CN101086044A - High-strength high elasticity Cu-Ti alloy and its preparing process - Google Patents

Abstract

The invention provides a high-strength and high-elasticity Cu-Ti alloy and a manufacturing method thereof. Ti in the alloy is 3.0-4.0 wt%, and the third element group: 0.01-0.5 wt%. The auxiliary raw materials are put into a non-vacuum intermediate frequency induction furnace, and are melted and casted under the protection of inert gas; the obtained slab is rolled, and the final rolling temperature in the hot rolling process and the intermediate annealing temperature in the cold rolling process are higher than the solid state of the alloy. Solvent solution treatment or recrystallization annealing treatment at 750°C-850°C; aging treatment at 350°C-450°C for 5-20 hours to obtain finished products. The invention controls the phase structure and crystal grain size of the alloy through a suitable production process, and obviously improves the comprehensive performance of the alloy.

Description

A kind of high-strength and high-elasticity Cu-Ti alloy and its manufacturing method

technical field

The invention relates to a Cu-Ti alloy, in particular to a high-strength and high-elasticity Cu-Ti alloy and a manufacturing method thereof, belonging to the technical field of nonferrous metals.

Background technique

Nowadays, electronic products are becoming smaller and lighter in size and lighter in weight, and electronic components are also miniaturized and lighter. Therefore, the thickness of the connector is getting thinner and the contact area is getting smaller and smaller. This requires higher and higher strength and electrical conductivity of connector materials. Some commonly used connectors such as tin phosphor bronze and brass can no longer meet the requirements of high-end electronic products. In addition, because beryllium bronze will produce toxic dust during smelting, and it is expensive. Therefore, Cu-Ti alloys with comparable strength to beryllium bronze will receive extensive attention.

Generally speaking, the production process of Cu-Ti alloy includes: vacuum melting-solid solution-hot rolling-cold rolling-intermediate annealing-finish rolling-aging, etc. Because the phase transformation process of Cu-Ti alloy is very complex, aging at low temperature will produce amplitude modulation decomposition structure, and cellular reaction will occur under the condition of overaging and high temperature, forming Widmanstatten lamellar structure. When the lamellar structure is formed, the performance of the alloy decreases. Therefore, how to avoid and suppress the growth of lamellar structure in the production process will be a key link to improve the performance of the alloy.

However, the method of vacuum melting Cu-Ti alloy has the following problems: ① Due to the high degree of vacuum required in the vacuum furnace melting process, the requirements for the sealing of the furnace body are very high, and composition measurement, composition adjustment and grilling cannot be carried out during smelting. Therefore, the requirements for the composition and impurity content of raw materials are very high; ②Vacuum smelting generally cannot adopt the method of rapid cooling, the ingot is prone to grain coarsening, and cracks are easy to appear in the deformation process, which reduces the quality of the finished strip. ③ The discontinuous operation of the vacuum furnace itself makes it only capable of small-scale production, but not continuous large-scale production, which limits its industrialization prospects.

Contents of the invention

The object of the present invention is to provide a high-strength and high-elasticity Cu-Ti alloy and its manufacturing method, starting from controlling the phase structure and grain size of the alloy, and improving the comprehensive performance of the Cu-Ti alloy.

The purpose of the present invention is achieved through the following technical solutions:

A high-strength and high-elasticity Cu-Ti alloy is characterized in that: the mass percentage of its components is as follows—

Ti 3.0～4.0wt%,

The third element group 0.01～0.5wt%,

The remainder of the alloy is Cu and unavoidable impurities.

Further, in the above-mentioned high-strength and high-elasticity Cu-Ti alloy, the third element group is at least one of Cr, Co, V, Zr, B, Ni, and P.

Furthermore, a method for manufacturing a high-strength and high-elasticity Cu-Ti alloy is characterized by comprising the following steps—

① First, put the main raw materials and auxiliary raw materials into a non-vacuum intermediate frequency induction furnace, and carry out melting and casting under the protection of inert gas;

②Roll the obtained slab, the final rolling temperature in the hot rolling process and the intermediate annealing temperature in the cold rolling process are higher than the solvus line of the alloy, and carry out solution treatment or recrystallization annealing treatment at 750°C to 850°C ;

③Aging treatment at 350°C-450°C for 5-20 hours to obtain the finished product.

