A corrosion-resistant white copper alloy containing a high proportion of special grain boundaries and a preparation method thereof

Abstract

The present invention belongs to the field of copper alloy technology, specifically relating to a corrosion-resistant white copper alloy containing a high proportion of special grain boundaries and a preparation method thereof. The corrosion-resistant white copper alloy comprises the following elements, measured by mass percentage: 9-12% Ni; 1.5-1.9% Fe; 0.6-1% Mn; 0.18-0.4% Cr; 0.03-0.05% Ce; the remainder being Cu; the mass ratio of Ni to Cr is 30-50:1; and the number of special grain boundaries in the corrosion-resistant white copper alloy is greater than 55%. Under room temperature conditions, the corrosion-resistant white copper alloy provided by the present invention has a tensile strength greater than 350 MPa, an elongation greater than 40%, a static full immersion uniform corrosion rate less than 0.015 mm / a, and a uniform corrosion rate ≤0.04 mm / a under 3 m / s artificial seawater scouring conditions. Compared with traditional B10 white copper alloy, the white copper alloy provided by the present invention has better mechanical properties and corrosion resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of copper alloys, and particularly relates to a corrosion-resistant white copper alloy and a preparation method thereof. Background Art

[0002] Copper and copper alloys are core materials for marine engineering due to their good corrosion resistance, high heat transfer coefficient, excellent mechanical properties, welding performance, and inhibition of marine microbial attachment.

[0003] Copper-nickel alloy is one of the most corrosion-resistant copper alloys. Due to its excellent seawater corrosion resistance and anti-fouling properties, it is widely used in the manufacture of seawater pipelines, ship propellers, and hull structures. Although copper-nickel alloy materials have been researched, produced, and put into use for many years, corrosion problems still occur during service in marine environments, and there are certain degrees of failure behavior, even causing serious leakage accidents, resulting in property and personnel losses. Among copper-nickel alloys, B10 alloy is currently the most industrially used corrosion-resistant white copper alloy (white copper is the elegant name for copper-nickel alloy). With the rapid development of my country's shipbuilding and marine industries, its application process faces harsh marine corrosion environments, such as high-velocity seawater erosion, which places higher demands on the mechanical properties, corrosion resistance, and service life of white copper alloy. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a corrosion-resistant white copper alloy and a preparation method thereof. The white copper alloy provided by the present invention has excellent mechanical and erosion corrosion resistance properties.

[0005] The present invention provides a corrosion-resistant white copper alloy, which comprises the following elements in percentage by mass:

[0006] Ni 9-12%; Fe 1.5-1.9%; Mn 0.6-1%; Cr 0.18-0.4%; Ce 0.03-0.05%; the balance is Cu; the mass ratio of Ni to Cr is 30-50:1; the number of special grain boundaries in the corrosion-resistant white copper alloy is more than 55%.

[0007] Preferably, the average grain size of the corrosion-resistant white copper alloy measured by the equivalent circle diameter method is 35 to 45 μm.

[0008] Preferably, under room temperature conditions, the tensile strength of the corrosion-resistant white copper alloy is greater than 350 MPa, and the elongation is greater than 40%; under room temperature conditions, the uniform corrosion rate of the corrosion-resistant white copper alloy in static artificial seawater immersion is less than 0.015 mm / a, and the uniform corrosion rate under 3 m / s artificial seawater flushing conditions is ≤0.04 mm / a.

[0009] The present invention provides a method for preparing the corrosion-resistant white copper alloy described in the above scheme, comprising the following steps:

[0010] The raw materials are smelted and cast according to the element composition of the corrosion-resistant white copper alloy to obtain an ingot;

[0011] homogenizing the ingot to obtain a homogenized billet;

[0012] hot-extruding the homogenized blank to obtain a copper rod blank;

[0013] Cold drawing the copper rod blank to obtain a drawn blank; the total deformation of the cold drawing is 70-95%;

[0014] The drawn blank is annealed to obtain the corrosion-resistant white copper alloy; the annealing temperature is 780-880° C., the holding time is 10-30 minutes, and the cooling method is water cooling.

