JPS63100151A - Aluminum-alloy member and combined working method thereof - Google Patents

Abstract

PURPOSE:To obtain an Al-alloy member excellent in mechanical properties and dimensional accuracy, by forming an Al alloy having specified compositional ranges into a near-final shape by increasing a forging ratio in the required part and then by subjecting the resulting forged stock to finish forming by partially changing the forging ratio. CONSTITUTION:The Al alloy has a composition principally consisting of, by weight, 4.0-7.5% Si, 0.2-1.2% Mg, <=0.5% Cu, and the balance essentially Al. By increasing the forging ratio in the part requiring strength and resistance to pressure and by reducing the forging ratio in the part other than the above, this Al alloy is forged into a stock of near-final shape, which is maintained at about 300-500 deg.C and subjected to finish forging by an impression method. In this way, the Al-alloy member in which internal defects are removed and which has complicated shape can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an excellent machine by forming an aluminum alloy cast material into a rough shape for forging, and by partially or entirely forging only by the impression of finish forging. The present invention relates to a highly reliable aluminum alloy member that has excellent dimensional properties and dimensional accuracy and has no internal defects removed, and a composite processing method thereof.

[Conventional technology]

In the past, iron-based materials were often used in strong parts that required high strength and high toughness, such as the drive parts of automobile parts, and pressure-resistant parts where fluid leakage was a problem, but in recent years iron-based materials have been used in lightweight parts such as passenger cars. With the advancement of aluminum alloys, cold forgings of aluminum alloys using wrought materials that are lightweight and have good mechanical properties have also been used.

However, cold forged products have little freedom in shape, and it is difficult to manufacture hollow shapes or shapes with high ribs. In addition, the forged material is in the shape of a round bar, and in order to obtain the final shape, impressions are required for each step of rolling, bending, rough forging, and finish forging, making the forging process complicated.

In addition, there are cast products such as die casting that can be made into complex shapes, but they have problems with internal defects and cast surfaces, and are said to be inferior to forged products in terms of strength, pressure resistance, and reliability. Therefore,
As disclosed in ``Aluminum or aluminum alloy member and manufacturing method thereof'' of Japanese Patent Application Laid-Open No. 59-223133, aluminum alloy is cast into a mold, and immediately after casting, the still hot member is taken out of the mold and slightly lower than the casting mold. A composite processing method that presses with small-sized impressions can be considered. However, by simply pressing the cast material with an impression slightly higher on average than the material, it is possible to finish the shape, but it is not possible to improve the mechanical properties or eliminate internal defects, which is the purpose of the present invention. etc., and it has the disadvantage that it cannot be applied to strength members or pressure-resistant parts.

[Problem that the invention seeks to solve]

In order to solve the above-mentioned problems of conventionally used cold forging and casting of iron-based materials and aluminum alloys, and composite processing of casting and forging, the present invention aims to solve the above-mentioned problems of the conventionally used cold forging and casting of iron-based materials and aluminum alloys, and the composite processing of casting and forging. The material is formed by sand molding, gravity casting, or die casting. In part, taking into account the vortex flow that is essential for complex shapes, we use aluminum casting alloys as the basis.
Taking into account forgeability, we determined the range of various components and used a new alloy with excellent castability and forgeability. Next, as for the shape of the cast material, the overall shape is close to the final shape, the forging ratio is large in parts that require strength and pressure resistance, and the other parts are small. By considering that the forging effect is appropriately applied to the necessary locations, an aluminum alloy member that is lightweight, has excellent mechanical properties and dimensional accuracy, and has a complex shape with no internal defects removed is manufactured.

[Means for solving problems]

The aluminum alloy material that will become the raw material for forging is cast by die casting, low pressure casting, sand casting, etc. into a shape close to the final shape after finish forging. At this time, casting is performed such that the dimensional ratios of corresponding parts of the member forming the final shape and the casting material are partially different.

Next, finish forging is performed using a finish forging impression while the formed material is held at 300 to 500°C. At this time, the cast material used as the raw material for forging is different from the round material used in cold forging of wrought materials, and the overall shape is close to the final shape. With only one impression, there are few restrictions on draft angle, corner radius, etc., and complex and large forged parts can be manufactured easily and at low cost. In addition, the dimensional ratio of the cast material and each part after forging is partially changed depending on the required strength and pressure resistance, so the forging effect can be effectively concentrated in the necessary parts. . Therefore, internal defects in the cast material are eliminated by the impact and pressure of forging, and a flow of the structure is created by forging in the direction where strength is required, making it possible to produce an aluminum alloy member with a good surface condition. Next, the flash of this forged product is trimmed using a press, etc., and the
By performing solution treatment at 540℃ for 1 to 6 hours and quenching by water cooling, and then tempering at 130 to 200℃ for 2 to 10 hours, it has excellent mechanical properties, a dense structure, and no internal defects. It is possible to obtain an aluminum alloy member having a composite structure of casting and forging.

