KR100691328B1 - Aluminum alloys for a form - Google Patents

Abstract

Aluminum alloys for a concrete form, which improve productivity and strength of the aluminum alloys by improving extrusion property of the aluminum alloys, and which can be conveniently used for the concrete form by reducing weight of the aluminum alloys and preventing deformation of the aluminum alloys, are provided. In an ordinary aluminum alloy with improved mechanical properties by adding predetermined amounts of Mg, Si, Mn, Fe, Cu and Be to Al as a principal raw material, an aluminum alloy for a concrete form comprises 0.65 to 0.80 wt.% of Mg, 0.40 to 0.55 wt.% of Si, 0.02 to 0.03 wt.% of Mn, 0.15 to 0.25 wt.% of Fe, 0.003 to 0.02 wt.% of Cu, 0.001 to 0.007 wt.% of Be, 0.01 to 0.007 wt.% of Cr and the balance of Al.

Description

Aluminum alloy for formwork {ALUMINUM ALLOYS FOR A FORM}

1 is a tissue photograph according to Example 1 of the present invention,

2 is a tissue photograph according to Example 2 of the present invention,

3 is a tissue photograph according to a third embodiment of the present invention,

The present invention relates to an aluminum alloy for formwork, and more particularly, to improve the extrudability to increase the productivity, at the same time to reduce the weight, and due to the use of Be tensile strength, yield strength, elongation, hardness (hereinafter " It is intended to provide a die-cast aluminum alloy to increase the mechanical properties.

Conventional Al alloys have a moderate extrudability, and after aging heat treatment, fine precipitates are formed to have an effect of increasing strength. Representative examples of this are Al-Mg-Si-based alloys, such as A6061 and A6063.

The composition of the A6061 alloy is 0.4 to 0.8 weight of Si, 0.15 to 0.4 weight of Cu, 0.8 to 1.2 weight of Mg, 0.04 to 0.35 weight of Cr, and the rest of Al. The composition of the A6063 alloy is 0.2 to 0.6 weight of Si and 0.1 to Cu. Weight, Mg 0.45 to 0.9 weight, Cr 0.1 weight, and the rest is Al.

However, the conventional A6061 alloy has a higher content of Mg and Si forming a fine precipitate than the A6063 alloy, so that an alloy having a higher strength than that of the A6063 alloy can be obtained. Although excellent extrudability, there was a limit to use for formwork because the strength is not high.

In addition, until now, various kinds of alloy aluminum have been developed as an extruded material (Japanese Patent Laid-Open No. 7-70688, Hei 6-287671, Hei 7-41897, etc.). Of course, there was a problem that the use is not suitable for the formwork did not meet the mechanical properties or expectations.

Therefore, in recent years there is a Korean Patent Publication No. 2001-17742 (high-strength aluminum alloy with excellent extrudability) invented to solve the above problems, looking at its configuration, Si: 0.64 ~ 0.73 wt%, Mg: 0.27 -0.55 weight%, Mn: 0.27-0.33 weight%, Cu: 0.4-0.6 weight%, Zn: 0.13-0.2 weight%, content of impurity Fe is 0.5 weight% or less, and remainder consists of Al.

Conventional Korean Patent Publication No. 2001-17742 (high strength aluminum alloy with excellent extrudability) having the above configuration also has a problem that mechanical properties do not meet expectations for use in formwork.

The present invention has been invented to solve this problem in view of the above problems, the object of the present invention is to increase the productivity by increasing the extrudability, as well as to increase the strength, to reduce the weight and to prevent deformation to formwork It is to provide a die-cast aluminum alloy to be used.

In the aluminum alloy for formwork of the present invention for achieving the above object in a conventional aluminum alloy by adding a predetermined amount of Mg, Si, Mn, Fe, Cu, Be to improve the mechanical properties to Al, which is the main raw material,
Mg: 0.65-0.80% by weight, Si: 0.40-0.55% by weight, Mn: 0.02-0.03% by weight, Fe: 0.15-0.25% by weight, Cu: 0.003-0.02, Be: 0.001-0.007% by weight, and Cr: 0.01-0.007% by weight, the remainder being Al.