[0015] Preferably, the smelting temperature is 1200-1350°C.

[0016] Preferably, the temperature of the heating and the casting is 1150-1250°C.

[0017] Preferably, the temperature of the homogenization treatment is 920-970° C., and the holding time is 4-6 hours.

[0018] Preferably, before the hot extrusion, the extrusion barrel and the die are preheated; the preheating temperature is 450-550°C.

[0019] Preferably, the deformation amount of the hot extrusion is 80-95%.

[0020] Preferably, before the homogenization treatment, the outer skin of the ingot is also turned off; the thickness of the turned outer skin is 2 to 3 mm.

[0021] The present invention provides a corrosion-resistant white copper alloy, which comprises the following elements, measured by mass percentage: 9-12% Ni; 1.5-1.9% Fe; 0.6-1% Mn; 0.18-0.4% Cr; 0.03-0.05% Ce; the balance being Cu; the mass ratio of Ni to Cr is 30-50:1; and the number of special grain boundaries in the corrosion-resistant white copper alloy is above 55%.

[0022] The present invention improves the corrosion potential and passivation ability by adding Ni element to the white copper alloy, and enhances the corrosion resistance of the alloy. The addition of Ni element has a certain improvement effect on the corrosion product film on the surface of the alloy. 2+It will fill the defective positions of the passivation film to make the corrosion product film complete and dense, thereby improving the corrosion resistance of the alloy. The solubility of Fe in copper alloys is relatively low. Adding a small amount of Fe can significantly refine the grains and improve the corrosion resistance and strength of the alloy. Adding an appropriate amount of Mn can significantly improve the strength of the alloy and its ability to resist impact corrosion. The Cr element has the function of refining the grains and is easy to passivate. The present invention adds a certain amount of Cr element and controls the ratio of Ni and Cr. The Cr ions will fill the cation vacancies of the passivation film Cu2O during the corrosion process, making the corrosion product film complete and dense, and significantly improving the resistance of the nickel silver alloy to high-flow seawater erosion corrosion. In addition, adding a trace amount of rare earth element Ce to the nickel silver alloy will form a dense film on the surface of the alloy after erosion corrosion, thereby improving the corrosion resistance.

[0023] The corrosion-resistant white copper alloy provided by the present invention has a high proportion of special grain boundaries (i.e., low ΣCSL grain boundaries). Compared with random grain boundaries, the free volume energy of low ΣCSL grain boundaries is lower, and they have stronger resistance to intergranular corrosion, thereby improving the intergranular corrosion resistance of the alloy.

[0024] The results of the examples show that at room temperature, the corrosion-resistant cupronickel alloy provided by the present invention has a tensile strength of >350 MPa, an elongation of >40%, a static full-immersion uniform corrosion rate of <0.015 mm / a, and a uniform corrosion rate of ≤0.04 mm / a under 3 m / s artificial seawater scouring conditions. Compared with the traditional B10 cupronickel alloy, the cupronickel alloy provided by the present invention has a tensile strength increased by 10-15%, a static full-immersion uniform corrosion rate reduced by 10-50%, and a corrosion rate reduced by 30-60% under 3 m / s artificial seawater scouring conditions. The corrosion-resistant cupronickel alloy prepared by the present invention can be used as an important working unit in marine equipment and engineering facilities such as ships, offshore oil platforms, coastal power plants, and desalination plants, assuming important functions such as heat exchange, cooling, and fire protection, and has broad application prospects.

