CVT ring member and method for manufacturing the same
AssigneesAichi Steel Corporation, Toyota Jidosha Kabushiki Kaisha
InventorsTakeshi Udagawa, Yukio Ito, Koji Nishida
Life of this patent
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Abstract
Provided is a CVT ring member having a nitrided layer on a surface thereof. The CVT ring member includes a chemical composition containing, by mass, C: 0.43 to 0.70%, Si: 2.50% or less, Mn: 1.00% or less, Cr: 1.50 to 4.00%, Mo: 0.50 to 3.00% and V: 1.00% or less while satisfying a relation of Formula 1: 159×C(%)+91×Si(%)+68×Cr(%)+198×Mo (%)+646≥1,000, and the balance being Fe and unavoidable impurities. The ring member has a tensile strength of 1,700 MPa or more. The nitrided layer has a surface hardness of HV800 to HV950.
Claims2
A CVT ring member comprising:
- a ring material;
- and
- a nitrided layer on a surface of the ring material;
- the ring material in contact with the nitrided layer having a chemical composition consisting of by mass:
- C:
- 0.43 to 0.70%, Si:
- 0.10 to 2.50%, Mn:
- 0.10 to 1.00%, Cr:
- 2.01 to 4.00%, Mo:
- 0.50 to 3.00% and V greater than 0 and up to 1.00%, and the balance being Fe and unavoidable impurities by mass;
- wherein the chemical composition satisfies a relation of Formula 1:
- 159×C (%)+91×Si (%)+68×Cr (%)+198×Mo (%)+646≥1195.74;
- and the ring material has a crystal grain size of 15 μm or less;
- wherein
- the ring member has a tensile strength of 1,700 MPa or more;
- the nitrided layer has a surface hardness of from HV800 to HV950;
- and
- the ring member has a fatigue strength equal to or greater than the fatigue strength of a maraging steel having a nitride layer and the composition on a mass basis of 18.7% Ni, 5.02% Mo, 0.30% V, 0.12% Al, 0.45% Ti and 9.2% Co.
A CVT ring member comprising:
- a ring material;
- and
- a nitrided layer on a surface of the ring material;
- the ring material in contact with the nitrided layer having a chemical composition consisting of by mass:
- C:
- 0.43 to 0.70%, Si:
- 0.10 to 2.50%, Mn:
- 0.10 to 1.00%, Cr:
- 2.01 to 4.00%, Mo:
- 0.50 to 3.00% and V greater than 0 and up to 1.00%, and the balance being Fe and unavoidable impurities by mass;
- wherein the chemical composition satisfies a relation of Formula 1:
- 159×C (%)+91×Si (%)+68×Cr (%)+198×Mo (%)+646≥1195.74;
- wherein the ring material has a crystal grain size of from 9.8 to 14.9 μm;
- wherein
- the ring member has a tensile strength of 1,700 MPa or more;
- the nitrided layer has a surface hardness of from HV800 to HV950;
- and
- the ring member has a fatigue strength equal to or greater than the fatigue strength of a maraging steel having a nitride layer and the composition on a mass basis of 18.7% Ni, 5.02% Mo, 0.30% V, 0.12% Al, 0.45% Ti and 9.2% Co.
Dependencies are inferred from the claim text.