Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
• • 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
  • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • 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
  • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
  • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
  • C21D8/0426—Hot rolling
• • 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
  • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
  • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
  • C21D8/0473—Final recrystallisation annealing
• • 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
  • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
  • C21D8/0478—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing involving a particular surface treatment

Definitions

• ABSTRACT A low carbon, vacuum degassed steel containing co- I lumbium, titanium and/or zirconium, having high duetility, no yield point elongation in the hot rolled and cold rolled and annealed conditions.
• the steel contains from 0.002 to 0.020 percent carbon, up to 0.60 percent manganese, from greater than 0.025 to 0.12 percent columbium, titanium when present from 0.015 to 0.12 percent, zirconium when present from 0.028 to 0.18 percent, up to 0.008 percent nitrogen, up to 0.010 percent total oxygen, up to 0.035 percent sulfur, up to 0.045 percent total aluminum, and balance substantially iron.
• the steel has extra-deep drawing quality.
• Field of the Invention relates to non-aging, low carbon, vacuum degassed steel containing columbium, titanium and/or zirconium, which has high ductility, a high tensile to yield strength ratio, and absence of yield point elongation in the hot rolled and cold rolled and annealed conditions.
• the steel has great utility for hot rolled, cold rolled box annealed, cold rolled continuously annealed, and cold rolled continuously annealed and hot dip metallic coated products, or nonmetallic coated products.
• the steel of that application exhibits substantially no yield point elongation in the annealed condition, has excellent surface characteristics, substantial freedom from inclusions and freedom from critical grain growth.
• the steel consists essentially of from about 0.002 to about 0.015 percent carbon, from about 0.02 percent to about 0.30 percent columbium, from about 0.05 percent to about 0.60 percent manganese, sulfur up to about 0.035 percent, oxygen up to about 0.010 percent, nitrogen up to about 0.012 percent, aluminum up to about 0.080 percent, phosphorus and silicon in residual amounts, and remainder substantially iron.
• U.S. Pat. No. 3,522,110, issued July 28, 1970, to M. Shimizu et al. discloses a method of producing cold rolled steel alleged to be non-aging and to have excellent deep drawing properties.
• the steel contains from greater than 0.001 percent to less than 0.020 percent carbon, less than 0.45 percent manganese, less than 0.015 percent oxygen, less than 0.007 percent nitrogen, from greater than 0.02'percent to less than 0.5 percent titanium (except titanium present as titanium oxides), and the balance iron.
• the steel may contain sulfur in amounts of less than 0.05 percent and small amounts of aluminum. Titanium must be present in amounts greater than four times the carbon content.
• the process involves hot rolling the material at a temperature higher than 780 C (1,436 F), cold rolling with a reduction of more than 30 percent, and annealing at a temperature of from 650 to 1,000 C (1,202 to 1,832 F). Continuous annealing is stated to produce better properties in the product.
• the steel consists essentially of 0.020 percent maximum carbon, 0.60 percent maximum manganese, 0.010 percent maximum nitrogen, 0.015 percent maximum oxygen, 0.15 percent to 0.30 percent titanium, and balance essentially iron.
• a maximum of 0.03 percent sulfur may be present, and aluminum may be present in small amounts.
• the weight ratio of titanium to the sum of the carbon and nitrogen contents must be at least 7:1.
• the product is produced by hot rolling, finishing at a temperature above 1,550 F (843 C), cooling and coiling within a temperature range of 900 to 1,200 F (482 to 649 C), cold reducing by 50 to percent, and batch annealing within the temperature range of 1,550 F (843C) and the alpha-gamma transformation temperature.
• British Pat. No. 1,192,794 in the name of Nippon Kokan l(.l(., published May 20, 1970, discloses a process of producing a low carbon steel alleged to be substantially non-aging and to have good deep drawing properties, which comprises reducing the carbon content of a rimmed molten steel to less than 0.02 percent by vacuum degassing, adding a carbide former, forming cold rolled sheets, and annealing the sheets at 700 to 950 C (1,292 to 1,742 F).
• the carbide former is titanium, vanadium, columbium, tantalum, zirconium, uranium, hafnium, or thorium, and must be added in sufficient amount to reduce the solute carbon content at the annealing temperature to less than 0.002 percent. In the case of titanium, the content must be more than four times the carbon content.
• titanium has long been considered a highly effective element in eliminating aging and yield point elongation in low carbon steels.
• titanium-treated steels produced in accordance with the prior art processes have inherently rather low tensile strength in the cold rolled and annealed condition. This will be apparent from the data given hereinafter, wherein the average tensile strength of titanium-treated steels typical of the prior art is about 303 MN/m in the cold rolled and annealed condition.