[0025] The present invention provides a method for preparing the aforementioned corrosion-resistant white copper alloy. This method utilizes a combination of hot extrusion, high-deformation cold drawing, and short-term annealing. By optimizing the distribution of grain boundary characteristics through appropriate processes, the white copper alloy prepared by the present invention exhibits excellent grain size uniformity, with an average grain size controllable between 35 and 45 μm and a number of special grain boundaries (low ΣCSL) exceeding 55%. Compared to conventional white copper alloys, the cold drawing deformation in the present invention is controlled at 70 to 95%. This high cold deformation accumulates a large amount of deformation energy and dislocations, accumulating a large amount of initial nucleation energy and nucleation sites for subsequent heat treatment, and matching the excellent mechanical properties and corrosion resistance of the final white copper alloy.

[0026] The present invention controls the annealing mode and performs short-time heat preservation at 780-880°C to eliminate deformed structure, control recrystallized structure and grain size, obtain a high proportion of special grain boundaries, and inhibit the occurrence of intergranular corrosion; at the same time, the use of water cooling can inhibit the precipitation of the second phase and prevent the occurrence of phase selection corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a statistical diagram of special grain boundaries of the corrosion-resistant white copper alloy prepared in Example 1;

[0029] Figure 2 This is a statistical diagram of the grain size of the corrosion-resistant white copper alloy prepared in Example 1;

[0030] Figure 3 This is a statistical diagram of special grain boundaries of the corrosion-resistant white copper alloy prepared in Example 2;

[0031] Figure 4 This is a statistical diagram of the grain size of the corrosion-resistant white copper alloy prepared in Example 2;

[0032] Figure 5 This is a statistical diagram of special grain boundaries of the corrosion-resistant white copper alloy prepared in Example 3;

[0033] Figure 6 This is a statistical diagram of the grain size of the corrosion-resistant white copper alloy prepared in Example 3;

[0034] Figure 7 This is a statistical diagram of special grain boundaries of the corrosion-resistant white copper alloy prepared in Comparative Example 1;

[0035] Figure 8 This is a statistical chart of the grain size of the corrosion-resistant white copper alloy prepared in Comparative Example 1. DETAILED DESCRIPTION

[0036] The present invention provides a corrosion-resistant white copper alloy, which comprises the following elements in percentage by mass:

[0037] Ni 9-12%; Fe 1.5-1.9%; Mn 0.6-1%; Cr 0.18-0.4%; Ce 0.03-0.05%; the balance is Cu; the mass ratio of Ni to Cr is 30-50:1; the number of special grain boundaries in the corrosion-resistant white copper alloy is more than 55%.

[0038] The corrosion-resistant cupronickel alloy provided by the present invention comprises 9-12% Ni, preferably 9.5-11.5%, and more preferably 10-11%, in terms of mass percentage. The present invention adds Ni element to the cupronickel alloy to improve the corrosion potential and passivation ability, thereby enhancing the corrosion resistance of the alloy. The addition of Ni element has a certain effect on improving the corrosion product film on its surface. 2+ It will fill the defective positions of the passivation film to make the corrosion product film complete and dense, thereby improving the corrosion resistance of the alloy.

[0039] The corrosion-resistant copper-nickel alloy provided by the present invention comprises 1.5-1.9% Fe by weight, preferably 1.6-1.8%, and more preferably 1.65-1.75%. Fe has a low solubility in copper alloys, and adding a small amount of Fe can significantly refine the grains, improving the corrosion resistance and strength of the alloy.

[0040] The corrosion-resistant copper-nickel alloy provided by the present invention comprises 0.6-1% Mn, preferably 0.7-0.9% Mn, in terms of mass percentage. In the present invention, adding an appropriate amount of Mn can significantly improve the strength and impact corrosion resistance of the alloy.

[0041] The corrosion-resistant cupronickel alloy provided by the present invention includes 0.18 to 0.4% Cr, preferably 0.2 to 0.35%, and more preferably 0.25 to 0.35%, in terms of mass percentage. In the present invention, the mass ratio of Ni to Cr is 30 to 50:1, preferably 35 to 45:1, and more preferably 38 to 42:1. In the present invention, the Cr element has the effect of refining grains and facilitates passivation. The present invention adds a certain amount of Cr element and controls the ratio of Ni to Cr. During the corrosion process, Cr ions fill the cation vacancies of the passivation film Cu2O, making the corrosion product film complete and dense, significantly improving the cupronickel alloy's resistance to high-velocity seawater erosion corrosion.

