Heat-resisting steel for exhaust valves

Patent metadata

Field	Value
Publication number	US-9745649-B2
Application number	US-201214240187-A
Country	US
Kind code	B2
Filing date	Aug 24, 2012
Priority date	Aug 24, 2011
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

The object of the present invention is to provide a heat-resistant steel for exhaust valves, having relatively small Ni content, high mechanical characteristics (for example, tensile strength, fatigue strength, wear resistance and hardness) at high temperature, and excellent oxidation resistance. The present invention provides a heat-resistant steel for exhaust valves, which includes: 0.45≦C<0.60 mass %, 0.30<N<0.50 mass %, 19.0≦Cr<23.0 mass %, 5.0≦Ni<9.0 mass %, 8.5≦Mn<10.0 mass %, 2.5≦Mo<4.0 mass %, 0.01≦Si<0.50 mass %, and 0.01≦Nb<0.30 mass %, with the balance being Fe and unavoidable impurities, in which the steel satisfies 0.02≦Nb/C<0.70 and satisfies 4.5≦Mo/C<8.9.

First claim

The invention claimed is:

1. A heat-resistant steel for exhaust valves, consisting of:
0.45≦C<0.60 mass %,
0.30<N<0.50 mass %,
19.0≦Cr<23.0 mass %,
5.0≦Ni<9.0 mass %,
8.5≦Mn<10.0 mass %,
2.5≦Mo<4.0 mass %,
0.01≦Si<0.50 mass %, and
0.01≦Nb<0.30 mass %,
with the balance being Fe and unavoidable impurities;
the heat-resistant steel for exhaust valves satisfying 0.02≦Nb/C≦0.61 and 4.5≦Mo/C≦8.0.

2. The heat-resistant steel for exhaust valves according to claim 1 , which satisfies 5.2≦Mo/C≦8.0.

3. A heat-resistant steel for exhaust valves, consisting of:
0.45≦C<0.60 mass %,
0.30<N<0.50 mass %,
19.0≦Cr<23.0 mass %,
5.0≦Ni<9.0 mass %,
8.5≦Mn<10.0 mass %,
2.5≦Mo<4.0 mass %,
0.01≦Si<0.50 mass %,
0.01≦Nb<0.30 mass %, and
0.0001≦(Al, Mg, Ca)<0.01 mass %
with the balance being Fe and unavoidable impurities;
the heat-resistant steel for exhaust valves satisfying 0.02≦Nb/C≦0.61 and 4.5≦Mo/C≦8.0.

4. A heat-resistant steel for exhaust valves, consisting of:
0.45≦C<0.60 mass %,
0.30<N<0.50 mass %,
19.0≦Cr<23.0 mass %,
5.0≦Ni<9.0 mass %,
8.5≦Mn<10.0 mass %,
2.5≦Mo<4.0 mass %,
0.01≦Si<0.50 mass %,
0.01≦Nb<0.30 mass %, and
at least one selected from 0.0001≦B<0.03 mass % and 0.0001≦Zr<0.1 mass %,
with the balance being Fe and unavoidable impurities;
the heat-resistant steel for exhaust valves satisfying 0.02≦Nb/C≦0.61 and 4.51≦Mo/C≦8.0.

5. The heat-resistant steel for exhaust valves according to claim 3 , which satisfies 5.2≦Mo/C≦8.0.

6. The heat-resistant steel for exhaust valves according to claim 4 , which satisfies 5.2≦Mo/C≦8.0.

7. A heat-resistant steel for exhaust valves, consisting of:
0.45≦C<0.60 mass %,
0.30<N<0.50 mass %,
19.0≦Cr<23.0 mass %,
5.0≦Ni<9.0 mass %,
8.5≦Mn<10.0 mass %,
2.5≦Mo<4.0 mass %,
0.01≦Si<0.50 mass %,
0.01≦Nb<0.30 mass %, and
0.0001≦(Al, Mg, Ca)<0.01 mass %, and
at least one selected from 0.0001≦B<0.03 mass % and 0.0001≦Zr<0.1 mass %,
with the balance being Fe and unavoidable impurities;
the heat-resistant steel for exhaust valves satisfying 0.02≦Nb/C≦0.61 and 4.5≦Mo/C≦8.0.

8. The heat-resistant steel according to claim 7 , which satisfies 5.2≦Mo/C≦8.0.

Assignees

• Osaki Mototsugu
• Ueta Shigeki
• Tsuyumu Takashi
• Daido Steel Co Ltd
• Honda Motor Co Ltd

Inventors

• Osaki Mototsugu
• Ueta Shigeki
• Tsuyumu Takashi

Classifications

• C22C38/02

  containing silicon · CPC title

• F01L3/02

  Selecting particular materials for valve-members or valve-seats; Valve-members or valve-seats composed of two or more materials · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C22C38/58 Primary

  with more than 1.5% by weight of manganese · CPC title

• C21D6/004

  containing Cr and Ni · CPC title