CN102051564A - Method for preparing ultra-fine crystal grain high-strength high-toughness copper alloy strip - Google Patents

Abstract

A method for preparing ultra-fine-grained, high-strength, high-toughness copper alloy strips. The copper alloy ingot is subjected to high-temperature annealing and then hot-rolled with a deformation amount of 40% to 70% to obtain a slab; Cold rolling with a deformation of 30 to 60%; intermediate annealing after cold rolling, then soaking the slab in liquid nitrogen for 5 to 30 minutes, taking it out for cold rolling immediately, and repeating cryogenic treatment and cold rolling after cold rolling Rolling, when the cumulative strain reaches 40-90%, low-temperature annealing is carried out to obtain the ultra-fine-grained high-strength and high-toughness copper alloy strip of the present invention with an average size of about 0.8 μm, and its tensile strength is 650-880 MPa. The elongation rate is 10-30%. The invention has simple production process and low processing cost, and can carry out cold deformation and annealing after cryogenic treatment on the existing production equipment to the copper alloy. Both have been improved, and have good industrial application prospects.

Description

A kind of preparation method of ultra-fine grain high-strength high-toughness copper alloy strip

technical field

The invention relates to a preparation method of a brass strip, in particular to a copper strip with ultra-fine crystal grains, high strength and high toughness and a preparation method thereof. It belongs to the technical field of thermal processing of nonferrous metals.

Background technique

In recent years, with the rapid development of communication, electronics, electric power industry and other fields, the application range of copper and its alloy strip products has been expanding, and higher requirements have been put forward for its performance. Copper alloy strips are of great significance.

Grain refinement is one of the most effective ways to increase the strength of materials. At present, ultra-fine-grained materials are mainly prepared through severe plastic deformation such as high-pressure torsion and equal-channel angular extrusion. The above methods require special molds, and the preparation process is cumbersome, costly, and inefficient, especially when the material is refined to below 1 μm. , the sharp drop in ductility has become a very prominent problem. This not only affects the performance of the material, but also leads to the difficulty of secondary forming, which ultimately limits the wider application of the material.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing copper alloy strips with ultra-fine grains, high strength and high toughness, which is simple in process, low in production cost and can realize industrial scale production.

A kind of preparation method of the copper alloy strip of ultra-fine grain high strength and high toughness of the present invention, comprises the following steps:

Step 1: Annealing

Cast the copper alloy ingot at: 700-850°C; holding time: 0.5-2 hours; water cooling and annealing;

The second step: hot rolling and intermediate annealing

Water-cool the copper alloy test piece obtained in the first step after hot rolling at 700-900°C, and the deformation is 40-70%; then place the hot-rolled water-cooled test piece at 600-750°C, holding time: 0.5-2 hours, then air-cool , for intermediate annealing;

The third step: room temperature cold rolling recrystallization annealing

After the test piece obtained in the second step is cold-rolled at room temperature with a deformation amount of 30-60%, it is recrystallized and annealed at 300-450 ° C; holding time: 0.5-2 hours, air-cooled;

Step 4: Cryogenic treatment and low temperature cold rolling

After soaking the test piece obtained in the third step in liquid nitrogen, perform multi-pass low-temperature cold rolling; before each pass of low-temperature cold rolling, soak the test piece in liquid nitrogen for 5-30 minutes; the cumulative deformation is 40-90%;

Step 5: Annealing

Heat the test piece obtained in the fourth step to: 250-380°C, holding time: 0.2-2 hours, air-cool, and anneal; that is, the average size of the present invention is about 0.8μm, the tensile strength is 650-880MPa, and the elongation is 10-30% ultra-fine grain high-strength and high-toughness copper alloy strip.

In the preparation method of a copper alloy strip with ultra-fine grains, high strength and high toughness of the present invention, the immersion time of the test piece in liquid nitrogen is 5 to 10 minutes, and the deformation amount of each pass of the low-temperature cold rolling is 10-20%.

In the fifth step of the method for preparing an ultrafine-grained high-strength and high-toughness copper alloy strip of the present invention, the annealing temperature is 280-350° C., and the holding time is 0.2-1 hour.

In the method for preparing a copper alloy strip with ultra-fine grains, high strength and high toughness of the present invention, the copper alloy is a brass alloy with a zinc content greater than or equal to 10 wt%.

Due to the adoption of the above-mentioned process, the present invention adopts the cold deformation and low-temperature annealing process after liquid nitrogen cryogenic treatment, and refines the structure through a large number of deformation twins produced during cold deformation and annealing twins produced after low-temperature annealing, so that the material It has high strength performance; at the same time, annealing twins can effectively improve the ductility of the material, and finally a copper alloy strip with ultrafine grains, high strength and high toughness is prepared. Compared with prior art, the present invention has following advantage and positive effect:

1. The cold rolling and annealing treatment after repeated liquid nitrogen cryogenic treatment can not only effectively improve the strength of the material, but also improve the ductility.