[0042] The corrosion-resistant cupronickel alloy provided by the present invention includes 0.03-0.05% Ce by mass, preferably 0.035-0.045% Ce, and more preferably 0.04%. The addition of a trace amount of the rare earth element Ce to the cupronickel alloy forms a dense film on the alloy surface after erosion corrosion, thereby improving corrosion resistance.

[0043] The corrosion-resistant white copper alloy provided by the present invention further comprises a balance of Cu and unavoidable impurities.

[0044] In the present invention, the corrosion-resistant white copper alloy contains at least 55% special grain boundaries (low ΣCSL grain boundaries). There is no upper limit on the number of special grain boundaries; the more the better. Compared to random grain boundaries, low ΣCSL grain boundaries have lower free volume energy and greater resistance to intergranular corrosion, thereby improving the alloy's intergranular corrosion resistance.

[0045] In the present invention, the average grain size of the corrosion-resistant white copper alloy measured by the equivalent circle diameter method is preferably 35 to 45 μm. The corrosion-resistant white copper alloy provided by the present invention has good grain size uniformity and good mechanical properties.

[0046] In the present invention, under room temperature conditions, the corrosion-resistant white copper alloy has a tensile strength greater than 350 MPa and an elongation greater than 40%. Under room temperature conditions, the corrosion-resistant white copper alloy has a uniform corrosion rate of less than 0.015 mm / a in static artificial seawater immersion, and a uniform corrosion rate of ≤0.04 mm / a under 3 m / s artificial seawater flushing conditions, and has good mechanical properties and corrosion resistance.

[0047] The present invention provides a method for preparing the corrosion-resistant white copper alloy described in the above scheme, comprising the following steps:

[0048] The raw materials are smelted and cast according to the element composition of the corrosion-resistant white copper alloy to obtain an ingot;

[0049] homogenizing the ingot to obtain a homogenized billet;

[0050] hot-extruding the homogenized blank to obtain a copper rod blank;

[0051] Cold drawing the copper rod blank to obtain a drawn blank; the total deformation of the cold drawing is 70-95%;

[0052] The drawn blank is annealed to obtain the corrosion-resistant white copper alloy; the annealing temperature is 780-880° C., the holding time is 10-30 minutes, and the cooling method is water cooling.

[0053] The present invention melts and casts raw materials corresponding to the elemental composition of the corrosion-resistant white copper alloy to obtain an ingot. In the present invention, the raw materials preferably include: electrolytic copper, electrolytic nickel, pure manganese, Cu-20Fe master alloy and Cu-20Cr master alloy.

[0054] In the present invention, the smelting process preferably includes the following steps: adding the prepared raw materials to a melting furnace, heating the furnace to a smelting temperature, and, after the melt is completely melted, introducing an inert gas and covering the melt with charcoal. In the present invention, the smelting temperature is preferably 1200-1350°C; the inert gas is preferably argon. The introduction of the inert gas and covering the melt with charcoal prevent oxidation of the metal elements.

[0055] In the present invention, in order to control the content of impurity elements, the raw materials are preferably placed in a three-high graphite crucible for smelting.

[0056] In the present invention, the casting temperature is preferably 1150-1250° C., more preferably 1180-1220° C. The casting method is preferably non-vacuum casting.

