JPWO2019087562A1 - Pressure ring, internal combustion engine, wire for pressure ring, and method for manufacturing wire for pressure ring - Google Patents

Abstract

The main part can be used for an internal combustion engine made of an aluminum alloy and has excellent productivity. The main part is used for an internal combustion engine made of an aluminum alloy, and the base material constituting the ring-shaped pressure ring main body having an abutment is mass%, C: 0.7 to 1.6%, Si: 0.00. 6 to 1.2%, Mn: 0.3 to 0.7%, P: 0 to 0.04%, S: 0 to 0.09%, Ni: 0.3 to 0.6%, Cr: 7 0.5 to 9.0%, Mo: 0.7 to 1.0%, V: 0 to 0.5%, W: 0.2 to 0.5%, Cu: 0.2 to 0.6%, Al: 0.1 to 0.5%, Nb: 0.05 to 0.15%, balance Fe and impurities, the base material has a Vickers hardness of 435 to 510, A pressure ring having nitride layers formed on upper and lower surfaces, an internal combustion engine using the same, a pressure ring wire used therefor, and a method for manufacturing the pressure ring wire.

Description

  The present invention relates to a pressure ring, an internal combustion engine, a pressure ring wire, and a method for manufacturing a pressure ring wire.

  In recent years, an internal combustion engine having at least an aluminum alloy cylinder block and an aluminum alloy piston has been widely used to reduce the weight of the internal combustion engine in order to improve fuel efficiency.

  On the other hand, piston rings used in internal combustion engines are required to have excellent wear resistance because they slide with a cylinder liner as a counterpart material. In order to meet this need, for example, Patent Document 1 proposes to use a sliding component having excellent wear resistance as an oil ring. This sliding part is mass%, C: 0.7-1.6%, Si: 0.5-3.0%, Mn: 0.1-3.0%, P: 0.05% or less , S: 0.01 to 0.12%, Ni: 0.3 to 1.5%, Cr: 7.0 to 13.0%, one or two of Mo and W: (Mo + 1 / 2W ) 0.5 to 1.7%, V: 0 to 0.70%, Cu: 0.1 to 1.0%, Al: 0.10 to 0.70%, Nb: 0 to 0 .30%, balance Fe and impurity component composition, the hardness is 52 HRC or more and less than 58 HRC (Vickers hardness (HV0.1) conversion, 545 or more and less than 655).

  In the sliding component described in Patent Document 1, self-lubricating properties are obtained by jointly adding S and Cu, which are not actively added in most steel materials, in order to inhibit the hot workability of steel materials. Is effectively exhibited and wear resistance is improved. Moreover, it can avoid that self-lubrication characteristic is inhibited, ensuring high fatigue strength by setting hardness to 52 HRC or more and less than 58 HRC.

International Publication No. 2016/152967

  On the other hand, a pressure ring manufactured through various processes such as coiling that bends into a ring-shaped member having an abutment using a wire rod is also important to have little breakage during coiling and small dimensional variations. is there.

  The present invention has been made in view of the above circumstances, and is a pressure ring that can be used in an internal combustion engine having at least an aluminum alloy cylinder block and an aluminum alloy piston, and has excellent productivity. It is an object to provide an internal combustion engine, a pressure ring wire used for manufacturing the pressure ring, and a method for manufacturing the pressure ring wire.

The above-mentioned subject is achieved by the following present invention. That is,
The pressure ring of the present invention is used in an internal combustion engine including at least an aluminum alloy cylinder block and an aluminum alloy piston, and includes a ring-shaped pressure ring main body portion having an abutment, and a base material constituting the pressure ring main body portion However, by mass%, C: 0.7% to 1.6%, Si: 0.6% to 1.2%, Mn: 0.3% to 0.7%, P: 0% to 0.04 %, S: 0% to 0.09%, Ni: 0.3% to 0.6%, Cr: 7.5% to 9.0%, Mo: 0.7% to 1.0%, V: 0% to 0.5%, W: 0.2% to 0.5%, Cu: 0.2% to 0.6%, Al: 0.1% to 0.5%, Nb: 0.05% ~ 0.15%, balance Fe and impurities, and the base material has a Vickers hardness H1av (HV0.1) of 435 to 510, Wherein the nitride layer on the surface of one side surface and the other side direction is formed.

One embodiment of the pressure ring of the present invention is a carbide particle having a nitride layer having a Vickers hardness HANav (HV0.1) of 900 or more and a maximum length of 3 μm or more existing in the cross section of the pressure ring body. It is preferable that the number of particles is 777 particles / mm ² or more.

In another embodiment of the pressure ring of the present invention, the number of particles is preferably 1058 particles / mm ² or more.

In another embodiment of the pressure ring of the present invention, the number of particles is preferably 1538 particles / mm ² or more.

  The internal combustion engine of the present invention includes an aluminum alloy cylinder block, an aluminum alloy piston disposed in a cylinder bore of the aluminum alloy cylinder block, and an outer peripheral surface of the aluminum alloy piston along the circumferential direction of the aluminum alloy piston. The pressure ring of the present invention disposed in an annular groove provided on the inner surface of the piston, and at least part of the inner wall surface on one side and the inner wall surface on the other side of the annular groove with respect to the axial direction of the aluminum alloy piston. An anodized film is formed.

