US3900347A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cold-drawn, straightened and stress relieved steel wire for prestressed concrete and method for production thereof
Assignee: Armco Inc
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Filing: 1974-08-27
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Granted: 1975-08-19
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Expires: 1994-08-27
Abstract
Abstract Cold-drawn, straightened and stress relieved high carbon steel wire for prestressed concrete, and a method for the production thereof, having reduced load loss due to stress relaxation and good ductility. The steel comprises, by weight percent, from about 0.70 percent to about 0.90 percent carbon, about 0.5 percent to about 1.0 percent manganese, about 0.025 percent maximum phosphorus, about 0.035 percent maximum sulfur, about 0.15 percent to about 0.35 percent silicon, about 0.010 percent to about 0.020 percent nitrogen, about 0.010 percent to about 0.030 percent columbium, and remainder essentially iron except for incidental impurities. The cold-drawn wire has a pearlitic microstructure wherein the pearlite colony size is reduced by adding columbium to confer good ductility, and sufficient uncombined nitrogen is present to provide improved stress relaxation properties. Processing includes austenitizing a hotreduced rod stock at about 980*C to about 1030*C and isothermal treating at about 540* to about 590*C, followed by air cooling. The stock is then cold-drawn into wire, straightened, and stress relieved.
Inventors
- 👤 James J Lorenzetti
- 👤 James N Cordea
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:04
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/12; C21; C21D; C21D8/00; C21D8/06; C21D8/08; C22C38/001
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
119 words
Cold-drawn, high carbon steel wire for prestressed concrete having a fully pearlitic microstructure, reduced load loss due to stress relaxation, and good ductility, said wire being cold-drawn from hot reduced rod stock having a tensile reduction-in-area value of at least about 25 percent after austenitizing and transformation to pearlite, said steel consisting essentially of, by weight percent, from about 0.70 to about 0.90 percent carbon, about 0.5 to about 1.0 percent manganese, about 0.025 percent maximum phosphorus, about 0.035 percent maximum sulfur, about 0.15 to about 0.35 percent silicon, about 0.010 to about 0.020percent total nitrogen, about 0.010 to about 0.030 percent columbium, substantially all the columbium being combined with carbon, and remainder essentially iron except for incidental impurities.
Claim 2
Dependent Claim
119 words
Cold-drawn, high carbon steel wire for prestressed concrete having a fully pearlitic microstructure, reduced load loss due to stress relaxation, and good ductility, said wire being cold-drawn from hot reduced rod stock having a tensile reduction-in-area value of at least about 25 percent after austenitizing and transformation to pearlite, said steel consisting essentially of, by weight percent, from about 0.70 to about 0.90 percent carbon, about 0.5 to about 1.0 percent manganese, about 0.025 percent maximum phosphorus, about 0.035 percent maximum sulfur, about 0.15 to about 0.35 percent silicon, about 0.010 to about 0.020percent total nitrogen, about 0.010 to about 0.030 percent columbium, substantially all the columbium being combined with carbon, and remainder essentially iron except for incidental impurities.
Claim 3
Dependent Claim
53 words
The wire claimed in claim 1, wherein carbon is from about 0.80 to about 0.85 percent, manganese is from about 0.80 to about 0.90 percent, silicon is from about 0.20 to about 0.30 percent, nitrogen is from about 0.011 to about 0.016 percent, and columbium is from about 0.014 to about 0.020 percent.
Claim 4
Dependent Claim
16 words
The wire claimed in claim 1, wherein at least about 0.008 percent uncombined nitrogen is present.