[0057] After obtaining the ingot, the present invention performs a homogenization treatment on the ingot to obtain a homogenized billet. Before the homogenization treatment, the present invention preferably removes the outer skin of the ingot; the thickness of the removed outer skin is preferably 2 to 3 mm. There is oxide scale on the surface of the ingot, which is a pollutant and a brittle impurity. The present invention removes the outer skin of the ingot to avoid affecting the subsequent deformation processing. In the present invention, the temperature of the homogenization treatment is preferably 920 to 970°C, more preferably 930 to 960°C, and further preferably 940 to 950°C; the holding time of the homogenization treatment is preferably 4 to 6 hours, more preferably 4.5 to 5.5 hours. The present invention utilizes homogenization treatment to eliminate internal stress and composition segregation to make the composition more uniform.

[0058] After obtaining a homogenized billet, the present invention performs hot extrusion on the homogenized billet to produce a copper rod billet. In the present invention, the hot extrusion process preferably includes preheating the extrusion barrel and die before hot extrusion; the preheating temperature is preferably 450-550°C, more preferably 480-520°C. In the present invention, after removing the homogenized billet, the hot extrusion process can be performed directly without cooling. In the present invention, the deformation of the hot extrusion process is preferably 80-95%, more preferably 83-92%, and even more preferably 85-90%.

[0059] After obtaining the copper rod blank, the present invention cold draws the copper rod blank to obtain a drawn blank; the total deformation of the cold drawing is 70-95%, preferably 75-90%, and more preferably 80-85%. The present invention controls the total deformation of the cold drawing to 70-95%. The large cold deformation accumulates a large amount of deformation energy and a large number of dislocations, which accumulates a large amount of original nucleation energy and nucleation sites for subsequent heat treatment processes, and matches the excellent mechanical properties and corrosion resistance of the final cupronickel alloy.

[0060] After obtaining the drawn blank, the present invention anneals the drawn blank to obtain the corrosion-resistant white copper alloy. In the present invention, the temperature of the annealing treatment is 780-880°C, preferably 800-860°C, and more preferably 820-840°C; the holding time of the annealing treatment is 10-30 minutes, preferably 15-25 minutes; and the cooling method of the annealing treatment is water cooling. The present invention performs a short-term holding at 780-880°C, which can eliminate the deformed structure, control the recrystallized structure and grain size, and obtain a high proportion of special grain boundaries, thereby inhibiting the occurrence of intergranular corrosion; at the same time, the use of water cooling can inhibit the precipitation of the second phase and prevent the occurrence of phase-selective corrosion.

[0061] The present invention adopts a technology that combines hot extrusion → cold drawing with a large deformation amount → short-time annealing treatment, and optimizes the grain boundary characteristic distribution of the alloy through appropriate processes. The white copper alloy prepared by the present invention has good grain size uniformity, which can be controlled between 35 and 45 μm, and the number of special grain boundaries (low ΣCSL) is more than 55%.

[0062] In order to further illustrate the present invention, the corrosion-resistant white copper alloy provided by the present invention is described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0063] Example 1

[0064] (1) Melting and casting: Electrolytic copper, electrolytic nickel, pure manganese, and Cu-20Fe and Cu-20Cr master alloys are used as raw materials. The composition and weight percentage (wt%) of each element are as follows: Ni 9%, Fe 1.9%, Mn 1%, Cr 0.18%, Ce 0.05%, and the balance of Cu and unavoidable impurities. The raw materials are added to a melting furnace. In order to control the content of impurities, a three-high graphite crucible is selected. The temperature is raised to 1250°C. After the melt is completely melted, it is uniformly stirred and covered with charcoal. An inert gas is passed through the furnace to protect the heat. The liquid alloy is then placed in a mold to cool by non-vacuum pouring. The casting temperature is controlled at 1150-1250°C to cast the desired ingot.

[0065] (2) Homogenization: After the outer skin of the ingot in step (1) is turned off by 2 mm, it is homogenized in a box-type resistance furnace at a homogenization temperature of 920° C. for 6 h.

[0066] (3) Hot extrusion: preheat the extrusion barrel and the die to 480°C, then take out the homogenized billet in step (2) and quickly send it to the extruder for hot extrusion. The extrusion deformation is 92%. The copper rod billet after extrusion is quenched in water.

