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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12431—Foil or filament smaller than 6 mils

Definitions

• the present invention relates to a high-strength steel. More particularly, the invention concerns a steel suitable for patenting and for the manufacture of highstrength wire. Steel in accordance with the invention is characterized by a very fine pearlite spacing in the patented condition.
• High-strength wire has been drawn from pearlitic steel for many years and it has been known that fine pearlite results in a higher-strength product than coarse pearlite.
• the fineness of the pearlite is determined in part by the heat treatment to which the steel is subjected.
• a common heat treatmentfor steel used in wire production is referred to as patenting.
• Patenting is a heat treatment applied to rods and wire having a carbon content of 0.4% and higher.
• the object of patenting is to obtain a structure which combines high tensile strength with high ductility. In the case of wire this structure provides the ability to withstand heavy drafting to produce the desired finished sizes with the required high tensile strength and toughness.
• Patenting is .always conducted as a continuous process and consists of first heating the material to a point well above the critical temperature and then cooling from the critical temperature at a rapid rate to a predetermined temperature level at which a transformation will yield the desired microstructure and mechanical properties.
• the work is continuously passed through a molten metal bath of controlled temperature.
• the patenting temperature and the speed of the patenting temperature are adjusted to provide minimum time at temperature.
• the transformation line is lowered too much, i.e. into the bainite range, coarse upper bainite is formed which results in a somewhat weaker metallurgical structure after working, i.e., drawing.
• the finest pearlite structure that can be developed for patenting is determined by the isothermal transformation characteristics of the steel being used.
• the present invention provides a novel steel composition which is capable of achieving a very fine pearlite spacing upon heat treating, e.g. patenting.
• a steel consisting essentially of, in percent by weight, 0.85 to 1.0% carbon, 1.0 to 4.0% cobalt, preferably 2.0 to 4.0% cobalt, up to 0.5 preferably 0.2 to 0.5% or at least one element from the group consisting of molybdenum, chromium and tungsten, up to 0.7% manganese, preferably 0.2 to 0.4%, and the balance iron with normal steel-making residuals.
• Any steel-making processes capable of producing a clean highquality melt may be employed in making an alloy in accordance with the invention.
• a characteristic of the novel steel composition described above is that in the patented condition, it can be made to achieve a pearlite spacing not greater than about 400 angstroms in a metallurgical structure consisting of at least pearlite, and preferably as close to pearlite as practical.
• fine pearlite spacing refers to the aforementioned maximum spacing of about 400 angstroms between carbide platelets in the pearlite.
• a series of 300 lb. heats of steel having the composition of steels A and B described in Table I were vacuum melted and cast into ingots which were then forged into 4-inch billets.
• the billets were hot rolled to -inch rod.
• the hot-rolled rod was drawn in four stages to 0.005- inch wire.
• the first patenting operation was. performed on the -inch rod and comprised heating at 1800 F. for 360 seconds, prequenching to 550 F. for 37 seconds, and reheating to 900 F. for 27 seconds.
• the rod was then dry drawn to 0.220-inch wire after which it was patented by heating at 1800 F. for seconds, prequenched to 550 F.
• the O.22()-inch wire was dry drawn to 0.102-inch wire and patented for the third time.
• the third patenting step comprised heating at 1800" F. for 75 seconds, prequenching to 550 F. for 12 seconds and reheating to 900 F. for 8 /2 seconds.
• the 0.102-inch wire was dry drawn to 0.032-inch wire and given a final patenting which comprised heating at 1800 F. for 1 8 seconds, prequenching 2 seconds at 550 F. and reheating to 1000 F. for 2% seconds.
• the patented 0.032-inch wire was then given a flash coating of copper and wet drawn (with water) to 0.005-inch wire.
• the pearlite spacing was less than 400 angstroms.
• the 2.0% cobalt wire had a yield strength of about 550,000 p.s.i. and the 4.0% cobalt had a yield strength of about 600,000 p.s.i.
• the wire When drawn to 0.003- inch diameter, the wire had a yield strength of 700,000 p.s.i. This is to be contrasted with plain wire of the same diameter treated in the same manner which has a yield strength of about 520,000 p.s.i. and is characterized by a pearlite spacing of greater than 400 angstroms.
• a steel wire not greater than 0.007-inch diameter having a yield strength of at least 550,000 p.s.i. and a pearlite spacing not greater than about 400 angstroms consisting essentially of, in percent by weight, 0.85 to 1.0% carbon, 1.0 to 4.0% cobalt, up to 0.5% of at least one element from the group consisting of molybdenum, chromium and tungsten, up to 0.7% manganese and the balance iron and normal steel-making residuals.
• a steel wire in accordance with claim 1 having 0.2 to0.5% of at least one of molybdenum, chromium and tungsten.
• a steel wire in accordance with claim 1 having 0.2

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (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 Strip Materials And Filament Materials (AREA)
• Heat Treatment Of Steel (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=24575341

Family Applications (1)

Country Status (5)

Cited By (5)

Citations (3)

• 1967
  • 1967-05-29 US US642134A patent/US3507711A/en not_active Expired - Lifetime
• 1968
  • 1968-05-08 GB GB21830/68A patent/GB1220870A/en not_active Expired
  • 1968-05-24 BE BE715669D patent/BE715669A/xx unknown
  • 1968-05-24 DE DE19681758401 patent/DE1758401A1/de active Pending
  • 1968-05-29 FR FR1579586D patent/FR1579586A/fr not_active Expired

Patent Citations (3)

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