US4279646A
Expired / Lapsed
US
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Free cutting steel containing sulfide inclusion particles with controlled aspect, size and distribution
Assignee: Daido Steel Co Ltd
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Filing: 1979-12-19
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Granted: 1981-07-21
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Expires: 1999-12-19
Abstract
Abstract A free cutting steel for machine structural use containing C up to 0.6%, Si up to 2.0%, Mn up to 2.0%, S 0.04 to 0.4%, Te 0.002 to 0.5% and O 0.0010 0.0300%, the balance being substantially Fe exhibits excellent machinability when the MnS-based inclusion is in the form of particles of 5 to 100μ long, 1 to 10μ wide, wherein the aspect ratio length/width is not larger than 10, and at the density of 20 to 200 particles per 1 mm 2 of the matrix cross section. A free cutting steel for machine structural use containing C up to 0.6%, Si up to 2.0%, Mn up to 2.0%, S 0.04 to 0.4% and Te up to 0.1%, wherein %Te/%S is at least 0.04, O up to 0.003% and N up to 0.0200%, the balance being substantially Fe exhibits improved rolling-contact fatique strength when at least 80% of sulfide-based inclusion particles of 10μ long or more have the aspect ratio length/width of 5 or less, and when areal percentage of alumina cluster in the matrix cross section is not higher than 0.5%.
Inventors
- 👤 Tetsuo Kato
- 👤 Shozo Abeyama
- 👤 Atsuyoshi Kimura
- 👤 Sadayuki Nakamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 03:23
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/60
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
89 words
A free cutting steel for machine structural use having excellent machinability comprising: C up to 0.6%, Si up to 2.0%, Mn up to 2.0%, S 0.04 to 0.4%, Te 0.002 to 0.50%, and O 0.0010 to 0.0300%, the balance being substantially Fe; and containing MnS-based inclusion in the form of particles of 5 to 100μ long, 1 to 10μ wide, wherein the aspect ratio defined by length/width is not larger than 10, and at a density of 20 to 200 particles per 1 mm 2 of matrix cross section.
Claim 2
Dependent Claim
89 words
A free cutting steel for machine structural use having excellent machinability comprising: C up to 0.6%, Si up to 2.0%, Mn up to 2.0%, S 0.04 to 0.4%, Te 0.002 to 0.50%, and O 0.0010 to 0.0300%, the balance being substantially Fe; and containing MnS-based inclusion in the form of particles of 5 to 100μ long, 1 to 10μ wide, wherein the aspect ratio defined by length/width is not larger than 10, and at a density of 20 to 200 particles per 1 mm 2 of matrix cross section.
Claim 3
Dependent Claim
15 words
A free cutting steel according to claim 1, which further contains P up to 0.10%.
Claim 4
Dependent Claim
15 words
A free cutting steel according to claim 1, which further contains Pb 0.03 to 0.30%.
Claim 5
Dependent Claim
28 words
A free cutting steel according to claim 1, which further contains one or more of Ni up to 4.5%, Cr up to 4.5% and Mo up to 1.0%.
Claim 6
Independent Claim
73 words
A method of making a free cutting steel for machine structural use having excellent machinability, which comprises hot rolling an ingot of a steel containing: C up to 0.6%, Si up to 2.0%, Mn up to 2.0%, S 0.04 to 0.4%, Te 0.002 to 0.50%, and O 0.0010 to 0.0300%, the balance being substantially Fe, under the condition of soaking temperature between 1,200° and 1,400° C., and a finishing temperature above 1,000° C.
Claim 7
Independent Claim
73 words
A method of making a free cutting steel for machine structural use having excellent machinability, which comprises hot rolling an ingot of a steel containing: C up to 0.6%, Si up to 2.0%, Mn up to 2.0%, S 0.04 to 0.4%, Te 0.002 to 0.50%, and O 0.0010 to 0.0300%, the balance being substantially Fe, under the condition of soaking temperature between 1,200° and 1,400° C., and a finishing temperature above 1,000° C.
Claim 8
Dependent Claim
101 words
A free cutting steel for machine structural use having improved rolling-contact fatigue strength comprising: C up to 0.6%, Si up to 2.0%, Mn up to 2.0%, S 0.04 to 0.4% and Te up to 0.1%, wherein the ratio %Te/%S is at least 0.04, O up to 0.0030%, and N up to 0.0200%, the balance being substantially Fe; characterized in that at least 80% of sulfide-based inclusion particles of 10μ long or more have the aspect ratio defined by length/width of 5 or less, and that the areal percentage of alumina cluster in the matrix cross section is not higher than 0.5%.
Claim 9
Dependent Claim
101 words
A free cutting steel for machine structural use having improved rolling-contact fatigue strength comprising: C up to 0.6%, Si up to 2.0%, Mn up to 2.0%, S 0.04 to 0.4% and Te up to 0.1%, wherein the ratio %Te/%S is at least 0.04, O up to 0.0030%, and N up to 0.0200%, the balance being substantially Fe; characterized in that at least 80% of sulfide-based inclusion particles of 10μ long or more have the aspect ratio defined by length/width of 5 or less, and that the areal percentage of alumina cluster in the matrix cross section is not higher than 0.5%.
Claim 10
Dependent Claim
57 words
A free cutting steel according to claim 6, which further contains one or more of the alloying elements selected from: P up to 0.1%, Pb up to 0.3%, Bi up to 0.3%, provided that Pb+Bi is not larger than 0.4%, Se up to 0.4%, provided that S+Se is not larger than 0.4%, and Ca up to 0.0100%.
Claim 11
Dependent Claim
70 words
A free cutting steel according to claim 6, which further contains one or more of the alloying elements selected from: Ni up to 6.0%, Cr up to 4.0%, Mo up to 2.0%, Al up to 2.0%, B up to 0.010%, V up to 0.5%, Ti up to 0.5%, Nb up to 0.5%, Ta up to 0.5%, Zr up to 0.5%, and REM (rare earth metals) up to 0.1% in total.
Claim 12
Dependent Claim
115 words
A free cutting steel according to claim 6, which further contains one or more of the alloying elements selected from: Ni up to 6.0%, Cr up to 4.0%, Mo up to 2.0%, Al up to 2.0%, B up to 0.010%, V up to 0.5%, Ti up to 0.5%, Nb up to 0.5%, Ta up to 0.5% Zr up to 0.5%, and REM up to 0.1% in total, together with one or more of the alloying elements selected from: P up to 0.1%, Pb up to 0.3%, Bi up to 0.3%, provided that Pb+Bi is not larger than 0.4%, Se up to 0.4%, provided that S+Se is not larger than 0.4%, and Ca up to 0.0100%.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-07-20 | 1985-01-19 | 1985-07-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-20 | 1989-01-19 | 1989-07-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-20 | 1993-01-19 | 1993-07-21 | $7700.00 | Window Closed / Lapsed |