A high-strength, creep-resistant, highly corrosion-resistant zinc alloy and its preparation method

Abstract

The present invention discloses a high-strength, creep-resistant, highly corrosion-resistant zinc alloy and a preparation method thereof. The components of the zinc alloy include, by mass percentage: 0.1% - 2.0% of Cu, 0.01% - 0.2% of Ti, 0.05% - 0.1% of Cr, 0.05% - 0.1% of X, and the balance is Zn and inevitable impurities, wherein X is at least one of Mg and Ni. The preparation method includes the following steps: weighing zinc source, copper source, titanium source, chromium source, magnesium source, nickel source; after melting the zinc source in a melting furnace, coating the copper source, titanium source, chromium source, nickel source, and magnesium source together with copper foil and pressing them into the zinc liquid in the melting furnace using a graphite bell, continuing to keep warm after the materials are completely melted, then stirring and skimming the slag, cooling and then stirring and skimming the slag again, and casting the materials into zinc alloy ingots; then successively performing hot rolling and cold rolling treatments to obtain zinc alloy sheets. The method of the present invention has high efficiency, simple operation, and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metal material manufacturing, and specifically relates to a high-strength, creep-resistant, and highly corrosion-resistant zinc alloy and a preparation method thereof. Background Art

[0002] Zinc is a non-ferrous metal second only to aluminum and copper in terms of application volume. It has a wide range of applications and can be used in the construction industry, infrastructure (electricity) industry, transportation, home appliance industry, clothing and luggage and other fields. The main structural zinc alloy for construction is zinc-copper-titanium alloy. Zinc-copper-titanium alloy sheets are mainly used for roofs and exterior walls of buildings such as airports, schools, clubs, churches and exhibition halls. Titanium can improve the creep resistance of zinc alloys, so that they will not produce metal fatigue after thermal expansion and contraction, and copper increases the mechanical strength and hardness of the alloy. Alloys containing these metal elements reduce the expansion coefficient of the sheet and are more suitable for areas with large temperature differences. Its advantages are: 1) Green and environmentally friendly, no formaldehyde release, and 100% recyclable; 2) Durable and long life, with a lasting characteristic of more than 80 to 100 years; 3) Self-repairing properties; 4) Very expressive architectural color, especially suitable for use in iconic buildings in cities.

[0003] At present, zinc-copper-titanium plates are mainly manufactured according to European standard EN988, and their components are zinc and a small amount of copper (0.08%) and titanium (0.06%). In view of the performance requirements of domestic projects, it is necessary to prepare zinc-copper-titanium alloy materials with high strength, high toughness, high creep resistance and high corrosion resistance.

[0004] In order to improve the performance of zinc alloy, other alloying elements need to be added to the alloy. However, since the melting point of zinc is much lower than that of copper, titanium and other metals, it is difficult to completely melt the added elements. In addition, the density of zinc is higher than that of conventional metals, which leads to serious burning problems in the smelting process of alloying elements such as titanium, magnesium and chromium, making the preparation of the alloy more difficult and difficult to achieve the expected effect. At present, the zinc alloy is often cast by preparing a multi-element intermediate alloy, adding the intermediate alloy material in batches, and adding a covering agent, and then the alloy microstructure is regulated by hot extrusion deformation. However, these processes will inevitably increase the alloy preparation process, resulting in increased costs, and the extruded material is difficult to be processed into building panels due to size limitations. Therefore, it is urgent to develop high-performance zinc alloys and their efficient and low-cost preparation processes to obtain high-performance zinc alloy building materials with application prospects. Summary of the invention

[0005] In view of the problems in the prior art, the present invention provides a high-strength, creep-resistant, high-corrosion-resistant zinc alloy and a preparation method thereof. The method of the present invention can simplify the zinc alloy preparation process, improve efficiency, reduce costs and is easy to operate.

[0006] The present invention adopts the following technical solutions:

[0007] A high-strength, creep-resistant, highly corrosion-resistant zinc alloy, the components of the zinc alloy including, by mass percentage: Cu 0.1% - 2.0%, Ti 0.01% - 0.2%, Cr 0.05% - 0.1%, X 0.05% - 0.1%, the balance being Zn and unavoidable impurities, wherein X is at least one of Mg and Ni.

