TWI393784B - Method for making heat resistant softened aluminum alloy - Google Patents

Description

Heat-resistant softening aluminum alloy manufacturing method

The present invention relates to a method for producing an aluminum alloy, and more particularly to a method for producing an aluminum alloy resistant to heat softening.

In the conventional method for manufacturing a heat-resistant softening aluminum alloy, an aluminum alloy of AA1050 or AA1100 is used as an example, and an aluminum-iron (Al-Fe)-based aluminum alloy material mainly composed of Fe element is added, and the aluminum content is as high as 99.0% by weight. (wt%) or more, it has the characteristics of high purity and low impurity, so it can be subjected to multiple surface chemical treatments, so that the surface of the product has a multi-layered uniform and bright color appearance, and this kind of product is deeply loved by consumers. However, in each surface chemical treatment, a high-temperature baking operation of 150 ° C to 240 ° C is required, and the multi-pass baking process causes the Al-Fe-based aluminum alloy material to be weakened by heat softening.

It is a common technique to add a manganese (Mn) element or a zirconium (Zr) element to increase the strength of the aluminum alloy. For example, Japanese Patent Laid-Open No. 64-51992, Japanese Laid-Open No. Hei 2-293189, and No. JP-A No. 01-306288 disclose that the strength of an aluminum alloy is increased by adding manganese to achieve baking resistance softening. The purpose of the Japanese Patent Laid-Open No. 61-51395 is to increase the strength of the aluminum alloy by adding zirconium element to achieve the purpose of baking resistance softening. However, in the above-mentioned patent document to which manganese is added, the addition amount of the manganese element alloy has reached the AA3003 standard, and although the strength is improved, due to the manganese element, the aluminum alloy generates many compounds of several tens of micrometers (μm) in the casting process. Thereby reducing the uniformity and gloss of the aluminum alloy surface. In the above-mentioned patent document to which a zirconium element is added, since the production of zirconium element is small and expensive, the production cost is high.

Therefore, it is necessary to provide an innovative and progressive method of manufacturing a heat-resistant aluminum alloy to solve the above problems.

The invention provides a method for manufacturing a heat-resistant softening aluminum alloy, comprising the steps of: (a) providing an aluminum embryo comprising 0.20 to 0.80 weight percent iron element, a weight percentage less than 0.2 bismuth element and a total weight percentage less than 0.10 The other alloying elements, the remaining weight percentage is aluminum; (b) performing a preheating step to maintain the aluminum embryo at a temperature above 480 ° C for at least two hours; (c) performing a hot rolling step; (d) Performing a first cold rolling step; (e) performing an intermediate annealing heat treatment step, performing an intermediate annealing heat treatment at 400 ° C or higher, the intermediate annealing heat treatment time is greater than one hour; and (f) performing a second cold rolling step. The aluminum alloy manufacturing method of the present invention can reduce the production cost, and the obtained aluminum alloy has the property of resisting heat softening.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart showing the method for producing a heat-resistant softened aluminum alloy of the present invention. The aluminum alloy manufacturing method of the present invention can be applied to a DC C casting process.

Referring to step S11, an aluminum embryo is first provided. In the present embodiment, the aluminum embryo comprises 0.20 to 0.80 weight percent (wt%) of iron element, bismuth element having a weight percentage of less than 0.2, and other alloying elements having a total weight percentage of less than 0.10. The remaining weight percentage is aluminum. Wherein, the aluminum embryo is formed by a casting step before step S11.

Referring to step S12, a preheating step is performed to maintain the aluminum embryo at a temperature above 480 ° C for at least two hours. Wherein, before the preheating step, a step of removing the aluminum germ surface layer is further included to remove the oxide of the aluminum germ surface layer. It should be noted that the preheating step may select the aluminum embryo to be heated to a specific temperature at a high temperature before the hot rolling, and then directly download the aluminum blank to the hot rolling stand for hot rolling (for example, The aluminum blank is placed in a preheating furnace above 480 ° C for at least two hours. This preheating step preheats and homogenizes the aluminum embryo.

Alternatively, the preheating step may also select the aluminum embryo to be placed in a homogenization furnace, maintained at a specific temperature for a long time, and then cooled to room temperature, and then transport the aluminum embryo to a high temperature furnace for high temperature. Preheating (for example, the aluminum embryo is first placed in a high temperature furnace above 480 ° C, the temperature is maintained for at least two hours, and after cooling the aluminum embryo to room temperature, the aluminum embryo is moved to a temperature above 480 ° C. Preheating in the furnace, this preheating step can homogenize the aluminum embryo. Wherein, after the aluminum embryo is cooled to room temperature, the step of removing the aluminum embryo surface layer is further included to remove the oxide of the aluminum embryo surface layer.