[0067] (4) Cold drawing: The copper rod blank prepared in step (3) is cold drawn, with a total deformation of 70%.

[0068] (5) Annealing: The drawn billet in step (4) was annealed at a temperature of 780°C, a holding time of 30 min, and water cooling. The obtained corrosion-resistant white copper alloy had an average grain size of 40 μm and a number of special grain boundaries (low ΣCSL) of 56%. The statistical diagrams of special grain boundaries and grain size are shown in Figure 2. Figure 1 and Figure 2 , Figure 2 The unit of the horizontal axis is μm.

[0069] The resulting corrosion-resistant cupronickel alloy was tested for performance, including room-temperature tensile properties, corrosion rate after static immersion in artificial seawater for 21 days at room temperature, and corrosion rate after flushing in artificial seawater at a flow rate of 3 m / s for 21 days at room temperature. The performance is shown in Table 1.

[0070] Table 1 Performance data of corrosion-resistant copper-nickel alloy of Example 1

[0071]

[0072] Note: The composition of the traditional B10 alloy is Cu-10Ni-1.6Fe-1Mn, and the preparation method is the same as that of Example 1.

[0073] Example 2

[0074] (1) Melting and casting: Electrolytic copper, electrolytic nickel, pure manganese, and Cu-20Fe and Cu-20Cr master alloys are used as raw materials. The composition and weight percentage (wt%) of each element are as follows: Ni 12%, Fe 1.6%, Mn 0.8%, Cr 0.4%, Ce 0.03%, and the balance of Cu and unavoidable impurities. The raw materials are added to a melting furnace. In order to control the content of impurities, a three-high graphite crucible is selected. The temperature is raised to 1350°C. After the melt is completely melted, it is uniformly stirred and covered with charcoal. An inert gas is passed through the furnace to protect the melt. The liquid alloy is then placed in a mold and cooled by non-vacuum pouring. The casting temperature is controlled at 1150-1250°C to cast the desired ingot.

[0075] (2) Homogenization: After the outer skin of the ingot in step (1) is turned off by 3 mm, it is homogenized in a box-type resistance furnace at a homogenization temperature of 970° C. for 4 h.

[0076] (3) Hot extrusion: preheat the extrusion barrel and the die to 550°C, then take out the homogenized billet in step (2) and quickly send it to the extruder for hot extrusion. The extrusion deformation is 87%. The copper rod billet after extrusion is quenched in water.

[0077] (4) Cold drawing: The copper rod blank prepared in step (3) is cold drawn, with a total deformation of 70%.

[0078] (5) Annealing: The cold drawn billet in step (4) was annealed at 880°C for 10 min. The cooling method was water cooling. The average grain size of the corrosion-resistant white copper alloy obtained was 37 μm, and the number of special grain boundaries (low ΣCSL) was 72%. The statistical diagrams of special grain boundaries and grain size are shown in Figure 2. Figure 3 and Figure 4 .

[0079] The resulting corrosion-resistant cupronickel alloy was tested for performance, including room-temperature tensile properties, corrosion rate after static immersion in artificial seawater for 21 days at room temperature, and corrosion rate after flushing in artificial seawater at a flow rate of 3 m / s for 21 days at room temperature. The performance is shown in Table 2.

[0080] Table 2 Performance data of corrosion-resistant copper-nickel alloy of Example 2

[0081]

[0082] Example 3

[0083] (1) Melting and casting: Electrolytic copper, electrolytic nickel, pure manganese, and Cu-20Fe and Cu-20Cr master alloys are used as raw materials. The composition and weight percentage (wt%) of each element are as follows: Ni 10%, Fe 1.8%, Mn 1%, Cr 0.3%, Ce 0.05%, and the balance of Cu and unavoidable impurities. The raw materials are added to a melting furnace. In order to control the content of impurities, a three-high graphite crucible is selected. The temperature is raised to 1300°C. After the melt is completely melted, it is uniformly stirred and covered with charcoal. An inert gas is passed through the furnace to protect the heat. The liquid alloy is then placed in a mold and cooled by non-vacuum pouring. The casting temperature is controlled at 1150-1250°C to cast the desired ingot.

