阅读说明：本技术 一种汽车立柱用7000系铝合金及其板材的制造方法 (7000 series aluminum alloy for automobile upright column and manufacturing method of plate thereof ) 是由 宋丰轩 林振良 黄海东 李庆 于 2020-08-06 设计创作，主要内容包括：本发明公开了一种汽车立柱用7000系铝合金及其板材的制造方法,属于合金材料技术领域。其中所述的汽车立柱用7000系铝合金,按重量百分比计由以下组分组成：Si≤0.05％,Fe≤0.1％,Cu 1.2～1.8％,Mn≤0.1％,Mg 2.2～2.6％,Cr≤0.1％,Zn 5.5～6.0％,Ti≤0.1％,Zr 0.04～0.1％,余量为Al和不可避免的杂质,所述不可避免的杂质的总量≤0.1％。按本发明所述配方及方法制得的板材具有更高的力学性能(抗拉强度在540MPa以上,屈服强度在460MPa以上,延伸率大于14％),而且热冲压成型合格率高(热冲压成型合格率在95％以上)。(The invention discloses 7000 series aluminum alloy for an automobile stand column and a manufacturing method of a 7000 series aluminum alloy plate, and belongs to the technical field of alloy materials. The 7000 series aluminum alloy for the automobile stand column comprises the following components in percentage by weight: less than or equal to 0.05 percent of Si, less than or equal to 0.1 percent of Fe, 1.2-1.8 percent of Cu, less than or equal to 0.1 percent of Mn, 2.2-2.6 percent of Mg, less than or equal to 0.1 percent of Cr, 5.5-6.0 percent of Zn, less than or equal to 0.1 percent of Ti, 0.04-0.1 percent of Zr, and the balance of Al and inevitable impurities, wherein the total amount of the inevitable impurities is less than or equal to 0.1 percent. The plate prepared by the formula and the method has higher mechanical property (the tensile strength is more than 540MPa, the yield strength is more than 460MPa, and the elongation is more than 14%), and the hot stamping forming qualification rate is high (the hot stamping forming qualification rate is more than 95%).)

1. The 7000 series aluminum alloy for the automobile upright is characterized by comprising the following components in percentage by weight:

less than or equal to 0.05 percent of Si, less than or equal to 0.1 percent of Fe, 1.2-1.8 percent of Cu, less than or equal to 0.1 percent of Mn, 2.2-2.6 percent of Mg, less than or equal to 0.1 percent of Cr, 5.5-6.0 percent of Zns, less than or equal to 0.1 percent of Ti, 0.04-0.1 percent of Zr, and the balance of Al and inevitable impurities, wherein the total amount of the inevitable impurities is less than or equal to 0.1 percent.

2. The manufacturing method for processing the 7000 series aluminum alloy for the automobile column of claim 1 into a plate comprises the steps of smelting and casting, soaking treatment, preheating and hot rolling, cold rolling, three-stage annealing treatment, transverse cutting and plate opening, hot stamping and forming and aging treatment, and is characterized in that in the three-stage annealing treatment step, the three-stage annealing treatment process comprises the following steps: 100-200 ℃/12-48 h + 200-300 ℃/12-48 h + 300-450 ℃/12-48 h.

3. The manufacturing method according to claim 2, wherein in the heat soaking step, a heat soaking process is: 400-450 ℃/2-8 h + 420-470 ℃/4-24 h + 430-480 ℃/12-48 h.

4. The manufacturing method according to claim 2, wherein in the preheating and hot rolling steps, the preheating is performed at 510 ± 5 ℃ for 4-20 hours; the hot rolling temperature is the same as the preheating temperature, and the hot rolling finishing temperature is controlled to be 300-350 ℃.

5. The method according to claim 2, wherein the preheating and hot rolling step is a step of hot rolling to a thickness of 4.0 to 6.0 mm.

6. The method according to claim 2, wherein in the cold rolling step, the cold rolling is performed in 3 to 4 passes with a total strain amount of 40 to 75%.

7. The method according to claim 2, wherein the cold rolling step comprises cold rolling to a thickness of 1.5 to 2.5 mm.