  The wire for a pressure ring of the present invention is in mass%, C: 0.7% to 1.6%, Si: 0.6% to 1.2%, Mn: 0.3% to 0.7%, P : 0% to 0.04%, S: 0% to 0.09%, Ni: 0.3% to 0.6%, Cr: 7.5% to 9.0%, Mo: 0.7% to 1.0%, V: 0% to 0.5%, W: 0.2% to 0.5%, Cu: 0.2% to 0.6%, Al: 0.1% to 0.5% , Nb: 0.05% to 0.15%, balance Fe and impurities, and Vickers hardness H2av (HV0.1) is 435 to 510.

  The manufacturing method of the wire for pressure rings of this invention is the mass%, C: 0.7% -1.6%, Si: 0.6% -1.2%, Mn: 0.3% -0.7 %, P: 0% to 0.04%, S: 0% to 0.09%, Ni: 0.3% to 0.6%, Cr: 7.5% to 9.0%, Mo: 0.0. 7% to 1.0%, V: 0% to 0.5%, W: 0.2% to 0.5%, Cu: 0.2% to 0.6%, Al: 0.1% to 0 Quenching process and quenching process of quenching wire having a composition composed of 0.5%, Nb: 0.05% to 0.15%, balance Fe and impurities at a temperature in the range of 1030 degrees to 1050 degrees A wire for pressure ring is manufactured through at least a tempering step of tempering the wire after passing through a temperature of 640 to 690 degrees.

  According to the present invention, a pressure ring that can be used in an internal combustion engine having at least an aluminum alloy cylinder block and an aluminum alloy piston and that is excellent in productivity, an internal combustion engine using the same, and the pressure ring It is possible to provide a pressure ring wire used for manufacturing and a manufacturing method thereof.

It is an external view of the pressure ring of this embodiment. It is a model end elevation which shows the cross-section of the pressure ring of this embodiment. Here, FIG. 2A is a diagram showing an example of the cross-sectional structure of the pressure ring of the present embodiment, and FIG. 2B is a diagram showing another example of the cross-sectional structure of the pressure ring of the present embodiment. FIG. 2C is a view showing another example of the cross-sectional structure of the pressure ring of the present embodiment. It is a schematic diagram which shows the reciprocating friction tester used for the abrasion resistance test.

  The pressure ring of the present embodiment is used in an internal combustion engine (hereinafter, sometimes referred to as “an internal combustion engine whose main part is made of an aluminum alloy”) having at least an aluminum alloy cylinder block and an aluminum alloy piston. A ring-shaped pressure ring main body having And the base material which comprises a pressure ring main-body part is the mass%, C: 0.7% -1.6%, Si: 0.6% -1.2%, Mn: 0.3% -0. 7%, P: 0% to 0.04%, S: 0% to 0.09%, Ni: 0.3% to 0.6%, Cr: 7.5% to 9.0%, Mo: 0 0.7% to 1.0%, V: 0% to 0.5%, W: 0.2% to 0.5%, Cu: 0.2% to 0.6%, Al: 0.1% to 0.5%, Nb: 0.05% to 0.15%, balance Fe and impurities, Vickers hardness H1av (HV0.1) of the base material is 435 to 510, pressure ring main body A nitride layer is formed on one surface and the other surface in the axial direction. Below, the detail of each component which comprises base materials other than Fe and an impurity is demonstrated.

(1) C: 0.7% by mass to 1.6% by mass (hereinafter simply referred to as “%”)
C is an element that partly dissolves in the matrix and contributes to improvement in hardness and fatigue strength, and another part contributes to improvement in wear resistance by generating carbide. However, if the content of C is too large, cold workability is lowered. Therefore, the C content needs to be 0.7% to 1.6%.

(2) Si: 0.6% to 1.2%
Si is an element having an effect of increasing strength at high temperatures. However, if the content of Si is too large, cold workability and tough ductility are reduced, and hot workability and thermal conductivity are impaired. Therefore, Si needs to be 0.6% to 1.2%.

(3) Mn: 0.3% to 0.7%
Mn is an element that acts as a deoxidizer when melting steel. Mn increases hardenability, increases strength, and improves hot workability, but if the Mn content is too large, machinability deteriorates. Therefore, the Mn content needs to be 0.3 to 0.7%.

(4) P: 0% to 0.04%
P is an element that inhibits toughness. The content of P needs to be 0% to 0.04%, and 0% is most preferable. However, since P is inevitably contained in the base material, the content of P is usually also It exceeds 0% and is 0.04% or less.

(5) S: 0% to 0.09%
S contributes to the improvement of self-lubricity and improves scuffing resistance and machinability. However, if the content of S is too large, corrosion resistance and workability are reduced. Therefore, the content of S needs to be 0% to 0.09%. The S content may be 0%, or may be more than 0% and 0.09% or less.

(6) Ni: 0.3% to 0.6%
Ni is an element that contributes to the maintenance of hardness. However, when there is too much content of Ni, the machinability in the annealing state before quenching and tempering will deteriorate. Therefore, the Ni content needs to be 0.3% to 0.6%.

