Method for producing high-strength beryllium-nickel alloy strip

Abstract

The application provides a preparation method of high-strength beryllium-nickel alloy strip, which comprises the following steps: taking materials, forging, surface cleaning, hot rolling, cold rolling, edge cutting and washing, and quenching; in the application, the cold rolling processing rate is controlled to be more than 70%, and the mechanical property can reach more than 1300 MPa without aging treatment, which is far higher than the existing technical level; the mechanical property in the prior art can be reached only after solid solution treatment and aging treatment; the application provides specific processing parameters of the alloy in the hot rolling and cold rolling processes, and determines the processing amount under each pass; the preparation process, the required processing technology, especially the optimal scheme of the hot rolling and cold rolling processes of the strip with different thicknesses are also provided; the application provides technical support for the preparation of nickel-beryllium alloy strips with different specifications and models according to the strips with different thicknesses prepared under different processing amounts.

Description

Technical Field

[0001] This invention relates to nickel-based corrosion-resistant alloys, and more particularly to a method for preparing high-strength beryllium nickel alloy strip. Background Technology

[0002] Beryllium-nickel alloy (Be-Ni alloy) is a high-performance alloy material mainly composed of beryllium (Be) and nickel (Ni). Due to its excellent strength, elasticity, fatigue resistance, and corrosion resistance, beryllium-nickel alloy strip is widely used in electrical components in aerospace, electronics, and precision instruments.

[0003] Beryllium-nickel alloys have poor machinability, but their machinability is significantly improved after solution treatment, and the subsequent cold working rate can reach over 70%. After cold rolling, strip products that meet the requirements can be obtained. After aging treatment, the strips can be used for various electronic components that operate below 400°C.

[0004] Due to the high stress inherent in nickel alloys, rolling foil strips is difficult. Furthermore, the addition of a small amount of beryllium makes the beryllium-nickel alloy too hard for direct cold rolling. Therefore, to meet specific application requirements, it is often processed into strip products. Existing technology also proposes a nickel-beryllium alloy with high strength, high elasticity, and high corrosion resistance, and its manufacturing method (CN201610657666.3). This patented technology involves "heating the ingot to 900-950℃ to form a billet and rolling it into a strip; the intermediate annealing temperature is 880-890℃, the holding time is 2.5-3 hours, the total processing rate between the two annealing cycles is between 50-55%, the processing rate per rolling pass is about 10-20%, and the finished product processing rate is controlled at 35-40%, i.e., Y-state alloy finished product." It is evident that this technology discloses hot rolling and its processing rate, but does not explicitly describe cold rolling. Therefore, the cold rolling process, processing rate, and whether the product cracks are unknown. Furthermore, the total hot rolling processing rate of this patent is between 50-55%, and the finished product processing rate is controlled between 35-40%.

[0005] Although the mechanical properties of this patented technology can reach a tensile strength of 1190 N / mm² 2 However, it has not undergone cold rolling, nor has it recorded the specific processing parameters during hot rolling and cold rolling. It lacks the control process for the processing rate under a single pass, and its mechanical properties are far lower than the technical level of this invention. Summary of the Invention

[0006] In view of the above-mentioned defects, the present invention proposes a method for preparing high-strength beryllium-nickel alloy strip, comprising the following steps: Material selection: Select alloy ingots with a beryllium content of 1.9-2.1 wt% and the balance being nickel; Forging: The ingot is held at 1000-1100℃ for 0.5-1 h before forging, and the pressing amount during forging is less than 5 mm each time; Surface cleaning: The blank obtained after forging is subjected to surface treatment to remove surface impurities by milling; Hot rolling: The billet obtained after surface cleaning is heated to 1000-1100℃ and held for 2.5-3 hours. It is rolled in multiple passes with more than 5 passes and a single pass processing rate of less than 35%. After rolling, it is recrystallized and annealed at 860-880℃, held for 0.5-1 hours, and then air-cooled. Strip surface treatment: Remove surface oxide scale, and the strip surface has a uniform metallic frosted surface; Cold rolling: The strip is rolled in multiple passes, with more than 4 passes, and the processing rate per pass is controlled to be less than 30%. Each pass is processed more than three times. After rolling, annealing is carried out at a temperature of 720-750℃ and held for 2-2.5 hours. Edge trimming and washing: Remove a small number of cracked areas on the edge of the strip that appeared during the rolling process, then pickle it, and finally cut it into strips with the required length, width and thickness.