Among them, the latter preheating step has a function of eliminating the segregation of the casting component and promoting the change of the crystal phase, although the treatment time is long and the cost is high, so that a better chemical surface quality can be obtained.

Referring to step S13, a hot rolling step is carried out, and in the present embodiment, the hot rolling step is carried out at 300 ° C to 480 ° C. Referring to step S14, a first cold rolling step is performed, and in the present embodiment, the first cold rolling step is performed at room temperature. Referring to step S15, an intermediate annealing heat treatment step is performed. In this embodiment, an intermediate annealing heat treatment is performed at 400 ° C or higher, and the intermediate annealing heat treatment time is greater than one hour. Preferably, the temperature of the intermediate annealing heat treatment is between 430 ° C and 480 ° C. Wherein, the intermediate annealing heat treatment step can make the alloying elements such as iron (Fe) and bismuth (Si) solid-dissolved in the aluminum embryo, so that in a baking process after the chemical treatment, the solid solution atoms are prevented from being poor. Dislocation movement to reduce the rate of strength softening, and achieve the effect of resistance to heat softening.

Referring to step S16, finally, a second cold rolling step is performed to manufacture the finished aluminum alloy. In this embodiment, the cold rolling run of the second cold rolling step is greater than 60%.

The aluminum alloy manufacturing method of the invention can reduce the production cost, and the obtained aluminum alloy has the effect of resisting heat softening.

The following are the comparative examples of the conventional aluminum alloy manufacturing method and the processes and conditions of the three examples of the heat-resistant softening aluminum alloy manufacturing method of the present invention, which are detailed as follows:

Conventional comparison example:

AA1050 aluminum alloy: iron content 0.22 wt%, niobium content 0.09 wt%, total amount of other alloying elements is less than 0.1 wt%, and the rest is aluminum content

In the conventional comparative example, in the process of melt casting the AA1050 aluminum alloy to form an aluminum embryo, another manganese element or zirconium element is added to increase the strength of the aluminum alloy, and finally the finished aluminum alloy product is further subjected to 220 ° C to 260 ° C. The baking test was performed and the baking test time was 5 hours.

Example 1:

AA1050 aluminum alloy: iron content 0.22 wt%, niobium content 0.09 wt%, total amount of other alloying elements is less than 0.1 wt%, and the rest is aluminum content.

Aluminum alloy manufacturing method: aluminum embryo preheating→hot rolling delay→first cold rolling extension→intermediate annealing heat treatment→second cold rolling extension (finished product)→baking test.

Among them, the aluminum embryo preheating temperature is 500 ° C, and maintained for two hours; the intermediate annealing heat treatment temperature is 430 ° C; the second cold rolling extension cold rolling elongation (thickness rolling amount) is 77%; baking test temperature is 220 ° C to 260 ° C, and baking test time is 5 hours.

Example 2:

AA1050 aluminum alloy: iron content 0.22 wt%, niobium content 0.09 wt%, total amount of other alloying elements is less than 0.1 wt%, and the rest is aluminum content.

Aluminum alloy manufacturing method: aluminum embryo homogenization → aluminum embryo preheating → hot rolling delay → first cold rolling delay → intermediate annealing heat treatment → second cold rolling delay (finished product) → baking test.

Among them, the aluminum embryo is homogenized at 590 ° C for nine hours, and then preheated at 500 ° C for two hours; the intermediate annealing heat treatment temperature is 430 ° C; the second cold rolling delay cold rolling (thickness rolling) The elongation was 77%; the baking test temperature was 220 ° C to 260 ° C, and the baking test time was 5 hours.

Example 3:

AA1100 aluminum alloy: iron content 0.75 wt%, niobium content 0.05 wt%, total alloying elements less than 0.1 wt%, and the rest is aluminum content.

Aluminum alloy manufacturing method: aluminum embryo homogenization → aluminum embryo preheating → hot rolling delay → first cold rolling delay → intermediate annealing heat treatment → second cold rolling delay (finished product) → baking test.

Among them, the aluminum embryo is homogenized at 550 ° C for nine hours, and then preheated at 500 ° C for two hours; the intermediate annealing heat treatment temperature is 450 ° C; the second cold rolling delay cold rolling (thickness rolling) The elongation was 67%; the baking test temperature was 220 ° C to 260 ° C, and the baking test time was 5 hours.

