US3709744A - Method for producing low carbon steel with exceptionally high drawability - Google Patents

Method for producing low carbon steel with exceptionally high drawability Download PDF

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Publication number
US3709744A
US3709744A US00015018A US3709744DA US3709744A US 3709744 A US3709744 A US 3709744A US 00015018 A US00015018 A US 00015018A US 3709744D A US3709744D A US 3709744DA US 3709744 A US3709744 A US 3709744A
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United States
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steel
values
sheet
temperature
value
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Expired - Lifetime
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US00015018A
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English (en)
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S Goodman
H Hu
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United States Steel Corp
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United States Steel Corp
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Assigned to USX CORPORATION, A CORP. OF DE reassignment USX CORPORATION, A CORP. OF DE MERGER (SEE DOCUMENT FOR DETAILS). Assignors: UNITED STATES STEEL CORPORATION (MERGED INTO)
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    • 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
    • C21D8/041—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 fabrication or treatment of ingot or slab
    • 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
    • C21D2201/00—Treatment for obtaining particular effects
    • C21D2201/05—Grain orientation
    • 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
    • C21D8/0421—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
    • C21D8/0436—Cold 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

Definitions

  • a sheet steel with exceptionally high drawability (R value greater than 1.5) and high yield strength is produced by adjusting the melt to less than 0.15% Mn, 0.03 to 0.1% C, 0.004 to 0.03% S and less than 150 p.p.m. oxygen.
  • the slab cast from the above melt is then hot rolled, only above the A temperature, cold reduced from 60 to 80% and soaked at temperatures of 1200 F. to 1350 F. for 12 to 30 hours.
  • R values greater than 2.0 may be obtained by finish hot rolling within a narrow temperature range (just above the A and employing less than 0.07/ Mn.
  • This invention is directed to a method of producing sheet steel of improved deep-drawing characteristics by judicious control of both the compositional and processing variables.
  • low-carbon sheet steels are used commercially for deep drawing. These are the low-carbon rimmed steels and the aluminum-killed steels.
  • Low-carbon rimmed steels are more economical and have better surface characteristics than aluminum-killed steels; however, they do not have the very high drawing properties of aluminum-killed steels which are necessary for more extreme draws.
  • Other elements, particularly titanium, having a high afiinity to oxygen, are also sometimes used, alone or in conjunction with conventional deoxidizers, as aluminum, in the production of killed steels.
  • Aluminum-titanium or aluminum/titanium-killed steels although, although superior in deep-drawing properties, do not appear to be practical for continuous casting.
  • the drawability of sheet material can be evaluated by simple tension tests. When a strip specimen is pulled to a greater length, its width and thickness are decreased.
  • the plastic strain ratio can serve as an indication of the degree of mechanical anistropy of the material. This ratio is referred to as the R value and is defined as the ratio of percent change in width (e,,, the width strain) to the percent change in thickness (e,, the thickness strain), i.e.
  • W and L are the width and length, respectively, of the gauge section, and the subscripts i and f refer to the initial and final measurements (before and after straining) of these dimensions.
  • This expression is based on the assumption that the volume of the gauge section remains constant during testing and it eliminates the direct measurement of the thickness which owing to its small value in a sheet material yields less accurate results.
  • the R value is, therefore, a useful parameter for indicating the degree of mechanical anisotropy of a given material.
  • the R value is equal to one. If R is less than one, the sheet thins unduly and is, therefore, undesirable for drawing operations. For very deep draws, it is preferable to have R values equal to or greater than about 1.5, preferably greater than 1.7.
  • R The difference among the individual R values indicates the earing tendency of the sheet during drawing.
  • a uniform value of R is also highly desirable.
  • the variation of R in the plane of the sheet is sometimes designated as AR, which is defined as:
  • the crystallographic texture of a specimen is normally determined by the construction of complete pole figures from X-ray intensity measurements; however, for detection of small variation in the texture, a direct comparison of two pole figures cannot reveal the detailed dilferences quantitatively. Accordingly, it has been found best to measure the integrated peak intensities of several reflections from the plane of the sheet and express them in units of corresponding peak intensities of a random specimen. The numerical values of these relative intensities so obtained are directly proportional to the pole densities of a specific plane lying parallel to the plane of the sheet. Since the drawability of a sheet depends on the relative population of specific crystallographic planes in the plane of the sheet, this technique is very useful. The intensities of five diflerent reflections, i.e.
