JPH04290680A - Wire material for piston ring - Google Patents

Abstract

PURPOSE:To improve the wire drawing workability and rolling workability and provide the superior heat resistance and abrasion resistance as piston ring, in the wire rod for piston ring which is made of stainless steel and used for a piston ring for internal combustion engine. CONSTITUTION:The wire material 1 for a piston ring has a carburized layer 2 having a wt.% of C: 0.6-1.2% and a depth of O.2-0.6mm on the surface of a basic material made of the ferrite group or martensite group stainless steel having a wt.% of C: 0.3% or less and Cr: 11-30%.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in piston ring wire rods used in piston rings for internal combustion engines.

0002

2. Description of the Related Art In internal combustion engines such as automobile engines, piston rings are attached to pistons for the purpose of maintaining airtightness and regulating lubricating oil. Conventionally, such piston rings have mainly been made of cast iron, but as the performance of internal combustion engines increases, the use of piston rings made of carbon steel for springs is increasing. The reason for this is that manufacturing is facilitated by coiling a wire having a desired cross-sectional shape, and that the piston ring can be made thinner and lighter due to improved rigidity.

[0003] Furthermore, since piston rings slide on the cylinder, they are required to have wear resistance and seizure resistance, and for this reason, their surfaces are subjected to hard Cr plating or nitriding treatment.

[0004] In recent years, martensitic stainless steel has been used as wire material for piston rings in order to further improve wear resistance, seizure resistance, and heat resistance. High Cr martensitic stainless steel (C: 0.6~0.9Wt%, Cr: 13~
Good results have been obtained as piston rings by subjecting 18 Wt%) to nitriding treatment.

[0005] The piston ring wire rod made of the above-mentioned high C and high Cr martensitic stainless steel has a rectangular cross-sectional shape or a complex irregular shape.

[0006]The manufacturing method consists of repeatedly subjecting a φ5.5 mm wire to several rounds of annealing and cold wire drawing to reduce the wire diameter, and then cold rolling it into the desired cross-sectional shape. do. Further, when processing into a complicated cross-sectional shape, several annealing treatments are performed even during the cold rolling process. And as a finishing treatment,
It was quenched and tempered to give it strength and heat resistance.

[0007]

By the way, the above-mentioned high C and high Cr martensitic stainless steel, particularly martensitic stainless steel with a large amount of C, has excellent characteristics as a piston ring. However, on the other hand, cold wire drawability and rolling workability are very poor, and as a result, the processing process for piston ring wire rods requires many annealing steps as described above, and cold drawing and rolling workability is extremely poor. The number of wire processing and cold rolling processing has also increased, and the processing cost has become much more expensive than conventional wire rods for piston rings made of carbon steel for springs.

In addition, as the processing process becomes complicated as described above, the surface quality of the piston ring may deteriorate due to scratches on the wire material or pitting corrosion during pretreatment and annealing treatment for cold wire drawing. It was lowering it. Furthermore, in the worst case, problems such as the wire breaking due to bending during the coiling process occur due to the above-mentioned defects.

The piston ring wire rod of the present invention has been developed to solve the problems of the prior art described above, and its purpose is to improve cold wire drawability and rolling workability, as well as improve The object of the present invention is to provide a wire material for a piston ring that has heat resistance and wear resistance suitable for a piston ring.

0010

[Means for Solving the Problems] In order to achieve the above object, the piston ring wire rod of the present invention has a carbon content of % by weight in the piston ring wire rod formed by cold working.
: 0.3% or less, Cr: 11-30% on the surface of the base material made of ferritic or martensitic stainless steel, C: 0.6%-1.2% in weight%, depth 0.2
It has a carburized layer of mm to 0.6 mm.

Next, the reason for limiting the composition of stainless steel in the above structure will be described.

[0012]C impairs cold wire drawability and rolling workability, and if it is contained in a large amount, a large amount of Cr carbide is formed, and the wire drawability and rolling workability are extremely reduced. Therefore, in order to obtain the above-mentioned good workability, the amount of C should be 0.
It is necessary to keep it to 3 Wt% or less.

[0013] Cr forms a solid solution in the matrix and provides heat resistance and abrasion resistance, as well as improving corrosion resistance. It is also an important element that improves nitriding properties. Therefore, in order to exhibit these effects, at least 11 wt% or more is required from the balance with the amount of C after carburizing. Also, 3
If it exceeds 0 Wt%, cold wire drawing workability and rolling workability will deteriorate, so the Cr content was set to 11 to 30 Wt%.

Further, the carburized layer is hardened by quenching and tempering to impart the necessary spring properties to the piston ring, and the carbon in the carburized layer is necessary together with Cr to obtain a nitrided layer with excellent wear resistance. be. Therefore, in order to exhibit these effects, the carburized layer should have a C content of 0.6 Wt% or more and a depth of 0.6 Wt%.
It needs to be 2 mm or more. In addition, the amount of C is 1.2Wt
If the depth exceeds 0.6 mm, the hardness increases too much, and if the depth exceeds 0.6 mm, the inside of the wire will be hardened, resulting in extremely poor coiling workability. The above C amount is 0.6Wt% to 1.2W
t%, preferably 0.75Wt% to 0.95Wt%.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A piston ring wire rod according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a piston ring wire used as a pressure piston ring, which has a substantially rectangular cross section with a thickness of 1.5 mm and a width of 3.0 mm, and the base material has a carbon content in weight%. :0.05%, Si:0.34
%, Mn: 0.52%, P: 0.011%, Cr: 27
．． Made of ferritic stainless steel with a chemical composition of 56%.