2 shows a baking test temperature-reducing strength diagram of a conventional aluminum alloy manufacturing method and an aluminum alloy manufacturing method of the first embodiment of the present invention; FIG. 3 shows a conventional aluminum alloy manufacturing method and a second embodiment of the present invention. The baking test temperature-reduction strength diagram of the aluminum alloy manufacturing method; FIG. 4 shows the baking test temperature-subduction strength diagram of the aluminum alloy manufacturing method of the conventional comparative example and the aluminum alloy manufacturing method of the inventive example 3. 2 to 4, the curve L1 represents the drop strength of the aluminum alloy of the conventional comparative example at different baking test temperatures; and the curve L2 represents the drop strength of the aluminum alloy of the example of the present invention at different baking test temperatures. .

It can be seen from FIG. 2 to FIG. 4 that the aluminum alloy obtained by the aluminum alloy manufacturing method of the present invention has a significantly superior yield strength (MPa) at 5 hours at different baking test temperatures. The lowering strength of the aluminum alloy produced by the conventional aluminum alloy manufacturing method, that is, the aluminum alloy produced by the aluminum alloy manufacturing method of the present invention has better heat softening resistance.

In addition, it is also shown from Examples 1 to 3 that even if the cold rolling elongation (67%) of the AA1100 aluminum alloy is lower than the cold rolling elongation (77%) of the AA1050 aluminum alloy, it is also increased by the increase of the iron element. It can make AA1100 aluminum alloy have better resistance to heat and softening.

The above embodiments are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Therefore, those skilled in the art can make modifications and changes to the above embodiments without departing from the spirit of the invention. The scope of the invention should be as set forth in the appended claims.

1 is a flow chart showing a method for producing a heat-resistant softening aluminum alloy according to the present invention; and FIG. 2 is a view showing a baking test temperature-subduction strength pattern of the aluminum alloy manufacturing method of the conventional comparative example and the aluminum alloy manufacturing method of the first embodiment of the present invention; 3 shows a baking test temperature-lowering strength diagram of a conventional aluminum alloy manufacturing method and an aluminum alloy manufacturing method of the second embodiment of the present invention; and FIG. 4 shows a conventional aluminum alloy manufacturing method and an inventive example 3 Baking test temperature-subduction strength diagram of aluminum alloy manufacturing method.

Claims (9)

A method for manufacturing a heat-resistant softening aluminum alloy, comprising the steps of: (a) providing an aluminum embryo comprising 0.20% to 0.80% by weight of iron element, less than 0.2% by weight of cerium element and other alloys having a total weight percentage of less than 0.10 Element, the remaining weight percentage is aluminum; (b) performing a preheating step, placing the aluminum embryo in a preheating furnace above 480 ° C, maintaining the temperature for at least two hours; (c) performing a hot rolling (d) performing a first cold rolling step; (e) performing an intermediate annealing heat treatment step, performing an intermediate annealing heat treatment at 400 ° C or higher, the intermediate annealing heat treatment time being greater than one hour until the iron element and the crucible The element is solid-solved in the aluminum embryo; and (f) performing a second cold rolling step; wherein a step of removing the aluminum surface layer is further included before the step (b). The method of producing an aluminum alloy according to claim 1, wherein a casting step is further included before the step (a) to form the aluminum embryo. The method for manufacturing an aluminum alloy according to claim 1, wherein in the step (b), the preheating step is to place the aluminum blank in a high temperature furnace above 480 ° C, maintain the temperature for at least two hours, and then cool the aluminum embryo. After reaching room temperature, the aluminum embryo was moved to a preheating furnace at 480 ° C or higher to preheat. The method for producing an aluminum alloy according to claim 3, wherein the step of removing the aluminum germ surface layer is performed after the aluminum embryo is cooled to room temperature. The method for producing an aluminum alloy according to claim 1, wherein the hot rolling step is carried out at 300 ° C to 480 ° C in the step (c). The method for producing an aluminum alloy according to claim 1, wherein the first cold rolling step is carried out at room temperature in the step (d). The method for producing an aluminum alloy according to claim 1, wherein in the step (e), the intermediate annealing heat treatment is performed at 430 ° C to 480 ° C. The method for producing an aluminum alloy according to claim 1, wherein in the step (f), the cold rolling run of the second cold rolling step is greater than 60%. The method for producing an aluminum alloy according to claim 1, which is applied to a DC C casting process.