CN101914704A - A kind of Cr-containing anti-creep extruded zinc alloy and preparation method thereof - Google Patents

Abstract

The invention relates to a Cr-containing anti-creep extruded zinc alloy, which belongs to the technical field of metal material manufacturing. The alloy is composed of the following components in terms of mass percentage: 0.05-3.0% of chromium, 0.5-2.5% of copper, 0.1-0.3% of titanium, and the rest is zinc and impurities whose total amount is not more than 0.05%. The alloy component may also contain: 0.1-1.0% aluminum by mass percentage. The preparation method is as follows: smelting by covering protection method, adding alloy elements in the form of pure zinc, pure aluminum and Cu-Cr, Zn-Cu, Zn-Ti master alloy respectively, the smelting temperature is 630-720 ℃, and the alloy melt is After mixing evenly, cast at 450-500°C, homogenize the ingot at 360-380°C for 6-10 hours, then extrude at 240-320°C with an extrusion ratio of 15-38, and then at 180-220°C Annealing 1 ~ 3h. The composition ratio of the invention is reasonable, and the prepared zinc alloy is a deformed zinc alloy suitable for extrusion, and has excellent creep resistance and comprehensive performance.

Description

A kind of Cr-containing anti-creep extruded zinc alloy and preparation method thereof

technical field

The invention discloses a zinc alloy and a preparation method thereof, in particular to a Cr-containing anti-creep extrusion zinc alloy and a preparation method thereof; belonging to the technical field of metal alloy material manufacture.

Background technique

Low creep resistance is one of the main bottlenecks limiting the popularization and application of wrought zinc alloys. In order to improve the creep resistance of zinc alloys, some foreign researchers have conducted some research on the deformation mechanism, alloying and process conditions of zinc alloys. Wrought zinc alloy until the 1960s, due to the progress of smelting and processing technology, the research work on improving the physical properties and comprehensive properties of zinc alloy has been accelerated, especially the mastery of high-strength creep-resistant zinc alloy melting technology and processing technology, It breaks the limitation that zinc alloy cannot be used as a structural material. In the late 1990s, Japan conducted a series of research on cold forging, heat-resistant and cast zinc alloys, and made some progress in the strength and creep resistance of materials, but the comprehensive performance needs to be improved, especially Little research has been done on extruded zinc alloys.

Domestic research on zinc-copper alloys is almost blank. Since the late 1990s, Guangzhou Institute of Metallurgy and Central South University have conducted preliminary research on zinc-copper alloys, but the research content is narrow and the research is not systematic and in-depth. In 1999, Guangdong Metallurgical Research Institute trial-produced several grades of zinc-copper-titanium alloy products for the continuous casting and rolling production line of Guangzhou Zinc Sheet Factory. The creep resistance performance has been improved, but not significant enough.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a Cr-containing creep-resistant extrusion zinc alloy with a reasonable component ratio and a preparation method thereof. The prepared zinc alloy is a deformed zinc alloy suitable for extrusion , has excellent creep resistance and comprehensive performance.

The purpose of the present invention is achieved in the following manner:

A Cr-containing anti-creep extruded zinc alloy consists of the following components by mass percentage:

Chromium 0.05-3.0%;

Copper 0.5-2.5%;

Titanium 0.1-0.3%;

The rest is zinc and unavoidable impurities, the total content of which is not more than 0.05%.

As preferably, the mass percent of each component of the alloy is:

Chromium 0.1-2.8%;

Copper 0.6～2.2%;

Titanium 0.15-0.25%;

The rest is zinc and unavoidable impurities, the total content of which is not more than 0.05%.

A Cr-containing anti-creep extruded zinc alloy consists of the following components by mass percentage:

Chromium 0.05-3.0%;

Copper 0.5-2.5%;

Titanium 0.1-0.3%;

Aluminum 0.1～1.0%;

The rest is zinc and unavoidable impurities, the total content of which is not more than 0.05%.

As preferably, the mass percent of each component of the alloy is:

Chromium 0.05-3.0%;

Copper 0.5-2.5%;

Titanium 0.1-0.3%;

Aluminum 0.25-0.8%;

The rest is zinc and unavoidable impurities, the total content of which is not more than 0.05%.

As a further preference, the mass percent of each component of the alloy is:

Chromium 0.1-2.8%;

Copper 0.6～2.2%;

Titanium 0.15-0.25%;

Aluminum 0.25-0.8%;

The rest is zinc and unavoidable impurities, the total content of which is not more than 0.05%.