[0007] In this invention, the cold rolling rate is controlled to reach over 70%, and without aging treatment, the mechanical properties can reach over 1300 MPa, far exceeding the level of existing technologies. The mechanical properties described in existing technologies require solution treatment and aging treatment to achieve.

[0008] This invention provides specific processing parameters for the alloy during hot rolling and cold rolling, and determines the processing amount for each pass; it also provides the optimal solution for the preparation process of strips of different thicknesses, the required processing process, especially the hot rolling and cold rolling processes; based on the strips of different thicknesses obtained under different processing amounts, this patent provides technical support for the subsequent preparation of nickel-beryllium alloy strips of various specifications and models.

[0009] Meanwhile, this patent has conducted rolling with a higher processing rate and found that the tensile strength of the alloy can be further improved as the cold rolling ratio increases. Furthermore, by adjusting the cold rolling amount, a rolling process for beryllium nickel strip of different thicknesses has been invented. Attached Figure Description

[0010] Figure 1 This is a diagram of the microstructure after cold rolling in Example 1.

[0011] Figure 2 This is a diagram of the microstructure after cold rolling in Example 2.

[0012] Figure 3 This is a diagram of the microstructure after cold rolling in Example 3. Detailed Implementation

[0013] The method for preparing high-strength beryllium nickel alloy strip proposed in this invention is as follows: Material selection: Select alloy ingots with a beryllium content of 1.9-2.1 wt% and the balance being nickel; Forging: The ingot is held at 1000-1100℃ for 0.5-1 h before forging. The pressure applied during each forging step is less than 5 mm. Surface cleaning: The blank obtained after forging is subjected to surface treatment to remove surface impurities by milling; Hot rolling: The billet obtained after surface cleaning is heated to 1000-1100℃ and held for 2.5-3 hours. It is rolled in multiple passes with more than 5 passes and a single pass processing rate of less than 35%. After rolling, it is recrystallized and annealed at 860-880℃, held for 0.5-1 hours, and then air-cooled. Strip surface treatment: Remove surface oxide scale, and the strip surface has a uniform metallic frosted surface; Cold rolling: The strip is rolled in multiple passes, with more than 4 passes, and the processing rate per pass is controlled to be less than 30%. Each pass is processed more than three times. After rolling, annealing is carried out at a temperature of 720-750℃ and held for 2-2.5 hours. Edge trimming and washing: Remove a small number of cracked areas on the edge of the strip that appeared during the rolling process, then pickle it, and finally cut it into strips with the required length, width and thickness.

[0014] Example 1 An alloy ingot with a beryllium content of 1.9 wt% and the balance being nickel was selected and placed in a muffle furnace at 1050°C for 0.5 h. After sufficient holding time, the red-hot ingot was placed on a free forging press for forging. A layer of glass powder was applied to the surface of the ingot. After multiple forging processes, the ingot was forged from 100 mm to 31 mm. After the resulting billet was fully cooled, the surface impurity layer was milled off.

[0015] The billet was then divided into three 10 mm thick pieces. One of these pieces was heated to 1050°C in a muffle furnace and held for 2.5 h before hot rolling. The alloy strip was rolled according to the process of 10→7→5→3.5→2.4→1.7. The roll spacing was adjusted in real time during each rolling pass, and the target thickness for each stage was achieved within three passes.

[0016] After rolling to 1.7 mm, the strip is annealed at 870℃ for 0.5 h and then cooled in air.

[0017] The strip is then placed on a belt sander to remove the oxide scale from its surface, and then put into a rolling mill for cold rolling. The processing sequence is 1.7→1.2→0.9→0.7, and each pass must ensure that the number of processing times is at least four.

