Method for controlling crush performance of 6-series aluminum alloy profile for automobile bumper beam

Abstract

A method for controlling the crushing performance of 6-series aluminum alloy profiles used in automotive crash beams includes the following steps: composition control; melting and casting; homogenization annealing; extrusion molding; quenching treatment; and aging treatment. The beneficial effects of this invention are: by controlling the Mg content in the 6-series aluminum alloy to 0.9%–0.945%, the Si content to 0.59%–0.615%, and the Mg / Si ratio to the range of 1.544–1.633, and by optimizing the melting, casting, extrusion, quenching, and aging processes, the proportion and distribution of the Mg₂Si strengthening phase are optimized, achieving stable control of the crushing performance. Experimental data show that when the Mg / Si ratio is between 1.544 and 1.633, the proportion of crushing performance grade 6 increases from 54.38% before control to 81.02%. When the Mg / Si ratio reaches 1.633, the expected proportion of crushing performance grade 6 can reach 93.12%, while the tensile strength and yield strength both achieve a synergistic increase of approximately 5 MPa. When Mg / Si > 1.633, the curvature of the curve decreases and shows a downward trend.

Description

Technical Field

[0001] This invention relates to a method for controlling the crush performance of 6-series aluminum alloy profiles used in automotive anti-collision beams, specifically a method for controlling the crush performance of 6-series aluminum alloy profiles used in automotive anti-collision beams. Background Technology

[0002] 6-series aluminum alloys (Al-Mg-Si series) are widely used in industrial profiles, automotive parts, and building profiles due to their good thermoplasticity, excellent corrosion resistance, ideal comprehensive mechanical properties, and ease of oxidation and coloring. However, the wide range of chemical compositions of this alloy leads to significant fluctuations in the performance of the produced profiles, which adversely affects subsequent deep processing and applications.

[0003] In 6-series aluminum alloys, Mg₂Si is the sole strengthening phase, and its content, distribution, and state play a decisive role in the material's properties. Mg and Si are the main elements forming the Mg₂Si strengthening phase, with a theoretical mass ratio of 1.73. When the Mg / Si ratio deviates from this theoretical value, excess Mg or Si will appear in the microstructure, thus affecting the material's strength, plasticity, and toughness. In current production, the Mg / Si ratio is typically controlled to be less than 1.73, resulting in a slight excess of Si to meet different performance requirements.

[0004] For aluminum alloy profiles used in automotive crash beams, in addition to conventional mechanical properties, crush performance is a key indicator for measuring their collision energy absorption capacity, directly related to vehicle safety. The quality of crush performance mainly depends on the material's stability during compression deformation, its resistance to crack propagation, and its energy absorption efficiency. In existing technologies, the control of the crush performance of 6-series aluminum alloys largely relies on empirical composition adjustments and process exploration, lacking a systematic composition-process-performance correlation model. This results in unstable product yield rates, making it difficult to meet the automotive industry's high requirements for material consistency and reliability. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings and defects of existing technologies by providing a method for controlling the crush performance of 6-series aluminum alloy profiles used in automotive crash beams. This invention optimizes the proportion and distribution of the Mg2Si strengthening phase in the 6-series aluminum alloy by controlling the Mg content to 0.9%–0.945%, the Si content to 0.59%–0.615%, and the Mg / Si ratio to the range of 1.544–1.633, along with optimized smelting, casting, extrusion, quenching, and aging processes. This achieves stable control of the crush performance. Experimental data shows that when the Mg / Si ratio is between 1.544 and 1.633, the proportion of crush performance at level 6 increases from 54.38% before adjustment to 81.02%. When the Mg / Si ratio reaches 1.633, the expected proportion of crush performance at level 6 can reach 93.12%, while both tensile strength and yield strength are synergistically improved by approximately 5 MPa. When the Mg / Si ratio exceeds 1.633, the curve curvature decreases and a downward trend appears. The method for controlling the crushing performance of the 6-series aluminum alloy profiles is compatible with existing production lines and has limited cost increases, making it suitable for large-scale industrial production.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for controlling the crush performance of 6-series aluminum alloy profiles for automotive anti-collision beams, comprising the following steps: composition control: controlling the mass percentage of Mg in the aluminum alloy to be 0.9%–0.945%, the mass percentage of Si to be 0.59%–0.615%, and the mass ratio of Mg to Si to be 1.544–1.633; smelting and casting: after adjusting the alloy composition according to the composition control requirements in S1, smelting, refining, and casting are performed to obtain a round ingot; homogenization annealing: the round ingot is subjected to homogenization annealing treatment; extrusion molding: the homogenized annealed round ingot is heated and extruded to obtain a profile; quenching treatment: the extruded profile is subjected to online quenching; aging treatment: the quenched profile is subjected to aging treatment.

