 0.2 mm / m.

[0057] Example 2 of the present invention provides a method for preparing tin-zinc bronze wire with specifications of as follows:

[0058] 1) Melting and casting: Charge according to the required components of the alloy. In an electric furnace, electrolytic copper, tin ingots, Cu-P master alloy, and Cu-Mg master alloy are added in sequence. The melting temperature is 1100 - 1300 °C, the casting temperature is 1170 - 1200 °C, the cooling water temperature is 25 °C, the cooling water pressure is 1.8 bar, the primary cooling water flow rate is 12 m 3 / h, the continuous casting speed is 70 mm / min, and the ingot specifications are

[0059] 2) Extrusion: The extrusion specifications are The extrusion ratio is 56.3, the extrusion temperature is 830 °C, and the extrusion speed is 6 mm / s.

[0060] 3) Intermediate stretching and annealing: After the extruded blank is pickled to remove the surface scale, it is first stretched to The wire blank is subjected to soft annealing at an annealing temperature of 520 °C, a heating-up time of 60 min, and a holding time of 210 min. After annealing, it is drawn to The wire blank is subjected to soft annealing at an annealing temperature of 420 °C, a heating-up time of 60 min, and a holding time of 300 min.

[0061] 4) Finish drawing: First draw to Skin-pass to Eliminate surface defects, and then continue to draw to the finish specification The drawing ratio is approximately 47.7%.

[0062] 5) Low-temperature annealing: The low-temperature annealing temperature of the wire is 190 °C. The time taken to rise from room temperature to this temperature is 30 min, and the holding time is 180 min.

[0063] Example 3 of the present invention provides a tin-zinc bronze bar with a specification of The preparation method of the tin-zinc bronze bar is as follows:

[0064] 1) Melting and casting: Charge according to the required components of the alloy. In an electric furnace, electrolytic copper, tin ingots, Cu-P master alloy, and Cu-Mg master alloy are added in sequence. The melting temperature is 1100 - 1300 °C, the casting temperature is 1220 - 1250 °C, the cooling water temperature is 27 °C, the cooling water pressure is 2.1 bar, the primary cooling water flow rate is 14 m 3 / h, the continuous casting speed is 55 mm / min, and the ingot specification is

[0065] 2) Extrusion: The extrusion specification is The extrusion ratio is 11.4, the extrusion temperature is 770 °C, and the extrusion speed is 2.6 mm / s.

[0066] 3) Intermediate drawing and annealing: After the extruded blank is pickled to remove the surface scale, it is first drawn to The bar blank is subjected to soft annealing at an annealing temperature of 570 °C, a heating-up time of 90 min, and a holding time of 270 min. After annealing, it is drawn to Then, it is subjected to soft annealing again at an annealing temperature of 480 °C, a heating-up time of 60 min, and a holding time of 240 min.

[0067] 4) Finish drawing: First draw to Skin-pass to Eliminate surface defects, and then continue to draw to the finish specification The drawing ratio is approximately 28.6%.

[0068] 5) Low-temperature annealing: The low-temperature annealing temperature of the bar is 230°C. The time taken to raise the temperature from room temperature to this temperature is 40 min, and the holding time is 150 min.

[0069] 6) Straightening: After low-temperature annealing, the bar is straightened on a precision straightening machine, and the straightness is ≤0.35 mm / m.

[0070] Example 4 of the present invention provides a method for preparing a tin-zinc bronze bar with a specification of as follows:

[0071] 1) Melting and casting: Ingredients are prepared according to the required composition of the alloy. Electrolytic copper, tin ingots, Cu-P master alloy, and Cu-Mg master alloy are successively added to an electric furnace. The melting temperature is 1100 - 1300°C, the casting temperature is 1190 - 1220°C, the cooling water temperature is 27°C, the cooling water pressure is 1.3 bar, the primary cooling water flow rate is 12.5 m 3 / h, the drawing speed is 65 mm / min, and the ingot specification is

[0072] 2) Extrusion: The extrusion specification is The extrusion ratio is 23.9, the extrusion temperature is 820°C, and the extrusion speed is 4.8 mm / s.

[0073] 3) Intermediate drawing and annealing: After pickling to remove the surface oxide scale, the extruded billet is first drawn to with a 42.9% reduction in area for softening annealing. The annealing temperature is 540°C, the heating-up time is 90 min, and the holding time is 240 min. After annealing, it is drawn to with a 36.9% reduction in area for another softening annealing. The annealing temperature is 460°C, the heating-up time is 60 min, and the holding time is 300 min.