[0018] After cold rolling, the strip with a thickness of 0.7 mm was annealed at 720℃ for 2 hours. Subsequently, the cracked parts at the edge of the rolled strip were removed, thus obtaining a beryllium nickel alloy Y-state strip with a thickness of 0.7 mm.

[0019] In this scheme, the cold rolling processing amount is 59%. Mechanical property testing showed that the tensile strength of this thickness strip reached 1380 MPa, and the yield strength was 1327 MPa. Microscopic observation of the microstructure of the cold-rolled strip is shown below. Figure 1 It can be seen that after cold rolling, the alloy microstructure is elongated and exhibits a fibrous morphology along the rolling direction, with cellular substructures appearing in the microstructure. Simultaneously, as the deformation increases, the size of the substructures within the microstructure gradually decreases, and the processed alloy microstructure shows significant deformation, with elliptical grains appearing in the microstructure. At this point, the grains are elongated, resulting in a higher aspect ratio, approximately 2.0.

[0020] Example 2 Alloy ingots with a beryllium content of 2 wt% and the balance being nickel were selected.

[0021] The ingot was placed in a muffle furnace and held at 1050°C for 0.5 h. After the holding time was sufficient, the red-hot ingot was placed on a free forging press for forging. A layer of glass powder was applied to the surface of the ingot. After multiple forgings, the ingot was forged from 100 mm to 35 mm. After the resulting billet was fully cooled, the surface impurity layer was milled off.

[0022] The billet was then divided into three 12 mm thick pieces. One piece was heated to 1050°C in a muffle furnace and held for 3 hours before hot rolling. The alloy strip was rolled according to the process of 12→8→5→3.5→2.4→1.7, with the roll spacing adjusted in real time during each pass. The target thickness for each stage had to be achieved within three passes. After rolling to 1.7 mm, the strip was annealed at 860°C for 1 hour and then air-cooled.

[0023] The strip is then placed on a belt sander to remove the oxide scale from its surface, and then cold-rolled in a rolling mill. The processing sequence is 1.7→1.2→0.9→0.7→0.5, with each pass requiring at least four passes. After cold rolling, the strip thicker than 0.7 mm is annealed at 740℃ for 2.5 hours. Subsequently, any cracks at the edges of the rolled strip are removed, resulting in a 0.5 mm thick beryllium-nickel alloy Y-state strip.

[0024] In this scheme, cold rolling accounts for 70% of the processing. Mechanical property testing showed that the tensile strength of this thickness of strip reached 1476 MPa, and the yield strength was 1425 MPa. Microscopic observation of the microstructure of the cold-rolled strip is shown below. Figure 2Because the orientation of the crystal lattice is prone to rotation when the processing amount is large, the originally disordered grains gradually become ordered, and their specific crystal faces and crystal phases tend to be in one direction. The grains transform from elliptical to strip-shaped, and at this time the grain aspect ratio is about 3.0, and its internal substructure is more obvious.

[0025] Example 3 Alloy ingots with a beryllium content of 2.1 wt% and the balance being nickel were selected.

[0026] The ingot was placed in a muffle furnace and held at 1100°C for 1 hour. After the holding time was sufficient, the red-hot ingot was placed on a free forging press for forging. A layer of glass powder was applied to the surface of the ingot. After multiple forgings, the ingot was forged from 100 mm to 33 mm. After the resulting billet was fully cooled, the surface impurity layer was milled off.

[0027] The billet was then divided into three 10 mm thick pieces. One piece was heated to 1050°C in a muffle furnace and held for 2.5 h before hot rolling. The alloy strip was rolled according to the process of 10→7→5→3.5→2.4→1.7, with the roll spacing adjusted in real time during each pass. The target thickness for each stage had to be achieved within three passes. After rolling to 1.7 mm, the strip was annealed at 880°C for 0.5 h and then air-cooled.