• the Forand patent contemplates the addition of an excess-of titanium, at. least part of which will go into solid solution. This is apparent from the requirement for a minimum of 0.15 percent titanium in Forand.
• the steels contain from 0.02 to 0.50 percent carbon, from 0.005 to 0.5 percent silicon, from 0.15 to 1.6 percent manganese, 0.005 to 0.050 percent columbium, phosphorus and sulfur in residual amounts, and remainder iron.
• U.S. Pat. No 2,999,749 issued Sept. 12, 1961 to E. R. Saunders et al. discloses a method for producing non-aging rimmed steel which includes adding to a molten steel an addition agent containing at least 25 percent manganese and at least one of columbium, tantalum, vanadium and boron in an amount sufficient to combine with the nitrogen present.
• a deoxidant such as zirconium, titanium, beryllium, magbe: greater than 0.025 wt. percent if nesium, aluminum, calcium, silicon and/or barium, may be incorporated in the addition agent.
• titanium and columbium When titanium and columbium are used, the amount of titanium must be equal to or lessthan 4- X wt. percent carbon 3.43 X wt. percent nitrogen, except titanium as titanium oxides. Thisqnay be expressed as:
• the factor following 0.025 wt. percent represents the amount of columbium required to combine with that portion of the total carbon not already combined with titanium.
• the precipitation hardening effect of columbium carbides is avoided if less than 0.003 to 0.004 wt. percent of carbon is so combined.
• zirconium and columbium When zirconium and columbium are used, the amount of zirconium must be equal to or less than 7.6 X wt. percent carbon 6.51 X wt. percent nitrogen, except zirconium as zirconium oxides and zirconium sultides. This may be expressed as:
• compositions of the alloys conform to the requirements set forth above in (1), (2a) or (2b), or in (3), (4a) or (4b), the steels will have the following characteristics: 7
• the steels of the invention exhibit a finer grain size than steels treated with titanium alone. This is advantageous for some applications of cold rolled and batch annealed material, e.g., avoidance of orange peel surface on drawn parts where appearance is important such as chromium plated parts requiring jewelryquality finish.
• the steel of the invention has the following composition in the ingot or hot rolled band stage, all the percentages being by weight:
• Titanium about 0.015 to 0.12%, except Ti as Ti oxides Zirconium about 0.028 to 0.18%, except Zr as Zr oxides & sulfides Carbon about 0.002 to 0.020%
• all the nitrogen is combined as titanium or zirconium nitrides, and all the carbon exceeding 0.003 to 0.004 percent is combined as titanium or zirconium carbides.
• zirconium is used, all the sulfur is combined as a zirconium sulfide.
• composition range in the cold rolled and annealed stage will be essentially the same as stated above for the ingot or hot rolled band stage.
• the material will be subjected to processing conditions tending to cause pickup of nitrogen (e.g., tight coil annealing of cold rolled strip in a hydrogen-nitrogen atmosphere)
• the steel of the invention is produced by melting a charge of steel in any conventional manner having a maximum carbon content of about 0.05 percent, vacuum degassing the steel to a carbon content of about 0.020 percent maximum, an oxygen content of about 0.010 percent maximum, and a nitrogen content of about 0.008 percent maximum, adding titanium or zirconium in an amount calculated to be sufficient to react with all the carbon, nitrogen and oxygen (plus sulfur in the case of zirconium), adding columbium in an amount sufficient to produce greater than 0.025 percent columbium in solid solution in the hot rolled stage, as determined by sheet analysis at room temperature.
• the degassed steel is then cast into ingots or strand cast, solidified, hot rolled to band thickness finishing at conventional temperatures of about 816 C to about 927 C, and coiled in accordance with conventional practice.
• the hot rolled product will then ordinarily be pickled and cold reduced to final gauge, and subjected to a final anneal at about 705 to 788 C in a batch anneal, or up to 900 C strip temperature in a continuous anneal.
• the degassing step includes deoxidizing by addition of sufficient aluminum to eliminate excessive evolution of gases in advance of the columbium and titanium or zirconium additions. Silicon or titanium could also be substituted for aluminum at this stage as a deoxidant.
• the present invention differs from the above-mentioned Shimizu et al. US. Pat. No. 3,522,110 in requiring titanium (or zirconium) in combination with columbium, with the titanium content being equal to or less than 4 times the carbon content plus 3.43 times the nitrogen content.
• the patentees disclose a composition containing 0.001 to 0.020 percent carbon and 0.02 to 0.5 percent titanium (except titanium as oxides), with the titanium content being greater than four times the carbon content.
