JP3675299B2 - Connecting rod made of Fe-based sintered alloy with high strength and toughness - Google Patents

Description

【００１６】
【表２】

【００１７】
【発明の効果】
表１、２に示される結果から、本発明焼結コンロッド１〜１５は、いずれも合金成分としてＰおよびＭｎを含有せず、従来焼結コンロッドを構成するＦｅ基焼結合金に相当する成分組成をもったＦｅ基焼結合金からなる比較焼結コンロッド１〜１１に比して一段と高い強度および靭性をもつことが明らかである。
上述のように、この発明の焼結コンロッドは、高強度と高靭性を兼ね備えているので、これの薄肉化および小寸化を可能とするものであるから、各種駆動装置の軽量化および高性能化に満足に対応することができるなど工業上有用な特性を有するのである。
【図面の簡単な説明】
【図１】焼結コンロッドの概略正面図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a connecting rod made of Fe-based sintered alloy having high strength and high toughness.
[0002]
[Prior art]
Conventionally, in general, for example, in a drive device such as an automobile or a generator, a connecting member for changing the reciprocating motion of the engine, which is a structural member, to a rotational motion with a crankshaft is illustrated in a schematic front view of FIG. A connecting rod is used.
Further, as these connecting rods, for example, as described in JP-A-9-177757, in mass% (hereinafter,% other than the theoretical density ratio indicates mass%),
Ni: 1.5-4.5%, Cu: 0.5-2.5%,
Mo: 0.75 to 2%, C: 0.3 to 0.6%,
Containing Fe and the remainder composed of Fe and inevitable impurities, and a Fe-based sintered alloy connecting rod composed of an Fe-based sintered alloy having a porosity of 2 to 8% (hereinafter referred to as a sintered connecting rod) It has been known.
[0003]
[Problems to be solved by the invention]
On the other hand, in recent years, drive devices such as automobile engines and generators have become lighter, higher in performance, and further downsized. As a result, the connecting rods, which are these structural members, are also made thinner and smaller. However, in the above-mentioned conventional sintered connecting rod, the Fe-based sintered alloy constituting this does not have the strength and toughness that can sufficiently satisfy these requirements. It is.
[0004]
[Means for Solving the Problems]
In view of the above, the inventors of the present invention focused on the above-described conventional sintered connecting rod, and as a result of researches aimed at improving the strength and toughness of the conventional sintered connecting rod, The contents of Ni, Cu, Mo and C, which are alloy components of the Fe-based sintered alloy constituting
Ni: 2 to 6%, Cu: 0.5 to 2.5%,
Mo: 0.5 to 1.3%, C: 0.2 to 0.8%,
And P and Mn as alloy components,
P: 0.1 to 0.3%, Mn: 0.2 to 0.65%,
In particular, the strength is improved by the P component, and the toughness is further improved by the Mn component. As a result, the sintered connecting rod has high strength and high toughness that can cope with thinning and downsizing sufficiently. The research result that it comes to have.
[0005]
This invention was made based on the above research results,
Ni: 2 to 6%, Cu: 0.5 to 2.5%,
Mo: 0.5 to 1.3%, C: 0.2 to 0.8%,
P: 0.1 to 0.3%, Mn: 0.2 to 0.65%,
And the remainder is composed of an Fe-based sintered alloy having a composition composed of Fe and inevitable impurities and a porosity of 2 to 8%.
[0006]
Next, the reason why the component composition and the porosity of the Fe-based sintered alloy constituting the sintered connecting rod of the present invention are limited as described above will be described.
(A) Component composition (a) Ni
The Ni component has an effect of improving toughness and coexistence with Cu in the coexistence with Cu, but if its content is less than 2%, the desired effect cannot be obtained in the above-mentioned operation, while its content When the content exceeds 6%, the wear resistance decreases, so the content was determined to be 2 to 6%.
[0007]
(B) Cu
The Cu component has the effect of improving toughness in the coexistence with Ni as described above and contributing to the improvement of thermal conductivity. However, if its content is less than 0.5%, the above effect has a desired effect. On the other hand, if the content exceeds 2.5%, the desired wear resistance cannot be ensured, so the content was determined to be 0.5 to 2.5%.
[0008]
(C) Mo
The Mo component has an effect of improving strength and improving heat resistance in the coexistence with Ni, but if its content is less than 0.5%, the desired effect cannot be obtained in the above-described operation, while its content If the amount exceeds 1.3%, the toughness will drop rapidly, so the content was determined to be 0.5 to 1.3%.
[0009]
(D) C
The component C has an effect of improving the strength and wear resistance, but if the content is less than 0.2%, the desired strength cannot be ensured, while the content exceeds 0.8%. And toughness will fall rapidly, The content was defined as 0.2 to 0.8%.
[0010]
(E) P