[0028] The strip is then placed on a belt sander to remove the oxide scale from its surface, and then put into a rolling mill for cold rolling. The processing sequence is 1.7→1.2→0.9→0.67→0.51→0.4, and each pass must ensure that the number of processing times is at least four.

[0029] After cold rolling, the strip with a thickness of 0.4 mm is annealed at 740℃ for 2 hours. Subsequently, the cracked parts at the edge of the rolled strip are removed, thus obtaining a beryllium nickel alloy Y-state strip with a thickness of 0.4 mm.

[0030] In this scheme, the cold rolling process accounts for 76%. Mechanical property testing showed that the tensile strength of this thickness of strip reached 1466 MPa, and the yield strength was 1363 MPa. Microscopic observation of the microstructure of the cold-rolled strip is shown below. Figure 3 The grain boundaries of the strip-shaped grains gradually become blurred due to fracture, and the grain aspect ratio increases to over 5.0.

[0031] As is well known to those skilled in the art, hot rolling can only change the size of the grains, not their shape. However, the mechanical properties of an alloy can only be improved by changing the grain shape so that the grains are aligned with the rolling direction and arranged neatly.

[0032] Example 1 uses this method to cold roll from 1.7 mm to 0.7 mm; Example 2 cold rolls from 1.7 mm to 0.5 mm; Example 3 cold rolls from 1.7 mm to 0.4 mm; as the final rolled thickness becomes thinner, combined with... Figures 1 to 3 As can be seen, the originally disordered grains gradually become ordered and elongated, transforming from elliptical to strip-shaped, with the grain aspect ratio gradually increasing. The grain ratio changes gradually from 2.0 to 3.0 to 5.0, demonstrating the significant effect of cold rolling. These changes in grain structure lay the foundation for the gradual optimization of the mechanical properties of the alloy strip, reaching the level of this invention. Conversely, these changes in grain structure cannot be achieved with hot rolling.

[0033] The embodiments of this solution have been described in detail above with reference to the accompanying drawings. However, this solution is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this patent.

Claims

1. A method for preparing high-strength beryllium-nickel alloy strip, characterized in that... Includes the following steps: Material selection: Select alloy ingots with a beryllium content of 1.9-2.1 wt% and the balance being nickel; Forging: The ingot is held at 1000-1100℃ for 0.5-1 h before forging, and the pressing amount during forging is less than 5 mm each time; Surface cleaning: The blank obtained after forging is subjected to surface treatment to remove surface impurities by milling; Hot rolling: The billet obtained after surface cleaning is heated to 1000-1100℃ and held for 2.5-3 hours. It is rolled in multiple passes, with more than or equal to 5 passes and a single pass processing rate of less than 35%. After rolling, it is recrystallized and annealed at 860-880℃, held for 0.5-1 hours, and then air-cooled. Strip surface treatment: Remove surface oxide scale, and the strip surface has a uniform metallic frosted surface; Cold rolling: The strip is rolled in multiple passes, with a maximum of 4 passes. The processing rate per pass is controlled to be less than 30%, and the number of processing steps per pass is greater than three. After rolling, annealing is performed at a temperature of 720-750℃ and held for 2-2.5 hours. The cold rolling processing rate is controlled to reach more than 70%. Edge trimming and washing: Remove a small number of cracked areas on the edge of the strip that appeared during the rolling process, then pickle it, and finally cut it into strips with the required length, width and thickness.

2. The method for preparing high-strength beryllium-nickel alloy strip as described in claim 1, characterized in that: In the hot rolling step, the alloy strip is rolled according to the process of 12→8→5→3.5→2.4→1.7; in the cold rolling step, the alloy strip is rolled according to the process of 1.7→1.2→0.9→0.7→0.

5.

3. The method for preparing high-strength beryllium-nickel alloy strip as described in claim 1, characterized in that: In the hot rolling step, the alloy strip is rolled according to the process of 10→7→5→3.5→2.4→1.7; in the cold rolling step, the alloy strip is rolled according to the process of 1.7→1.2→0.9→0.67→0.51→0.4.

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