(7) Cr: 7.5% to 9.0%
Cr combines with C to form carbides and has the effect of increasing the hardness of the nitride layer formed during nitriding, thereby contributing to improved wear resistance of the nitride layer. Further, Cr is an element that is partly dissolved in the matrix to enhance the corrosion resistance and enhance the hardenability and temper softening resistance of the matrix. However, if the content of Cr is too large, coarse carbides increase and machinability deteriorates, thermal conductivity decreases, and scuffing resistance is impaired. Therefore, the Cr content needs to be 7.5% to 9.0%.

(8) Mo: 0.7% to 1.0%
Mo contributes to improvement of wear resistance as a composite carbide, and solidifies in the matrix to impart toughness and heat resistance of the material. However, when there is too much content of Mo, thermal conductivity, machinability, and toughness will fall. Therefore, the Mo content needs to be 0.7% to 1.0%.

(9) V: 0% to 0.5%
V forms carbides and nitrides during tempering, and these carbides and nitrides suppress coarsening of crystal grains during quenching and suppress a decrease in toughness. However, if the content of V is too large, the thermal conductivity, machinability and toughness are lowered. Therefore, the content of V needs to be 0% to 0.5%. The V content may be 0%, or may be more than 0% and 0.5% or less.

(10) W: 0.2% to 0.5%
W contributes to improvement of wear resistance as a composite carbide, and solidifies in the matrix to impart toughness and heat resistance of the material. However, if there is too much content of W, machinability and toughness will fall and cost will also become high. Therefore, the W content needs to be 0.2% to 0.5%.

(11) Cu: 0.2% to 0.6%
Cu is an element that contributes to improving the strength, corrosion resistance, and self-lubricity of steel. However, when there is too much content of Cu, red hot embrittlement will be caused and hot workability will deteriorate. Therefore, the Cu content needs to be 0.2% to 0.6%.

(12) Al: 0.1% to 0.5%
Al is an element that forms an intermetallic compound with Ni or the like and precipitates and hardens to increase the strength. Further, it is an element that forms an AlN when nitrided and has a function of significantly hardening the surface. However, if the content of Al is too large, Al is a strong ferritizing element, and therefore increases the ferrite in the structure and inhibits the hardness. Therefore, the content of Al needs to be 0.1% to 0.5%.

(13) Nb: 0.05% to 0.15%
Nb is an element that increases high-temperature strength, creep strength, and hardening. However, when there is too much content of Nb, hardenability and machinability will be reduced. Therefore, the Nb content needs to be 0.05 to 0.15%.

The base material having the above composition is an alloy steel having a martensite composition, and an average linear expansion coefficient in the range of room temperature to 200 ° C. is about 12.7 × 10 ⁻⁶ / ° C. On the other hand, the linear expansion coefficient of an aluminum alloy cylinder block of an internal combustion engine whose main part is made of an aluminum alloy is generally about 15 × 10 ⁻⁶ / ° C. to 21 × 10 ⁻⁶ / ° C. The difference from the linear expansion coefficient is small. Therefore, even when the aluminum alloy cylinder block becomes hot and thermally expands, the pressure ring can sufficiently expand following the expansion of the aluminum alloy cylinder block. In this case, the increase in the gap between the pressure rings is suppressed, and as a result, the amount of blow-by gas that leaks out of the gas in the combustion chamber to the outside via the gap between the pressure rings is suppressed. Further, it is possible to suppress the output reduction and fuel consumption deterioration of the internal combustion engine due to the increase in the amount of blow-by gas.

  That is, the pressure ring of the present embodiment is extremely compatible with an internal combustion engine whose main part is made of an aluminum alloy since the main part can reduce the amount of blow-by gas from the initial stage of use of the internal combustion engine made of an aluminum alloy.

  In the present specification, the aluminum alloy cylinder block includes a cylinder block made entirely of an aluminum alloy and a cylinder block made mainly of an aluminum alloy. Here, examples of the cylinder block whose main part is made of an aluminum alloy include a cylinder block manufactured by casting a cast iron cylinder liner with an aluminum alloy.

  Further, in the pressure ring of the present embodiment, the breakage of the wire during coiling can be greatly reduced by setting the Vickers hardness H1av (HV0.1) of the base material to 510 or less. In addition, by setting the Vickers hardness H1av (HV0.1) of the base material to 435 or more, a pressure obtained after nitriding to form a nitrided layer on a ring-shaped member having a joint obtained after coiling The dimensional variation of the ring main body can be reduced. For this reason, the pressure ring of this embodiment has a high yield during manufacture and is excellent in productivity. Note that the Vickers hardness H1av (HV0.1) of the base material is preferably 435 to 498, and more preferably 480 to 498. In the present specification, the Vickers hardness H1av (HV0.1) of the base material means an average value obtained by measuring a portion of the pressure ring main body portion where the nitrided layer is not formed. This is substantially the same value as the Vickers hardness H2av (HV0.1) of the wire for the pressure ring used for producing the main body.

  Note that the present inventors pay attention to the fact that the linear expansion coefficient, which is inseparably related to the composition, is close to the linear expansion coefficient of the aluminum alloy cylinder block, and is substantially the same as the sliding component disclosed in Patent Document 1. A base material having a composition of Further, from the viewpoint of obtaining wear resistance and high fatigue strength, the hardness of the base material is also 52 HRC or more and less than 58 HRC as disclosed in Patent Document 1 (545 or more and less than 655 in terms of Vickers hardness (HV0.1)). It is considered that it is more advantageous.