[0007] Furthermore, the melting temperature in the smelting and casting process is 750℃±10℃, and the standing time after refining is not less than 1 hour.

[0008] Furthermore, in the melting and casting process, the hot end temperature is 720℃±10℃, the cold end temperature is 700℃±10℃, and the casting speed is 70mm / min±10mm / min.

[0009] Furthermore, in the smelting and casting process, a 40ppi filter plate is used for filtration during casting, and aluminum titanium boron wire is added to refine the grain size.

[0010] Furthermore, the aluminum-titanium-boron wire is 5Ti-1B wire, and the wire feeding speed is 25cm / min±5cm / min.

[0011] Furthermore, in the extrusion molding process, the head temperature of the short round ingot used for extrusion is set at 480±10℃, the temperature gradient is 20-50℃ / m, the extrusion speed is 4.0mm / s±0.5mm / s, and the extrusion outlet temperature is controlled at 560℃±10℃.

[0012] Furthermore, in the quenching process, the quenching cooling rate is not less than 200℃ / s, and after quenching, the profile is left to stand for no more than 6 hours.

[0013] Furthermore, in the aging process, the aging process is an over-aging process, and the over-aging process is a single-stage aging process. The aging temperature is 210℃±5℃, and the aging time is 7h±0.5h.

[0014] A 6-series aluminum alloy profile for automotive anti-collision beams is prepared using any one of the methods described above.

[0015] After adopting the above technical solution, the beneficial effects of the present invention are as follows: 1. This invention optimizes the proportion and distribution of the Mg2Si reinforcing phase by controlling the Mg and Si contents to 0.9%–0.945% and 0.59%–0.615%, respectively, and the Mg / Si ratio to within the range of 1.544–1.633. This results in a good balance between the strength and plasticity of the profile and a significantly enhanced resistance to crack propagation. Experimental data shows that when the Mg / Si ratio is between 1.544 and 1.633, the proportion of crushability grade 6 increases from 54.38% to 81.02%. When the Mg / Si ratio reaches 1.633, the expected proportion of crushability grade 6 can reach 93.12%, effectively achieving stable control of crushability performance.

[0016] 2. While improving crushing performance, the tensile strength and yield strength of the profile are also steadily increased by about 5MPa, achieving a good match between strength and toughness, and meeting the requirements of automotive anti-collision beams for high comprehensive mechanical performance.

[0017] 3. The optimized melting, casting, extrusion, quenching and aging processes are compatible with existing production lines, require no additional large equipment, have limited cost increases, are easy to implement and promote, and are suitable for large-scale industrial production. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This is a chart showing the percentage of superior crushing results in existing technologies.

[0020] Figure 2 This is a graph showing the proportion of excellent crushing results in this invention.

[0021] Figure 3 This is a schematic diagram of the crushing curve in this invention. Detailed Implementation

[0022] Before adjustment, the Mg content in this 6-series alloy was 0.9%–1%, and the Si content was 0.58%–0.65%. Statistical analysis was performed on the crushing performance test results of a large number of Mg / Si samples to obtain… Figure 1 The test results. (By...) Figure 1 The regression equation shows that the proportion of samples with excellent crushability (level 6) increases with the increase of the Mg / Si mass ratio. When the Mg / Si mass ratio reaches 1.544, the expected proportion of samples with excellent crushability is 90.28%. The R² value is 0.2773, indicating poor curve coupling. This may be because in the test data, more than two-thirds of the samples have a small Mg / Si mass ratio (less than 1.54), while data with larger Mg / Si ratios are scarce, suggesting a significant degree of randomness in the data.

