Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0226—Hot rolling

Definitions

• a related object of this invention is to provide an inexpensive plain carbon steel having increased nitrogen content, and control the hot rolling and coiling temperature during processing to provide high strength steel strip.
• Yet another object of this invention is the provision of a method of producing a steel with high yield strength from plain carbon steel having a high nitrogen content.
• a steel blank having the following preferred composition, is provided: C, .16 to .20%; Mn, .40 to 58%; N, .010 to .013%; S, .040% max.; P, .020% max.; Si, .020% max.; Fe and residual impurities, balance.
• the blank is heated to hot rolling temperature and then conventionally hot reduced to steel strip on a multiple stand hot rolling mill. It is necessary that the blank be heated to a sufficiently high temperature so that the temperature of the strip as it emerges from the final stand, i.e., the finishing temperature, is at least 1520 F.
• the strip After the strip emerges from the final stand it is rapidly cooled to below 1050" F. and then coiled on a conventional coiler. It has been found that the preferable way to rapidly cool the strip to below 1050 F. before it enters the coiler is by the use of water sprays impinging on the strip between the final stand and the coiler.
• the resulting coil of strip will have a yield strength of at least 50,000 p.s.i. Also, the yield strength and other mechanical properties of the strip will be remarkably uniform throughout the length of the coiled strip.
• steel strip having a yield strength of over 50,000 p.s.i. can be produced from steel falling within the following broader composition limits: C, .10 to .20%; Mn, .40 to 60%; N, .008 to 015%; S, .050% max.; P, .040% max.; Si, .10% max.; Fe and residual impurities, balance.
• the coiled strip of steel produced by this invention is eminently suited for use in construction.
• excellent building purlins can be roll formed from this steel.
• a method of producing a coiled strip of hot rolled steel having a yield-strength of at least 50,000 p.s.i. in the hot rolled condition comprising the steps of providing a blank of steel consisting essentially of from .10% to .20% carbon, from .40% to .60% manganese, from .008% to .015 nitrogen, .040% maximum phosphorus, .050% maximum sulphur, .10% maximum silicon, the balance iron and residual impurities, the composition of said steel being further characterized by the limitation that when the percentage of any one of the carbon, manganese, or nitrogen is near the lower limit, the percentages of the remaining two elements should be near their higher limits, hot rolling the blank to form a strip of steel while maintaining the finishing temperature of said trip above 1520" F., rapidly cooling said strip to below 1050 F, and coiling said cooled strip.
• a carbon steel sheet having .10% to .20% carbon, .40% to .60% manganese, .040% maximum phosphorus, .050% maximum sulphur, .10% maximum silicon, and from 008% to .015% nitrogen, the balance iron and residual impurities, the composition of said steel being further characterized by the limitation that when the percentage of any one of the carbon, manganese, or nitrogen is near the lower limit, the percentages of the remaining two elements should be near their higher limits, having the properties of 50,000 p.s.i. yield-strength in the rolled condition and having been produced by hot rolling a blank of said steel with the finishing temperature having been maintained above 1520 F. and having been rapidly cooled to a temperature less than 1050 F. before coiling.
• a coiled strip of carbon steel having .16% to .20% carbon, .40% to .58% manganese, .020% maximum phosphorus, .040% maximum sulphur, .020% maximum silicon, and from 010% to .013% nitrogen, the balance iron and residual impurities, having the properties of 50,000 p.s.i. yield-strength in the hot rolled condition and having been produced by hot rolling a blank of said steel with the finishing temperature having been maintained above '1520 F. and having been rapidly cooled to a temperature less than 1050 F. before coiling.
• a method of producing a coiled strip of hot rolled steel, having a yield-strength of at least 50,000 p.s.i. in the hot rolled condition comprising the steps of providing a blank of steel consisting essentially of from .16% to .20% carbon, .40% to .58% manganese, .020% maximum phosphorous, 040% maximum sulphur, .020% maximum silicon, and from .010% to .013% nitrogen, the balance iron and residual impurities, hot rolling the blank to form a strip of steel while maintaining the finishing temperature of said strip above 1520 F., rapidly cooling said strip to below 1050 F. and coiling said cooled strip.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)
• Heat Treatment Of Steel (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22791136

Family Applications (1)

Country Status (5)

Cited By (5)

Citations (2)

• 0
  • BE BE635419D patent/BE635419A/xx unknown
• 1962
  • 1962-07-25 US US212464A patent/US3245844A/en not_active Expired - Lifetime
• 1963
  • 1963-07-23 DE DE19631433798 patent/DE1433798A1/de active Pending
  • 1963-07-24 ES ES290282A patent/ES290282A1/es not_active Expired
  • 1963-07-24 GB GB29390/63A patent/GB1004198A/en not_active Expired

Patent Citations (2)

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