  On the other hand, the outer peripheral surface of the pressure ring is exposed to intense sliding with the inner peripheral surface of the cylinder liner, and the one side surface and the other side surface in the axial direction of the pressure ring (hereinafter referred to as “upper surface” and “lower surface, respectively”). Is the upper inner wall surface and lower inner wall surface of the annular groove provided on the outer peripheral surface of the aluminum alloy piston (the inner surface on one side of the annular groove with respect to the axial direction of the aluminum alloy piston). Exposure to the wall surface and the other inner wall surface). The progress of wear must be suppressed as much as possible on any of the outer peripheral surface, the upper surface, and the lower surface. However, even if the outer peripheral surface, the upper surface, and the lower surface are formed of a base material itself having a hardness of 52 HRC or more and less than 58 HRC, the wear resistance is insufficient under the above-described sliding environment, so that the wear progresses over time. It cannot be suppressed sufficiently. Therefore, in order to ensure excellent wear resistance that can withstand the above-mentioned sliding environment without depending on the wear resistance of the base material itself, the upper and lower surfaces of the pressure ring main body constituting the pressure ring are nitrided. It is necessary to form a nitride layer by treatment and form a nitride layer by nitriding treatment on the outer peripheral surface of the pressure ring main body portion or to form a hard coating covering the outer peripheral surface of the pressure ring main body portion.

  Accordingly, the present inventors have taken into consideration the above-mentioned circumstances, and regarding the wear resistance required for the pressure ring, after forming a nitride layer on the upper surface and the lower surface of the pressure ring body portion, the outer peripheral surface of the pressure ring body portion In order to cope with this problem, a nitride layer is formed or a hard coating is applied. In this case, the wear resistance due to the composition and hardness of the base material itself that has not been nitrided is not important. For this reason, the inventors reviewed the hardness of the base material itself mainly from the viewpoint of productivity, and set the Vickers hardness H1av (HV0.1) of the base material within a range of 435 to 510.

  In the pressure ring of the present embodiment, the nitride layer is formed on the upper surface and the lower surface of the pressure ring main body. By forming a nitride layer on the upper and lower surfaces of the pressure ring body, even if the pressure ring slides, the upper inner wall surface and lower inner wall surface of the annular groove provided on the outer peripheral surface of the aluminum alloy piston For a long time, wear of both the pressure ring and the annular groove can be suppressed. Such an effect is the same when the anodized film is provided in the annular groove. For this reason, in the pressure ring of the present embodiment, the sealing performance between the annular groove of the aluminum alloy piston and the pressure ring can be maintained over a long period of time. Can be suppressed.

  Further, the Vickers hardness HANav (HV0.1) of the nitride layer is preferably 900 or more. Thereby, wear of both the pressure ring and the annular groove can be suppressed more effectively. Further, in order to suppress excessive wear of the upper inner wall surface and the lower inner wall surface of the annular groove, the nitride layer preferably has a Vickers hardness HANav (HV0.1) of 1300 or less.

  Of the various elements contained in carbon steel, Al, Cr, Mo, Ti, V, Mn, and Si are known to contribute to improving the hardness of the nitrided layer in improving the hardness of the nitrided layer. However, the pressure ring of the present embodiment contains a large amount of Cr (7.5% to 9.0%) among these elements, and also contains 0.1% to 0.5% of Al. . For this reason, the Vickers hardness MNav (HV0.1) of the nitride layer can be easily set to 900 or more. The nitride layer may be formed on the outer peripheral surface of the pressure ring main body as necessary.

Further, when the Vickers hardness MNav (HV0.1) of the nitride layer is 900 or more, the number of carbide particles having a maximum length of 3 μm or more present in the cross section of the pressure ring main body is 577 pieces / mm ² or more. Preferably, it is 1058 / mm ² or more, more preferably 1538 / mm ² or more. By setting the number of carbide particles to 577 / mm ² or more, the surface of the nitride layer formed on the pressure ring main body portion not only improves the wear on the surface but also the material of the counterpart material that slides in contact with the surface of the nitride layer. It becomes easy to reduce wear. Here, when the nitride layer surfaces are the upper surface and the lower surface of the pressure ring, the counterpart material is an aluminum alloy that constitutes the upper inner wall surface and the lower inner wall surface of the annular groove provided on the outer peripheral surface of the aluminum alloy piston, or And an anodized film formed on the upper inner wall surface and the lower inner wall surface.

The upper limit of the number of carbide particles having a maximum length of 3 μm or more is not particularly limited, but if it is too large, cracks along the carbide may occur or workability may be reduced. The number is preferably 2000 pieces / mm ² or less. In the pressure ring of this embodiment, the number of carbide particles having a maximum length of 3 μm or more can be easily set to 577 / mm ² or more due to the composition of the base material.

  Next, the shape and cross-sectional structure of the pressure ring of this embodiment will be described in more detail. FIG. 1 is an external view of the pressure ring of this embodiment, and is a view of the pressure ring as viewed from the upper surface or the lower surface. In FIG. 1, symbol C is the central axis of the pressure ring. The pressure ring 10 shown in FIG. 1 has a ring shape having an abutment G. In FIG. 1, the description of the hard coating is omitted. FIG. 2 is a schematic end view showing an example of a cross-sectional structure of the pressure ring according to the present embodiment, and more specifically, a view showing a cross-sectional structure between reference numerals A1-A2 in FIG.