The preparation method of the Cr-containing creep-resistant extrusion zinc alloy is as follows: the alloy is smelted by a covering protection method, chromium, copper, and titanium are respectively added in the form of Cu-Cr, Zn-Cu, and Zn-Ti intermediate alloys, and zinc Aluminum and aluminum are added in the form of pure zinc and pure aluminum respectively. The melting temperature is 630-720°C. After the alloy melt is mixed evenly, it is cast into ingots at 450-500°C; the ingots are homogenized at 360-380°C for 6~ After 10 hours, extrude at 240-320°C with an extrusion ratio of 15-38; anneal at 180-220°C for 1-3 hours after extrusion.

The preparation method of the Zn-Ti master alloy is as follows: adding pure Ti accounting for 4-8% of the total mass of the Zn-Ti master alloy into the Zn melt for melting at a melting temperature of 830-920°C, and after the Ti is completely melted and mixed evenly , keep warm for 25 to 35 minutes, and then cast into ingots.

The invention discloses a method for preparing a Cr-containing anti-creep extruded zinc alloy: the smelting is carried out in a medium-frequency induction furnace.

Because the present invention adopts the above components and preparation method, copper, chromium and zinc form the second phase of CuZn ₄ and CrZn ₁₇ intermetallic compound. The second phase of this intermetallic compound has high melting point, high hardness, strong stability and multi-distribution At the grain boundary, stabilize the grain boundary and hinder the movement of dislocations during the creep process, improve the creep resistance of the alloy, and achieve the effect of creep resistance. Secondly, Ti can also form a hard TiZn ₁₅ second phase with zinc, which is dispersed in the matrix to improve the creep resistance of the alloy. The second phase is crushed during extrusion at a temperature of 240-320°C, so that these second phases can be finer and dispersed, which can effectively improve the creep resistance and comprehensive performance of the alloy. At the same time, Al is added to refine the grains, and at the same time promote the uniform distribution of the second phase particles, reduce the segregation of harmful impurities, thereby effectively inhibiting the brittleness and corrosion tendency of the material, and improving the creep resistance and mechanical properties of the alloy. performance and corrosion resistance. In addition, due to the addition of alloy elements such as Cu, Cr and Ti, the recrystallization temperature of the alloy is increased, the growth of recrystallized grains of the alloy is effectively inhibited, and the creep resistance of the alloy is further improved. The mechanism of action of each component in the alloy is described in detail below:

Cr is almost insoluble in zinc at room temperature. Cr can refine grains and strengthen alloys. Chromium and zinc can form hard and stable intermetallic compounds. CrZn ₁₇ is distributed at grain boundaries, stabilizing grain boundaries and hindering sites during creep Staggered movement improves the creep resistance of the alloy and achieves the effect of creep resistance; Cr increases the recrystallization temperature of the alloy, effectively inhibits the growth of the recrystallized grains of the alloy, and further improves the creep resistance of the alloy. Experiments have shown that if the Cr content is too low, the grain refinement is not obvious, and there is almost no CrZn ₁₇ formation, which has little effect on improving the creep resistance; but when the content (mass fraction%) exceeds 3.0%, the intermetallic compound CrZn ₁₇ is too much Segregation at the grain boundary, the plasticity of the alloy is greatly reduced. Therefore, when we set the Cr content (mass fraction%) at 0.05-3.0%, the creep resistance and comprehensive performance of the alloy are the best.

The role of Cu is mainly manifested in the following aspects: first, Cu dissolves in the Zn matrix to produce solid solution strengthening, and second, forms an intermetallic compound ε phase (CuZn ₄ ), resulting in second phase strengthening. The solid solubility of Cu in zinc at room temperature is very small. It can be seen from the phase diagram that when the copper content (mass fraction%) exceeds 1.25%, copper will form ε phase (CuZn ₄ ) with zinc and distribute at the grain boundary, making the alloy have Excellent creep resistance and good comprehensive performance; when the copper content is too low, the alloy strengthening effect is not obvious, and the ε phase (CuZn ₄ ) will not be generated or too little, so the creep resistance has almost no effect; when When the copper content is too high, there will be too much ε phase (CuZn ₄ ) formed at the grain boundary, which will lead to a sharp drop in the plasticity of the alloy. After a large number of experimental analysis, the copper content (mass fraction%) is finally set between 0.5 and 2.5%, so that In order to ensure that the alloy can obtain good comprehensive performance while having good creep resistance. It is also found in the test that when the grain boundary ε phase is too much, it will promote intergranular corrosion and make the corrosion resistance of the alloy worse.

Al can refine grains, and also play a role of solid solution strengthening, so that the tensile strength and creep strength of the alloy are significantly improved, and it also has a certain effect on improving the corrosion resistance of the alloy. During the smelting process of the alloy, Al can greatly improve the fluidity of the zinc liquid, thereby improving its casting performance, and aluminum forms a dense oxide layer on the surface of the molten liquid, and can form slag, which can prevent the alloy from oxidation. Improving the castability of the alloy has great benefits. The addition amount (mass fraction%) of Al in the alloy of the present invention is: 0.1-1.0%.