• the titanium content is equal to or less than four times the carbon content plus 3.43 times the nitrogen content.
• a minimum of 0.15 percent titanium is required in a steel having a maximum carbon of 0.020 percent and a maximum nitrogen of 0.010 percent, with the titanium content being a minimum of seven times the carbon plus nitrogen contents.
• the present invention requires titanium (or zirconium) and columbium, with a maximum titanium content of 0.12 percent and equal to or less than four times the carbon content plus 3.43 times the nitrogen content.
• titanium and zirconium have substantially equivalent functions when added with columbium, from what has been said above it will be apparent that there are some differences. It has been discovered that, unlike columbium, titanium and zirconium do not produce a precipitation hardening effect. On the other hand, titanium has only a very slight effect in retarding recrystallization, whereas zirconium has a strong effect in retarding recrystallization, comparable to that of columbium.
• Zirconium scavenges carbon, nitrogen and sulfur in the presence of columbium, manganese and aluminum. Titanium behaves similarly with respect to carbon and nitrogen. Titanium is a stronger carbide former than columbium. However, both titanium and zirconium preferentially react with nitrogen before carbon.
• exemplary compositions may be calculated in accordance with formulas (l) and (2a) or (2b), or (3) and (4a) or (4b), which will exhibit the desired properties.
• formulas (l) and (2a) or (2b), or (3) and (4a) or (4b) which will exhibit the desired properties.
• a tabulation is set forth below for titanium and columbium additions wherein the total carbon, nitrogen and columbium weight percents are given; the weight percent titanium includes the amount available to form carbides and nitrides, but excludes titanium as titanium oxides.
• columbium and titanium-treated steels and the columbium-treated steels in Table 11 are listed in the order of increasing carbon contents, respectively. It will be noted that carbon contents ranging from 0.0022 to 0.018 percent and coiling temperatures ranging from 649 to 726 C had very little effect on the tensile and elongation properties of hot rolled columbium and titanium-treated steels. In contrast to this, in a columbium-treated steel having a carbon content above about 0.005 percent low coiling temperature causes precipitation hardening. However, at lower carbon'levels coiling temperature has little effect on the hot rolled properties of columbium-treated steel.
• composition and properties of a columbium and zirconium-treated heat are set forth below in Tables V and V1, respectively.
• the columbium and zirconium-treated steel has a yield point elongation and relatively low r, value. 1n all other samples, wherein the uncombined columbium ranges from 0.027 to 0.044 percent, the product has no yield point elongation and thus is non-aging.
• Non-aging, low carbon steel having substantially no yield point elongation in the hot rolled and cold rolled and annealed conditions, consisting essentially of from about 0.002 percent to about 0.020 percent carbon, up to about 0.60 percent manganese, from greater than 0.025 percent to about 0.12 percent columbium, at least one of titanium and zirconium, titanium when present being from about 0.015 percent to about 0.12 percent, zirconium when present being from about 0.028 percent to about 0.18 percent, up to about 0.008 percent nitrogen, up to 0.010 percent total oxygen, up to about 0.035 percent sulfur, up to about 0.045 percent total aluminum, and balance substantially iron ex-' cept for incidental impurities, the titanium content being equal to or less than four times the weight percent carbon plus 3.43 times the weight percent nitrogen except titanium as titanium oxide, the zirconium content being equal to or less than 7.6 times the weight percent carbon plus 6.51 times the weight percent nitrogen except zirconium as zirconium sulfide and zirconium
• the steel claimed in claim 1 consisting essentially of from about 0.002 percent to about 0.010 percent carbon up to about 0.35 percent manganese, from greater than 0.025 percent to about 0.060 percent columbium, at least one of titanium and zirconium, titanium being from about 0.015 percent to about 0.061 percent, zirconium being from about 0.028 percent to about 0.12 percent, from about 0.002 percent to about 0.006 percent nitrogen, up to about 0.004 percent total oxygen, up toabout 0.020 percent sulfur, up to about 0.010 percent phosphorus, from about 0.015 percent to about 0.020 percent total aluminum, up to about 0.015 percent silicon, and balance substantially iron except for incidental impurities.
• the steel claimed in claim 1 consisting essentially of from about 0.002 percent to about 0.006 percent carbon, up to about 0.35 percent manganese, from greater than 0.025 percent to about 0.040 percent columbium, at least one of titanium and zirconium, titanium being from about 0.015 percent to about 0.045 percent, zirconium being from about 0.028 to 0.085 percent, from about 0.002 percent to about 0.006 percent nitrogen, up to about 0.004 percent total oxygen, up to about 0.01 percent sulfur, up to about 0.010 percent phosphorus, from about 0.015 percent to about 0.020 percent total aluminum, up to about 0.015 percent silicon, and balance substantially iron except for incidental impurities.
