7000-series aluminum alloy wire for additive manufacturing and preparation method thereof

Abstract

The present invention relates to the technical field of manufacturing of metal materials, and in particular to a 7000-series aluminum alloy wire for additive manufacturing and a preparation method thereof. The wire was prepared by subjecting an Al—Ti—B intermediate alloy containing TiB.sub.2 particles generated in situ to severe plastic deformation to obtain an intermediate alloy containing TiB.sub.2 nanoparticles having a particle size of 50-1,000 nm or a mixture of two different particles; using the intermediate alloy containing TiB.sub.2 nanoparticles as a matrix raw material, adding other metal or intermediate alloy for smelting to obtain an alloy melt; preparing a wire blank with the alloy melt; subjecting the wire blank to hot rolling, drawing, intermediate annealing and surface treatment to obtain an Al—Zn—Mg—Cu alloy wire reinforced by particles at nano scale or submicron scale.

Claims

1. A method of preparing a 7000-series aluminum alloy wire for additive manufacturing, comprising the following steps: step 1: subjecting an Al—Ti—B intermediate alloy containing TiB.sub.2 particles generated in situ to plastic deformation to obtain an intermediate alloy containing TiB.sub.2 nanoparticles having a particle size of 50-1,000 nm; step 2: adding other metal or intermediate alloy into the intermediate alloy containing TiB.sub.2 nanoparticles obtained in step 1 to obtain a mixed material, smelting the mixed material at 750-780° C. to obtain a smelted material, and casting the smelted material into a cast round rod; step 3: subjecting the cast round rod obtained in step 2 to hot extrusion to obtain a wire blank with φ of 8-10 mm; and step 4: subjecting the wire blank obtained in step 3 to hot rolling, drawing, intermediate annealing and surface treatment to obtain the 7000-series aluminum alloy reinforced by particles, wire with φ of 1.0 mm-2.4 mm.

2. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 1, wherein the plastic deformation in step 1 is implemented by a high-speed friction stir process with a stirring needle at 800-2,000 r/min for 1-5 times.

3. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 2, wherein the cast round rod in step 3 is subjected to homogenizing heat treatment at 450-490° C. for 10-24 h before hot extrusion at 400-450° C. at 5-10 mm/min.

4. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 3, wherein the hot rolling in step 4 is carried out at 350-420° C. for 0.5-1 h, and the drawing is carried out at a normal temperature.

5. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 4, wherein the intermediate annealing in step 4 is carried out at 380-430° C. for 1-6 h, and the surface treatment comprises surface scraping, sizing, degreasing and cleaning.

6. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 1, wherein the plastic deformation in step 1 is implemented by an equal-channel angular pressing process with a channel angle of 90-120 degrees for 1-5 cycles.

7. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 6, wherein the cast round rod in step 3 is subjected to homogenizing heat treatment at 450-490° C. for 10-24 h before hot extrusion at 400-450° C. at 5-10 mm/min.

8. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 7, wherein the hot rolling in step 4 is carried out at 350-420° C. for 0.5-1 h, and the drawing is carried out at a normal temperature.

9. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 8, wherein the intermediate annealing in step 4 is carried out at 380-430° C. for 1-6 h, and the surface treatment comprises surface scraping, sizing, degreasing and cleaning.

10. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 1, wherein the plastic deformation in step 1 is implemented by a high-pressure torsion process with 1-20 turns.

11. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 10, wherein the cast round rod in step 3 is subjected to homogenizing heat treatment at 450-490° C. for 10-24 h before hot extrusion at 400-450° C. at 5-10 mm/min.

12. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 11, wherein the hot rolling in step 4 is carried out at 350-420° C. for 0.5-1 h, and the drawing is carried out at a normal temperature.

13. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 12, wherein the intermediate annealing in step 4 is carried out at 380-430° C. for 1-6 h, and the surface treatment comprises surface scraping, sizing, degreasing and cleaning.

14. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 1, wherein the cast round rod in step 3 is subjected to homogenizing heat treatment at 450-490° C. for 10-24 h before hot extrusion at 400-450° C. at 5-10 mm/min.

15. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 14, wherein the hot rolling in step 4 is carried out at 350-420° C. for 0.5-1 h, and the drawing is carried out at a normal temperature.