[0008] Furthermore, the phase composition of the microstructure in the zinc alloy is a matrix phase Zn and particulate second phases distributed in the matrix phase Zn; the particulate second phases are intermetallic compounds of ZnTi, ZnCuTi, ZnCu, ZnCr and / or ZnTiMg, ZnTiNi; the maximum size of the particulate second phases in the matrix phase Zn ≤ 5 μm.

[0009] A preparation method of a high-strength, creep-resistant, highly corrosion-resistant zinc alloy as described above, the method comprising the following steps:

[0010] (1) Weigh zinc source, copper source, titanium source, chromium source, magnesium source, nickel source according to the components of the zinc alloy.

[0011] (2) After melting the zinc source in a melting furnace, wrap the copper source, titanium source, chromium source, nickel source, magnesium source together with copper foil and press them into the zinc liquid in the melting furnace using a graphite bell. After the materials in the melting furnace are completely melted, keep warm for 10 min - 30 min, then stir and skim the slag. Cool the melting furnace to the casting temperature and then stir and skim the slag again. Finally, cast the materials in the melting furnace into zinc alloy ingots.

[0012] (3) Carry out hot rolling and cold rolling treatments on the zinc alloy ingots in sequence to obtain zinc alloy plates. The tensile strength of the zinc alloy plates is 240 - 350 MPa, the elongation at break is 35 - 65%, the creep rate is 1.0 - 1.5×10 -9 s -1 -1, and the corrosion potential is -1.10 - -1.05 V.

[0013] Furthermore, the zinc source is a 0# pure zinc block, the copper source is pure copper, the titanium source is pure titanium, the chromium source is a copper-chromium or zinc-chromium master alloy, the magnesium source is a copper-magnesium or zinc-magnesium master alloy, the nickel source is pure nickel; the copper source, the titanium source, the chromium source, the magnesium source, the nickel source are all processed into chips.

[0014] Furthermore, in step (2), the temperature for melting the zinc source in the melting furnace is 650°C - 750°C; the total time for stirring and skimming the slag twice after the materials in the melting furnace are completely melted and when the melting furnace is cooled to the casting temperature in step (2) is less than 5 min; the casting temperature for casting the materials in the melting furnace into zinc alloy ingots in step (2) is 580°C - 600°C;

[0015] Furthermore, before hot rolling the zinc alloy ingot, the surface defects are removed until the surface is smooth; before hot rolling the zinc alloy ingot, it is heat-insulated at 250°C to 300°C for 2h to 5h, the reduction per pass of hot rolling is 15% to 30%, and the total deformation of hot rolling is 85% to 95%; in step (3), the reduction per pass of cold rolling is less than 10%.

[0016] The beneficial technical effects of the present invention: The present invention adopts adding appropriate alloying elements and combining an efficient and low-cost alloy preparation process to obtain a high-performance zinc alloy sheet for construction. The beneficial effects are as follows: (1) The raw materials used in alloy preparation are pure metals or master alloys that can be widely obtained, with a wide source and low cost. During the alloy melting process, no covering agent is required. The raw materials in the form of debris are added to the melt in one step by pressing them into the melt using a graphite bell, which accelerates the melting of the raw materials, reduces the burning loss of alloying elements, improves the alloy preparation efficiency, and makes each component evenly distributed in the matrix. (2) Through hot rolling deformation, the second phase in the alloy is fragmented, and the refined microstructure helps to improve the mechanical properties, creep resistance, and corrosion resistance of the alloy; combined with the control of cold rolling deformation, the alloy surface is optimized, and the precipitation of solid solution elements in the alloy is inhibited, ensuring the alloy properties to the greatest extent. The method of the present invention can simplify the zinc alloy preparation process, improve efficiency, reduce costs, and is easy to operate, and can obtain a zinc alloy sheet for construction with good surface quality, high strength, high creep resistance, and high corrosion resistance. Description of the Drawings

[0017] Figure 1 It is the scanning electron microscope (SEM) map of the zinc alloy microstructure in Example 1;

[0018] Figure 2 It is the scanning electron microscope (SEM) map of the zinc alloy microstructure in Example 2;

[0019] Figure 3 It is the scanning electron microscope (SEM) map of the zinc alloy microstructure in Example 3;

[0020] Figure 4 It is the scanning electron microscope (SEM) map of the zinc alloy microstructure in Comparative Example 1. Detailed Embodiments

[0021] By reading the detailed description of the non-restrictive embodiments with reference to the drawings, the features, purposes, and advantages of the present invention will become more obvious. The technical solutions of the present invention will be described in detail below with reference to the drawings and specific embodiments.