The P component has the effect of improving the sinterability, promoting the densification and further improving the strength, but if the content is less than 0.1%, the desired improvement effect cannot be obtained in the above action. On the other hand, if the content exceeds 0.3%, the toughness will rapidly decrease, so the content was determined to be 0.1 to 0.3%.
[0011]
(F) Mn
In the coexistence with Ni and Cu, the Mn component has an action that contributes to a further improvement in toughness. However, if its content is less than 0.2%, the desired excellent toughness cannot be secured, while that If the content exceeds 0.65%, strength reduction is unavoidable, so the content was determined to be 0.2 to 0.65%.
[0012]
(B) It is extremely difficult to make the porosity smaller than 2%, even if hot isostatic pressing (HIP) treatment is performed after sintering or sintering is performed by hot pressing treatment. On the other hand, when the porosity exceeds 8%, the strength suddenly decreases, so the porosity was determined to be 2-8%.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, the sintered connecting rod of the present invention will be specifically described with reference to examples.
As raw material powders, Fe powder, Fe-Mo alloy powder (Mo: containing 3%), Fe-P alloy powder (P: containing 25%), Fe having a predetermined average particle diameter in the range of 5 to 50 μm, Fe -Mn alloy powder (Mn: 1% contained), Cu powder, Ni powder, and graphite powder are prepared. These raw material powders are blended in the blending compositions shown in Tables 1 and 2, respectively, and zinc stearate is used as a lubricant. 0.75% added and mixed for 30 minutes with a V-type mixer, pressed into a green compact at a predetermined pressure within a range of 550 to 750 MPa, and this green compact was subjected to a mesh belt type sintering furnace. After maintaining for 20 minutes at a predetermined temperature within a range of 1100 to 1250 ° C. in a nitrogen atmosphere of 5% hydrogen, gradually cooling to 550 ° C. at a predetermined cooling rate within a range of 5 to 40 ° C./min and then allowing to cool. Sintered and some of these (table With respect to those having * in the column of porosity, the component composition is substantially the same as the above composition by performing HIP treatment under the conditions of pressure: 200 MPa, temperature: 950 ° C., treatment time: 2 hours. And the Fe-based sintered alloy having the porosity shown in Tables 1 and 2, and both have the shape shown in FIG. 1 and the overall length: 200 mm, the outer width of the piston pin insertion hole. : 35 mm × thickness: 20 mm, outer width of crank pin insertion hole: 65 mm × thickness: 20 mm of the present invention sintered connecting rods 1 to 15 and comparative sintering not containing P and Mn as alloy components Connecting rods 1 to 11 were produced.
[0014]
Next, for the purpose of evaluating the strength, the above-mentioned various sintered connecting rods are vertically mounted in a state where the piston pin insertion hole and the crank pin insertion hole are gripped, respectively, and the piston pin insertion hole and the crank Each pin insertion hole was pulled up and down, and the tensile stress at break was measured.
Similarly, for the purpose of evaluating toughness, in the state where a horizontal U groove of width: 2 mm × depth: 7 mm is formed on the front side of the central portion in the length direction of the above various sintered connecting rods, And the impact stress at the time of breakage was measured by hitting with a hammer from the opposite side of the horizontal U-groove. The measurement results are shown in Tables 1 and 2.
[0015]
[Table 1]

[0016]
[Table 2]

[0017]
【The invention's effect】
From the results shown in Tables 1 and 2, the sintered connecting rods 1 to 15 of the present invention do not contain P and Mn as alloy components, and the component composition corresponding to the Fe-based sintered alloy constituting the conventional sintered connecting rod. It is apparent that the comparative sintered connecting rods 1 to 11 made of Fe-based sintered alloy having a higher strength and toughness.
As described above, since the sintered connecting rod of the present invention has both high strength and high toughness, it is possible to reduce the thickness and size of the drive rod. It has industrially useful characteristics, such as being able to respond satisfactorily to conversion.
[Brief description of the drawings]
FIG. 1 is a schematic front view of a sintered connecting rod.

Claims (1)

% By mass
Ni: 2 to 6%, Cu: 0.5 to 2.5%,
Mo: 0.5 to 1.3%, C: 0.2 to 0.8%,
P: 0.1 to 0.3%, Mn: 0.2 to 0.65%,
Fe-based sintered alloy having high strength and high toughness, characterized in that it is composed of a Fe-based sintered alloy having a composition comprising Fe and the inevitable impurities, and a porosity of 2 to 8% Conrod made.

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