[0074] 4) Final drawing: First draw to Skin-pass to eliminate surface defects, and then continue to draw to the final product specification with a reduction in area of approximately 32%.

[0075] 5) Low-temperature annealing: The low-temperature annealing temperature of the bar is 210°C. The time taken to raise the temperature from room temperature to this temperature is 40 min, and the holding time is 150 min.

[0076] 6) Straightening: After low-temperature annealing, the bar is straightened on a precision straightening machine, and the straightness is ≤0.2 mm / m.

[0077] Example 5 of the embodiments of the present invention provides a Method for preparing tin-zinc bronze wire rod is as follows:

[0078] 1) Melting and casting: Weigh materials according to the required components of the alloy. In an electric furnace, electrolytic copper, tin ingots, Cu-P master alloy, and Cu-Mg master alloy are added in sequence. The melting temperature is 1100 - 1300 °C, the casting temperature is 1170 - 1200 °C, the cooling water temperature is 26 °C, the cooling water pressure is 1.7 bar, the primary cooling water flow rate is 13.2 m 3 / h, the drawing and casting speed is 70 mm / min, and the ingot specification is

[0079] 2) Extrusion: The extrusion specification is The extrusion ratio is 56.3, the extrusion temperature is 825 °C, and the extrusion speed is 5.7 mm / s.

[0080] 3) Intermediate drawing and annealing: After the extruded billet is pickled to remove the surface scale, it is first drawn to with a 43.8% reduction in area. The wire billet is subjected to softening annealing. The annealing temperature is 520 °C, the heating-up time is 60 min, the holding time is 210 min. After annealing, it is further drawn to with a 49.8% reduction in area. The wire billet is subjected to softening annealing. The annealing temperature is 420 °C, the heating-up time is 60 min, and the holding time is 300 min.

[0081] 4) Final drawing: First draw to Skin-pass to Eliminate surface defects, and then continue to draw to the final product specification The reduction in area is approximately 47.7%.

[0082] 5) Low-temperature annealing: The low-temperature annealing temperature of the wire rod is 190 °C. The time from room temperature to this temperature is 30 min, and the holding time is 180 min.

[0083] Example 6 of the embodiments of the present invention provides a Method for preparing tin-zinc bronze bar is as follows:

[0084] 1) Melting and casting: Weigh materials according to the required components of the alloy. In an electric furnace, electrolytic copper, tin ingots, Cu-P master alloy, and Cu-Mg master alloy are added in sequence. The melting temperature is 1100 - 1300 °C, the casting temperature is 1220 - 1250 °C, the cooling water temperature is 29 °C, the cooling water pressure is 2.2 bar, the primary cooling water flow rate is 14.7 m 3 / h, the drawing and casting speed is 55 mm / min, and the ingot specification is

[0085] 2) Extrusion: The extrusion specifications are The extrusion ratio is 11.4, the extrusion temperature is 764 °C, and the extrusion speed is 2.8 mm / s.

[0086] 3) Intermediate stretching and annealing: After the extruded billet is pickled to remove the surface scale, it is first stretched to with a 40.5% processing rate, and then the bar billet is subjected to soft annealing. The annealing temperature is 570 °C, the heating-up time is 90 min, the holding time is 270 min. After annealing, it is stretched to with a 40% processing rate, and then soft annealing is carried out again. The annealing temperature is 480 °C, the heating-up time is 60 min, and the holding time is 240 min.

[0087] 4) Final stretching: First stretch to Skin-pass to Eliminate surface defects, and then continue to stretch to the final product specifications The processing rate is about 28.6%.

[0088] 5) Low-temperature annealing: The low-temperature annealing temperature of the bar is 230 °C. The time from room temperature to this temperature is 40 min, and the holding time is 150 min.

[0089] Example 7 of the present invention provides a method for preparing tin-zinc bronze wire with specifications of as follows:

[0090] 1) Melting and casting: Weigh the ingredients according to the required alloy composition, and sequentially add electrolytic copper, tin ingots, Cu-P master alloy, and Cu-Mg master alloy into the electric furnace. The melting temperature is 1100 - 1300 °C, the casting temperature is 1180 - 1210 °C, the cooling water temperature is 32 °C, the cooling water pressure is 1.8 bar, the primary cooling water flow rate is 15 m 3 / h, the continuous casting speed is 65 mm / min, and the ingot specifications are

[0091] 2) Extrusion: The extrusion specifications are The extrusion ratio is 47.7, the extrusion temperature is 800 °C, and the extrusion speed is 5 mm / s.