  As shown in FIGS. 2A, 2B, and 2C, the pressure ring 10 includes a ring-shaped pressure ring body portion 20 having an abutment G, and an outer periphery of the pressure ring body portion 20. The nitride film 40 is formed on the upper surface portion 24U and the lower surface portion 24B of the pressure ring main body portion 20. The nitride layer 40 may also be formed on the inner peripheral surface side portion 24L of the pressure ring main body 20 as shown in FIGS. 2 (A), 2 (B), and 2 (C). As shown in FIG. 2C, the pressure ring main body 20 may also be formed on the outer peripheral surface side portion 24R. When the pressure ring 10 shown in FIGS. 1 and 2 is used by being mounted in an annular groove of an aluminum alloy piston, the surface 32 of the hard coating 30 is in contact with the inner wall surface of the cylinder as the outer peripheral sliding surface 12 of the pressure ring 10. Then, the upper surface 26 and the lower surface 28 of the pressure ring main body 20 make contact with the upper inner wall surface and the lower inner wall surface of the annular groove as the upper surface 14 and the lower surface 16 of the pressure ring 10.

  The thickness of the nitride layer 40 (side surface nitride layer) formed on the upper surface side portion 24U and the lower surface side portion 24B of the pressure ring body 20 is preferably 10 μm or more, and more preferably 20 μm or more. The upper limit of the thickness of the side surface nitrided layer is not particularly limited, but is preferably 200 μm or less for practical use. Further, as illustrated in FIG. 2C, the outer peripheral surface side portion 24R of the pressure ring main body 20 may be nitrided to provide the outer peripheral surface portion 24R with the nitride layer 40 (outer peripheral surface nitride layer). Good. The thickness of the outer peripheral surface portion nitrided layer can be the same as the thickness of the side surface portion nitrided layer. Moreover, when the outer peripheral surface portion nitrided layer is provided, the hard coating 30 may be omitted. Any known hard coating can be used as the hard coating, and examples thereof include a DLC coating and a CrN coating.

  The pressure ring 10 of the present embodiment is used in an internal combustion engine that includes at least an aluminum alloy cylinder block and an aluminum alloy piston disposed in a cylinder bore of the aluminum alloy cylinder block. Here, the pressure ring 10 is arrange | positioned in the annular groove provided in the outer peripheral surface of the aluminum alloy piston along the circumferential direction of the aluminum alloy piston. The upper inner wall surface and the lower inner wall surface of the annular groove may be made of the same material as the main body portion of the aluminum alloy piston, but anodized on at least a part of the upper inner wall surface and the lower inner wall surface. A film may be formed, and an anodic oxide film may be formed on the entire upper inner wall surface and lower inner wall surface.

The pressure ring 10 of the present embodiment performs various steps of coiling and nitriding using a pressure ring wire having the same composition and Vickers hardness (HV0.1) as the base material constituting the pressure ring body 20. Can be produced. Here, the method of forming the nitride layer by nitriding is not particularly limited, but gas nitriding, salt bath nitriding, ion nitriding (plasma nitriding), or the like can be used. In the case of gas nitriding, a nitrided layer is formed by performing heat treatment on a ring-shaped member obtained by coiling in a gas atmosphere containing nitrogen. The thickness and surface hardness of the nitride layer can be controlled by appropriately selecting heating temperature / time, atmospheric gas composition, and the like. The gas containing nitrogen includes, for example, a mixed gas containing NH ₃ and N _2, and the processing temperature can be appropriately selected within a range of, for example, about 500 degrees to 600 degrees. For example, it can be suitably selected within a range of about 2 hours to 10 hours. In the case of the salt bath nitriding treatment, for example, a nitride layer is formed by immersing a ring-shaped member obtained by coiling in a sodium cyanide salt bath. In the case of ion nitriding treatment, a nitride layer can be formed using glow discharge in vacuum. Further, when the pressure ring 10 has the hard coating 30, a step of forming a hard coating by a PVD (Physical Vapor Deposition) method or the like is further performed.

  Moreover, the pressure ring wire includes a quenching process and a quenching process in which a wire having the same composition as that of the base material constituting the pressure ring main body portion 20 is quenched at a temperature within a range of 1030 degrees to 1050 degrees. It can be produced through at least a tempering step of tempering the passed wire at a temperature in the range of 640 to 690 degrees. In such a manufacturing process, the Vickers hardness H2av (HV0.1) of the wire for pressure ring is adjusted within the range of 435 to 510 by setting the temperature at the time of tempering within the range of 640 to 690 degrees. be able to. The Vickers hardness H2av (HV0.1) of the pressure ring wire is preferably 435 to 498, and more preferably 480 to 498. Moreover, the temperature at the time of tempering is preferably 650 to 690 degrees, and more preferably 650 to 660 degrees.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

1. Evaluation of breakage and dimensional variation
(1) Sample preparation In mass%, C: 1.1%, Si: 0.7%, Mn: 0.5%, P: 0.02%, S: 0.03%, Ni: 0.4% Cr: 8.41%, Mo: 0.9%, V: 0.1%, W: 0.3%, Cu: 0.4%, Al: 0.2%, Nb: 0.09%, The wire having the composition composed of the remaining Fe and impurities was quenched at a temperature in the range of 1040 ° ± 10 °. Next, the wire rod after the quenching treatment is tempered by changing the temperature every 10 degrees within a range of 630 to 700 degrees, so that the pressure rings of Examples A1 to A7 and Comparative Examples A1 to A2 are used. A wire was obtained. Table 1 shows the tempering temperatures at the time of creating the pressure ring wires of the examples and comparative examples.