Claim 5
Independent Claim
153 words
A METHOD OF PRODUCING COLD-DRAWN STEELWIRE FOR PRESTRESSED CONCRETE HAVING REDUCED LOAD LOSS DUE TO STRESS RELAXATION AND GOOD DUCTILITY, COMPRISING THE STEPS OF PROVIDING A SILICON KILLED, HOT REDUCED ROD STOCK CONSISTING ESSENTIALLY OF, BY WEIGHT PERCENT, FROM ABOUT 0.70 TO ABOUT 0.90 PERCENT CARBON, ABOUT 0.5 TO ABOUT 1.0 PERCENT MANGANESE, ABOUT 0.025 PERCENT MAXIMUM PHOSPHORUS, ABOUT 0.035 MAXIMUM SULFUR, ABOUT 0.15 TO ABOUT 0.35 PERCENT SILICON, ABOUT 0.010 TO ABOUT 0.020 PERCENT TOTAL NITROGEN ABOUT 0.010 TO ABOUT 0.030 PERCENT COLUMBIUM, AND REMAINDER IRON EXCEPT FOR INCIDENTAL IMPURITIES, AUSTENITIZING SAID STOCK BY HEATING IN THE RANGE OF ABOUT 980* TO ABOUT 1030*C, TRANSFORMING SAID STOCK TO A FULLY PEARLITIC MICROSTRUCTURE BY ISOTHERMAL HEATING TO ABOUT 540* TO ABOUT 590*C, AND AIR COOLING, WHEREBY TO OBTAIN A PEARLITE COLONY SIZE RANGING BETWEEN ABOUT 15 AND 30U, AND COLD-DRAWING, STRAIGHTENING AND STRESS RELIEVING SAID ROD STOCK INTO WIRE OF DESIRED FINAL DIAMETER.
Claim 6
Independent Claim
153 words
A METHOD OF PRODUCING COLD-DRAWN STEELWIRE FOR PRESTRESSED CONCRETE HAVING REDUCED LOAD LOSS DUE TO STRESS RELAXATION AND GOOD DUCTILITY, COMPRISING THE STEPS OF PROVIDING A SILICON KILLED, HOT REDUCED ROD STOCK CONSISTING ESSENTIALLY OF, BY WEIGHT PERCENT, FROM ABOUT 0.70 TO ABOUT 0.90 PERCENT CARBON, ABOUT 0.5 TO ABOUT 1.0 PERCENT MANGANESE, ABOUT 0.025 PERCENT MAXIMUM PHOSPHORUS, ABOUT 0.035 MAXIMUM SULFUR, ABOUT 0.15 TO ABOUT 0.35 PERCENT SILICON, ABOUT 0.010 TO ABOUT 0.020 PERCENT TOTAL NITROGEN ABOUT 0.010 TO ABOUT 0.030 PERCENT COLUMBIUM, AND REMAINDER IRON EXCEPT FOR INCIDENTAL IMPURITIES, AUSTENITIZING SAID STOCK BY HEATING IN THE RANGE OF ABOUT 980* TO ABOUT 1030*C, TRANSFORMING SAID STOCK TO A FULLY PEARLITIC MICROSTRUCTURE BY ISOTHERMAL HEATING TO ABOUT 540* TO ABOUT 590*C, AND AIR COOLING, WHEREBY TO OBTAIN A PEARLITE COLONY SIZE RANGING BETWEEN ABOUT 15 AND 30U, AND COLD-DRAWING, STRAIGHTENING AND STRESS RELIEVING SAID ROD STOCK INTO WIRE OF DESIRED FINAL DIAMETER.
Claim 7
Dependent Claim
49 words
The method claimed in claim 4, wherein said rod stock contains from about 0.80 to about 0.85 percent carbon, about 0.80 to about 0.90 percent manganese, about 0.20 to about 0.30 percent silicon, about 0.011 to about 0.016 percent nitrogen, and about 0.014 percent to about 0.020 percent columbium.
Claim 8
Dependent Claim
18 words
The method claimed in claim 4, wherein said prestressed wire contains at least about 0.008 percent uncombined nitrogen.
Claim 9
Dependent Claim
44 words
The method claimed in claim 4, wherein the columbium content is so selected as to result in formation of small columbium carbide particles which are distributed in the asutenite grain boundaries in the hot reduced rod stock, whereby to control the austenite grain size.
References Cited (Backward Citations)
US3532560A
Cited
US3844848A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-18 | 1979-02-17 | 1979-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-18 | 1983-02-17 | 1983-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-18 | 1987-02-17 | 1987-08-19 | $7700.00 | Window Closed / Lapsed |