The surface of the base material of the piston ring wire 1 has a carburized layer 2 hardened by quenching and tempering with a C content of 0.75 Wt% and a depth of 0.32 mm.

Next, a method for manufacturing the piston ring wire 1 will be explained.

[0019] The above ferritic stainless steel wire rod φ5.
After annealing 5 mm, a wire having a wire diameter of 2.6 mm was formed by cold wire drawing, and then a deformed wire having a substantially rectangular cross section of the above dimensions was formed by cold rolling. Then, this irregularly shaped wire rod was subjected to gas carburization at a temperature of 1030℃,
A carburized layer with a depth of 0.32 mm was formed with a C content of 0.75 Wt%. Finally, a quenching and tempering process was performed at a quenching temperature of 1040°C and a tempering temperature of 700°C to harden the carburized layer.

What is shown in FIG. 2 is a piston ring wire material 3 used for an integrated oil piston ring, and its shape has a substantially I-shaped cross section with a thickness of 4.5 mm and a width of 3.2 mm. The material is C: 0.04%, Si:
0.50%, Mn 0.68%, P: 0.012%, S:
0.004%, Ni: 0.55%, Cr: 13.76%
Made of ferritic stainless steel with a chemical composition of

The surface of the base material of the piston ring wire 3 has a carburized layer 4 hardened by quenching and tempering with a C content of 0.64 Wt% and a depth of 0.25 mm.

Next, a method for manufacturing the piston ring wire 3 will be explained.

[0023] The above ferritic stainless steel φ5.5m
After annealing the wire, the wire diameter is reduced to φ4 by cold wire drawing.
．． The wire was made into a 1 mm wire, and then a deformed wire having a substantially I-shaped cross section with the above dimensions was formed by cold rolling. Then, this irregular wire was gas carburized at a temperature of 1025° C. to form a carburized layer with a C content of 0.92 Wt% and a depth of 0.25 mm. And finally, the quenching temperature is 1040℃ and the tempering temperature is 6.
A quenching and tempering treatment at 60° C. was performed to harden the carburized layer.

What is shown in FIG. 3 is a piston ring wire material 5 used for the side rail of an oil piston ring, and its shape is a thickness a of 0.56 mm and a width b of 2.92 m.
It has an approximately track-shaped cross section of m, and the base material has a C:0 by weight%.
．． 28%, Si: 0.15%, Mn: 0.41%, P:
0.011%, S: 0.005%, Cr: 19.26%
Made of martensitic stainless steel with a chemical composition of

The surface of the base material of the piston ring wire 5 has a carburized layer 6 which has been hardened by quenching and tempering and has a C content of 1.21 Wt% and a depth of 0.22 mm.

Next, a method for manufacturing the piston ring wire 3 will be explained.

[0027] The above martensitic stainless steel wire rod φ
After annealing 5.5 mm, a wire having a wire diameter of 3.2 mm is obtained by cold wire drawing, and then annealing is performed. Next, cold wire drawing is performed again to reduce the wire diameter to φ1.75.
After forming the wire into a wire of mm, an annealing treatment was performed, and then a deformed wire rod having a substantially rectangular cross section of the above dimensions was formed by cold rolling. Then, this irregularly shaped wire rod was subjected to gas carburization at a temperature of 1030°C, with a C content of 1.01 Wt% and a depth of 0.22
A carburized layer of mm thick was formed. And finally, the quenching temperature is 10
Quenching and tempering at 40°C and tempering temperature of 740°C,
The carburized layer was hardened.

[0028] Piston rings subjected to nitriding treatment were manufactured using the piston ring wire rods 1, 3, and 5 obtained according to the present invention, and the heat resistance and wear resistance of the piston rings were tested and evaluated. I did it.

As a result, it was confirmed that the piston ring was made of high C and high Cr martensitic stainless steel and had approximately the same heat resistance and wear resistance as a nitrided piston ring.

[0030] Furthermore, the piston ring wire of the present invention is
In terms of manufacturing cost, it is about 30 to 50% lower than the conventional piston ring wire rod made of high C and high Cr martensitic stainless steel.

[0031]

[Effects of the Invention] Since the piston ring wire rod of the present invention has the above structure, it has excellent cold wire drawability and rolling workability, and can be easily manufactured even with a complicated shape of the piston ring wire rod. When made into a piston ring, the nitriding treatment provides excellent heat resistance and wear resistance.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the piston ring wire material of the present invention.

FIG. 2 is a schematic diagram showing another embodiment of the piston ring wire rod of the present invention.

FIG. 3 is a schematic view showing another embodiment of the piston ring wire according to the present invention.

[Explanation of symbols]

1, 3, 5 Wire rod for piston rings 2, 4, 6 Carburized layer

Claims (1)

[Claims] Claim 1: In a piston ring wire rod formed by cold working, C: 0.3% or less, Cr
C: on the surface of a base material made of ferritic or martensitic stainless steel having a content of 11 to 30% by weight:
A wire rod for a piston ring, characterized by having a carburized layer of 0.6% to 1.2% and a depth of 0.2mm to 0.6mm.