JP3151590B2 - High fatigue strength Al alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al alloy having a high fatigue strength, and particularly to an Al alloy having a high fatigue strength at a high temperature.

[0002]

2. Description of the Related Art Heretofore, there has been known an Al alloy which aims at achieving a fine and uniform metal structure by crystallization of an amorphous phase in order to achieve both heat resistance and toughness.

[0003]

The most important requirement for the constituent material of a lightweight engine part for an automobile is that the constituent material has excellent fatigue strength at a high temperature during operation of the engine. Al alloys have not yet satisfied the above requirements.

[0004] The present invention has been made in view of the above, by identifying a set formation and metal structure, it can exhibit excellent fatigue strength at high temperatures, and to provide the Al alloy.

[0005]

The high fatigue strength Al alloy according to the present invention is an Al alloy containing Fe, Ti and Si as alloying elements, and the balance being Al.
i and Si content is 4 atomic% ≦ Fe ≦ 6.
8 atomic%, 0.5 atomic% ≦ Ti ≦ 1.2 atomic%, 1.5
Atomic% ≦ Si ≦ 2.5 atomic%, the Fe content and Ti
The relationship of 5.6 ≦ Fe / Ti ≦ 8 is established with the content.
And also Ri average particle diameter D ₁ is D ₁ ≦ 1 [mu] m der of Al crystal grains constituting the matrix (face-centered cubic structure), further the average particle diameter D ₂ of the gold <br/> intermetallic compound D ₂ ≦ It characterized a 0.5μm der Turkey <br/>.

[0006]

[0007] High fatigue strength Al alloy has an average particle diameter D ₃
Contains 1.5 μm ≦ D ₃ ≦ 10 μm ceramic particles, and the volume fraction Vf of the ceramic particles is 0.5% ≦ V
It is characterized by f ≦ 10%.

[0008]

[Action] content of which is Fe, Ti and Si alloying element, when the relationship and metal structure of Fe / Ti identifies as above, A l alloy, a uniform and fine metal structure
As a result, it has excellent heat resistance and toughness, and also has high fatigue strength at high temperatures.

[0009] Among the alloying elements, Fe contributes to the improvement of heat resistance. However, when the Fe content is Fe <4 atomic%, the heat resistance decreases, while when the Fe content is 6.8 atomic%, the toughness and ductility are significantly reduced.

[0010] Ti and Si contribute to the improvement of the ability to form an amorphous phase. However, if the Si content is Si <1.5 atomic% or Si> 2.5 atomic%, uniform and fine
Since the ability to form an amorphous phase required to obtain a fine metal structure is reduced, toughness and fatigue strength at high temperatures are reduced.

When the Fe content is 4 at% ≦ Fe ≦ 6.8 at% and the Si content is 1.5 at% ≦ Si ≦ 2.5 at%, the Fe content and the Ti content are Between 5.
By satisfying the relationship of 6 ≦ Fe / Ti ≦ 8,
As described above, it is possible to form an Al alloy having excellent characteristics. From this, the Ti content is 0.5 atomic% ≦ Ti
Set to ≦ 1.2 atomic%.

[0012]

[0013] The average particle diameter D ₁ is D ₁ of the Al particles> 1
μm or the average particle diameter D ₂ of the intermetallic compound is D ₂ >
When the thickness is 0.5 μm, the heat resistance, or the heat resistance and the fatigue strength at high temperatures are reduced.

[0014] The average particle diameter D ₃ and its volume fraction Vf of the ceramic particles identified as above, without impairing the characteristics of the Al alloy, it is possible to improve the wear resistance. However, the average particle diameter D ₃ of the ceramic particles is D ₃ <
At 1.5 μm, the above effect cannot be obtained, while D ₃ > 10
In the case of μm, the fatigue strength at high temperatures decreases and the wear amount of the mating member increases. When the volume fraction Vf of the ceramic particles is Vf <0.5%, the above effect cannot be obtained. On the other hand, when Vf> 10%, the fatigue strength at high temperatures decreases and the wear amount of the mating member increases.

