CN114351063B - Short-process heat treatment method for CuNiSn alloy bar - Google Patents
Short-process heat treatment method for CuNiSn alloy bar Download PDFInfo
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Abstract
The invention provides a short-flow heat treatment method of a CuNiSn alloy bar, which is characterized in that a casting is sequentially subjected to pretreatment, water seal hot extrusion and two-stage aging, wherein the two-stage aging comprises the following steps: first-stage aging, wherein the heating temperature range of the extruded bar is 250-350 ℃, the heating speed is 5-10 ℃/min, and the temperature is kept for 100-500 min; secondary aging, wherein the heating temperature range of the extruded bar is 350-450 ℃, the heating speed is 5-10 ℃/min, and the temperature is kept for 200-500 min. The invention realizes a short-process heat treatment method for preparing the CuNiSn alloy bar, and effectively improves the mechanical property uniformity and the obdurability of the CuNiSn alloy bar, particularly a large-size bar. The prepared CuNiSn alloy bar meets the requirement of high-toughness elastic materials, and can be widely applied to important fields of aerospace, aviation, electronics and the like. The invention has simple process flow and convenient operation, is convenient for large-scale production and meets the requirement of rapid development of modern industry.
Description
Technical Field
The invention relates to the field of heat treatment of metal materials, in particular to a short-process heat treatment method for improving the mechanical property uniformity of a CuNiSn alloy bar. Is mainly suitable for preparing high-toughness elastic materials required by industries such as aerospace, ocean field and the like.
Background
The CuNiSn alloy belongs to typical aging strengthening alloy, has mechanical and physical properties equivalent to those of beryllium bronze, has the characteristics of corrosion resistance, good weldability, low cost, no toxicity and the like, becomes an optimal ideal material for replacing the beryllium bronze, and has better performance than the beryllium copper alloy at 250 ℃. The high-elasticity-resistance high-elasticity-modulus material is widely applied to relays, electric switches, chemical and marine components, elastic sensitive elements of precision instruments and the like, and has been developed and applied to workpieces such as bearings and heavy-load bearing bushes in view of excellent performance.
The CuNiSn series alloy generally needs to be subjected to a relatively complex preparation process (casting-homogenization-plastic processing-solid solution-aging) in the actual production process. The strength of the alloy can be effectively improved through the heat treatment of plastic processing, but the plasticity of the alloy is inevitably sacrificed, so that the material with good matching of the plasticity and the strength is difficult to obtain, and cold rolling is a main mode for producing plates and difficult to process into large-size bars.
The heat treatment process is a common means for improving the performance of the CuNiSn alloy, and the common heat treatment process is solid solution and aging treatment. Through solution treatment, crystal grains grow rapidly, and the mechanical property of the alloy is greatly influenced. Particularly for large-sized bars, the problems of different cooling speeds inside and outside the bars, larger difference of inside and outside crystal grains, cracking of alloy bars and the like can be caused due to higher solid solution temperature of cast ingots in the process of solution treatment and quenching. For large-size CuNiSn alloy bars, the problem of non-uniformity of internal and external structures is particularly outstanding, and the non-uniformity of the structures is further aggravated because the internal and external deformations of the bars are different in the subsequent hot processing process; in addition, for large-sized bars subjected to hot extrusion, large macroscopic stress is easy to occur due to different internal and external tissue deformation, so that the bars are cracked. Although the mechanical properties of the CuNiSn alloy can be effectively improved by adjusting the aging process and controlling the time-effect behaviors of the CuNiSn alloy such as amplitude modulation decomposition, order transformation, discontinuous precipitation and the like, the CuNiSn alloy has poor heat conduction capability, and the deformation potential of the alloy cannot be effectively released by the common aging treatment, so that the internal and external mechanical properties of the alloy bar are uneven, and the alloy bar is more prominent in large-size bars.
Chinese patent 201711352543.X discloses a multistage combined shape-changing heat treatment method of a super-high strength CuNiSn elastic copper alloy, which mainly solves the problem of insufficient alloy strength through cold deformation and multistage aging, but has lower plasticity ratio, the product of strength and plasticity (the product of strength and plasticity) is only 6279MPa, and meanwhile, the preparation process is complex, large-sized bars are difficult to produce, and the application range of the alloy material prepared by the method is limited.