  • the intensity of the (222) reflection which is the second order reflection of the (111) therefore represents the amount of (111) texture.
  • the intensity of the (200) reflection represents the amount of the (100) texture, respectively.
  • n is a second fundamental factor in deep drawability, in conjunction wtih R values.
  • the exponent n is determined experimentally as the slope of the plot of log true stress versus log true strain in the region of uniform strain.
  • High n values are favorable to improved drawability, although the n value is more markedly dependent upon microstructural factors than upon crystallographic texture.
  • n usually varies from 0.20 to about 0.30 in drawing quality steels.
  • a further object of this invention is to provide a composition of only moderately low carbon content which will yield a combination of high E values and low AR values without sacrificing yield strength and without the necessity of subjecting sheets thereof to expensive de- Composition, wt. percent Broad Preferred Element:
  • other elements e.g. Al or T1
  • FIG. 1 is a graph depicting how the R value obtainable is a function of hot rolling temperature.
  • FIG. 2 is a graph relating manganese content of the steel compositions of this invention with obtainable R values for sheets processed as herein described.
  • compositions (Table I, samples I and II) were Another object of this invention is to provide a process 50 hot rolled to a final thickness of 0.100 in. in six nearly for producing sheets of the above compositions so that maximum E value potential may be achieved.
  • This invention is based on the discovery that a number of compositional and processing variables are critical for providing maximum E values.
  • the carbon content of deep-drawing steels is generally in the range of .03 to .1%.
  • the melt of such a steel is adjusted so that the Mn content is kept below about 0.15% and the oxygen content below about .015 the subsequent critical mechanical and heat treatments will yield a steel with the desirable high E values.
  • the cast slab, having a composition within the foregoing range be hot rolled at a temperature sufiiciently high to ensure that the final hot rolling pass be made above the temperature at which proeutectoid ferrite will form.
  • a range of 0.01% to about 0.03 sulfur is desirable, both for minimizing planar anisotropy and increasing the yield strength (e.g., see also steels N through Q).
  • the upper limit being determined by the tendency to hot shortness with such low Mn steels.
  • addition elements such as Al or Ti are used to diminish this problem, then somewhat higher values of sulfur may be employed.
  • composition variable found critical for the purpose of this invention is the oxygen content, which should be low to minimize or prevent hot shortness of the steel during hot rolling. It may be seen from Table IV that when the oxygen content in the steel reached a lavel of 250-300 p.p.m., there was a detrimental effect on the development of a steel with high If values.
  • the product of this invention is therefore produced in the following manner.
  • the heat is melted to the prescribed composition.
  • Vacuum carbon deoxidation of the melt is employed to reduce the oxygen content of the steel to 150 ppm. or less so that the resulting steel slab (produced by either convention ingot practice or by continuous casting) has a composition within the prescribed range.
  • the slabs are hot rolled (reheated if needed) at a sufiiciently high temperature (-2250 F.) to ensure that the final hot rolling pass is made at a temperature above that at which proeutectoid ferrite will form.
  • the steel is then coiled at about 1000 F.-1150 F. and cooled in air to room temperature. Hot mill scale is removed and the steel is cold reduced 60-80% to final gauge.
  • the desired maximum E values will not be as readily obtained with cold reduction outside of this range, and it is therefore preferable to adjust the hot rolled thickness, so that a cold reduction of about 70% will provide the final gauge.
  • the strip is then open wound and box annealed by conventional practice, i.e. slow heating to soak temperature and a soak of approximately 1300" F. for a minimum of 12 hours, with about 20 hours being preferred to obtain the desired texture and high E values disclosed by this invention.
  • a method for producing a sheet steel of exceptionally high drawability which comprises (a) adjusting the composition of a steel melt so that it consists essentially of manganese .005 to .15%, car- 7 bon .03 to .1%, sulfur .004 to .03% and less than .015% oxygen, balance iron;
  • planar anisotropy of the sheet is minimized by adjusting sulfur content of the melt to above .01%.
  • step (a) is accomplished by vacuum carbon deoxidation.
  • composition of the melt is adjusted so that it consists essentially of, by weight percent carbon-0.03 to 0.075 manganese-0.005 to 0.07 silicon0.06 max. sulfur0.01 to 0.02
  • composition in accord with claim 9 consisting essentially of carbon0.03 to 0.075 manganese-0.005 to 0.07 silicon0.06 max. sulfur-'0.01 to 0.02 phosphorus-0.01 max. oxygen--0.01 max. iron-balance.