[0022] Example 1

[0023] In this embodiment, a high-strength, creep-resistant, and highly corrosion-resistant zinc alloy is designed. The components of the zinc alloy and their mass percentages are as follows: Cu 1.0%, Ti 0.1%, Cr 0.05%, Ni 0.05%, and the rest is Zn. The scanning electron microscope (SEM) image of the microstructure of the zinc alloy in Example 1 is shown in Figure 1 .

[0024] The preparation method of the zinc alloy is as follows: Add 0# zinc ingots into the crucible of the melting furnace, and then heat to 700 °C. After the 0# zinc ingots are completely melted, weigh pure copper, pure nickel, pure titanium, and copper-chromium master alloy processed into chips according to the ratio, wrap them with copper foil, and press them into the zinc liquid using a graphite bell. After the materials are completely melted, keep warm for 20 min, and then carry out stirring and slag skimming treatments, with the stirring and slag skimming time controlled within 2 min. After the melt cools to 580 °C, stir and skim the slag again, and the time for the second stirring and slag skimming is also controlled within 2 min. Finally, pour the melt into a graphite mold to obtain zinc alloy ingots. Use a milling machine to remove the surface oxide scale of the zinc alloy ingots, and after obtaining a smooth surface, place them in a heat treatment furnace and keep warm at 250 °C for 2 h. Subsequently, perform hot rolling with a single-pass reduction of 20%, and the total hot rolling deformation is 85% to obtain a hot-rolled sheet with a thickness of 4 mm. After the hot-rolled sheet is completely cooled, cold roll the sheet to 2 mm with a single-pass deformation of 8% to obtain the finished alloy sheet.

[0025] The microstructure of the high-strength, creep-resistant, and highly corrosion-resistant zinc alloy prepared in this embodiment includes a matrix phase Zn and particulate second phases distributed in the matrix phase. The particulate second phases distributed in the matrix phase are ZnTi, ZnCuTi, ZnCu, ZnCr, and ZnTiNi intermetallic compounds. The maximum size of the second phase is less than 2 μm. The tensile strength of the finished alloy sheet is 280 MPa, the elongation at break is 45%, the creep rate is 1.45×10 -9 s -1 , and the corrosion potential is -1.087 V.

[0026] Example 2

[0027] In this embodiment, a high-strength, creep-resistant, and highly corrosion-resistant zinc alloy is designed. The components of the zinc alloy and their mass percentages are as follows: Cu 1.0%, Ti 0.1%, Cr 0.05%, Mg 0.05%, and the rest is Zn. The scanning electron microscope (SEM) image of the microstructure of the zinc alloy in Example 2 is shown in Figure 2 .

[0028] The preparation method of the zinc alloy is as follows: Add 0# zinc blocks into the crucible of the melting furnace, and then heat to 650 °C. After the 0# zinc blocks are completely melted, weigh the pure copper, pure titanium, copper-chromium, and copper-magnesium master alloys processed into chips according to the ratio, wrap them with copper foil, and press them into the zinc liquid using a graphite bell. After the materials are completely melted, keep warm for 25 minutes, and then carry out stirring and slag skimming. The stirring and slag skimming time is controlled within 1 minute. After the melt cools to 600 °C, stir and skim the slag again, and the stirring and slag skimming time for the second time is controlled within 2 minutes. Finally, pour the melt into a graphite mold to obtain a zinc alloy ingot. Use a milling machine to remove the surface oxide scale of the zinc alloy ingot, and after obtaining a smooth surface, place it in a heat treatment furnace and keep warm at 300 °C for 3 hours. Subsequently, perform hot rolling with a single-pass reduction of 15%, and the total hot rolling deformation is 90% to obtain a hot-rolled sheet with a thickness of 4 mm. After the hot-rolled sheet is completely cooled, cold-roll the sheet to 1.5 mm with a single-pass deformation of 10% to obtain the finished alloy sheet.

