Martensitic stainless steel and antifriction bearing using the same
View Patent ↗A martensitic stainless steel with high hardness and high corrosion resistance consists of, by weight %, 0.35 to 0.45% of C, not more than 0.2% of Si, not more than 0.3% of Mn, not more than 0.02% of P, not more than 0.02% of S, 15 to 17% of Cr, 1.5 to 2.5% of Mo, 0.001 to 0.003% of B, 0.15 to 0.25% of N, and the balance of Fe and inevitable impurities.
1. An antifriction bearing comprising:
an inner ring;
an outer ring; and
a rolling element,
wherein at least one of the inner ring, the outer ring, and the rolling element is made of a martensitic stainless steel consisting essentially of, by weight %, 0.35 to 0.45% of C, less than 0.2% of Si, not more than 0.3% of Mn, not more than 0.02% of P, not more than 0.02% of S, 15 to 17% of Cr, 1.5 to 2.5% of Mo, 0.001 to 0.003% of B, 0.015 to 0.25% of N, 0.1 to 0.2% of W, and the balance of Fe and inevitable impurities, wherein BN is precipitated but M 23 C 6 type Carbide is not precipitated in the martensitic stainless steel.
2. The antifriction bearing according to claim 1 , wherein, when the amount of C is represented as CW and the amount of N is represented as NW, the total of CW and NW is in a range of 0.60 to 0.65%.
3. The antifriction bearing according to claim 1 , wherein the amount of Si is not more than 0.18 weight %.
4. The antifriction bearing according to claim 1 , wherein the amount of Mn is 0.25 weight % or more and the martensitic stainless steel includes 7.3% or less of residual austenite.
5. The antifriction bearing according to claim 1 , wherein the martensitic stainless steel has a hardness of not less than HRC 60.
6. A martensitic stainless steel consisting essentially of, by weight %, 0.35 to 0.45% of C, less than 0.2% of Si, not more than 0.3% of Mn, not more than 0.02% of P, not more than 0.02% of S, 15 to 17% of Cr, 1.5 to 2.5% of Mo, 0.001 to 0.003% of B, 0.15 to 0.25% of N, 0.1 to 0.2% of W, and the balance of Fe and inevitable impurities, wherein BN is precipitated but M 23 C 6 type Carbide is not precipitated in the martensitic stainless steel.
7. The martensitic stainless steel according to claim 6 , wherein, when the amount of C is represented as CW and the amount of N is represented as NW, the total of CW and NW is in a range of 0.60 to 0.65%.
8. The martensitic stainless steel according to claim 6 , wherein the amount of Si is not more than 0.18 weight %.
9. The martensitic stainless steel according to claim 6 , wherein the amount of Mn is 0.25 weight % or more and the martensitic stainless steel includes 7.3% or less of residual austenite.
10. The martensitic stainless steel according to claim 6 , wherein the martensitic stainless steel has a hardness of not less than HRC 60.