[0092] 3) Intermediate stretching and annealing: After the extruded billet is pickled to remove the surface scale, it is first stretched to with a 42% processing rate, and then the bar billet is subjected to soft annealing. The annealing temperature is 550 °C, the heating-up time is 60 min, the holding time is 180 min. After annealing, it is stretched to The billet is softened and annealed at an annealing temperature of 450 °C, a heating-up time of 90 min, and a holding time of 240 min.

[0093] 4) Finish drawing: The billet is first drawn to Skived to Remove surface defects, and then continue to draw to the finished product specifications The processing rate is about 35%.

[0094] 5) Low-temperature annealing: The low-temperature annealing temperature of the bar is 220 °C. The time from room temperature to this temperature is 30 min, and the holding time is 210 min.

[0095] 6) Straightening: After low-temperature annealing The bar is straightened on a precision straightening machine, and the straightness ≤ 0.2 mm / m.

[0096] Comparative example 1: Commercially available QSn4-3 bar.

[0097] Comparative example 2 (original comparative example 3): The chemical composition is the same as that of Example 1. The intermediate drawing and annealing in the preparation process are different from those of Example 1, and the finished product does not have low-temperature annealing. The specific preparation process is as follows:

[0098] 1) Melting and casting: Charge according to the required composition of the alloy. In an electric furnace, electrolytic copper, tin ingots, Cu-P master alloy, and Cu-Mg master alloy are added in sequence. The melting temperature is 1100 - 1300 °C, the casting temperature is 1190 - 1220 °C, the cooling water temperature is 29 °C, the cooling water pressure is 1.4 bar, the primary cooling water flow rate is 13 m 3 / h, the casting speed is 65 mm / min, and the ingot specification is

[0099] 2) Extrusion: The extrusion specification is The extrusion ratio is 23.9, the extrusion temperature is 810 °C, and the extrusion speed is 5 mm / s.

[0100] 3) Intermediate drawing and annealing: After the extruded billet is pickled to remove the surface oxide scale, it is first drawn to with a 21% processing rate, and then the billet is softened and annealed at an annealing temperature of 540 °C, a heating-up time of 90 min, and a holding time of 240 min. After annealing, it is drawn to with a 23.4% processing rate, and then softened and annealed again at an annealing temperature of 540 °C, a heating-up time of 90 min, and a holding time of 240 min. After annealing, it is drawn to Then soft annealing is carried out at an annealing temperature of 540 °C, with a heating-up time of 90 min and a holding time of 240 min. After annealing, it is stretched to The annealing temperature is 540 °C, the heating-up time is 90 min, and the holding time is 240 min.

[0101] 4) Finish stretching: First stretch to Skin-pass to Eliminate surface defects, and then continue to stretch to the finished product specifications The processing rate is about 32%.

[0102] 5) Straightening: After low-temperature annealing The bars are straightened on a precision straightening machine, and the straightness is ≤0.2 mm / m.

[0103] The following tests are carried out on the microstructures of the 7 examples and 3 comparative examples obtained, and the results are recorded in Table 2.

[0104] The proportion of twins and the grain size are observed under a metallographic microscope;

[0105] The proportion of texture is observed under an X-ray diffractometer;

[0106] The following performance tests are carried out on the 7 examples and 3 comparative examples, and the results are recorded in Table 3.

[0107] Tensile strength Rm, yield strength Rp0.2 and elongation A50: Test according to GB / T228.1-2021 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature".

[0108] Conductivity: Measure according to GB / T351-2019 "Method for measuring resistivity of metallic materials".

[0109] Table 1 Chemical compositions of examples and comparative examples

[0110]

[0111] Table 2 Microstructures of examples and comparative examples

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[0113] Table 3 Mechanical properties of examples and comparative examples

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[0115] As can be seen from Table 2, the proportion of twin area, the average grain size and the <100> direction texture area of the examples are all higher than those of Comparative Example 1 (commercially purchased QSn4-3 is larger than that of the bars); in Comparative Example 2, the intermediate drawing reduction rate is small, and the last annealing of the intermediate annealing still uses a relatively high temperature annealing. As a result, the grain size of the bar is larger than that of the Example, and the proportion of the twin area and the proportion of the <100> direction texture area are significantly lower than those of the Example.