[0015]

EXAMPLES [Example 1 ] [ A] Various Al alloys were produced by the following method in order to set the contents of Fe and Si. (A) Melts of various compositions were prepared, and then various powders were produced using the respective melts under the application of an air atomizing method. Thereafter, each powder was subjected to a classification treatment to obtain a powder having a particle size of 90 μm or less. (B) Using each powder (particle diameter 90 μm or less), pressure 40
By performing cold isostatic pressing (CIP) under the condition of 00 kgf / cm ² , a plurality of short columnar billets having a diameter of 78 mm and a length of 80 mm were formed. (C) Each billet is set in a muffle furnace at 500 ° C., and is kept in an Ar flow atmosphere for 30 minutes to perform a degassing process, and the billet is extruded at a temperature of 500 ° C.
Temperature. (D) Each billet was directly extruded to obtain an Al alloy as an extruded material. Processing conditions are: container temperature 40
The temperature was set at 0 ° C., the die temperature was 400 ° C., the inner diameter of the container was 80 mm, the die hole diameter was 22 mm, and the extrusion ratio was 13.2.

Various test pieces were prepared from each Al alloy, and the test pieces were used for the tensile test at room temperature, the Charpy impact test, the tensile test at 200 ° C.
A fatigue test was performed at ℃. However, test pieces for Charpy impact test are those smooth without notch, also fatigue test certain tensile test piece - the compressive cyclic stress is applied, pulling upon rupture with the stress repeated several 10 ⁷ times -
The compressive cyclic stress was taken as the fatigue durability strength. These are the same hereinafter.

Table 1 shows the compositions of various Al alloys, and Table 2 shows the results of various tests. In Table 1, Examples 1 to 5 of the Al alloy were obtained by changing the Fe content while keeping the contents of Ti and Si constant, and Examples 6 to 10 of the Al alloy were obtained by keeping the contents of Fe and Ti constant. This is one in which the Si content is changed. In the column of evaluation in Table 2, “○” means that the required characteristics are satisfied, and “×” means that the required characteristics are not satisfied. This is the same in each of the following tables.

[0018]

[Table 1]

[0019]

[Table 2]

As is clear from Table 2, Examples 3, 4, 7 to 9 of the Al alloy have excellent heat resistance and toughness, and also have excellent fatigue strength at high temperatures. From this, the Fe content is 4 atomic% ≦ Fe ≦ 6.8 atomic%
In, also the Si content is set to the 1.5 atomic% ≦ Si ≦ 2.5 atomic%. Which is the lower limit of F e 4 atomic%
Is demonstrated in the following example.

[B] To set the Fe / Ti and Ti contents, various Al alloys were produced in the same manner as described above. And various test pieces were produced from each Al alloy, and various tests similar to the above were performed using these test pieces.

Table 3 shows the compositions of various Al alloys, and Table 4 shows the results of various tests. In Table 3, Examples 11 to 25 of the Al alloy were obtained by changing the contents of Fe and Ti while keeping the Si content constant. However, the Fe content is set to be constant for each of a plurality of examples.

[0023]

[Table 3]

[0024]

[Table 4]

As apparent from Table 4, Example 1 of Al alloy
2,13,16,17,20,23,24 have excellent heat resistance and toughness, and also have excellent fatigue strength at high temperatures. From this, Fe / Ti is 5.6.
≦ Fe / Ti ≦ 8 and the Ti content is 0.5 atomic% ≦
Each is set to Ti ≦ 1.2 atomic%. Furthermore, Fe
It can be seen that the lower limit of the content is 4 atomic% from Examples 12 and 13.

To summarize the above facts, in the preferred Al alloy, the contents of Fe, Ti and Si are 4 atomic% ≦ Fe ≦ 6.8 atomic% and 0.5 atomic% ≦ Ti ≦
1.2 atomic%, 1.5 atomic% ≦ Si ≦ 2.5 atomic%, and 5.6 ≦ Fe / T between the Fe content and the Ti content.
The relationship of i ≦ 8 is established.

The metal structures of Examples 1 to 4, 7 to 9, 12, and 13 were examined. The results shown in Table 5 were obtained.