[0029] The microstructure of a high-strength, creep-resistant, and highly corrosion-resistant zinc alloy prepared in this example includes a matrix phase Zn and particulate second phases distributed in the matrix phase. The particulate second phases are ZnTi, ZnCuTi, ZnCu, ZnCr, and ZnTiMg intermetallic compounds. The maximum second-phase size is less than 2 μm. The tensile strength of the finished alloy sheet is 345 MPa, the elongation at break is 40%, the creep rate is 1.38×10 -9 s -1 , and the corrosion potential is -1.076 V.

[0030] Example 3

[0031] In this example, a high-strength, creep-resistant, and highly corrosion-resistant zinc alloy is designed. The components and their mass percentages of the zinc alloy are: Cu 1.5%, Ti 0.2%, Cr 0.1%, Mg 0.03%, Ni 0.03%, and the rest is Zn. The scanning electron microscope (SEM) pattern of the microstructure of the zinc alloy in Example 3 is shown in Figure 3 .

[0032] The preparation method of the zinc alloy is as follows: Add 0# zinc ingots into the crucible of the melting furnace, and then heat to 750°C. After the 0# zinc ingots are completely melted, weigh pure copper, pure titanium, copper-chromium, copper-magnesium master alloy, and pure nickel processed into chips according to the ratio, wrap them with copper foil, and press them into the zinc liquid using a graphite bell. After the materials are completely melted, keep warm for 30 minutes, and then carry out stirring and slag skimming. The stirring and slag skimming time is controlled within 2 minutes. After the melt cools to 590°C, stir and skim the slag again, and the stirring and slag skimming time for the second time is controlled within 3 minutes. Finally, pour the melt into a graphite mold to obtain a zinc alloy ingot. Use a milling machine to remove the surface oxide scale of the zinc alloy ingot, and after obtaining a smooth surface, place it in a heat treatment furnace and keep warm at 260°C for 4 hours. Then, carry out hot rolling with a single-pass reduction of 25%, and the total hot rolling deformation is 95% to obtain a hot-rolled sheet with a thickness of 4 mm. After the hot-rolled sheet is completely cooled, cold roll the sheet to 2.5 mm with a single-pass deformation of 5% to obtain the finished alloy sheet.

[0033] The microstructure of a high-strength, creep-resistant, and highly corrosion-resistant zinc alloy prepared in this example includes a matrix phase Zn and particulate second phases distributed in the matrix phase. The particulate second phases are intermetallic compounds of ZnTi, ZnCuTi, ZnCu, ZnCr, ZnTiMg, and ZnTiNi. The maximum second-phase size is less than 5 μm. The strength of the finished alloy sheet is 243 MPa, the elongation at break is 60%, the creep rate is 1.30×10 -9 s -1 , and the corrosion potential is -1.098 V.

[0034] Comparative Example 1

[0035] The alloy composition of this comparative example is as follows: the mass fraction of Cu is 1.0%, the mass fraction of Ti is 0.1%, and the rest is Zn. The scanning electron microscope (SEM) pattern of the microstructure of the zinc alloy in Comparative Example 1 is shown in Figure 4 .

[0036] Add 0# zinc ingots into the crucible of the melting furnace, and then heat to 750°C. After the 0# zinc ingots are completely melted, weigh pure copper and pure titanium processed into chips according to the ratio, wrap them with copper foil, and press them into the zinc liquid using a graphite bell. After the materials are completely melted, keep warm for 20 minutes, and then carry out stirring and slag skimming. The stirring and slag skimming time is controlled within 2 minutes. After the melt cools to 580°C, stir and skim the slag again, and the stirring and slag skimming time for the second time is controlled within 2 minutes. Finally, pour the melt into a graphite mold to obtain a zinc alloy ingot.

[0037] The surface oxide scale of the zinc alloy ingot was removed by a milling machine. After obtaining a smooth surface, it was placed in a heat treatment furnace and held at 250 °C for 4 h. Subsequently, hot rolling was carried out with a single-pass reduction of 20%, and the total hot rolling deformation was 90% to obtain a hot-rolled sheet with a thickness of 4 mm. After the hot-rolled sheet was completely cooled, the sheet was cold-rolled to 2 mm with a single-pass deformation of 8% to obtain the finished alloy sheet.