Ti can react with zinc to form the intermetallic compound TiZn ₁₅ , which is distributed at the grain boundary, which has a good supplementary effect on improving the creep resistance of the alloy; in addition, Ti is added as a modifier, mainly to refine the basic phase, And improve the morphology and distribution of brittle compounds, impurities and inclusions and other second phases. The addition amount (mass fraction %) of Ti in the present invention is: 0.1-0.3%.

In summary, the composition ratio of the present invention is reasonable, and the prepared zinc alloy is a deformed zinc alloy suitable for extrusion, which has excellent creep resistance and comprehensive performance, and is especially suitable for sanitary plumbing, hardware and automobile manufacturing It is a very promising material for parts and other fields.

Detailed ways

The present invention will be described in further detail below in conjunction with specific examples 1-9.

The production process flow of Cr-containing anti-creep extruded zinc alloy in the embodiment of the present invention is as follows:

Raw material preparation and batching-------preparation of master alloy------alloy casting------homogenization treatment------ingot extrusion------annealing-- ----Inspect the finished product.

Specifically, it can be expressed as follows: the creep-resistant zinc alloy is smelted in an intermediate frequency induction furnace using the covering protection method, and chromium, copper, and titanium are added in the form of Cu-Cr, Zn-Cu, and Zn-Ti master alloys respectively, while zinc and aluminum are respectively added. It is added in the form of simple substance, and the melting temperature is 630-720°C, so that chromium, copper, titanium and aluminum are quickly melted and mixed uniformly in the zinc melt, and then cast into zinc alloy ingots at 450-500°C. The ingot is homogenized at 360-380°C for 6-10 hours, then extruded into a round bar at 240-320°C, the extrusion ratio is 15-38, annealed at 180-220°C for 1-3 hours after extrusion, and finally inspected finished product. The preparation method of the Zn-Ti master alloy is as follows: adding pure Ti, which accounts for 4-8% of the total mass of the Zn-Ti master alloy, into the Zn melt for melting, the melting temperature is 830-920°C, and after the Ti is completely melted and mixed uniformly , heat preservation for 30 minutes, the alloy is smelted in an intermediate frequency induction furnace; the preparation method of the Cu-Cr master alloy is: adding pure Cr accounting for 3 to 7% of the total mass of the Cu-Cr master alloy into the Cu melt for melting, and the melting temperature is 1150 ~1250°C, the alloy is melted in a medium frequency induction furnace.

The composition of the Cr-containing creep-resistant extruded zinc alloy of Examples 1-9 of the present invention is shown in Table 1. According to the process of the present invention, the alloys of Examples 1-9 are melted into ingots and extruded into round bars. The specific preparation process The parameters are shown in Table 2; in addition, the Zn-Cu-Ti alloy is used as a comparative example, the specific composition of the comparative alloy is shown in Table 1, and the alloy preparation process parameters are shown in Table 2.

The creep properties and room temperature mechanical properties of the alloys of the examples and comparative examples were tested. The creep test is carried out on the RWS50 electronic creep relaxation testing machine. The sample is placed in a heating furnace that maintains a constant temperature (automatically adjustable temperature) to ensure that the temperature fluctuations of the upper, middle and lower sections are controlled within ±1°C to achieve constant temperature loading. . The testing machine maintains a constant load through electronic control adjustment. Before the temperature rises, an initial force not exceeding 10% of the total test force is applied to the sample. The relative error of the force value within the operating range of the testing machine is not greater than ±1%, and the relative variation of the indication value is not greater than 1%. Greater than 1.0%. The strain measurement adopts a special extension fixture fixed on the test piece, the end of the fixture is drawn out of the furnace, and then two axial extensometers are used to measure the displacement of the fixture on both sides, and the extensometer is checked with an appropriate incremental force before the test If necessary, adjust the extensometer so that the percentage of the difference between the average value of the readings on both sides and the reading on either side divided by the average value is not greater than 15%. The computer is used to control and collect data throughout the test process, and record axial force and deformation in real time. The creep loading stress is 70Mpa, and the temperature is room temperature 25°C. The performance indicators of the alloys prepared in Examples 1-9 and the comparative alloys are shown in Table 3.