The role of each component forming the aluminum alloy for formwork of the present invention having the above characteristics and the reason for limiting the use range will be described in detail as follows.

Mg is an element necessary to give sufficient strength to Al. It combines with Si during aging treatment to form Mg 2 Si (magnesium silicate) intermetallic compound, which is a precipitated phase, and improves its strength. The amount of Mg is 0.65-0.80 wt%, which is 0.65. If less than% by weight is combined with Si, it is not effective enough to form Mg2Si, an intermetallic compound for strength improvement, and when the amount exceeds 0.80% by weight, there is a problem of lowering productivity due to low extrudability. Therefore, Mg is preferably used 0.65-0.80% by weight.

In addition, in the Al-Mg-based alloy, as the Mg content increases, the stacking defect energy value is lowered, so that the distance between the partial potentials is widened, and thus the stacking defect area is widened. In this state, if the material is deformed, cross-slip of dislocations is difficult and work hardening is increased. As a result, deformation proceeds uniformly, resulting in an improvement in elongation.

Therefore, Mg is preferably used 0.65-0.80% by weight.

Si is the basic element of Al alloy system with Mg, and it combines with Mg to form Mg2Si to improve strength during aging treatment. The amount of Si is 0.40-0.55% by weight. It does not form Mg2Si, which is an intermetallic compound necessary for strength improvement, in combination with, and it has a low effect and adversely affects the surface of the alloy material. There is this. Therefore, it is preferable to use 0.45-0.55 weight% of Si.

Mn combines with Al to form a dispersed phase such as Al6Mn, Al12Mn, and the like, and combines with Al, Fe, Si, and the like to form a quaternary compound of Al Fe Mn Si. These dispersed phases are uniformly dispersed into a fine phase of 0.05-0.5 μm in matrix before aging treatment to exhibit the mechanical properties required for medium strength molded products.

In addition, aging treatment results in Mn-based dispersed phases precipitating and dispersing fine and uniform Mg 2 Si in the position of a stable phase (αAl Fe Mn) Si compound in the alloy structure. ), And promotes the transformation of the unstable βAl Fe Si phase to the stable α phase to relieve stress concentrated at the crack tip.

The amount of Mn that plays such a role is 0.02-0.03% by weight. When the amount of Mn used is less than 0.02% by weight, the effect of improving the strength is low due to the miniaturization effect of the alloy structure, and the strength is further improved when it exceeds 0.03% by weight. Rather than reducing the strength, the Mn element is preferably added in an amount of 0.02 to 0.03% by weight.

Fe is contained as an impurity of Al alloy, and combines with Al, Mn, Si, etc. to form quaternary compounds to improve strength. The amount used is 0.15-0.25% by weight. There is a problem to lower the limit to 0.15-0.25% by weight.

Cr is an element necessary for miniaturizing the recrystallized grains and making the structure uniform, as well as an element used for improving the strength. The amount of Cr used is 0.01-0.007% by weight, and if it exceeds 0.01% by weight, Cr forms coarse intermetallic compounds. There is a problem that the strength falls, if less than 0.007% by weight is used, there is little effect. Therefore, the composition range of Cr is limited to 0.007 to 0.01 wt%.

Cu is used to enhance solid solution and increase toughness. The amount of Cu used is 0.003-0.02% by weight. If less than 0.003% by weight of Cu is used, there is no increase in employment and toughness, and when 0.02% by weight of Cu is used, Although reinforcement and toughness may be increased, deformation occurs during cooling after extrusion. Therefore, it is preferable to use 0.003-0.02 weight% of Cu.