• Hot rolled thin bar having no yield point elongation, good formability and drawability and high tensile to yield strength ratios, consisting essentially of from about 0.002 percent to about 0.020 percent carbon, up to about 0.60 percent manganese, from greater than 0.025 percent to about 0.12 percent columbium, at least one of titanium and zirconium, titanium when present being from about 0.015 percent to about 0.12 percent, zirconium when present being from about 0.028 percent to about 0.18 percent, up to about 0.008 percent nitrogen, up to 0.010 percent total oxygen, up
• the titanium content being equal to or less than four times the weight percent carbon plus 3.43 times the weight percent nitrogen except titanium as titanium oxide
• the zirconium content being equal to or less than 7.6 times the weight percent carbon plus 6.51 times the weight percent nitrogen except zirconium as zirconium sulfide and zirconium oxide, there being greater than'0.025 percent columbium in uncombined form, and not more than 0.004 percent carbon combined with columbium.
• a cold reduced and annealed steel product having no yield point elongation, high plastic strain ratio, high tensile to yield strength ratio, and good tensile elongation consisting essentially of from about 0.002 percent to about 0.020 percent carbon, up to about 0.60 percent manganese, from greater than 0.025 percent to about 0.12 percent columbium, at least one of titanium and zirconium, titanium when present being from about 0.015 percent to about 0.12 percent, zirconium when present being from about 0.028 percent to about 0.18 percent, up to about 0.008 percent nitrogen, up to 0.010 percent total oxygen, up to about 0.035 percent sulfur, up to about 0.045 percent total aluminum, and balance substantially iron except for incidental impurities, the titanium content being equal to or less than four times the weight percent carbon plus 3.43 times the weight percent nitrogen except titanium as titanium oxide, the zirconium content being equal to or less than 7.6 times the weight percent carbon plus 6.51 times the weight percent nitrogen except zirconium as zirconium sul
• a method of producing a non-aging, low carbon steel having substantially no yield point elongation in the hot rolled and cold rolled and annealed conditions which comprises melting a charge of steel having a maximum carbon content of about 0.05 percent, vacuum degassing the steel to obtain a melt having a carbon content of about 0.020 percent maximum, a total oxygen content of about 0.010 percent maximum, a nitrogen content of about 0.008 percent maximum, up to about 0.6 percent manganese, up to about 0.035 percent sulfur, and balance substantially iron, deoxidizing by addition of a deoxidant chosen from the class consisting of aluminum, titanium and silicon, adding at least one of titanium and zirconium, titanium when used being added in an amount sufficient to obtain a titanium content in the hot rolled stage within the range of about 0.015 percent to about 0.12 percent, and zirconium when used being added in an amount sufficient to obtain a zirconium content in the hot rolled stage within the range of about 0.028 percent to about 0.18 percent, adding columbium in an amount
• the method of claim 8 including the steps of cleaning the surfaces of the cold rolled material, and applying a-metallic coating.
• the method of claim 8 including the steps of cleaning the surfaces of the cold rolled material, and applying a non-metallic coating.
• the method of claim 7, including the steps of pickling the hot rolled band, cold rolling to final gauge, cleaning the surfaces of the cold rolled material, and continuously annealing.

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Cited By (23)

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• 1972
  • 1972-05-19 US US00255108A patent/US3765874A/en not_active Expired - Lifetime
• 1973
  • 1973-04-26 ZA ZA732841A patent/ZA732841B/xx unknown
  • 1973-05-01 AU AU55079/73A patent/AU469152B2/en not_active Expired
  • 1973-05-04 CA CA170,473A patent/CA983293A/en not_active Expired
  • 1973-05-09 GB GB2214173A patent/GB1402492A/en not_active Expired
  • 1973-05-10 BE BE130964A patent/BE799357A/xx unknown
  • 1973-05-16 DE DE2324788A patent/DE2324788C2/de not_active Expired
  • 1973-05-16 NL NL7306803A patent/NL7306803A/xx not_active Application Discontinuation
  • 1973-05-17 SE SE7306999A patent/SE406089B/sv unknown
  • 1973-05-18 FR FR7318234A patent/FR2185690B1/fr not_active Expired
  • 1973-05-18 BR BR3676/73A patent/BR7303676D0/pt unknown
  • 1973-05-19 JP JP5622673A patent/JPS5412883B2/ja not_active Expired
  • 1973-05-19 ES ES414942A patent/ES414942A1/es not_active Expired
• 1976
  • 1976-12-06 SE SE7613671A patent/SE7613671L/xx unknown

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