Martensitic stainless steel having excellent hardness by subzero treatment

• US 4,846,904 A
• Filed: 05/19/1988
• Issued: 07/11/1989
• Est. Priority Date: 05/25/1987
• Status: Expired due to Fees

• Current Assignee: Nippon Metal Industry Company Limited (Nippon Steel Corporation)
• Original Assignee: Nippon Metal Industry Company Limited (Nippon Steel Corporation)
• Inventors: Arai, Hiroshi, Tanioka, Jyou, Mashimo, Kazuo, Murakami, Tadahiko
• Primary Examiner(s): Yee, Deborah
• Application Number:
  US07/195,841
• Time in Patent Office: 418 Days
• Field of Search: 420/56-61, 148/325, 148/326, 148/327
• US Class Current: 148/325
• CPC Class Codes: C21D 6/002 containing Cr C21D6/004 takes precedence
• CPC Class Codes: C21D 6/04 Hardening by cooling below 0 degrees Celsius
• CPC Class Codes: C22C 38/18 containing chromium
• CPC Class Codes: C22C 38/20 with copper
• CPC Class Codes: C22C 38/22 with molybdenum or tungsten
• CPC Class Codes: C22C 38/38 with more than 1.5% by weight of manganese
• CPC Class Codes: C22C 38/40 with nickel

Abstract

This invention provides the following stainless steels called invention steel 1 and invention steel 2.

Invention steel 1 is a subzero treatment hardening type martensitic stainless steel characterized by comprising not more than 0.4% by weight of C, not more than 0.4% by weight of N, not more than 15% by weight of Mn, not more than 12% by weight of Ni, 10 to 23% by weight of Cr, not more than 3.0% by weight of Mo, not more than 5.0% by weight of Cur, not more than 2.0% by weight of Si, and the remaining portion consisting of inevitable impurities and Fe and satisfying the following formaulae (1), (2) and (3),

[Cr %]+1.5[Si %]+[Mo %]-[Mn %)]-1.3[Ni %]-[Cu %]-19 [C %]-19[N

%]≦12.0 Formula (1)

27.5≦[Cr %]+1.3[SDi %]+1.3[Mn %]+1.5[Ni %]+[Cu %]+[Mo %]+15[C

%]+20[N %]≦32.0 Formula (2)

and

1.3[Ni %]+[Mn %]+[Cu %]>4.0                                Formula (3)

Invention steel is a subzero treatment hardening type martensitic stainless characterized by comprising not more than 0.4% by weight of C, not more than 0.4% by weight of Mn, not more than 3.0% by weight of Ni, 10 to 23% by weight of Cr, not more than 3.0% by weight of Mo, not more than 2.0% by weight of Cu, not more than 2.0% by weight of Si and the remaining portion consisting of inevitable impurities and Fe and satisfying the above formulae (1) and (2), and the following formula (4),

1.3[Ni %]+[Mn %]+[Cu %]≦4.0                         Formula (4)

Claims

1. A shaped and treated martensitic stainless steel having a hardening degree of over 1.3, obtained by hot rolling or cold rolling stainless steel which comprises not more than 0.4% by weight of C, not more than 0.4% by weight of N, not more than 15% by weight of Mn, not more than 12% by weight of Ni, 10 to 23% by weight of Cr, not more than 3.0% by weight of Mo, not more than 5.0% by weight of Cu, not more than 2.0% by weight of Si and the remaining portion consisting of Fe and inevitable impurities,

wherein the stainless steel composition satisfies the following formulae (1), (2) and (3)

View Dependent Claims (2, 3, 4, 5, 6, 7)

2. A stainless steel according to claim 1 wherein the Mn content is from more than 4.0% by weight to 15.0% by weight and the Ni content is from more than 3.0% by weight to 12.0% by weight.

3. A stainless steel according to claim 1 wherein the Mn content is from more than 4.0% by weight to 15.0% by weight and the Ni content is not more than 3.0% by weight.

4. A stainless steel according to claim 1 wherein the Mn content is not more than 4.0% by weight and the Ni content is from more than 3.0% by weight to 12.0% by weight.

5. A stainless steel according to claim 1 wherein the Mn content is not more than 4.0% by weight, the Ni content is not more than 3.0% by weight and the Cu content is from more than 2.0% by weight to 5.0% by weight.

6. A stainless steel according to claim 1 wherein the Mn content is not more than 4.0% by weight, the Ni content is from more than 3.0% by weight to 12.0% by weight and the Cu content is from more than 2.0% by weight to 5.0% by weight.

7. A stainless steel according to claim 1 wherein the Mn content is not more than 4.0% by weight, the Ni content is not more than 3.0% by weight and the Cu content is not more than 2.0% by weight.

8. A shaped and treated martensitic stainless steel having a hardening degree of over 1.3, obtained by hot rolling or cold rolling stainless steel which comprises not more than 0.4% by weight of C, not more than 0.4% by weight of N, not more than 4% by weight of Mn, not more than 3.0% by weight of Ni, 10 to 23% by weight of Cr, not more than 3.0% by weight of Mo, not more than 2.0% by weight of Cu, not more than 2.0% by weight of Si and the remaining portion consisting of Fe and inevitable impurities,

wherein the stainless steel composition satisfies the following formulae (1), (2) and (4)