  Next, coiling was performed under the same conditions using the pressure ring wires of each of the examples and comparative examples, thereby obtaining a pressure ring wire in a state of being wound in a cylindrical shape. In addition, as the wire for a pressure ring in a state of being wound in a cylindrical shape, two types of members having an outer diameter of 80.5 mm and a member having an outer diameter of 50 mm were produced. The number of windings of the pressure ring wire was, in principle, 400 when the outer diameter was 80.5 mm and 300 when the outer diameter was 50 mm. However, when breakage occurred frequently during coiling, coiling was stopped before the predetermined number of turns was reached.

  Thereafter, a ring-shaped member having an abutment is produced from the pressure ring wire wound in a cylindrical shape, and the ring-shaped members of any of the examples and comparative examples are used by using the ring-shaped members of the examples and comparative examples. Also in the member, gas nitriding treatment was performed under the same conditions so that the Vickers hardness (HV0.2) of the nitrided layer surface was 1000 or more. This obtained the pressure ring main-body part. Note that the formation position of the nitride layer is the same as that shown in FIG.

(2) Measurement of Vickers hardness of pressure ring wire and upper surface of nitride layer Vickers hardness was measured based on JIS Z 2244 “Vickers hardness test-test method”.

  Here, the Vickers hardness (HV0.1) of the pressure ring wire is obtained by mirror-polishing the cross section of the pressure ring wire (cross section orthogonal to the longitudinal direction of the wire), and then approximately the center of the mirror-polished cross section. It was determined by measurement using a micro Vickers hardness tester under conditions of a test force of 0.9807 N and a test force holding time of 15 s. In the measurement, the pressure ring wires of each of the examples and the comparative examples were measured at five locations at different measurement positions. First, measurement was performed five times at each of the five measurement points P1 to P5, and the primary average value hn at each measurement point Pn was obtained (n is an integer of 1 to 5). Subsequently, an average value H2av (secondary average value) was further determined based on the five primary average values h1 to h5. The results are shown in Table 1. For reference, the minimum value H2min and the maximum value H2max among the five primary average values h1 to h5 are also shown in Table 1.

  In addition, about the pressure ring main-body part of each Example and comparative example in which the nitride layer was formed, the cross section (cross-section orthogonal to the circumferential direction) of the pressure ring main-body part is mirror-polished, and then the substantially central part of the mirror-polished cross-section The average value H1av, the maximum value H1max, and the minimum value H1min of the Vickers hardness (HV0.1) were obtained from the measurement conditions similar to the above (that is, the portion where the nitride layer is not formed). As a result, the average value H1av, the maximum value H1max, and the minimum value H1min of the Vickers hardness (HV0.1) of the base material constituting the pressure ring main body part are also the average of the Vickers hardness (HV0.1) of the wire for the pressure ring. It was confirmed that the values were substantially the same as the value H2av, the maximum value H2max, and the minimum value H2min.

  Moreover, about the Vickers hardness (HV0.2) of the nitride layer formed in the pressure ring main-body part, the measurement sample was prepared in the following procedures and the measurement was implemented. First, the upper surface 26 of the pressure ring main body of each example and comparative example was polished. Then, with respect to the polished upper surface, when the position where the abutment G is provided in the circumferential direction is set to 0 degree, a micro Vickers hardness tester is used at three positions of 90 degrees, 180 degrees, and 270 degrees. Then, measurement was performed under the conditions of a test force of 1.961 N and a test force holding time of 15 s, and it was confirmed whether or not the average value of Vickers hardness at three measurement positions was 1000 or more. As a result, it was confirmed that the Vickers hardness (HV0.2) of the nitride layer formed on the pressure ring body was 1000 or more in any of the examples and comparative examples.

(3) Evaluation of breakage during coiling The number of breaks per winding number (number of coiling) during coiling was evaluated. When counting the number of breaks, it is determined whether or not there is a break for each length of one pressure ring, and there are two or more breaks within the length range of one pressure ring. In some cases, the number of breaks was counted as one. In addition, in the test example in which the number of breakage is zero, each ring corresponding to the length of one pressure ring is obtained by slightly extending the wire for a pressure ring wound in a cylindrical shape on both sides in the axial direction. Regarding the portion, it was confirmed whether the interval between the ring portions adjacent in the axial direction was uniform (equal pitch) or non-uniform (non-uniform pitch). The evaluation results are shown in Table 1. The evaluation criteria for breakage evaluation shown in Table 1 are as follows.
A: The number of breaks per 100 coilings (100 windings) is 0, and the pitch is uniform.
B: The number of breaks per 100 coilings (100 windings) is 0, and the pitch is uneven.
C: The number of breaks per 100 coilings (100 windings) is 1 or more.