Next, the reason for limiting the range of components is that if Si is less than 4%, there will be a problem with fluidity during casting, and if it is more than 7.5%, forging deformability will be reduced. When Mg becomes 0.2% or less, M
The precipitation effect of g5iz cannot be obtained, problems arise in strength and toughness, and the tensile strength after heat treatment decreases.

Ti is added to refine grains, but 0.
If it is less than 1%, no finer graining effect will be obtained, and if it is more than 0.2%, it will form a compound and become brittle, adversely affecting elongation. Sr contributes to improving strength and toughness by granulating and refining the eutectic structure, but if it is less than 0.01%, it has no effect, and if it is more than 0.05%, it is necessary for refining. You will lose a large amount. If Cr is less than 0.04%, the strength will not be improved, and if it is more than 0.35%, it will malnutrition the toughness.

〔Example〕

(Example 1) Table 1 is a composition comparison table between an aluminum alloy with excellent castability and forgeability implemented in the present invention and a JIS standard product.

Table 1 shows 1 considering the castability and forgeability implemented in the present invention.
It is a composition comparison table of an aluminum alloy and a JIS standard product showing an example.

AC4C is an aluminum alloy for casting, 6061
is an aluminum alloy for cold forging. In this example, in order to achieve characteristics that combine good forgeability and castability, S
The content of i is specified, and 'g+Cr is
In order to refine the crystals, Ti and Sr are added.

Using the alloy according to the present invention, an outer diameter of 35 m/m was produced using a sand mold.
A round bar is made, and the height of this test piece is 32 m/m, 3
Table 2 shows the mechanical properties of the results of forging into three types, 0 m/m and 15 m/m. For comparison, the mechanical properties of AC4C, which has relatively good forging properties among aluminum casting alloys, are also shown. The alloy in this example has a thickness of 1 after forging.
It was possible to forge up to 0+/m (forging ratio 71%), but A
C4C has a limit of 15 m/m (forging ratio of 57%), and if forged to a thickness less than that, cracks would occur, making it impossible to continue forging.

Next, the forged material having a thickness of 15 m/m (forging ratio 57%) was subjected to solution treatment, and the mechanical properties after quenching by water cooling and tempering are shown in Table 3.

Table 3 As shown in Table 2, the tensile strength and elongation of AC4C and the implemented alloy are improved by forging the cast material, and in particular, the elongation shows a remarkable increase. 3rd to
As shown in the table, the mechanical properties of both alloys after T6 treatment are markedly improved, and this tendency is particularly remarkable for the alloy of this example, which is comparable to the T6 treated wrought material 6061. It is possible to have mechanical properties such as

(Example 2) Using the alloy components in Example 1, a cast material was made with a sand mold, and by pressing only once using a press forging impression, the internal defects of the cast product were removed and airtightness was achieved. Figure 1 shows an example of an excellent pressure-resistant component. (a) in Figure 1
(b) shows the shape after forging, and (b) shows the original shape after casting. By adding about 20% extra thickness to the inside of the cast material and pressing it, internal defects can be removed. , has a dense structure and withstands an airtight test of 80 kgf/cd,
It can be put to practical use as a pressure-resistant and airtight member.

Table 4 compares the airtightness of a sand molded product and a forged product thereof, and it can be seen that the forged product has a density closer to the theoretical density by removing internal defects.

Table 4 □□ Figure 5 (a) shows the micro weave of the forged product, and (bl shows the micro-m weave of the sand mold cast product). You can check it.

(Example 3) Taking advantage of the good castability of aluminum alloy AC4C for castings, we used low-pressure casting to form a material into a shape that is close to the final shape after forging. An example of an arm idler that is die-forged using a hammer will be described.

In this example, the amount of CuO is reduced to improve forgeability, the amount of Mg is increased to ensure strength after heat treatment, and Ti and Sr are added to refine the grains. weight%
So, Si near, 0%, Mg: 0.8%, Ti: 0.15
%, Sr: 0.03%, Cr: 0.3%, Fe: 0.2
%, the balance being substantially Al.

Figure 2 is a front view of the arm idler implemented in the present invention;
Figure 3 (a) is a cross-sectional view after finish forging, (b)
(C1 is A+ A+', B+ B+' in (a)
A cross-sectional view is shown. Figure 4(a) is a cross-sectional view of the cast material that will be the raw material for finish forging, fbl, (C1 is ta+
AZ AZ'.