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  • 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 Steel (AREA)
US00015018A 1970-02-27 1970-02-27 Method for producing low carbon steel with exceptionally high drawability Expired - Lifetime US3709744A (en)

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US1501870A 1970-02-27 1970-02-27

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US (1) US3709744A (enrdf_load_stackoverflow)
BE (1) BE763282A (enrdf_load_stackoverflow)
CA (1) CA947123A (enrdf_load_stackoverflow)
DE (1) DE2108788A1 (enrdf_load_stackoverflow)
FR (1) FR2080808B1 (enrdf_load_stackoverflow)
GB (1) GB1339458A (enrdf_load_stackoverflow)
SE (1) SE375326B (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3926692A (en) * 1974-09-30 1975-12-16 United States Steel Corp Drawability of deoxidized steels by the addition of phosphorus and silicon
US4042380A (en) * 1975-05-14 1977-08-16 Kobe Steel, Ltd. Grain refined free-machining steel
EP0132365A3 (en) * 1983-07-20 1988-08-31 Armco Inc. Process of making aluminum killed low manganese deep drawing steel

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4069070A (en) * 1975-11-20 1978-01-17 United States Steel Corporation Method of producing low carbon tin-mill gage steel without annealing border
JPS5531159A (en) * 1978-08-26 1980-03-05 Sumitomo Metal Ind Ltd Manufacture of high strength cold rolled steel plate for press working

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2003110B1 (enrdf_load_stackoverflow) * 1968-03-02 1974-07-12 Yawata Iron & Steel Co
JPS541644B1 (enrdf_load_stackoverflow) * 1968-07-29 1979-01-27

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3926692A (en) * 1974-09-30 1975-12-16 United States Steel Corp Drawability of deoxidized steels by the addition of phosphorus and silicon
US4042380A (en) * 1975-05-14 1977-08-16 Kobe Steel, Ltd. Grain refined free-machining steel
EP0132365A3 (en) * 1983-07-20 1988-08-31 Armco Inc. Process of making aluminum killed low manganese deep drawing steel

Also Published As

Publication number Publication date
FR2080808A1 (enrdf_load_stackoverflow) 1971-11-19
DE2108788A1 (de) 1971-09-09
FR2080808B1 (enrdf_load_stackoverflow) 1975-02-21
CA947123A (en) 1974-05-14
GB1339458A (en) 1973-12-05
BE763282A (fr) 1971-08-23
SE375326B (enrdf_load_stackoverflow) 1975-04-14

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Owner name: USX CORPORATION, A CORP. OF DE, STATELESS

Free format text: MERGER;ASSIGNOR:UNITED STATES STEEL CORPORATION (MERGED INTO);REEL/FRAME:005060/0960

Effective date: 19880112