2. The high-strength and high-toughness copper alloy strip prepared by the present invention can be directly put into use, thereby improving the service life of existing products; it can also be deep-processed and formed, and the application range of the copper alloy strip can be expanded.

3. The production process of the present invention is simple, the existing equipment can be used to directly put into production, the production cost is low, large-scale production can be easily realized, and there is good industrial prospect.

The present invention obviously refines the copper alloy crystal grains through cold deformation after cryogenic treatment and low-temperature annealing. Compared with the test piece without cryogenic treatment, its strength and ductility are improved in different degrees, and the strength is solved to a certain extent. There is a contradiction between the ebb and flow of toughness; the production process is simple and can be prepared on existing production equipment, which is of great significance to the direct use or secondary processing of copper alloy strips; it has a good industrial application prospect.

Description of drawings

Accompanying drawing 1 is the EBSD orientation phase diagram of the test piece of Example 1 of the present invention after annealing at 300°C for 0.2 hours.

Accompanying drawing 2 is the grain boundary misorientation distribution diagram of the test piece of Example 1 of the present invention after annealing at 300° C. for 0.2 hours.

Accompanying drawing 3 is the metallographic structure diagram of the test piece of the embodiment 2 of the present invention after being annealed at 250 ℃ for 0.5 hours.

Accompanying drawing 4 is the EBSD orientation phase diagram of the specimen of Example 3 of the present invention after annealing at 280° C. for 1 hour.

Accompanying drawing 5 is the EBSD orientation phase diagram of the test piece of Example 4 of the present invention after annealing at 300°C for 0.5 hours.

Accompanying drawing 6 is the tensile strength and elongation curve of the brass alloy strip prepared in Example 3 of the present invention after annealing at 300° C. for different times.

In the figure: From Figures 1 and 2, it can be seen that the entire structure of the specimen in Example 1 has been uniformly refined to about 1 μm after low-temperature annealing, and there are a large number of annealing twins and deformation twins in the structure.

It can be seen from Figure 3 that the microstructure of the specimen in Example 2 has been uniformly refined to about 0.6 μm after low-temperature annealing, and there are many lath-shaped annealing twins in the microstructure.

It can be seen from Figure 4 that the microstructure of the specimen in Example 3 has been uniformly refined to about 0.5 μm after low-temperature annealing, and there are many lath-shaped annealing twins and a small amount of deformation twins in the microstructure.

It can be seen from Figure 5 that the microstructure of the specimen in Example 4 has been uniformly refined to about 0.7 μm after low-temperature annealing, and there are many lath-shaped deformation twins and annealing twins in the microstructure.

It can be seen from Fig. 6 that compared with the test piece without cryogenic treatment, the strength and ductility of the copper alloy strip prepared by the process of the present invention are always greater than that of the test piece without cryogenic treatment. It shows that the invention can not only improve the strength of the material, but also improve its ductility.

Detailed ways

Below in conjunction with embodiment, the present invention is described in detail:

Example 1

The brass alloy ingot containing 70% copper is annealed at 800°C for 1 hour and then hot rolled, the deformation is controlled to 60%, and the hot rolling temperature is 780°C to obtain a slab; the slab is subjected to 600°C for 1 hour After the intermediate annealing, cold rolling is carried out, and the deformation is controlled to 50%; after the cold rolling, an intermediate annealing is carried out for 1 hour, and the annealing temperature is 350 ° C; Soak the test piece in liquid nitrogen for 10 minutes. After the single-pass cold rolling, quickly soak the test piece in liquid nitrogen, repeat cryogenic treatment and low-temperature cold rolling, and carry out low-temperature treatment at 300°C for 0.2 hours after the deformation reaches 50%. annealing. That is, the ultra-fine-grained high-strength and high-toughness copper alloy strip of the present invention is obtained. Referring to attached drawing 1, it can be seen that after low-temperature annealing, the entire structure has been uniformly refined to about 1 μm, and there are a large number of annealing twins and deformation twins in the structure. At this time, the strength of the brass alloy strip is 675MPa, and the elongation is 24%. .

Example 2

The brass alloy ingot containing 68% copper is annealed at 700°C for 2 hours and then hot rolled, the deformation is controlled to 40%, and the hot rolling temperature is 700°C to obtain a slab; the slab is subjected to 680°C for 2 hours After the intermediate annealing, cold rolling is carried out, and the deformation is controlled to 60%; after the cold rolling, the intermediate annealing is carried out for 2 hours, and the annealing temperature is 450 ° C; Soak the test piece in liquid nitrogen for 5 minutes. After the single-pass cold rolling, quickly soak the test piece in liquid nitrogen, repeat cryogenic treatment and low-temperature cold rolling, and carry out low-temperature treatment at 250°C for 0.5 hours after the deformation reaches 60%. annealing. That is, the ultra-fine-grained high-strength and high-toughness copper alloy strip of the present invention is obtained. Referring to accompanying drawing 3, it can be seen that the structure has been uniformly refined to about 0.6 μm after low-temperature annealing, and there are many lath-shaped annealing twins in the structure. crystal, its tensile strength is 720MPa, and its elongation is 18%.

