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US3642468A - Steel sheet for press forming - Google Patents

Steel sheet for press forming Download PDF

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Publication number
US3642468A
US3642468A US858244A US3642468DA US3642468A US 3642468 A US3642468 A US 3642468A US 858244 A US858244 A US 858244A US 3642468D A US3642468D A US 3642468DA US 3642468 A US3642468 A US 3642468A
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US
United States
Prior art keywords
steel
percent
weight
value
steel sheet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US858244A
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English (en)
Inventor
Shinichi Nagashima
Hiroshi Takechi
Youichi Matsuo
Hiroshi Kato
Mineo Shimizu
Nobuyuki Takahashi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Nippon Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Steel Corp filed Critical Nippon Steel Corp
Application granted granted Critical
Publication of US3642468A publication Critical patent/US3642468A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • 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

  • ABSTRACT A steel sheet for press forming having excellent deep drawability and stretchability, the steel of the sheet having W in an amount of from about 0.007 and up to about 0.15 percent.
  • the steel can also have one element selected from the group consisting of Cr and V in an amount of 0.02 to 0.3 percent. It has less than 0.1% C and 0.01 to 0.50% Mn.
  • the present invention relates to steel sheet for press forming.
  • Steel sheet used for automobiles and for other press operations is required to have a good deep drawability, stretchability and strain aging property.
  • T average plastic strain ratio
  • r is the value of r in the rolling direction
  • r is the value 'of r in the direction of 45 to the rolling direction
  • r is the value ofr in the direction of 90 to the rolling direction.
  • the deep drawability is better when the value is larger, and in the usual rimmed steelTis about l.3.
  • the stretchability indicates the extent of ductility of a material when the material is deformed under biaxial tension and is generally determined by using a work hardening exponent (n) as a'standard. Also, n shows the extent of work hardening and in practice is obtained by a tensile test of a material.
  • the stretchability is better when the value is larger and in a usual rimmed steel, the n value is about 0.22.
  • An Erichsen test is usually used as the standard, in which test a punch is inserted into a test blank under the condition that the inflow of the material from an outer flange portion into the deforming portion is restrained and the punch travel until the sample is ruptured is measured.
  • the stretchability is better when the value is larger and in the usual rimmed steel the value is about 10-1 1.
  • a conical cup test is also employed for showing the combined effect of the deep drawability and the stretchability. The effect is better when the value is smaller and in the usual rimmed steel the valueis about 38 mm.
  • the strain aging property is as follows. When sheet steel is subjected to a plastic deformation, an uneven pattern called stretcher strain" sometimes appears on the surface of the sheet, which impairs the appearance of the article, and hence in order to avoid the formation of the stretcher strain, a light skin pass rolling is usually conducted. However, when a period of time has passed following the application of the skin pass rolling, the effect of the skin pass rolling is lost and the stretcher strain appears again during forming of the steel sheet. This phenomenon is called strain aging. The extent of the strain aging is determined by, for example, providing a prestrain of 8 percent to a sample, keeping the sample for 1 hour at 100 C., and measuring the changed amount of the yield stress before and after the test (A87). in the usual rimmed steel the value (138 is about 5 kgJsq. mm., and ifthe value is less than 1.5 kg./sq. mm., the steel is considered to be nonaging.
  • the inventors have found, as a result of investigations made in order to improve the above-mentioned properties of steel sheet, that the properties can be markedly improved by the addition ofa specific element. i
  • a principle object of this invention is to provide steel sheet having very excellent deep drawability and stretchability by adding a small amount of'W to the steel.
  • Another object of the present invention is to provide steel sheet having very excellent deep drawability and stretchability by the addition of W and also having a good nonaging property by the addition of another element.
  • FIG. 1 is a graph showing Tvalue of the steel sheet in the cold rolling direction, in the direction of 45 to the cold rolling direction, and in the direction of 90 to the cold rolling direction;