In order to obtain the best obdurability effect of the CuNiSn alloy, the field needs to develop a new heat treatment process to shorten the preparation process and effectively improve the mechanical property uniformity of the material alloy so as to meet the requirement of the rapid development of the modern industry on the higher and higher requirements of the copper alloy material.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a short-process heat treatment method of a CuNiSn alloy bar so as to improve the uniformity of the mechanical property of the CuNiSn alloy bar, and the method is particularly suitable for improving the strength, toughness and uniformity of the mechanical property of a CuNiSn alloy large-size (the diameter is more than 80 mm) bar.
In order to achieve the purpose, the invention adopts the following technical scheme:
a short-process heat treatment method of a CuNiSn alloy bar is characterized in that: sequentially carrying out pretreatment, water seal hot extrusion and two-stage aging on the casting; the method specifically comprises the following steps and process parameters:
the method comprises the following steps: pretreatment of
(1) Heating the extrusion billet along with a furnace at the heating speed of 10-15 ℃/min and the heating temperature of 800-900 ℃,
(2) Homogenizing and annealing at 800-900 deg.c for not less than 7 hr,
(3) After the homogenization annealing stage is finished, discharging from the furnace and air cooling;
step two: water seal hot extrusion
(1) Heating the extrusion tool at 300-400 deg.c and the extrusion cylinder at 350-500 deg.c for at least 30min,
(2) Heating the pretreated extrusion blank at 900-970 ℃, preserving the heat for not less than 2 hours,
(3) Water sealing hot extrusion, wherein the temperature range is 900-970 ℃, and the hot extrusion speed is 2-5 mm/s;
step three: two stage aging
Primary aging: the heating temperature range of the extruded bar is 250-350 ℃, the heating speed is 5-10 ℃/min, and the temperature is kept for 100-500 min;
secondary aging: the heating temperature range of the extruded bar is 350-450 ℃, the heating speed is 5-10 ℃/min, the temperature is kept for 200-500 min, air cooling is carried out to the room temperature after two-stage aging, and the CuNiSn alloy bar with high toughness and uniform mechanical property is obtained.
Preferably, the homogenization annealing temperature in the pretreatment of the step one ranges from 810 to 860 ℃ and the time is 7 to 9 hours.
Preferably, the heating temperature range of the extrusion tool in the second step is 340-380 ℃, the heating temperature range of the extrusion cylinder is 380-420 ℃, the heat preservation time is 30-50 min, the heating range of the pretreated extrusion blank is 900-940 ℃, the heat preservation time is 2-5 h, the water seal hot extrusion temperature range is 900-940 ℃, and the hot extrusion speed is 2-3 mm/s.
Preferably, the step three is double-stage aging, and the step one is aging: the heating temperature range of the extrusion bar is 280-320 ℃, the heating speed is 5-10 ℃/min, and the temperature is kept for 150-250 min; secondary aging: the heating temperature range of the extruded bar is 380-420 ℃, the heating speed is 5-8 ℃/min, the temperature is kept for 360-480 min, and the extruded bar is air-cooled to the room temperature after two-stage aging.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention provides a short-process heat treatment method of a CuNiSn alloy bar, which does not need a solid solution treatment process, simplifies the heat treatment process, realizes a short process, and can effectively improve the mechanical property uniformity and the obdurability of the CuNiSn alloy bar. The detection results of the bars of the embodiment show that the relative strength nonuniformity is less than 3 percent; the product of strength and elongation is more than 8400MPa, and the maximum can reach 17000 MPa. Is particularly suitable for preparing large-size (the diameter is more than 80 mm) bars of CuNiSn alloy.
2. The invention expands the application of CuNiSn alloy bars, in particular to large-size bars, meets the requirements of high-toughness elastic materials, and can be widely applied to important fields of aerospace, navigation, electronics and the like.
3. The method has simple process flow and convenient operation, and accords with the development direction of high strength, high toughness, high wear resistance, high elasticity, green and environment-friendly of the high-performance copper alloy; is convenient for large-scale production to meet the requirement of rapid development of modern industry.
Detailed Description
The present invention will be described in more detail with reference to the following embodiments, but the present invention is not limited to these embodiments.