Table 1 embodiment and comparative example alloy composition (mass fraction %)

Embodiment and comparative example alloy Cr Cu Ti Al Zn Embodiment 1: Zn-Cr-Cu-Ti 0.05 2.50 0.10 - Surplus Embodiment 2: Zn-Cr-Cu-Ti 0.56 2.20 0.15 - Surplus Embodiment 3: Zn-Cr-Cu-Ti 1.0 1.50 0.12 - Surplus Embodiment 4: Zn-Cr-Cu-Ti 1.92 1.55 0.30 - Surplus Embodiment 5: Zn-Cr-Cu-Ti 3.0 0.5 0.16 - Surplus Embodiment 6: Zn-Cr-Cu-Ti 0.10 1.00 0.20 - Surplus Embodiment 7: Zn-Cr-Cu-Ti-Al 1.07 1.00 0.18 0.10 Surplus Embodiment 8: Zn-Cr-Cu-Ti-Al 1.12 1.45 0.20 0.55 Surplus Embodiment 9: Zn-Cr-Cu-Ti-Al 0.62 2.05 0.30 1.00 Surplus Comparative example: Zn-Cu-Ti - 1.25 0.2 - Surplus

Table 2 alloy preparation process parameters

Table 3 Alloy Performance Test Results

Comparing Table 3 with the performance testing results of Examples 1-9 of the present invention and comparative examples of alloys, it can be seen that the Cr-containing creep-resistant extrusion zinc alloy of the present invention has more excellent creep resistance than the comparative example Zn-Cu-Ti alloy Variable performance and comprehensive performance. This shows that the composition ratio of the present invention is reasonable, and the prepared zinc alloy is a deformed zinc alloy suitable for extrusion, which has excellent creep resistance and comprehensive performance, and is especially suitable for sanitary plumbing, hardware and automobile manufacturing parts, etc. It is a very promising material.

Claims (8)

1. creep-resisting extruded zinc alloy that contains Cr, form by following component by mass percentage:

Chromium 0.05～3.0%;

Copper 0.5～2.5%;

Titanium 0.1～0.3%;

All the other are zinc and unavoidable impurities, and the total content of impurity is not more than 0.05%.

2. a kind of creep-resisting extruded zinc alloy that contains Cr according to claim 1, form by following component by mass percentage:

Chromium 0.05～3.0%;

Copper 0.5～2.5%;

Titanium 0.1～0.3%;

Aluminium 0.1～1.0%;

All the other are zinc and unavoidable impurities, and the total content of impurity is not more than 0.05%.

3. a kind of creep-resisting extruded zinc alloy that contains Cr according to claim 1, form by following component by mass percentage:

Chromium 0.1～2.8%;

Copper 0.6～2.2%;

Titanium 0.15～0.25%;

All the other are zinc and unavoidable impurities, and the total content of impurity is not more than 0.05%.

4. a kind of creep-resisting extruded zinc alloy that contains Cr according to claim 2, form by following component by mass percentage:

Chromium 0.05～3.0%;

Copper 0.5～2.5%;

Titanium 0.1～0.3%;

Aluminium 0.25～0.8%;

All the other are zinc and unavoidable impurities, and the total content of impurity is not more than 0.05%.

5. a kind of creep-resisting extruded zinc alloy that contains Cr according to claim 2, form by following component by mass percentage:

Chromium 0.1～2.8%;

Copper 0.6～2.2%;

Titanium 0.15～0.25%;

Aluminium 0.25～0.8%;

All the other are zinc and unavoidable impurities, and the total content of impurity is not more than 0.05%.

6. prepare the method for the creep-resisting extruded zinc alloy of a kind of Cr of containing as claimed in claim 1 or 2, comprise the steps:

(1) alloy adopts the covering protection method to carry out melting, chromium, copper, titanium add with Cu-Cr, Zn-Cu, Zn-Ti master alloy form respectively, zinc, aluminium then add with pure zinc, fine aluminium form respectively, smelting temperature is 630～720 ℃, after treating that the alloy liquation mixes, be cast into ingot casting at 450～500 ℃;

(2) ingot casting is after 360～380 ℃ of homogenizing are handled 6～10h, and at 240～320 ℃ of extrusion moldings, extrusion ratio is 15～38;

(3) after the extruding, at 180～220 ℃ of annealing 1～3h.

7. according to right 6 described a kind of preparation methods that contain the creep-resisting extruded zinc alloy of Cr, it is characterized in that: described Zn-Ti master alloy is that the pure Ti that will account for Zn-Ti master alloy total mass 4～8% adds melting in the Zn liquation, 830～920 ℃ of smelting temperatures, after treating that Ti all melts and mixes, be incubated 25～35 minutes, be cast into ingot casting again.

8. according to right 6 or 7 described a kind of preparation methods that contain the creep-resisting extruded zinc alloy of Cr, it is characterized in that: described melting is to carry out in medium-frequency induction furnace.