(4) Evaluation of dimensional variation after nitriding treatment The pressure ring main body after the nitriding layer 40 is formed after coiling so that the outer diameter is 80.5 mm, 20 pressures for each example and comparative example. The amount of change in the clearance of the free end of the ring body was measured and the variation was evaluated. For Comparative Example A1, the pressure ring main body portion where no breakage occurred was used for measuring the amount of change in the free-opening clearance. The amount of change in the free end clearance is measured by measuring the distance m between the ends of both ends on the center line of the thickness dimension a1 in the free state of the pressure ring, and the change in free end clearance allowed for each pressure ring. Judgment was made by confirming whether the amount was within the control range of variation in the amount (0.5 mm or less). The evaluation results are shown in Table 1. The evaluation criteria for the dimensional variations shown in Table 1 are as follows.
A: All the variations in the amount of change in the free opening clearance of the 20 pressure ring main body portions are within the range in which the management range is further reduced by half.
B: All variations in the amount of change in the free opening clearance of the 20 pressure ring main body portions are within the control range.
C: Among the 20 pressure ring body parts, the variation in the amount of change in the free joint clearance of at least one pressure ring body part is out of the management range.

2. Evaluation of Wear Amount (1) Sample Preparation As a ring-shaped member, a ring-shaped member (Example B1) manufactured under the same conditions as Example A4 was prepared. Moreover, the ring-shaped member produced by coiling using HPM31 made from Hitachi Metals as a pressure ring wire (Comparative Example B1), and the ring-shaped member produced by coiling using SKD61 as a pressure ring wire (Comparative Example B2) was also prepared. Although both HPM31 and SKD61 have different base metal compositions from Example B1, the Cr content in the base material that greatly affects the formation and hardness of the nitrided layer constitutes the base material constituting the pressure ring of this embodiment. It is a steel material relatively close to the Cr content in it.

Subsequently, a gas nitriding process was performed on these three types of ring-shaped members using a mixed gas containing NH ₃ and N ₂ as the atmospheric gas. At this time, the processing temperature: 500 to 600 ° C., the processing time: 2 hours to 10 hours, so that the Vickers hardness HANav (HV0.1) of the nitride layer formed on any ring-shaped member is substantially the same. Thus, nitriding conditions were appropriately selected. Thereby, the pressure ring sample which consists only of a pressure ring main-body part was obtained. The nitride layer was formed on the entire surface of the pressure ring sample as in the case illustrated in FIG. Table 2 shows the Cr content in the base material constituting the pressure ring sample of each Example and Comparative Example and the Vickers hardness HANav (HV0.1) of the nitride layer.

(2) Measurement of Vickers Hardness of Nitrided Layer Section Vickers hardness was measured based on JIS Z 2244 “Vickers Hardness Test—Test Method”. Here, for the Vickers hardness (HV0.1) of the nitride layer cross section, a measurement sample was prepared and measured according to the following procedure. First, when the position where the abutment G is provided in the circumferential direction is 0 degree, the pressure ring sample is cut at three positions of 90 degrees, 180 degrees, and 270 degrees, and the three cut surfaces Polished. Next, for each cut surface, a test force of 0.9807 N using a micro Vickers hardness tester at a position 10 μm deep from the outermost surface excluding the cut surface (position within the range where the nitrided layer is formed) The measurement was performed under the condition of a force holding time of 15 s. And the average value HNav of the measured value in three cut surfaces was calculated | required.

(3) Measurement of the number of carbide particles The number of carbide particles is measured by observing a surface of a pressure ring sample (cross section orthogonal to the circumferential direction of the pressure ring), performing an etching process with a marble reagent, etc., and then performing a metal microscope observation. did. Here, in the metal microscope observation, nine arbitrary positions were measured with respect to the cross section of the pressure ring main body, and the field-of-view size (0.088 mm × 0.066 mm size, area: 0. 0 mm) at each measurement position. The number of carbide particles present in the structure photograph in which 0058 mm ² ) was magnified 400 times was visually counted. At this time, the carbide particles to be counted were only carbide particles having a maximum length of 3 μm or more. The field size (total area: 0.052 mm ²⁾ of the measurement positions of nine locations based on the total number of carbide particles present in, obtained carbide particles per unit area (pieces / mm ^2). The results are shown in Table 2.

(3) Abrasion resistance test For the abrasion resistance test, a reciprocating friction tester 100 shown in FIG. 3 was used. The reciprocating friction tester 100 is configured such that the test piece 102 is pressed against the plate 104 by applying a load P by a spring load, and the plate 104 reciprocates to slide both.

  Here, a pin type test piece made of the same material as that of the pressure ring sample is used as the test piece 102, and a nitride layer is formed at the tip of the test piece 102. Here, the nitride layer was formed by performing a gas nitriding process under the same conditions as the pressure ring sample. As the plate 104, an aluminum alloy plate made of the same material as the upper inner wall surface and the lower inner wall surface of the annular groove of the aluminum alloy piston was used. The aluminum alloy plate used as the plate 104 has an anodized film formed on the surface thereof. When sliding, the tip of the test piece 102 on which the nitride layer was formed was brought into contact with the surface of the plate 104 (the surface on which the anodized film was formed), and lubricating oil was supplied using a tubing pump or air dispenser. . The test conditions for the wear resistance test are shown below.