Example 3

The brass alloy ingot containing 70% copper was annealed at 850°C for 0.5 hours, then water-cooled for hot rolling, the deformation was controlled to 70%, and the hot rolling temperature was 780°C to obtain a slab; the slab was subjected to 750°C for 0.5 hours After the intermediate annealing, cold rolling is carried out, and the deformation is controlled at 30%. After the cold rolling, the intermediate annealing is carried out for 0.5 hours, and the annealing temperature is 300°C; the slab is cut into two parts at this time, and they are respectively numbered as the first group and the second group. two groups. Then the first group of test pieces were subjected to multi-pass cold rolling. During cold rolling, the test pieces were soaked in liquid nitrogen for 30 minutes before deformation in each pass, and repeated cryogenic treatment and low-temperature cold rolling. After the deformation reached 40%, every Cut a part of the test piece at a time for strength test until the deformation reaches 90%; carry out multi-pass cold rolling on the second group of test pieces, and cut the test piece every other time after the deformation reaches 40% One part is prepared for strength testing until the deformation reaches 90%; low-temperature annealing is carried out on the first and second groups of test pieces, the annealing temperature is controlled at 280 ° C, and the temperature is kept for 1 hour to obtain the ultra-fine grain high strength of the present invention. Ductile copper alloy strip. The first and second groups of test pieces were tested for strength, and the tensile strength and elongation curves 1 and 2 of Fig. 5 were respectively obtained. Referring to accompanying drawing 6, it can be seen that when the deformation amount is 70%, the tensile strength and elongation of the test piece are both good, and the tensile strength is 750MPa, and the elongation is 16%. At the same time, referring to Figure 4, it can be seen that after low-temperature annealing, the structure has been uniformly refined to about 0.5 μm, and there are many lath-shaped annealing twins and a small amount of deformation twins in the structure.

Example 4

The brass alloy ingot containing 80% copper is annealed at 850°C for 1 hour, then water-cooled for hot rolling, the deformation is controlled to 60%, and the hot rolling temperature is 850°C to obtain a slab; After the intermediate annealing, cold rolling is carried out, and the deformation amount is controlled to 40%; after the cold rolling, an intermediate annealing is carried out for 1 hour, and the annealing temperature is 350°C; Soak the parts in liquid nitrogen for 30 minutes, repeat cryogenic treatment and low-temperature cold rolling, and perform low-temperature annealing at 300°C for 0.5 hours after the deformation reaches 90%. That is, the ultra-fine-grained high-strength and high-toughness copper alloy strip of the present invention is obtained. Referring to Figure 5, it can be seen that after low-temperature annealing, the structure has been uniformly refined to about 0.7 μm, and there are many lath-shaped deformation twins and annealing twins in the structure, with a tensile strength of 820 MPa and an elongation of 13%. .

Claims (4)

1. the preparation method of a superfine crystal particle high-intensity high-tenacity copper alloy plate strip comprises the steps:

The first step: annealing

Copper alloy casting ingot is existed: 700～850 ℃; Soaking time: after 0.5～2 hour; Water-cooled, annealing;

Second step: hot rolling and process annealing

With the first step gained copper alloy test specimen water-cooled after 700～850 ℃ of hot rollings, deflection is 40～70%; Then with water-cooled test specimen after the hot rolling at 600～750 ℃, soaking time: air cooling after 0.5～2 hour, carry out process annealing;

The 3rd step: the cold rolling and recrystallization annealing of normal temperature

With the second step gained test specimen carry out deflection be 30～60% normal temperature cold rolling after, in 300～450 ℃, soaking time: 0.5～2 hour, air cooling carried out recrystallization annealing;

The 4th step: sub-zero treatment and low temperature are cold rolling

With the 3rd step gained test specimen put soak in the liquid nitrogen after, it is cold rolling to carry out multi-pass low temperature; Cold rolling preceding test specimen is put of every time low temperature soaked 5～30 minutes in the liquid nitrogen; Cumulative deformation 40～90%;

The 5th step: annealing

The 4th step gained test specimen is heated to: 250～380 ℃, soaking time: 0.2～2 hour, air cooling, annealing; Promptly get superfine crystal particle high-intensity high-tenacity copper alloy plate strip.

2. the preparation method of a kind of superfine crystal particle high-intensity high-tenacity copper alloy plate strip according to claim 1 is characterized in that: the soak time of described test specimen in liquid nitrogen is 5～10 minutes, and described low temperature is cold rolling, and every time deflection is 10～20%.

3. the preparation method of a kind of superfine crystal particle high-intensity high-tenacity copper alloy plate strip according to claim 2 is characterized in that: described annealing temperature is 280～350 ℃, and soaking time is 0.2～1 hour.

4. the preparation method of a kind of superfine crystal particle high-intensity high-tenacity copper alloy plate strip according to claim 3 is characterized in that: described copper alloy is the brass alloys of zinc content more than or equal to 10wt%.

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