JP2737376B2 - Al alloy two-stage powder forged member with high fatigue strength and high toughness - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] This invention uses an atomized Al alloy powder as a raw material powder, and performs a two-stage powder forging of the green compact to produce an Al alloy member. Al alloy 2 with high fatigue strength and high toughness by specifying the composition of the Al alloy 2
It relates to a stepped powder forged member.

[Conventional technology]

Conventionally, for example, as described in Japanese Patent Publication No. 2-9099, Si: 8 to 30% by weight (hereinafter,% indicates weight%), and Cu, Mg, Ni, Fe, And one or more of Mn:
Atomized Al alloy powder having a composition of 0.1 to 10%, with the balance being Al and unavoidable impurities, used as a raw material powder, and an Al alloy powder produced by subjecting the green compact thereof to hot forging. Forged members are known.

It is also known that these conventional aluminum alloy powder forged members are applied as structural members such as engines and compressors.

[Problems to be Solved by the Invention] On the other hand, the speed and performance of various engines in recent years have been remarkable, and the use environment of these structural members tends to be even more severe. However, since the conventional aluminum alloy powder forged members do not have sufficient fatigue strength and toughness, it is currently impossible to satisfactorily cope with them.

[Means for solving the problem]

Therefore, the present inventors have focused on the above-mentioned conventional Al alloy powder forged member from the above-described viewpoint, and have conducted research to improve the fatigue strength and toughness thereof, and as a result, used as a raw material powder. Atomized Al alloy powder contains: Si: 12-30%, Cu: 0.1-10%, Fe: 0.1-10%, Mg: 0.1-3%, P: 0.001-0.05%, Ti: 0.2-1% Then, the remainder is specified as an atomized Al alloy powder having a composition consisting of Al and unavoidable impurities, and the powder compacted from this is subjected to two-stage powder forging, preferably 350 to 520.
When the closed die forging is performed twice at a temperature of ° C., P and Ti contained as alloy components in the atomized Al alloy powder are combined with the two-stage powder forging action described above to produce an Al alloy 2 Research results have been obtained that it acts to significantly improve the fatigue strength and toughness of a stepped powder forged member.

The present invention has been made based on the above research results, and includes: Si: 12 to 30%, Cu: 0.1 to 10%, Fe: 0.1 to 10%, Mg: 0.1 to 3%, P: 0.001 to 0.05 %, Ti: 0.2 to 1%, with the balance being an Al alloy having a composition comprising Al and inevitable impurities, and having high fatigue strength and high toughness.
It is characterized by a two-stage powder forged alloy member.

Next, the reason why the component composition of the Al alloy constituting the aluminum alloy two-stage powder forged member of the present invention is limited as described above will be described.

(A) Si The Si component reduces the coefficient of thermal expansion of the member,
Has the effect of improving wear resistance, but its content is 12%
If the content is less than 30%, the desired effect cannot be obtained. On the other hand, if the content exceeds 30%, the toughness decreases and machining becomes difficult, so the content is set to 12 to 30%. Was.

(B) Cu and Mg These components are precipitated as fine intermetallic compounds such as Mg ₂ Si and Cu ₂ Al by aging treatment after two-stage powder forging to improve the strength of members. Although it has an effect, the desired strength improvement effect cannot be obtained if its content is less than Cu: 0.1% and Mg: less than 0.1%, respectively, while its content exceeds Cu: 10% and Mg: 3%, respectively. And, since the toughness of the member will be reduced, the content is respectively Cu:
0.1-10%, Mg: 0.1-3%.

(C) Fe The Fe component contains Al-Fe-
It precipitates as a Si-based intermetallic compound and has the effect of improving the strength, heat resistance, and abrasion resistance of the member. However, if the content is less than 0.1%, the desired effect cannot be obtained in the above-described effect. If the content exceeds 10%, the toughness of the member decreases, so the content is set to 0.1 to 10%.

(D) P and Ti These components have the effect of significantly improving the fatigue strength and toughness of the member when they coexist. Therefore, the desired fatigue strength and toughness can be ensured regardless of whether P alone or Ti is contained. And the content of P and Ti is less than 0.001% and less than 0.2% of P: less than 0.2%, so that the desired improvement effect cannot be obtained in the above-mentioned action. The effect of P is saturated with P: 0.05% and Ti: 1%, and even if the content is further increased, no further improvement effect can be obtained.
1 to 0.05%, Ti: 0.2 to 1%.

〔Example〕

Next, the aluminum alloy two-stage powder forged member of the present invention will be specifically described with reference to examples.

An Al alloy melt having the component composition shown in Table 1 was prepared by a normal melting method, and was made into an Al alloy powder having a particle size of 100 mesh or less by an air atomizing method, and 6 ton / cm ^{2 was} obtained from the Al alloy powder. A green compact having a size of 10 mm x 23 mm x 55 mm is press-molded at a pressure of, and the green compact is first heated at 480 ° C in the atmosphere at a heating rate of 15 ° C / min. In a closed mold, the first stage of powder forging was applied at a pressure of 8 ton / cm ² to obtain a primary powder forging material with a theoretical density ratio of 98% or more, each having dimensions of 11 mm × 16 mm × 57 mm. Then, using a closed type, in the air, at a heating rate of 15 ° C./mi
n 、 Heating temperature: 480 ℃ 、 Pressure: 8ton / cm ^{2 under} the same conditions, the second stage of hot forging, water-cooled to form a secondary powder forging material with dimensions of 14mm × 12mm × 60mm, finally In this, the temperature: 1
The present invention Al having substantially the same component composition as the Al alloy powder by subjecting to aging treatment at 70 ° C. for 6 hours.
Alloy two-stage powder forged member (hereinafter referred to as powder forged member of the present invention) 1-19, and a comparative Al alloy two-stage powder forged member (hereinafter, referred to as
1-9.

Each of the comparative powder forged members 1 to 9 has a component content (marked with * in Table 1) of any of the constituent components of the Al alloy constituting the same, which is out of the scope of the present invention. It is.

Next, the tensile strength, the fatigue strength, and the Charpy impact value of the various powder forged members obtained as a result were measured for the purpose of evaluating the strength and toughness. Table 1 shows the results of these measurements.

In addition, the fatigue strength was represented by a stress that did not break even after performing a cantilever rotating bending fatigue test at a rotation speed of 4000 rpm and repeating the test up to 1 × 10 ⁷ times.

〔The invention's effect〕

From the results shown in Table 1, the powder forged members of the present invention 1 to 1
19 has high fatigue strength and high toughness, both due to the co-presence of P and Ti, especially as alloy components, as shown in the comparative powder forged members 1 to 9,
When the content of any one of the components of the Al alloy is out of the range of the present invention, it is apparent that at least one of the properties of fatigue strength and toughness is inferior.

As mentioned above. The Al alloy two-stage powder forged member of the present invention has high fatigue strength and high toughness, and has the same high strength and low coefficient of thermal expansion as conventional Al alloy powder forged members, so under severe conditions. It has industrially useful characteristics such as exhibiting excellent performance over a long period of time even when used as a structural member of various types of operating engines.

Claims (1)

(57) [Claims] (1) Si: 12 to 30%, Cu: 0.1 to 10%, Fe: 0.1 to 10%, Mg: 0.1 to 3%, P: 0.001 to 0.05%, Ti: 0.2 to 1%. A two-stage powder forged member made of an Al alloy having high fatigue strength and high toughness, characterized in that the remainder is composed of an Al alloy having a composition of Al and unavoidable impurities (at least by weight).