Technical Field

The invention relates to an alloy material, in particular to 7000 series aluminum alloy for an automobile upright post and a manufacturing method of a plate thereof.

Background

In order to improve the cruising ability of new energy automobiles, light aluminum alloy materials are used for manufacturing and processing automobile parts, and the automobile parts become a lightweight mode widely adopted in modern times. According to the calculation, the endurance mileage of the automobile can be improved by about 5.5% when the weight of the automobile is reduced by 10%. At present, aluminum alloys for new energy automobiles are mainly 5000 series aluminum alloys and 6000 series aluminum alloys, and because the strength is low and the tensile strength is below 400MPa, the aluminum alloys are mainly used as parts with low force bearing requirements, such as covering parts and decorating parts of automobiles, and are difficult to be used as force bearing structural parts of automobiles.

7000 series aluminum alloy belongs to ultrahigh strength aluminum alloy, the tensile strength of which can reach more than 500MPa, and the aluminum alloy is an ideal structural material, but the application of the aluminum alloy in new energy automobiles is greatly limited due to the difficulty in forming and high requirements of the performance on processing and heat treatment technologies. The invention patent with publication number CN106756673A discloses a processing technique of 7075 aluminum alloy material automobile B column, which softens 7075 aluminum alloy through high temperature solution treatment, then carries out punch forming, and rapidly quenches the formed alloy to room temperature by cooling of a stamping die. The application of the integrated thermal forming technology is beneficial to the 7000 series alloy to be directly applied to the existing steel automobile upright post production line for producing and manufacturing aluminum automobile parts. However, the 7000 series alloy has high quenching sensitivity, and the temperature of the alloy after solid solution is obviously reduced when the alloy is transferred to a stamping die, and the temperature of the alloy is increased in the stamping process, so that the 7000 series alloy has poor solid solution quenching effect in the forming quenching process, and the strength of the aged part is low. Therefore, the tensile strength of the 7075 aluminum alloy in the invention (CN106756673A) after aging is 480-520 MPa, which is greatly lower than that of the 7075-T6 alloy under the normal condition (about 570 MPa). The alloy strength is reduced, under the premise of ensuring safety, the section thickness of the new energy automobile column is required to be increased inevitably, and the design and forming difficulty is increased while the lightweight effect of aluminum automobile parts is reduced due to the increase of the thickness.

In view of the above, the present invention provides a 7000 series aluminum alloy suitable for integral thermal forming and a method for manufacturing a plate thereof, so as to reduce the quenching sensitivity of the alloy and improve the high temperature formability thereof, thereby manufacturing an aluminum plate for a new energy automobile pillar with good formability and high strength.

Disclosure of Invention

The invention aims to solve the technical problem of providing a 7000 series aluminum alloy suitable for producing a new energy automobile stand column by an integrated thermal forming technology and a manufacturing method of a 7000 series aluminum alloy plate, wherein the 7000 series aluminum alloy is high in mechanical property (tensile strength is more than 540MPa, yield strength is more than 460MPa, and elongation is more than 14%) and high in hot stamping forming qualification rate (the hot stamping forming qualification rate is more than 95%) on the basis of ensuring good stamping property of the alloy plate.

In order to solve the technical problems, the invention adopts the following technical scheme:

the 7000 series aluminum alloy for the automobile upright column comprises the following components in percentage by weight:

less than or equal to 0.05 percent of Si, less than or equal to 0.1 percent of Fe, 1.2-1.8 percent of Cu, less than or equal to 0.1 percent of Mn, 2.2-2.6 percent of Mg, less than or equal to 0.1 percent of Cr, 5.5-6.0 percent of Zn, less than or equal to 0.1 percent of Ti, 0.04-0.1 percent of Zr, and the balance of Al and inevitable impurities, wherein the total amount of the inevitable impurities is less than or equal to 0.1 percent.