Be plays a role of preventing the increase in strength and deformation of the alloying material due to coarsening of grains. The amount of Be used is 0.001-0.007 wt%, but when used below 0.001 wt%, coarsening of grains does not occur normally. Of course, the strength is not maintained, the deformation occurs, if the amount exceeds 0.007% by weight can be expected to increase the strength due to the coarsening of the crystal grains, but the deformation does not occur, which leads to difficulty in extrusion. Therefore, Be is preferably used 0.001-0.007% by weight.

Hereinafter, the present invention will be described in detail with reference to Examples.

Example 1

Example 1 is Mg: 0.72% by weight, Si: 0.48% by weight, Mn: 0.02% by weight, Fe: 0.21% by weight, Cr: 0.007% by weight, to determine the mechanical properties according to the composition ratio of the Al alloy element of the present invention, Cu: 0.01% by weight, Be: 0.0013% by weight, the remainder is made of Al, and billetized by the usual method, the billet is billet temperature 490-530 ℃, container temperature 430-450 ℃, mold temperature 430 Specimens were prepared at −450 ° C., outlet temperature 520-550 ° C., cooling water temperature 20-40 ° C., and extrusion rate 5.5-7 m / min.

As a result of measuring the mechanical properties using the prepared specimens, the mechanical properties of Example 1 were found to be tensile strength 296MPa, yield strength 265MPa, elongation 12%, hardness 99.1HV. In addition, the tissue photograph of Example 1 is shown in FIG.

Example 2

Example 2 Mg: 0.69% by weight, Si: 0.47% by weight, Mn: 0.02% by weight, Fe: 0.23% by weight, Cr: 0.001% by weight, to determine the mechanical properties according to the composition ratio of the Al alloy element of the present invention, Cu: 0.003% by weight, Be: 0.003% by weight, and the remainder is made of Al, and billetized by the usual method, the billet is billet temperature 490-530 ℃, container temperature 430-450 ℃, mold temperature 430 Specimens were prepared at −450 ° C., outlet temperature 520-550 ° C., cooling water temperature 20-40 ° C., and extrusion rate 5.5-7 m / min.

As a result, the mechanical properties of Example 2 were shown to be 300MPa tensile strength, 274MPa yield strength, 11% elongation, 101HV strength. And, the organizational picture of Example 2 was shown as FIG.

Example 3

Example 3 is Mg: 0.73% by weight, Si: 0.42% by weight, Mn: 0.03% by weight, Fe: 0.18% by weight, Cr: 0.01% by weight to determine the mechanical properties according to the composition ratio of the Al alloy element of the present invention, Cu: 0.02% by weight, Be: 0.007% by weight, the remainder is made of Al, and billetized by the usual method, and then the billet is billet temperature 490-530 ° C, container temperature 430-450 ° C, mold temperature 430 Specimens were prepared at −450 ° C., outlet temperature 520-550 ° C., cooling water temperature 20-40 ° C., and extrusion rate 5.5-7 m / min.

As a result, the mechanical properties of Example 3 were found to be tensile strength 303MPa, yield strength 279MPa, elongation 10%, strength 102.5HV. And, the organizational picture of Example 3 is shown as FIG.

As shown in Examples 1 to 3, it can be seen that as the content of Be, Mn, and Cr increases, tensile strength, yield strength, and strength are improved, and elongation is decreased.

As described above, the alloy of the present invention has an effect of being suitable for use as a formwork because of its high strength and low deformation, as well as its productivity due to the improvement of extrudability and its strength characteristics comparable to those of ordinary steel materials.

Claims (1)

In a conventional aluminum alloy obtained by adding a predetermined amount of Mg, Si, Mn, Fe, Cu, Be to improve the mechanical properties to Al as the main raw material, Mg: 0.65-0.80% by weight, Si: 0.40-0.55% by weight, Mn: 0.02-0.03% by weight, Fe: 0.15-0.25% by weight, Cu: 0.003-0.02, Be: 0.001-0.007% by weight, and Cr: 0.01-0.007% by weight, the remainder made of Al aluminum die-casting alloy.

Images