A cross-sectional view of Bz Bx' is shown. The material shown in Figure 3 is 48
After soaking at 0℃, place it in the impression of the finishing mold 4
The shape of the finish forging shown in Figure 3 is obtained by applying multiple blows. The inner and outer dimensions of the raw material 4' are 28a+10+φ, the outer diameter 5' is 39m/a+φ, and the height 6' is 25m+/m, and the inner diameter 4 is 28.4m/mφ and the outer diameter 5 is 39.
It is forged to a diameter of 7m/mφ and a height of 27m/an.

Similarly, 7', 8', and 13' are respectively 28m/mφ,
38.5m/mφ, 36.0m/m, which is 28.
It is molded to 4m/m, 38.3m/m, and 39m/m. A' of the cross section At At' is 18+m/m.

10' is 10m/m, and the cross sections A, -A,' after forging are
a is 15.5m/m, 10 is 1O, same as before forging
IIl/111, 2011/R1 of 11' in cross section at Bz Bt', 1011I of 12'
/I11 is cross section B.

-Bl' 11 17.5m/+a, 12 10m
It is forged to 111. Regarding the R shape,
For example, the R size of 15' and 16' in the raw material is 8R, but after finish forging, the R size of 15.16 is 4R. When this forged product was subjected to prescribed heat treatment, it showed good mechanical properties, and as shown in Table 6,
It was possible to have properties comparable to those of 61.

Table 3 [Effects of the invention] (11 Using a light alloy material with casting characteristics and forging characteristics, a raw material before forging is manufactured by casting, and it is shaped into the final shape with only one impression of finishing forging. By forging, the forging process can be simplified and mold impressions can be reduced.

(2) By using raw materials as cast materials, complex,
It is now possible to produce large forged products, and by changing the forging ratio of each part of the forged product to improve the mechanical properties of the parts that require strength, and by effectively generating impact force, it is possible to produce equipment with the same capacity. This allows for larger forging.

(3) By eliminating internal defects in the cast material, it can be used as pressure-resistant parts with complex shapes.

(4) By subjecting the finished forged product to T6 treatment under appropriate conditions, it can be used as a strong component with a complex shape.

(5) A higher forging yield of 80% is possible compared to the conventional forging yield of 50%.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view of the pressure-resistant component of Example (2), in which (a) is a cross-sectional view of the product after finish forging, and (b) is a cross-sectional view of the sand mold cast product. Fig. 2 is a front view of the arm idler of Example 3, Fig. 3 shows the shape after finish forging of Fig. 2, (1) is an overall sectional view, and (b) and (C) are (a). At A+',
It is a figure which shows the cross section of B+-Bl'. Figure 4 shows the shape of the cast material, where (a) is an overall sectional view, (b), fc) are A4 Az' of (a),
Bz B! ' is a diagram showing a cross section of '. Figure 5 is a photograph of the metallographic structure of a forged product and a sand casting product. (b) Figure 1 (b) (c) Figure 3 (b) (c) Figure 4 Figure 5 ca)

Claims (1)

[Scope of Claims] 1) An aluminum alloy cast product with a shape close to the final shape is used as a raw material for finish forging, and due to the forging effect, it has excellent mechanical properties and dimensional accuracy that surpass those of cast materials. Aluminum alloy member characterized by having no internal defects in the formed material (2) The aluminum alloy member contains Si:
4.0-7.5%, Mg: 0.2-1.2%, Cu:≦
0.5% and the remainder is substantially Al, the aluminum alloy member according to claim 1 (3) The components of the aluminum alloy member are in weight %, Si:
4.0-7.5%, Mg: 0.2-1.2%, Cu:≦
0.5%, Ti: 0.1~0.2%, Sr: 0.01~
0.05%, Cr: Ti in the range of 0.04 to 0.35%
, Sr, and Cr, and the remainder is substantially Al. By partially changing the dimensional ratio of each corresponding part of the cast material that is the raw material and the part that will form the final shape after finish forging, the material is cast into a shape that is close to the final shape as a whole. , Through the forging process using only impressions after finish forging, the forging ratio is increased in parts that require strength and pressure resistance, and the forging ratio in other parts is set to 0 or small, and the forging ratio is partially changed to achieve the final finish. Composite processing method for aluminum alloy members characterized by forming a shape (5) Composite processing method for aluminum light alloy members according to claim 4, characterized in that the forging ratio is 5 to 65% (6) The composition of the aluminum alloy member is Si:
4.0-7.5%, Mg: 0.2-1.2%, Cu:≦
0.5% and the remainder is substantially Al, the aluminum alloy member (7) according to claims 4 to 5, wherein the components of the aluminum alloy member are in weight %, Si:
4.0-7.5%, Mg: 0.2-1.2%, Cu:≦
0.5%, Ti: 0.1~0.2%, Sr: 0.01~
0.05%, Cr: Ti in the range of 0.04 to 0.35%
, Sr, and Cr, and the remainder is substantially Al. Method