16. The method of preparing the 7000-series aluminum alloy wire for additive manufacturing according to claim 15, wherein the intermediate annealing in step 4 is carried out at 380-430° C. for 1-6 h, and the surface treatment comprises surface scraping, sizing, degreasing and cleaning.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a metallographic structure of an original Al-2.3Ti—B alloy in Example 1;

(2) FIG. 2 shows a metallographic structure of an Al-2.3Ti—B alloy after severe plastic deformation in Example 1;

(3) FIG. 3 shows a metallographic structure of an Al—Zn—Mg—Cu alloy wire reinforced by TiB2 particles obtained in Example 1;

(4) FIG. 4 shows a metallurgical structure of a welded seam of an Al—Zn—Mg—Cu alloy wire reinforced by TiB2 particles obtained in Example 1;

(5) FIG. 5 shows a real welded seam of a conventional Al—Zn—Mg—Cu alloy wire without addition of a severe plastic deformed Al—Ti—B intermediate alloy in Comparative Example 1;

(6) FIG. 6 shows a metallurgical structure of a welded seam of the conventional Al—Zn—Mg—Cu alloy wire without addition of a severe plastic deformed Al—Ti—B intermediate alloy in Comparative Example 1; and

(7) FIG. 7 shows an x-ray powder diffraction (XRD) pattern of an Al—Zn—Mg—Cu alloy reinforced by TiB2 particles obtained in Example 1.

DETAILED DESCRIPTION

(8) The present invention is described in more detail below with reference to the specific implementations.

(9) A 7000-series aluminum alloy wire for additive manufacturing, prepared by smelting and processing an Al—Ti—B intermediate alloy containing TiB2 nanoparticles with other metal or intermediate alloy, where the nanoparticles having a particle size of 50-1,000 nm in the wire are dispersed in an alloy matrix, and the wire has the following chemical components in weight percentage: Zn: 5.0-7.5%, Mg: 1.5-3.0%, Cu: 1.0-2.5%, Ti: 1.0-3.0%, Sc: 0-0.6%, Cr: 0.05-0.2%, B and/or C: 0.2-1.0%, and Al and other inevitable impurity elements as balance. Moreover, a weight ratio of Ti to B in the Al—Ti—B intermediate alloy is x:1, where 2.2<x≤3.

(10) The inventors have found through a large number of experiments that within the following parameter ranges, a prepared Al—Zn—Mg—Cu alloy wire reinforced by particles has low sensitivity to hot cracking during solidification in additive manufacturing, and a relatively high strength after solidification. In the present invention, five groups are listed and illustrated.

(11) The parameters for a 7000-series aluminum alloy wire for additive manufacturing and a preparation method thereof in each of Examples 1-5 of the present invention were shown in Table 1:

(12) TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 x 2.3 2.3 2.5 2.8 3 Smelting temperature (° C.) 760 750 770 780 760 Homogenizing Holding 500 470 480 520 530 heat treatment temperature (° C.) Holding time (h) 12 24 20 10 6 Heat extrusion Extruding 400 420 430 440 450 temperature (° C.) Extruding speed 5 5 5 10 10 (mm/min) Hot rolling Holding 400 350 360 410 420 temperature (° C.) Holding time (h) 1 1 1 0.5 0.5 Intermediate Annealing 400 380 390 420 430 annealing temperature (° C.) Holding time (h) 5 6 4 2 1

(13) Now Example 1 was taken as an example to illustrate another technical solution of the present invention. a preparation method of the 7000-series aluminum alloy wire for additive manufacturing.

(14) A preparation method of a 7000-series (Al—Zn—Mg—Cu) aluminum alloy having components in weight percentage of Al-6Zn-2.5Mg-1.5Cu-1.94Ti-0.85B-0.2Cr was used as an example to describe the method in detail. That is, preparation of 100 kg of the alloy needed 6 kg of pure zinc, 2.5 kg of pure magnesium, 3.0 kg of Al-50Cu intermediate alloy, 4 kg of Al-5Cr intermediate alloy, and a remaining 84.5 kg of Al-2.3Ti—B intermediate alloy.

(15) The preparation method of the 7000-series aluminum alloy wire for additive manufacturing included the following steps:

(16) Step 1: 84.5 kg of the Al-2.3Ti—B intermediate alloy containing TiB2 particles generated in situ with most particles having a size of 2-5 μm was prepared and subjected to severe plastic deformation to obtain an Al—Ti—B intermediate alloy containing TiB2 nanoparticles having a size of 50-1,000 nm.

(17) The severe plastic deformation is implemented by a high-speed friction stir process with a stirring needle at 800-2,000 r/min for 1-5 times, or an equal-channel angular pressing process with a channel angle of 90-120 degrees for 1-5 cycles, or a high-pressure torsion process with 0.5-5 turns. In this example, the high-speed friction stir process was adopted.

(18) Step 2: the Al—Ti—B intermediate alloy containing TiB2 nanoparticles obtained in step 1 was used as a matrix raw material. 6 kg of pure zinc, 2.5 kg of pure magnesium, 3.0 kg of Al-50Cu intermediate alloy, 4 kg of Al-5Cr intermediate alloy were added for smelting at 760° C., and casted into a cast round rod.