[0038] The microstructure of the zinc alloy prepared in this comparative example contains a matrix phase Zn and particulate secondary phases distributed in the matrix phase. The particulate secondary phases are intermetallic compounds of ZnTi, ZnCuTi, and ZnCu. The maximum secondary phase size is less than 10 μm. The strength of the finished alloy sheet is 203 MPa, the elongation at break is 85%, and the creep rate is 9.92×10 -8 s -1 , and the corrosion potential is -1.143 V.

[0039] Compared with Comparative Example 1, in Examples 1-3, since only Cu and Ti are contained in the alloy structure of Comparative Example 1, the secondary phases in the microstructure are coarser, the creep rate is significantly greater than that of the three examples, and the corrosion potential and strength are lower than those of the three examples. In the examples, due to the fine, uniform, and dispersed secondary phases, it is the key to obtaining excellent properties. The preparation method of the high-strength, high creep-resistant, and high corrosion-resistant zinc alloy of the present invention, each step cooperates with each other. By controlling the alloy element ratio, after melting, hot rolling, and cold rolling, the fine secondary phases in the obtained alloy microstructure effectively inhibit grain boundary slip during the creep process, while improving the strength and corrosion resistance, making the comprehensive performance index of the finally obtained product excellent and improving the market competitiveness of the product.

[0040] The above are only the preferred embodiments of the present invention and do not limit the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, under the technical inspiration provided by the present invention, other equivalent improvements can also be made, and the purposes of the present invention can be achieved, all of which should be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a high-strength, creep-resistant, and highly corrosion-resistant zinc alloy, characterized in that, The method includes the following steps: (1) Weigh zinc source, copper source, titanium source, chromium source, magnesium source, nickel source according to the components of the zinc alloy. The components are in mass percentage: Cu 0.1% - 2.0%, Ti 0.01% - 0.2%, Cr 0.05% - 0.1%, X 0.05% - 0.1%, and the rest is Zn and inevitable impurities, where X is at least one of Mg and Ni; (2) Place the zinc source in a melting furnace to melt at a temperature of 650°C - 750°C. Subsequently, wrap the copper source, titanium source, chromium source, nickel source, and magnesium source together with copper foil and press them into the zinc liquid in the melting furnace using a graphite bell. After the materials in the melting furnace are completely melted, keep them warm for 10 min - 30 min, then stir and skim the slag. Cool the melting furnace to the casting temperature and stir and skim the slag again. The total time of stirring and skimming the slag twice, once after the materials in the melting furnace are completely melted and once after the melting furnace is cooled to the casting temperature, is less than 5 min. Finally, cast the materials in the melting furnace into zinc alloy ingots, and the casting temperature is 580°C - 600°C; (3) Perform hot rolling and cold rolling on the zinc alloy ingots in sequence to obtain zinc alloy sheets. Remove surface defects of the zinc alloy ingots to a smooth surface before hot rolling; keep the zinc alloy ingots at 250°C - 300°C for 2 h - 5 h before hot rolling. The reduction per pass of hot rolling is 15% - 30%, and the total deformation of hot rolling is 85% - 95%; the reduction per pass of cold rolling is less than 10%; the phase composition of the microstructure in the zinc alloy is the matrix phase Zn and the particulate secondary phase distributed in the matrix phase Zn; the particulate secondary phase is intermetallic compounds such as ZnTi, ZnCuTi, ZnCu, ZnCr, and / or ZnTiMg, ZnTiNi; the maximum size of the particulate secondary phase in the matrix phase Zn ≤ 5 μm.

2. The preparation method of the high-strength, creep-resistant, and highly corrosion-resistant zinc alloy according to claim 1, characterized in that, The zinc source is 0# pure zinc block, the copper source is pure copper, the titanium source is pure titanium, the chromium source is copper-chromium or zinc-chromium master alloy, the magnesium source is copper-magnesium or zinc-magnesium master alloy, and the nickel source is pure nickel; the copper source, the titanium source, the chromium source, the magnesium source, and the nickel source are all processed into debris.

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