The diameter of the ingot used in the examples is 260mm, and the chemical composition of the ingot is shown in Table 1:
table 1: cuNiSn ingot chemical composition (wt/%) alloy design detection mass fraction
Example 1
A short-process heat treatment method for a CuNiSn alloy bar comprises the following steps and process parameters:
the method comprises the following steps: pretreatment of
(1) Cutting the cast ingot into a blank for extrusion, loading the blank into a tube hearth of a medium-frequency induction furnace, and heating the blank in a cooling furnace at the speed of 10 ℃/min to the temperature required by homogenizing annealing;
(2) Carrying out homogenization annealing at 840 +/-15 ℃ for 8 h;
(3) Discharging from the furnace for air cooling after the homogenization annealing stage is finished, removing oxide skin, and performing cutting processing to obtain a blank for extrusion used in the step two;
step two: water seal hot extrusion
(1) Heating the extrusion tool to 360 +/-15 ℃, heating the extrusion cylinder to 400 +/-15 ℃, and keeping the temperature for 40min;
(2) Heating the pretreated extrusion blank to 920 +/-15 ℃, and preserving heat for 2 hours;
(3) Water-seal hot extrusion temperature is 920 +/-15 ℃, hot extrusion speed is 3mm/s, graphite lubricant is used for lubrication, and the extruded alloy bar material obtained by water-seal hot extrusion is processed to obtain a bar material with the diameter of 92 mm;
step three: two stage aging
(1) Primary aging:
heating the extrusion bar to 300 +/-15 ℃, heating at the speed of 10 ℃/min, keeping the temperature for 180min, and then carrying out secondary aging;
(2) Secondary aging:
heating the extruded bar to 400 +/-10 ℃, heating at the speed of 8 ℃/min, keeping the temperature for 480min, performing two-stage aging, and then cooling to room temperature by water to obtain the CuNiSn alloy bar with high toughness and uniform mechanical properties.
Example 1 samples were taken at the edge of the bar, D/4 and D/2 to test the mechanical properties, see Table 2:
TABLE 2 mechanical Property measurements
As shown in Table 2, the mechanical property values of the bar at the edge, D/4 and D/2 are relatively close, which indicates that the mechanical properties of the bar are uniform.
Example 2
A short-process heat treatment method for CuNiSn alloy bars comprises the following steps and process parameters:
the method comprises the following steps: pretreatment of
(1) Cutting the cast ingot into a blank for extrusion, loading the blank into a tube hearth of a medium-frequency induction furnace, cooling and heating the blank in a cooling furnace at the speed of 10 ℃/min to the temperature required by homogenization annealing;
(2) Carrying out homogenization annealing at 840 +/-15 ℃ for 8 h;
(3) Discharging from the furnace for air cooling after the homogenization annealing stage is finished, removing oxide skin, and performing cutting processing to obtain a blank for extrusion used in the step two;
step two: water seal hot extrusion
(1) Heating the extrusion tool to 360 +/-15 ℃, heating the extrusion cylinder to 400 +/-15 ℃, and keeping the temperature for 40min;
(2) Heating the pretreated extrusion blank to 920 +/-15 ℃, and preserving heat for 2 hours;
(3) Water-seal hot extrusion temperature is 920 +/-15 ℃, hot extrusion speed is 3mm/s, graphite lubricant is used for lubrication, and the extruded alloy bar material obtained by water-seal hot extrusion is processed to obtain a bar material with the diameter of 92 mm;
step three: two stage aging
(1) Primary aging:
heating the extruded bar to 300 +/-15 ℃, heating at a speed of 5 ℃/min for 180min, and then carrying out secondary aging;
(2) Secondary aging:
heating the extruded bar to 400 +/-10 ℃, heating at the speed of 5 ℃/min, keeping the temperature for 360min, and cooling the extruded bar to room temperature after two-stage aging to obtain the CuNiSn alloy bar with high toughness and uniform mechanical properties.
Example 2 samples were taken at the edge of the bar, D/4 and D/2 to determine the mechanical properties, see Table 3:
TABLE 3 mechanical Property measurements
As shown in Table 3, the mechanical property values of the bar at the edge, D/4 and D/2 are relatively close, which indicates that the mechanical properties of the bar are uniform.