[0028]

[Table 5]

The average particle diameter D ₁ of the Al crystal grains constituting the matrix and the average particle diameter D ₂ of the intermetallic compound were determined by measuring the particle diameters of 100 particles in a transmission electron microscope image and averaging them. Things. This is the same hereinafter.

As is evident from Table 5, the compositional requirements are satisfied, and the average grain size D ₁ of Al crystal grains is D ₁ ≦ 1.
μm and the average particle diameter D ₂ of the intermetallic compound is D ₂ ≦ 0.
An Al alloy having excellent mechanical properties as shown in Examples 3, 4, 7 to 9, 12, and 13, particularly excellent fatigue strength at high temperatures, by satisfying the fineness requirement on the metal structure such as 5 μm. Is obtained . Example 2 In this example, spherical Al ₂ O as the ceramic particles
Is added ₃ particles was Al ₉₁ Fe ₆ Ti ₁ Si ₂ alloys (examples of Table 1 8, the unit of numerical atomic%, hereinafter the same) we describe a.

The order to set the [A] Al ₂ O ₃ volume fraction Vf of the particle, the particle size powder was obtained following powder 90μm in the same manner as in Example 1. Next, the powder and Al ₂ O ₃ particles were sufficiently mixed using a V-type blender, and thereafter, various Al alloys were manufactured in the same manner as in Example 1 using the mixed powder. Various test pieces were prepared from each of the Al alloys, and were subjected to the same Charpy impact test, tensile test at 200 ° C., fatigue test at 200 ° C. and chip-on-disk wear test as described above.

The wear test conditions are as follows. Dimensions of test piece 10mm in length, 10mm in width
cm ² ), thickness 5mm, disc material Silicon chrome steel (JIS SWOSC, carburizing material), disc diameter 1
35mm, disc rotation speed 25m / sec, test piece pressing force 200kgf, lubricating oil supply 5cc / min, sliding distance 18km. The thickness reduction of the test piece was measured as the amount of wear.

Table 6 shows the compositions of various Al alloys.
7 shows various test results.

[0034]

[Table 6]

[0035]

[Table 7]

As is clear from Table 7 , Example 2 of Al alloy
Nos. 7 to 30 have excellent heat resistance and toughness and ductility, as well as excellent fatigue strength at high temperatures, and also excellent wear resistance. In Example 31, although the amount of wear of the test piece was small,
Low fatigue strength at high temperatures. From this, Al ₂
The volume fraction Vf of O ₃ particles is set to 0.5% ≦ Vf ≦ 10% .

[ B] In order to set the average particle diameter D ₃ of the Al ₂ O ₃ particles, various Al alloys were produced in the same manner as described above. And various test pieces were produced from each Al alloy, and various tests similar to the above were performed using these test pieces.

Table 8 shows the compositions of various Al alloys.
9 shows various test results.

[0039]

[Table 8]

[0040]

[Table 9]

As is clear from Table 9 , Example 3 of Al alloy
Nos. 3 to 36 have excellent heat resistance and toughness and ductility, as well as excellent fatigue strength at high temperatures, and also have excellent wear resistance and a small amount of wear of the disk as the mating member. From this, the average particle diameter D of the Al ₂ O ₃ particles
₃ is set to 1.5 μm ≦ D ₃ ≦ 10 μm.

Excellent mechanical properties and abrasion resistance as described above
27-30 and Examples 33-36 of Al alloys having
Is an engine valve spring retainer 1 shown in FIG.
It is suitable as a constituent material. [Application Example] In this application example, the manufacture of a connecting rod for an engine will be described.

The same composition as Example 3 in Table 1 (Al _91.4 Fe _5.6
Were selected powder Ti ₁ Si ₂₎ same composition as Example 19 powder powder Contact good beauty Table 3 _{(Al 91.9 Fe 5.5 Ti 0.6 Si} 2). (A) Each powder was filled into a cavity of a mold. (B) For each powder, at room temperature, molding pressure 5000 kgf / cm
^By performing compression molding under the conditions of 2 , a powder preform P having a shape similar to the shape of the connecting rod was formed as shown in FIG.