Still further, in the manufacturing method of the above-mentioned high-strength and high-elasticity Cu-Ti alloy, in step ②, the crystal grain diameter is controlled to be 2-10 μm during the manufacturing process.

Still further, in the manufacturing method of the above-mentioned high-strength and high-elasticity Cu-Ti alloy, the step ③ aging process controls the diameter of the Cu-Ti intermetallic compound phase on the section perpendicular to the rolling direction to be 0.02-0.2 μm.

The outstanding substantive features and remarkable progress of the technical solution of the present invention are mainly reflected in:

(1) The technical scheme of the present invention adopts non-vacuum smelting technology to produce high-strength and high-elasticity Cu-Ti alloys with qualified components, low impurity content and good quality;

(2) The present invention controls the phase structure and grain size of the alloy through a suitable production process, significantly improves the overall performance of the alloy, greatly reduces the production cost, optimizes the production process, and has remarkable economic benefits.

Description of drawings

Below in conjunction with accompanying drawing, technical solution of the present invention will be further described:

Figure 1: TTT curves for generating 1% TiCu ₃ photolamellar structures.

Detailed ways

The technical scheme of the invention uses inert gas protection for melting and casting, avoiding the action of alloy elements and oxygen and nitrogen in the air; gas protection is provided in the melting and pouring process to realize the continuous production of Cu-Ti alloy. In the rolling process, the final rolling temperature of hot rolling and the intermediate annealing temperature in the cold rolling process are slightly higher than the solvus of the alloy, which can effectively prevent the alloy from forming a lamellar structure in this process. By controlling the intermediate annealing time, the grain The particle size is controlled at 2-10 μm. Through a suitable aging process, the diameter of the Cu-Ti intermetallic compound phase on the cross section perpendicular to the rolling direction is controlled between 0.02-0.2 μm. By adding an appropriate amount of the third element group, the occurrence of overaging can be delayed, the occurrence of cellular reaction can be suppressed, and the electrical conductivity of the alloy can be improved without reducing the strength of the alloy.

1) Non-vacuum melting

Since the Cu-Ti alloy contains 3.0-4.0wt% Ti, when titanium is above 650°C, oxygen will diffuse into titanium to form a hard oxide layer; in addition, above 700°C, nitrogen and titanium will react violently to form TiN. If it is smelted in the atmosphere, problems such as air absorption, oxygen absorption, and non-metallic inclusions will occur; similar problems are also likely to occur in the open casting process, which will affect the performance of the material. However, the present invention adopts the submerged Cu-Ti alloy horizontal continuous casting technology. On the basis of the traditional horizontal continuous casting technology, the submerged copper replenishment process is adopted to completely seal the launder and the melting furnace, and fill in inert gas to ensure that the melt and the air It is completely isolated to avoid defects such as air absorption and slag inclusion in the melt during smelting, laundering and pouring; during the production process, it can be fed at any time through the feeding hole to adjust the alloy composition.

2) Solution treatment during rolling

Cu-Ti alloy forms a supersaturated solid solution through solid solution treatment. When aging at low temperature in this state, a metastable amplitude-modulated structure will be formed. Aging, the final precipitation of stable TiCu ₃ phase will soften the alloy. On the other hand, under the condition of insufficient solid solution, incomplete solid solution titanium will remain in the parent phase in the state of TiCu ₃ . In order to maximize the hardening under aging treatment, it is necessary to completely disappear the TiCu ₃ phase in the solution treatment of the preceding process, so that titanium is completely dissolved in the parent phase. Therefore, it is necessary to heat to a temperature at which the solid solution temperature of titanium exceeds the titanium content. In addition, Cu-Ti alloys can increase their yield strength through fine grains in the annealing process, and the grain size on the cross-section perpendicular to the rolling direction is between 2 and 10 μm; if it exceeds 10 μm, it cannot be achieved due to fine grain size. The resulting high strengthening; if it is less than 2 μm, it is possible to remain incompletely recrystallized parts, which will deteriorate the processability of the alloy. In the process of producing Cu-Ti alloy, the final recrystallization annealing process is equivalent to solution treatment. In solution treatment, the crystal grains are refined and the yield strength is improved. In copper containing about 3wt% titanium, at 750 ° C Solution treatment or recrystallization annealing treatment is carried out between ~850°C.

