Piston ring and its production method
AssigneeRiken
InventorYuji Shima
Life of this patent
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Abstract
To provide a piston ring free from microwelding to a piston while exhibiting excellent wear resistance in side surfaces, for a long period of use in a high-temperature, high-pressure environment, and its production method, a nitride layer is formed on at least one of upper and lower side surfaces of the piston ring, and then subjected to a phosphate chemical conversion treatment, such that the nitride layer has at least one of granular and vermicular surface forms.
Claims13
A piston ring made of steel, which has a nitride layer formed on at least one of upper and lower side surfaces, said nitride layer having at least one of granular and vermicular surface forms, wherein
- a surface roughness curve of said nitride layer has the maximum height Rz of 2.5-6 μm.
A piston ring made of steel, which has a nitride layer formed on at least one of upper and lower side surfaces, said nitride layer having at least one of granular and vermicular surface forms, wherein
- a matrix of said piston ring, on which said nitride layer is formed, is made of a steel comprising C, Si, Mn and Cr as indispensable alloy elements, and Mo, V and B as optional alloy elements;
- the composition of said indispensable alloy elements comprising by mass 0.45-0.65% of C, 0.15-0.35% of Si, 0.65-1.00% of Mn, and 0.60-1.10% of Cr;
- the composition of said optional alloy elements comprising by mass less than 0.35% of Mo, less than 0.25% of V, and less than 0.001% of B;
- and the total amount of said indispensable alloy elements and said optional alloy elements being less than 3.0% by mass,
- said nitride layer has hardness of 700 HV0.05 or more in a range from the outermost surface to the depth of 30 μm, and
- said nitride layer has a hardness reduction ratio of 3 HV0.05/μm or less in a range from the outermost surface to the depth of 30 μm in a depth direction.
A piston ring made of steel, which has a nitride layer formed on at least one of upper and lower side surfaces, said nitride layer having at least one of granular and vermicular surface forms, wherein
- a matrix of said piston ring, on which said nitride layer is formed, is made of a steel comprising C, Si, Mn and Cr as indispensable alloy elements, and Mo, V and B as optional alloy elements;
- the composition of said indispensable alloy elements comprising by mass 0.45-0.65% of C, 0.15-0.35% of Si, 0.65-1.00% of Mn, and 0.60-1.10% of Cr;
- the composition of said optional alloy elements comprising by mass less than 0.35% of Mo, less than 0.25% of V, and less than 0.001% of B;
- and the total amount of said indispensable alloy elements and said optional alloy elements being less than 3.0% by mass, and
- the hardness of said matrix is 90-100% of the hardness before nitriding.
Dependencies are inferred from the claim text.