[0116] The microstructure of the material determines its properties. As can be seen from Table 3, the tensile strength of the Examples is higher than that of Comparative Example 1 (the commercially available QSn4-3 bars), and the yield ratio Rm / Rp of the Examples 0.2 is also lower than that of Comparative Example 1; in Comparative Example 2, the temperature of the second annealing in the intermediate drawing and annealing steps is higher than that of the Example. As a result, the strength and yield ratio Rm / Rp 0.2 of the bar are lower than those of the Example.

[0117] As Figure 1 shown, the grain size of the tin-zinc bronze alloy prepared in Example 1 is 17.4 μm, the grain size is moderate, within the range of 10-25 μm required by the present invention. There are relatively many twins distributed in the microstructure, with a proportion reaching 53.6%, meeting the requirement of 40-60% of the present invention. The dark microstructure is the <100> direction texture, with a proportion reaching 62.7%, meeting the requirement of 55-70% of the present invention. The light microstructure is the <111> direction texture, with a proportion of 37.3%, meeting the requirement of 30-45% of the present invention.

[0118] As Figure 2 shown, the grain size of the microstructure of the product provided in Comparative Example 1 is 7.2 μm, the grains are fine, there are relatively few twins distributed in the microstructure, with a proportion of only 15.5%, there is very little dark <100> direction texture, with a proportion of only 11.6%, and there is a lot of light <111> direction texture, with a proportion reaching 71.4%.

Claims

1. A tin-zinc bronze alloy, characterized in that: Including Sn, Zn, Cu, X elements and inevitable impurities, the sum of the mass percentages of all elements is 100%, wherein Sn: 3-5wt%, Zn: 2-4wt%, X elements including P: 0.005-0.03wt%; The microstructure of the tin-zinc bronze alloy is <100> Directional texture and <111> Directional texture composition, among which <100> The area proportion of directional texture is 55-70%. <111> The area proportion of directional texture is 30-45%.

2. The tin-zinc bronze alloy according to claim 1, characterized in that: The yield strength ratio Rp of the tin-zinc bronze alloy 0.2 / Rm is 0.78-0.90, of which Rp 0.2 Rm is the yield strength and Rm is the tensile strength.

3. The tin-zinc bronze alloy according to claim 2, characterized in that: The tensile strength of the tin-zinc bronze alloy is Rm≥550Mpa, and the yield strength is Rp 0.2 ≥430Mpa.

4. The tin-zinc bronze alloy according to claim 1, characterized in that: The elongation A of the tin-zinc bronze alloy 50 ≥10%, conductivity ≥18%IACS.

5. The tin-zinc bronze alloy according to claim 1, characterized in that: The area of ​​twins in the structure of the tin-zinc bronze alloy accounts for 40-60%.

6. The tin-zinc bronze alloy according to claim 1, characterized in that: The average grain size of the tin-zinc bronze alloy is 10-25 μm.

7. The tin-zinc bronze alloy according to claim 1, characterized in that: The X element also includes Mg: 0.001-0.01wt%, Fe≤0.03%, Ni≤0.02wt%, and Pb≤0.01%.

8. A method for preparing the tin-zinc bronze alloy according to any one of claims 1 to 7, characterized in that: The process flow of the preparation method includes: smelting → semi-continuous casting → extrusion → intermediate stretching and annealing → finished product stretching → low-temperature annealing; Mixing and smelting the tin-zinc bronze alloy according to the mass percentage of each component; The extrusion temperature is 740-860° C., the extrusion ratio is 10-60, and the extrusion speed is 2-6 mm / s.

9. The method for preparing the tin-zinc bronze alloy according to claim 8, characterized in that: The process flow of intermediate stretching and annealing includes: first stretching→first annealing→second stretching→second annealing; The temperature of the first annealing is 500-580°C, the processing rate of the second stretching is 35-50%, and the temperature of the second annealing is 420-480°C.

10. The method for preparing the tin-zinc bronze alloy according to claim 9, characterized in that: The processing rate of the first stretching is 40-60%.

11. The method for preparing the tin-zinc bronze alloy according to claim 9, characterized in that: The heating time of the first annealing is 60-120 minutes, and the holding time is 120-300 minutes.

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