  The wear resistance test was performed three times for each example and comparative example, and the average value of the wear amount of the test piece 102 and the average value of the wear amount of the plate 104 were obtained. Table 2 shows the results of the abrasion resistance test.

-Test conditions-
・ Load P: 50N
・ Average speed of reciprocation of plate 104: 300rpm
-Reciprocating stroke of plate 104: 50mm
・ Test time: 120 min
・ Lubricant: 5w-30 engine oil ・ Drip amount of lubricant: 1 ml / hr
-Material of plate 104: Aluminum alloy plate (AC8A) (anodized film is formed on the surface)

10: pressure ring 12: outer peripheral sliding surface 14: upper surface 16: lower surface 20: pressure ring main body 22: outer peripheral surface 24B: lower surface side portion 24L: inner peripheral surface side portion 24R: outer peripheral surface side portion 24U: upper surface side portion 26 : Upper surface 28: Lower surface 30: Hard coating 32: Surface 40: Nitrided layer 100: Reciprocating friction tester 102: Test piece 104: Plate

The manufacturing method of the wire for pressure rings of this invention is the mass%, C: 0.7% -1.6%, Si: 0.6% -1.2%, Mn: 0.3% -0.7 %, P: 0% to 0.04%, S: 0% to 0.09%, Ni: 0.3% to 0.6%, Cr: 7.5% to 9.0%, Mo: 0.0. 7% to 1.0%, V: 0% to 0.5%, W: 0.2% to 0.5%, Cu: 0.2% to 0.6%, Al: 0.1% to 0 Quenching process and quenching process of quenching wire having a composition composed of 0.5%, Nb: 0.05% to 0.15%, balance Fe and impurities at a temperature in the range of 1030 degrees to 1050 degrees a tempering step to temper the wire at a temperature in the range of 640 ° 690 ° passing through a through at least a Vickers hardness H2av (HV0.1) is a pressure ring for wire is 435 to 510 And characterized in that the elephants.

Claims (7)

Used in an internal combustion engine having at least an aluminum alloy cylinder block and an aluminum alloy piston,
It has a ring-shaped pressure ring main body with an abutment,
The base material constituting the pressure ring main body portion is mass%, C: 0.7% to 1.6%, Si: 0.6% to 1.2%, Mn: 0.3% to 0.7 %, P: 0% to 0.04%, S: 0% to 0.09%, Ni: 0.3% to 0.6%, Cr: 7.5% to 9.0%, Mo: 0.0. 7% to 1.0%, V: 0% to 0.5%, W: 0.2% to 0.5%, Cu: 0.2% to 0.6%, Al: 0.1% to 0 0.5%, Nb: 0.05% to 0.15%, the composition comprising the balance Fe and impurities,
Vickers hardness H1av (HV0.1) of the base material is 435 to 510,
A pressure ring, wherein a nitride layer is formed on one surface and the other surface in the axial direction of the pressure ring main body. The number of carbide particles having a Vickers hardness MNav (HV0.1) of the nitrided layer of 900 or more and a maximum length of 3 μm or more present in the cross section of the pressure ring main body is 577 particles / mm ^2. It is the above, The pressure ring of Claim 1 characterized by the above-mentioned. The pressure ring according to claim ² , wherein the number of particles is 1058 particles / mm ² or more. The pressure ring according to claim ² , wherein the number of particles is 1538 particles / mm ² or more. An aluminum alloy cylinder block;
An aluminum alloy piston disposed in a cylinder bore of the aluminum alloy cylinder block;
The pressure ring according to any one of claims 1 to 4, disposed on an outer circumferential surface of the aluminum alloy piston, in an annular groove provided along a circumferential direction of the aluminum alloy piston,
An internal combustion engine in which an anodized film is formed on at least a part of one inner wall surface and the other inner wall surface of the annular groove with respect to the axial direction of the aluminum alloy piston. In mass%, C: 0.7% to 1.6%, Si: 0.6% to 1.2%, Mn: 0.3% to 0.7%, P: 0% to 0.04%, S: 0% to 0.09%, Ni: 0.3% to 0.6%, Cr: 7.5% to 9.0%, Mo: 0.7% to 1.0%, V: 0% -0.5%, W: 0.2% -0.5%, Cu: 0.2% -0.6%, Al: 0.1% -0.5%, Nb: 0.05% -0 .15%, balance Fe and impurities composition,
Vickers hardness H2av (HV0.1) is 435-510, The wire for pressure rings characterized by the above-mentioned. In mass%, C: 0.7% to 1.6%, Si: 0.6% to 1.2%, Mn: 0.3% to 0.7%, P: 0% to 0.04%, S: 0% to 0.09%, Ni: 0.3% to 0.6%, Cr: 7.5% to 9.0%, Mo: 0.7% to 1.0%, V: 0% -0.5%, W: 0.2% -0.5%, Cu: 0.2% -0.6%, Al: 0.1% -0.5%, Nb: 0.05% -0 A quenching step of quenching a wire having a composition of 15%, the balance Fe and impurities at a temperature in the range of 1030 degrees to 1050 degrees;
A tempering step of tempering the wire that has undergone the quenching step at a temperature within a range of 640 degrees to 690 degrees;
A method for producing a wire for a pressure ring, wherein the wire for a pressure ring is produced through at least the above.

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