In this powder preform P , the crank pin hole 3 is formed in the portion 2 corresponding to the large end, but the piston pin hole is not formed in the portion 4 corresponding to the small end. (C) Each powder preform P is heated for about 4
The temperature was raised to 550 ° C. in a minute, and then the powder preform P was subjected to a mold temperature of 200 ° C. and a forging pressure of 6000 kgf / cm.
Powder forging was performed under the conditions of ² to obtain a forged member having substantially the same shape as the connecting rod. (D) Each forged member is subjected to a predetermined machining process or the like including a cutting process for dividing a portion 2 corresponding to the large end portion into two parts.
3 was obtained. The connecting rod 5 includes a connecting rod body 7 having a half of the crankpin hole 3 and a piston pin hole 6, and a cap 1 having a half of the crankpin hole 3 formed by a half of the portion 2 corresponding to the large end.
0, and the cap 10 is attached to the connecting rod body 7 by two.
It is fixed using two bolts 8 and two washers 9. The total weight of the connecting rod 5 including the bolt 8 and the washer 9 was about 320 g.

Next, each connecting rod 5 was subjected to a single-piece fatigue test. In this test, as shown in FIG. 3 , rods 11 and 12 were passed through the piston pin hole 6 and the crank pin hole 3 of the connecting rod 5, respectively.
2 was supported by a hydraulic fatigue tester and a tensile load was repeatedly applied to the connecting rod 5 at a temperature of 150 ° C. and R = 0.1. In this simple fatigue test, the practical connecting rod, 10 ⁷ times endurance load 3
It is required to be 500 kgf.

Table 10 shows the results of a single fatigue test.

[0047]

[Table 10]

[0048] As is apparent from Table 10, Example 1 of the connecting rod of the example 3 in Table 1 and <br/> constituent material has been fulfilled the characteristics required for practical use connecting rod, an example 19 of Table 3 Example 2 of a connecting rod used as a constituent material does not have the above-described characteristics.
From this, it is understood that Example 3 and the like in Table 1 are suitable as constituent materials for connecting rods .

[0049]

According to the present invention, by specifying a set formation and metal structure as described above, it is possible to provide an Al alloy which can exhibit excellent fatigue strength at high temperatures.

[Brief description of the drawings]

FIG. 1 is a front view of a valve spring retainer .

FIG. 2 is a plan view of a powder preform.

FIG. 3 is a plan view of a connecting rod.

[Explanation of symbols]

1 valve spring retainer P powder preform 5 connecting rod

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kensuke Honma 1-4-1 Chuo, Wako-shi, Saitama Inside of Honda R & D Co., Ltd. (56) References JP-A 7-54012 (JP, A) JP-A Heisei 7-71437 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 21/00 B22F 3/20

Claims (4)

(57) [Claims] 1. An Al alloy containing Fe, Ti and Si as alloying elements, with the balance being Al.
The contents of Ti and Si are 4 atomic% ≦ Fe ≦ 6.8 atomic%, 0.5 atomic% ≦ Ti ≦ 1.2 atomic%, 1.5 atomic% ≦ Si ≦ 2.5 atomic%, respectively, 5.6 ≦ Fe between the Fe content and the Ti content
/ Ti ≦ 8, the average particle diameter D ₁ of Al crystal grains constituting the matrix is D ₁ ≦ 1 μm, and the average particle diameter D ₂ of the intermetallic compound is D ₂ ≦ 0.5 μm. A high fatigue strength Al alloy characterized by the following. Wherein a constituent material of the connecting rod for an engine, according to claim 1 Symbol placement high fatigue strength Al alloy. 3. The average particle diameter D ₃ is 1.5 μm ≦ D ₃ ≦ 10.
The ceramic particles having a particle size of μm, wherein the volume fraction Vf of the ceramic particles is 0.5% ≦ Vf ≦ 10%.
1 Symbol placement high fatigue strength Al alloy. 4. The high fatigue strength Al alloy according to claim 3 , which is a constituent material of a valve spring retainer for an engine.