[0023] In 6-series aluminum alloys, a smaller Mg / Si mass ratio indicates a higher excess of Si, which tends to segregate at grain boundaries, leading to alloy embrittlement and reduced strength and ductility. As the Mg / Si ratio increases, more Mg2Si strengthening phases are formed, increasing strength, while the excess Si content decreases, resulting in a reduction in the number of larger precipitates (Si-rich phases) and a decrease in strength. The combined effect of these two factors leads to a slight decrease in strength and an increase in ductility. Furthermore, excess Si in the matrix tends to form brittle Si-containing phases. As the Mg / Si ratio increases, the number of brittle phases decreases, while the microstructure becomes more uniform, resulting in more even stress distribution, increased toughness, and improved crack resistance.

[0024] A higher Mg / Si mass ratio indicates a higher likelihood of Mg excess. When Mg is in excess, it reduces the solubility of Mg2Si in the aluminum matrix, causing the strengthening phase to precipitate from the aluminum matrix and form coarse, unmelted Mg2Si phases. This results in poorer metal fluidity and reduced deformation capacity. Example

[0025] The technical solution adopted in this specific embodiment includes the following steps: S1, Composition control: The mass percentage of Mg in the aluminum alloy is controlled to be 0.9% to 0.945%, the mass percentage of Si is controlled to be 0.59% to 0.615%, and the mass ratio of Mg to Si is 1.544 to 1.633.

[0026] S2, Smelting and Casting: After adjusting the alloy composition according to the composition control requirements in S1, smelting, refining and casting are carried out to obtain round ingots; the smelting temperature is 750℃±10℃, the standing time after refining is not less than 1 hour, the hot end temperature during casting is 720℃±10℃, the cold end temperature is 700℃±10℃, the casting speed is 70mm / min±10mm / min, a 40ppi filter plate is used for filtration during the casting process, and aluminum titanium boron wire is added to refine the grains, wherein the aluminum titanium boron wire is 5Ti-1B wire, and the wire feeding speed is 25cm / min±5cm / min.

[0027] S3, Homogenization Annealing: The round ingot is subjected to homogenization annealing treatment.

[0028] S4, Extrusion molding: The homogenized annealed round ingot is heated and extruded to obtain the profile; wherein, the head temperature of the short ingot of the round ingot used for extrusion is set at 480±10℃, the temperature gradient is 20-50℃ / m, the extrusion speed is 4.0mm / s±0.5mm / s, and the extrusion outlet temperature is controlled at 560℃±10℃.

[0029] S5, Quenching treatment: The extruded profile is quenched online, wherein the quenching cooling rate is not less than 200℃ / s, and the profile is left to stand for no more than 6 hours after quenching.

[0030] S6, Aging treatment: The quenched profile is subjected to aging treatment, wherein the aging treatment is over-aging treatment, and the over-aging treatment is single-stage aging. The aging temperature is 210℃±5℃, and the aging time is 7h±0.5h.

[0031] The prepared profiles were subjected to transverse crush tests using a 150-ton text equipment from Hungary at a test speed of 220 mm / min. Test results show that the crush curve exhibits a stable, progressive folding pattern; the load increases with increasing compression displacement; a slight decrease occurs upon contact with the ribs within the cavity, followed by a stable state; no sudden fracture is observed. The crush performance rating is 6. (See reference...) Figure 3 As shown. Meanwhile, the tensile strength of the profile is 290 MPa, and the yield strength is 275 MPa, representing an increase of approximately 5 MPa compared to before the adjustment.

[0032] Comparative Example Profiles were prepared using conventional processes before composition control, with a composition range of Mg 0.9%–1.0% and Si 0.58%–0.65%. The Mg / Si ratio fluctuated significantly, mostly less than 1.544. Other process parameters were the same as in the previous example.