(19) Step 3: the cast round rod obtained in step 2 was subjected to homogenizing heat treatment at 500° C. for 12 h. Then hot extrusion was carried out at 400° C. at 5 mm/min to obtain a wire blank with φ of 8-10 mm.

(20) Step 4: the wire blank obtained in step 3 was subjected to hot rolling at 400° C. for 1 h, drawing at a normal temperature, intermediate annealing at 400° C. for 5 h, and surface treatment to obtain an Al—Zn—Mg—Cu alloy wire reinforced by TiB2 particles with φ of 1.0 mm-2.4 mm. In this step, the surface treatment included surface scraping with a thickness of 0.01-0.02 mm, sizing, degreasing and cleaning.

(21) Moreover, a comparative example was listed to compare with the Al—Zn—Mg—Cu alloy wires reinforced by particles obtained in Examples 1-5 in a test:

(22) Comparative Example 1 referred to a conventional Al—Zn—Mg—Cu alloy wire (without a severe plastic deformed Al—Ti—B intermediate alloy).

(23) The alloy wires obtained in Examples 1-5 and Comparative Example 1 were tested:

(24) An ECLIPSE MA200 optical microscope manufactured by Nikon was used for metallographic examination on the alloy wires obtained in Examples 1-5 and Comparative Example 1 with results shown in FIGS. 1-5:

(25) An ECLIPSE MA200 optical microscope manufactured by Nikon was used for metallographic examination on the alloy wires obtained in Examples 1-5 and Comparative Example 1 with results shown in FIGS. 1-5:

(26) FIG. 1 showed a metallographic structure of an original Al-2.3Ti—B intermediate alloy without severe plastic deformation in Example 1. It can be seen that, the TiB2 particles in the intermediate alloy were all at micron scale (2-50 μm) with a large distribution range of particle size. Large particles were irregular and had an obvious grain boundary with matrix grains.

(27) FIG. 2 showed a metallographic structure of Al-2.3Ti—B intermediate alloy after severe plastic deformation in Example 1. It can be seen that, the TiB2 particles after severe plastic deformation were all at nano scale with a narrow distribution range of particle size. The TiB2 particles were dispersed among matrix grains.

(28) FIG. 3 showed a metallographic structure of the Al—Zn—Mg—Cu alloy wire (with a composition of Al-6Zn-2.5Mg-1.5Cu-1.94Ti-0.85B-0.2Cr) reinforced by TiB2 particles obtained in Example 1. A direction indicated by an arrow in FIG. 3 referred to a processing direction. It can be seen from FIG. 3 that, during alloy smelting and processing, TiB2 particles was not changed in size, and a second phase and TiB2 nanoparticles had a fine size with even distribution and dispersion. There was no obvious coarse second phase or particle agglomeration.

(29) FIG. 4 showed a metallographic structure of the Al—Zn—Mg—Cu alloy wire reinforced by TiB2 particles after melting by welding obtained in Example 1. As can be seen from FIG. 4, no welding hot cracks were found in a weld seam structure. The grains were fine equiaxed grains. The second phase and TiB2 nanoparticles had a fine size with even distribution and dispersion. There was no obvious coarse second phase or particle agglomeration.

(30) FIG. 5 showed a real welded seam of the conventional (without severe plastic deformed Al—Ti—B intermediate alloy) Al—Zn—Mg—Cu alloy wire after welding in Comparative Example 1. It can be seen from the figure that, there were obvious hot cracks due to solidification (as indicated by an arrow). FIG. 6 showed a metallographic structure of a welded seam of the conventional Al—Zn—Mg—Cu alloy wire (without severe plastic deformed Al—Ti—B intermediate alloy) after welding in Comparative Example 1. As can be seen from the figure, the grains in the weld seam structure were coarse dendritic grains.

(31) 2. XRD Characterization

(32) An X-ray diffractometer was used to measure the alloys obtained in Examples 1-5 and Comparative Example 1. Taking the Al—Zn—Mg—Cu alloy wire reinforced by TiB2 particles obtained in Example 1 as an example, an XRD pattern was shown in FIG. 7. XRD test results proved presence of TiB2 nanoparticles in the Al—Zn—Mg—Cu alloy.

(33) The above are only examples of the present invention, and common knowledge such as specific structures and characteristics known in the art is not described here too much. It should be noted that those skilled in the art may further make several variations and improvements without departing from the scope of the present invention, but such variations and improvements should also be deemed as falling within the protection scope of the present invention without affecting the implementation effect and practicability of the patent. The protection scope claimed in this application shall be based on contents of claims, and disclosure in the specification such as the detailed description may be used to interpret the contents of the claims.