3) Aging treatment

The aging temperature should be selected between 350°C and 450°C. If the temperature is lower than 350°C, the precipitation of Cu-Ti intermetallic compound phase is insufficient, and high strength and electrical conductivity cannot be obtained; if it is higher than 450°C, the Cu-Ti intermetallic compound phase tends to be coarsened and over-aged, resulting in The strength of the alloy is reduced. The aging time is between 5 and 20 hours. In addition, during the aging cooling process, in order to cause sufficient precipitation of the Cu-Ti intermetallic compound phase, the cooling rate from the aging temperature to 200°C should not be higher than 50°C/hour.

4) The addition of the third element group

In order to delay the grain growth during the recrystallization annealing process and suppress the precipitation of the TiCu ₃ phase, an appropriate amount of the third element group is added to form the second phase particles. It can be formed during the previous annealing process, and its shape hardly changes during the cold rolling and aging process. The third element group is one or more of Cr, Co, V, Zr, B, Ni, P, and the content is 0.01-0.5 wt%. The addition of these elements does not affect the formation of the amplitude-modulated structure, and the second-phase particles formed are not for precipitation hardening, but for the purpose of inhibiting grain growth and overaging.

【Example】

Using industrial electrolytic copper, sponge titanium and other trace alloy elements as raw materials, graphite crucible is used for smelting in a gas-shielded non-vacuum intermediate frequency induction furnace.

20 kg of ingots were kept at 850°C for 24 hours. Through ICP analysis, the alloy composition is shown in Table 1. Then, the cast ingot was hot-rolled at 850° C., and solution treatment was performed at 860° C. for 1 hour after the hot rolling. Some samples were taken out from the material after solid solution and annealed at different temperatures and times to observe the precipitation law of TiCu ₃ phase. The TTT curve is shown in Figure 1.

In addition, the thickness of the plate after solid solution is 10mm, cold rolling is carried out after milling, rolling 2mm, and recrystallization annealing is carried out under the condition of 780°C under the protection of argon for 5min, and the plate after annealing is cold rolled to 1mm, and finally 380°C After aging treatment for 10h, the performance of the alloy was tested, and the test results are shown in Table 1.

Table 1 Composition and properties of the alloy

Sample No Element Performance hardness strength Conductivity 1  Cu-3.5Ti-Re 345 1167 14% 2   Cu-3.5Ti-0.1Cr-Re 351 1159 18%

It can be seen from Figure 1 that by adding 0.1wt% titanium, the precipitation of TiCu ₃ phase is delayed, and the amplitude modulation structure containing TiCu ₄ phase is more fully precipitated, and the electrical conductivity of the alloy is improved without affecting the strength.

The embodiment shows that the technological process of the present invention is simple and easy to implement. According to the technological process of the present invention, through non-vacuum furnace technology, solid solution treatment or recrystallization annealing treatment and aging treatment, high-strength and high-elasticity Cu with qualified chemical composition and excellent quality can be produced. -Ti alloy.

Claims (5)

1. high-strength high elasticity Cu-Ti alloy, it is characterized in that: the quality percentage composition of its composition is as follows---

Ti 3.0～4.0wt％，

The 3rd groups of elements 0.01～0.5wt%,

All the other components of this alloy are Cu and unavoidable impurities.

2. a kind of high-strength high elasticity Cu-Ti alloy according to claim 1 is characterized in that: described the 3rd groups of elements is at least a among Cr, Co, V, Zr, B, Ni, the P.

3. make the method for the described a kind of high-strength high elasticity Cu-Ti alloy of claim 1, it is characterized in that may further comprise the steps---

1. at first main raw material and auxiliary material are dropped in the antivacuum medium-frequency induction furnace, under the protection of inert gas condition, carry out founding;

2. the strand that obtains is rolled, finishing temperature in the course of hot rolling and the process annealing temperature in the cold-rolled process are higher than the solvus of alloy, carry out solution treatment or recrystallization annealing processing at 750 ℃～850 ℃;

3. 350 ℃～450 ℃ ageing treatment 5～20 hours, obtain finished product.

4. the manufacture method of a kind of high-strength high elasticity Cu-Ti alloy according to claim 3 is characterized in that: step 2. in the manufacturing processed control crystal grain diameter at 2～10 μ m.

5. the manufacture method of a kind of high-strength high elasticity Cu-Ti alloy according to claim 3, it is characterized in that: step is aging treatment process 3., makes the diameter perpendicular to Cu-Ti intermetallic compound phase on the rolling direction cross section be controlled at 0.02～0.2 μ m.