[0033] Performance test results show that only 54.38% of the samples achieved a crushing performance level of 6, with significant fluctuations in the crushing curves and some samples exhibiting sudden load drops. The tensile strength was approximately 285 MPa, and the yield strength was approximately 270 MPa, indicating that the overall performance was significantly lower than that of the embodiments of this invention. Implementation effect

[0034] This invention optimizes the proportion and distribution of the Mg2Si strengthening phase in a 6-series aluminum alloy by controlling the Mg content to 0.9%–0.945%, the Si content to 0.59%–0.615%, and the Mg / Si ratio to 1.544–1.633, along with optimized smelting, casting, extrusion, quenching, and aging processes. This achieves stable control of the crushability. Statistical results are shown in Table 1 below. When Mg / Si < 1.544, the proportion of 6-level crushability is 54.38%; when Mg / Si is between 1.544 and 1.633, it increases to 81.02%. Through crushability control, the... Figure 2 The regression equation obtained from the data analysis shows that when the Mg / Si ratio reaches 1.633, the expected proportion of crushability grade 6 can reach 93.12%. Simultaneously, both tensile strength and yield strength achieve a synergistic increase of approximately 5 MPa. When Mg / Si > 1.633, the curve curvature decreases and a downward trend appears. This method for controlling the crushability of 6-series aluminum alloy profiles exhibits good compatibility with existing production lines, limited cost increase, and is suitable for large-scale industrial production. .

[0035] Table 1. Number of Stage 6 Collapses with Different Mg / Si Values A 6-series aluminum alloy profile for automotive anti-collision beams is prepared using any one of the methods described above.

[0036] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling the crush performance of 6-series aluminum alloy profiles used in automotive anti-collision beams, characterized in that: It includes the following steps: S1, Composition control: The mass percentage of Mg in the aluminum alloy is controlled to be 0.9% to 0.945%, the mass percentage of Si is controlled to be 0.59% to 0.615%, and the mass ratio of Mg to Si is 1.544 to 1.633; S2, Smelting and Casting: After adjusting the alloy composition according to the composition control requirements in S1, smelting, refining and casting are carried out to obtain round ingots; S3, Homogenization annealing: The round ingot is subjected to homogenization annealing treatment; S4, Extrusion molding: The homogenized and annealed round ingot is heated and extruded to obtain the profile; S5, Quenching treatment: Online quenching of the extruded profile; S6, Aging treatment: Aging treatment is performed on the quenched profiles.

2. The method for controlling the crush performance of 6-series aluminum alloy profiles for automotive anti-collision beams according to claim 1, characterized in that: The melting temperature in S2 is 750℃±10℃, and the standing time after refining is not less than 1 hour.

3. The method for controlling the crush performance of 6-series aluminum alloy profiles for automotive anti-collision beams according to claim 1, characterized in that: In S2, the hot end temperature during casting is 720℃±10℃, the cold end temperature is 700℃±10℃, and the casting speed is 70mm / min±10mm / min.

4. The method for controlling the crush performance of 6-series aluminum alloy profiles for automotive anti-collision beams according to claim 1, characterized in that: In S2, a 40ppi filter plate is used for filtration during the casting process, and aluminum titanium boron wire is added to refine the grains.

5. The method for controlling the crush performance of 6-series aluminum alloy profiles for automotive anti-collision beams according to claim 1, characterized in that: The aluminum-titanium-boron wire is 5Ti-1B wire, and the wire feeding speed is 25cm / min±5cm / min.

6. The method for controlling the crush performance of 6-series aluminum alloy profiles for automotive anti-collision beams according to claim 1, characterized in that: In S4, the head temperature of the short round ingot for extrusion is set at 480±10℃, the temperature gradient is 20-50℃ / m, the extrusion speed is 4.0±0.5mm / s, and the extrusion outlet temperature is controlled at 560±10℃.

7. The method for controlling the crush performance of 6-series aluminum alloy profiles for automotive anti-collision beams according to claim 1, characterized in that: In S5, the quenching cooling rate is not less than 200℃ / s, and after quenching, the profile is left to stand for no more than 6 hours.

8. The method for controlling the crush performance of 6-series aluminum alloy profiles for automotive anti-collision beams according to claim 1, characterized in that: In S6, the aging process is an over-aging process, and the over-aging process is a single-stage aging process. The aging temperature is 210℃±5℃, and the aging time is 7h±0.5h.

9. A 6-series aluminum alloy profile for automotive anti-collision beams, characterized in that, It is prepared by the method described in any one of claims 1-8.

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