Further, the 7000 series aluminum alloy for the automobile pillar of the present invention preferably has a composition in weight percent: less than or equal to 0.05 percent of Si, less than or equal to 0.1 percent of Fe, 1.2-1.5 percent of Cu, less than or equal to 0.1 percent of Mn, 2.3-2.5 percent of Mg, less than or equal to 0.1 percent of Cr, 5.6-5.9 percent of Zn, less than or equal to 0.1 percent of Ti, 0.05-0.09 percent of Zr, and the balance of Al and inevitable impurities, wherein the total amount of the inevitable impurities is less than or equal to 0.1 percent.

The invention also provides a manufacturing method for processing the 7000 series aluminum alloy for the automobile stand column into a plate, which comprises the steps of smelting and casting, soaking treatment, preheating and hot rolling, cold rolling, three-stage annealing treatment, transverse cutting and plate splitting, hot stamping and forming and aging treatment, wherein in the three-stage annealing treatment step, the three-stage annealing treatment process comprises the following steps: 100-200 ℃/12-48 h + 200-300 ℃/12-48 h + 300-450 ℃/12-48 h.

The smelting and casting steps of the manufacturing method are the same as those of the prior art, specifically, the aluminum alloy is smelted at 740-760 ℃, and then the aluminum alloy is made into an ingot, preferably a flat ingot (the thickness is preferably 400-700 mm).

In the soaking treatment step of the manufacturing method, the soaking treatment adopts three-level homogenization heat treatment, and the specific process is as follows: 400-450 ℃/2-8 h + 420-470 ℃/4-24 h + 430-480 ℃/12-48 h.

In the preheating and hot rolling steps of the manufacturing method, the preheating is preferably controlled to be carried out at 510 +/-5 ℃ for 4-20 hours; the hot rolling temperature is the same as the preheating temperature, and the hot rolling finishing temperature is controlled to be 300-350 ℃. During hot rolling, the deformation pass of the hot rolling is usually 14 to 18 passes, and the total deformation is 90 to 99 percent. In the present application, the ingot after soaking is usually finally hot-rolled to a hot-rolled aluminum alloy sheet having a thickness of 4.0 to 6.0 mm.

In the cold rolling step of the manufacturing method, the deformation pass of the cold rolling is 3-4 passes, the total deformation is 40-75%, and the final cold rolling temperature is controlled to be 80-130 ℃. In the present application, the hot-rolled aluminum alloy sheet is generally cold-rolled to a thickness of 1.5 to 2.5 mm.

And after the aluminum alloy is subjected to the steps of smelting and casting, soaking treatment, preheating and hot rolling, cold rolling and three-stage annealing treatment, the finished coiled material is obtained. The obtained finished coiled material needs to be cut into corresponding specifications according to the requirements of customers, namely the step of transversely cutting the plate.

In the hot stamping forming step of the manufacturing method, the hot stamping forming temperature is 490 +/-3 ℃, and the hot stamping forming die is cooled by adopting room-temperature water circulation. And carrying out aging treatment on the molded sample, wherein the aging temperature is 100-170 ℃, and the time is 12-24 h.

Compared with the prior art, the Zr element is added, the contents of Zn, Mg and Cu are regulated and controlled at the same time, and the quenching sensitivity of the alloy is improved, so that the reduction of the solid solubility of the alloy in the hot stamping forming quenching process is reduced, and the strength of the alloy after aging is improved; furthermore, the invention adopts multi-stage low-temperature annealing treatment, inhibits the occurrence of recrystallization in the quenching process of hot stamping forming, regulates the proportion of a recrystallization texture and a rolling texture, and improves the stamping performance of the plate while maintaining the high strength of the alloy; moreover, the uniformity of the structure and the performance of the plate is improved by adopting a three-stage soaking treatment process, and the stamping performance of the plate is further improved; the method provided by the invention has the advantages that the quenching sensitivity of the alloy can be effectively reduced and the stamping performance of the alloy (the hot stamping forming qualification rate is more than 95%) can be improved through one-step interaction and influence, so that the 7000 series aluminum upright post for the new energy automobile, which has good formability and high strength, can be prepared through an integrated hot forming technology, the tensile strength of the obtained upright post is more than 540MPa, the yield strength is more than 460MPa, and the elongation is more than 14%.

Detailed Description

The present invention will be better understood from the following detailed description of specific examples, which should not be construed as limiting the scope of the present invention.