Example 3
A short-process heat treatment method for CuNiSn alloy bars comprises the following steps and process parameters:
the method comprises the following steps: pretreatment of
(1) Cutting the cast ingot into a blank for extrusion, loading the blank into a tube hearth of a medium-frequency induction furnace, cooling and heating the blank in a cooling furnace at the speed of 10 ℃/min to the temperature required by homogenization annealing;
(2) Carrying out homogenization annealing at 820 +/-15 ℃ for 10 hours;
(3) Discharging from the furnace for air cooling after the homogenization annealing stage is finished, removing oxide skin, and performing cutting processing to obtain a blank for extrusion used in the step two;
step two: water seal hot extrusion
(1) Heating the extrusion tool to 345 +/-15 ℃, heating the extrusion cylinder to 355 +/-15 ℃, and keeping the temperature for 60min;
(2) Heating the pretreated blank for extrusion to 930 +/-15 ℃, and preserving heat for 2 hours;
(3) Water-sealing hot extrusion temperature is 930 +/-10 ℃, hot extrusion speed is 3mm/s, graphite lubricant is used for lubrication, and the extruded alloy bar obtained by water-sealing hot extrusion is processed to obtain a bar with the diameter of 92 mm;
step three: two stage aging
(1) Primary aging:
heating the extruded bar to 300 +/-15 ℃, heating at a speed of 10 ℃/min for 200min, and then carrying out secondary aging;
(2) Secondary aging:
heating the extruded bar to 385 plus or minus 10 ℃, heating at the speed of 5 ℃/min, keeping the temperature for 420min, and cooling the bar to room temperature after two-stage aging to obtain the CuNiSn alloy bar with high toughness and uniform mechanical property.
Example 3 samples were taken at the edge of the bar, D/4 and D/2 to test the mechanical properties, see Table 4:
TABLE 4 mechanical Property measurement values
As shown in Table 4, the mechanical property values of the bar at the edge, D/4 and D/2 are relatively close, which indicates that the mechanical properties of the bar are uniform.
Example 4
A short-process heat treatment method for a CuNiSn alloy bar comprises the following steps and process parameters:
the method comprises the following steps: pretreatment of
(1) Cutting the cast ingot into a blank for extrusion, loading the blank into a tube hearth of a medium-frequency induction furnace, and heating the blank in a cooling furnace at the speed of 15 ℃/min to the temperature required by homogenizing annealing; (2) carrying out homogenization annealing at 840 +/-15 ℃ for 7 hours;
(3) After the homogenization annealing stage, discharging from the furnace for air cooling, removing oxide skin, and performing cutting processing to obtain the blank for extrusion in the step two;
step two: water seal hot extrusion
(1) Heating the extrusion tool to 370 +/-10 ℃, heating the extrusion cylinder to 410 +/-10 ℃, and keeping the temperature for 40min;
(2) Heating the pretreated blank for extrusion to 910 +/-10 ℃, and preserving heat for 3 hours;
(3) The water seal hot extrusion temperature is 910 +/-10 ℃, the hot extrusion speed is 3mm/s, the graphite lubricant is used for lubrication, and the extruded alloy bar obtained by water seal hot extrusion is processed to obtain a bar with the diameter of 92 mm;
step three: two stage aging
(1) Primary aging:
heating the extruded bar to 280 +/-15 ℃, heating at a speed of 10 ℃/min for 250min, and then carrying out secondary aging;
(2) Secondary aging:
heating the extruded bar to 400 +/-10 ℃, heating at the speed of 8 ℃/min, keeping the temperature for 360min, and cooling the bar to room temperature after two-stage aging to obtain the CuNiSn alloy bar with high toughness and uniform mechanical property.
Example 4 samples were taken at the edge of the bar, D/4 and D/2 to test the mechanical properties, see Table 5:
TABLE 5 mechanical Property measurement values
As shown in Table 5, the mechanical property values of the bar at the edge, D/4 and D/2 are relatively close, which indicates that the mechanical properties of the bar are uniform.
The mechanical property uniformity is represented by a relative strength non-uniformity rate Delta M and is vertical to the extrusion direction on a horizontal plane:
△M＝(|M i -M 0 |max)/M 0 ×100％
wherein M is 0 Denotes the average value of the tensile strength in a horizontal plane perpendicular to the extrusion direction, M i The values representing the tensile strength in the horizontal plane were measured in 3 positions at the edge of the bar, D/4 and D/2.