[0084] (2) Homogenization: After the outer skin of the ingot in step (1) is turned off by 2 mm, it is homogenized in a box-type resistance furnace at a homogenization temperature of 970° C. for 4 h.

[0085] (3) Hot extrusion: preheat the extrusion barrel and the die to 500°C, then take out the homogenized billet in step (2) and quickly send it to the extruder for hot extrusion. The extrusion deformation is 92%. The copper rod billet after extrusion is quenched in water.

[0086] (4) Cold drawing: The copper rod blank prepared in step (3) is cold drawn, and the total deformation amount is 95%.

[0087] (5) Annealing: The drawn billet in step (4) was annealed at a temperature of 850°C, a holding time of 15 min, and water cooling. The corrosion-resistant white copper alloy obtained had an average grain size of 42 μm and a number of special grain boundaries (low ΣCSL) of 56%. The statistical graphs of special grain boundaries and grain size are shown in Figure 2. Figure 5 and Figure 6 .

[0088] The resulting corrosion-resistant cupronickel alloy was tested for performance, including room-temperature tensile properties, corrosion rate after 21 days of static immersion at room temperature, and corrosion rate after 21 days of rinsing in artificial seawater at a flow rate of 3 m / s at room temperature. The performance is shown in Table 3.

[0089] Table 3 Performance data of corrosion-resistant copper-nickel alloy of Example 3

[0090]

[0091]

[0092] Comparative Example 1

[0093] (1) Melting and Casting: Electrolytic copper, electrolytic nickel, pure manganese, and Cu-20Fe master alloy are used as raw materials. The composition and weight percentage (wt%) of each element are as follows: Ni 10%, Fe 1.75%, Mn 0.8%, and the balance Cu and unavoidable impurities. The raw materials are added to a melting furnace. In order to control the content of impurities, a three-high graphite crucible is selected. The temperature is raised to 1350°C. After the melt is completely melted, it is uniformly stirred and covered with charcoal. The furnace is kept warm with inert gas protection. The liquid alloy is then placed in a mold and cooled by non-vacuum pouring. The casting temperature is controlled at 1150-1250°C to cast the desired ingot.

[0094] (2) Homogenization: After the outer skin of the ingot in step (1) is turned off by 3 mm, it is homogenized in a box-type resistance furnace at a homogenization temperature of 950° C. for 4 h.

[0095] (3) Hot extrusion: preheat the extrusion barrel and the die to 500°C, then take out the homogenized billet in step (2) and quickly send it to the extruder for hot extrusion. The extrusion deformation is 85%. The copper rod billet after extrusion is quenched in water.

[0096] (4) Cold drawing: The copper rod blank prepared in step (3) was cold drawn, with a total deformation of 9.2%.

[0097] (5) Annealing: The cold drawn billet in step (4) was annealed at 800°C for 20 min. The cooling method was water cooling. The average grain size of the obtained white copper alloy was 77 μm, and the number of special grain boundaries (low ΣCSL) was 3.8%. The statistical diagrams of special grain boundaries and grain size are shown in Figure 2. Figure 7 and Figure 8 .

[0098] The resulting cupronickel alloy was tested for performance, including room-temperature tensile properties, corrosion rate after static immersion in artificial seawater for 21 days at room temperature, and corrosion rate after flushing in artificial seawater at a flow rate of 3 m / s for 21 days at room temperature. The performance is shown in Table 4.