The above results indicate that the relative intensity non-uniformities are all less than 3%; the product of strength and elongation is more than 8400MPa, and the maximum can reach 17000 MPa. In example 1, the tensile strength of the alloy was 980MPa or more, the yield strength was 830MPa or more, the elongation was 8% or more, and the Δ M value was 2.55%. In example 2, the tensile strength of the alloy is kept to be more than 940MPa, the yield strength is more than or equal to 830MPa, the elongation is more than or equal to 9.4 percent, and the Delta M value is 2.60 percent. In example 3, the alloy retained tensile strength of more than 1010MPa, the yield strength of more than 850MPa, the elongation of more than 8.6%, and the Δ M value of 0.08%. In example 4, the alloy has tensile strength of more than 970MPa, yield strength of more than 830MPa, elongation of more than 10 percent and a Delta M value of 1.41 percent. By adopting the heat treatment process, the CuNiSn alloy has good obdurability and mechanical property uniformity. The invention is suitable for industrial production and can meet the requirements of aerospace, aviation, navigation and electronic industries on high-toughness elastic materials.
The present invention can be better realized, the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalents or equivalent replacements fall within the protection scope of the present invention.
Claims (4)
1. A short-process heat treatment method for CuNiSn alloy bars is characterized by comprising the following steps: sequentially carrying out pretreatment, water seal hot extrusion and two-stage aging on the casting; the method specifically comprises the following steps and process parameters:
the method comprises the following steps: pretreatment of
(1) Heating the extrusion billet along with a furnace at the heating speed of 10-15 ℃/min and the heating temperature of 800-900 ℃,
(2) Homogenizing annealing at 800-900 deg.c for 7 hr or longer,
(3) After the homogenization annealing stage is finished, discharging and air cooling;
step two: water seal hot extrusion
(1) Heating the extrusion tool at 300-400 deg.c and the extrusion cylinder at 350-500 deg.c for at least 30min,
(2) Heating the pretreated extrusion blank at 900-970 ℃, preserving the heat for not less than 2 hours,
(3) Water sealing hot extrusion, wherein the temperature range is 900-970 ℃, and the hot extrusion speed is 2-5 mm/s;
step three: two stage aging
Primary aging:
the heating temperature range of the extruded bar is 250-350 ℃, the heating speed is 5-10 ℃/min, and the temperature is kept for 100-500 min;
secondary aging:
the heating temperature range of the extruded bar is 350-450 ℃, the heating speed is 5-10 ℃/min, the temperature is kept for 200-500 min, air cooling is carried out to the room temperature after two-stage aging, and the CuNiSn alloy bar with high toughness and uniform mechanical property is obtained.
2. The short-process heat treatment method of a CuNiSn-based alloy bar according to claim 1, wherein: the homogenization annealing temperature range in the pretreatment of the first step is 810-860 ℃, and the time is 7-9 h.
3. The short-process heat treatment method of a CuNiSn-based alloy bar according to claim 1, wherein: and in the second step, the heating temperature of the extrusion tool is 340-380 ℃, the heating temperature of the extrusion cylinder is 380-420 ℃, the temperature is kept for 30-50 min, the heating temperature of the pretreated extrusion blank is 900-940 ℃, the temperature is kept for 2-5 h, the water seal hot extrusion temperature is 900-940 ℃, and the hot extrusion speed is 2-3 mm/s.
4. The short-process heat treatment method for CuNiSn alloy bars as claimed in claim 1, characterized in that: the three steps of the two-stage aging are carried out,
primary aging: heating the extruded bar at 280-320 deg.c and 5-10 deg.c/min for 150-250 min;
secondary aging: the heating temperature range of the extruded bar is 380-420 ℃, the heating speed is 5-8 ℃/min, the temperature is kept for 360-480 min, and the extruded bar is air-cooled to the room temperature after two-stage aging.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4142918A (en) * | 1978-01-23 | 1979-03-06 | Bell Telephone Laboratories, Incorporated | Method for making fine-grained Cu-Ni-Sn alloys |
| WO2014196563A1 (en) * | 2013-06-04 | 2014-12-11 | 日本碍子株式会社 | Copper-alloy production method, and copper alloy |
| EP3085799B1 (en) * | 2015-04-22 | 2018-01-17 | NGK Insulators, Ltd. | Copper alloy and method for manufacturing the same |
| CN105256171B (en) * | 2015-10-30 | 2017-06-30 | 中南大学 | A kind of adonic bar and preparation method thereof |
| CN108060325B (en) * | 2017-12-15 | 2019-08-27 | 中南大学 | The multistage-combination deformation heat treatment method of the strong CuNiSn series elastic copper alloy of superelevation |
| CN111363948B (en) * | 2020-04-24 | 2021-11-09 | 浙江大学 | Efficient short-process preparation method of high-strength high-conductivity copper alloy |
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