[0099] Table 4 Performance data of comparative example 1

[0100]

[0101] From the results of the above embodiments and comparative examples, it can be seen that the corrosion-resistant white copper alloy provided by the present invention has excellent mechanical properties (including tensile strength and elongation after fracture) and resistance to high-velocity seawater erosion corrosion. Specifically, the tensile strength is greater than 350MPa, the elongation is greater than 40%, the static full immersion uniform corrosion rate is less than 0.015mm / a, and the uniform corrosion rate under 3m / s artificial seawater erosion conditions is ≤0.04mm / a. Compared with the traditional B10 white copper alloy, the tensile strength of the new white copper alloy resistant to high-velocity erosion provided by the present invention is increased by 10-15%, the static full immersion uniform corrosion rate is reduced by 10-50%, and the corrosion rate under 3m / s artificial seawater erosion is reduced by 30-60%. In addition, compared with comparative example 1, embodiments 1 to 3 of the present invention increase the number of special grain boundaries, and the obtained corrosion-resistant white copper alloy has enhanced resistance to intergranular corrosion, thereby having better resistance to seawater erosion corrosion.

[0102] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A corrosion-resistant white copper alloy, characterized in that: In terms of mass percentage, it includes the following elements: Ni 9-12%; Fe 1.5-1.9%; Mn 0.6-1%; Cr 0.18-0.4%; Ce 0.03-0.05%; the balance is Cu; the mass ratio of Ni to Cr is 30-50:1; the number of special grain boundaries in the corrosion-resistant white copper alloy is greater than 55%; The average grain size of the corrosion-resistant white copper alloy measured by the equivalent circle diameter method is 35-45 μm; Under room temperature conditions, the corrosion-resistant cupronickel alloy has a tensile strength greater than 350 MPa and an elongation greater than 40%. Under room temperature conditions, the corrosion-resistant cupronickel alloy has a uniform corrosion rate of less than 0.015 mm / a when fully immersed in static artificial seawater, and a uniform corrosion rate of less than or equal to 0.04 mm / a when flushed with 3 m / s artificial seawater. The preparation method of the corrosion-resistant white copper alloy comprises the following steps: The raw materials are smelted and cast according to the element composition of the corrosion-resistant white copper alloy to obtain an ingot; homogenizing the ingot to obtain a homogenized billet; hot-extruding the homogenized blank to obtain a copper rod blank; cold drawing the copper rod blank to obtain a drawn blank; wherein the total deformation of the cold drawing is 70-95%; The drawn blank is annealed to obtain the corrosion-resistant white copper alloy; the annealing temperature is 780-880° C., the holding time is 10-30 minutes, and the cooling method is water cooling.

2. The method for preparing the corrosion-resistant white copper alloy according to claim 1, characterized in that: The following steps are involved: The raw materials are smelted and cast according to the element composition of the corrosion-resistant white copper alloy to obtain an ingot; homogenizing the ingot to obtain a homogenized billet; hot-extruding the homogenized blank to obtain a copper rod blank; Cold drawing the copper rod blank to obtain a drawn blank; the total deformation of the cold drawing is 70-95%; The drawn blank is annealed to obtain the corrosion-resistant white copper alloy; the annealing temperature is 780-880° C., the holding time is 10-30 minutes, and the cooling method is water cooling.

3. The preparation method according to claim 2, characterized in that The smelting temperature is 1200-1350°C.

4. The preparation method according to claim 2, characterized in that The casting temperature is 1150-1250°C.

5. The preparation method according to claim 2, characterized in that The temperature of the homogenization treatment is 920-970° C., and the holding time is 4-6 hours.

6. The preparation method according to claim 2, characterized in that Before the hot extrusion, the extrusion cylinder and the die are preheated; the preheating temperature is 450-550°C.

7. The preparation method according to claim 2 or 6, characterized in that The deformation amount of the hot extrusion is 80-95%.

8. The preparation method according to claim 2 or 5, characterized in that Before the homogenization treatment, the outer skin of the ingot is also turned off; the thickness of the outer skin turned off is 2-3 mm.

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