  • FIG. 2 is a graph showing the relation between the amounts of chromium and vanadium in steel sheetcontaining them and Tvalue.
  • the inventors have succeeded in producing a steel sheet for press forming having very excellent press formability by preparing steel containing from about 0.007 to about 0.15 percent by weight of W in the steel manufacturing step in a converter, an open-hearth furnace or an electric furnace or in an ingot making step, subjecting it to hot rolling and cold rolling, and then annealing the steel at a temperature higher than the recrystallization temperature, but lower than the Ac transformation temperature.
  • the strain aging property in influenced by C and especially N present as a solid solution in steel sheet Accordingly, if the N present as a solid solution is fixed as a nitride, the strain aging property of the steel can be reduced or eliminated.
  • W-containing steel sheet the addition of W only is not effective to give a nonaging property to the steel sheet since W has a poor affinity for N.-.'Therefore, the addition of Al, Ti, Zr, Cr, V, B, etc., which has a high affinity for N may be considered.
  • a good nonaging property can be obtained together with an excellent deep drawability and stretchability.
  • a small amount of Cu, P and like may also be added if necessary in a range such that the effect of W is not injured by the addition thereof.
  • the numerals in FIG. 1 show the sample numbers in Table 1.
  • the extent of the formation ofears" (Ar) can be approximately shown by A 0 w/ r45
  • the difference (Ar) in the usual rimmed steel is about 0.6, whereas the difference in the steel of this invention is 0.1 0.2 in an excellent one. and less than 0.4 even in a worse one. Among them, several examples are shown in 'liable 3.
  • Table 4 the results of measuring the values of index (111) and index (100) of the steel of this invention parallel to the sample plane (rolling plane) by an X-ray integral diffraction intensity in which it is shown that the index (1 l 1) is about two or three times as large as that of the comparative material and the index (100) is about one-third to one-third of that ofthe comparative material, which shows the excellency of the mechanical properties of the steel.
  • the range of the content of W in the steel of this invention is from about 0.007 up to about 0.15 percent, preferably 0.007 to 0.08 percent. 1f the content of W is less than the value, the characteristics of the steel are almost the same as those of the usual rimmed steel containing no W, and the deviation of the analytical value becomes larger, which reduces the effect of the addition thereof. Furthermore, if the content is larger than the upper limit, the bad influences thereof on the mechanical properties, such as tensile strength becomes larger and elongation becomes less, which is undesirable. Accordingly, the most preferred range ofW is 0.007 to 0.08 percent.
  • Usual soft steel contains 0.030.l percent by weight of C, but by subjecting the steel to vacuum melting or treating it in vacuo, the content of the C can be reduced. it is confirmed that the effect of W is remarkable in steel containing any amount of C.
  • the content ofC in the steel ofthis invention may be reduced greatly, for example, to less than 0.01 percent by a vacuum treatment and the like during steel manufacturing, but the content of C can also be reduced or controlled by subjecting the steel sheet to a decarburization annealing after rolling.
  • the content of Mn in steel has an intimate relation with the content of S with respect to red shortness and usually the amount of Mn added is about 10 times as large as that of S on taking into consideration segregation.
  • Mn hardens the material and reduces the mechanical properties thereof, there is an upper limit for the amount thereof, and the amount thereof in conventional soft steel is about 0.25-0.50 percent.
  • the steel of this invention has an advantage in that when it is subjected to similar treatments, the finishing temperature need not be higher than the transformation temperature (Ar This is contrary to the usual case, in which in order to obtain excellent press formability of the final product, it is desirable that the finishing temperature of rolling in conventional hot rolling be higher than the transformation temperature (Ar Furthermore, the cold rolling reduction of the steel of this invention is preferably 40-85 percent and in particular, most preferably 60-80 percent.
  • the annealing after cold rolling is conducted at a temperature higher than the recrystallization temperature, but lower than the transformation temperature (Ac and it is effectively carried out in an inert atmosphere or in a carburizing atmosphere.
  • the aforesaid facts show that the steel of this invention is steel sheet having an excellent press formability.
  • Steel sheet for press forming having excellent deep drawability and stretchability, the steel of said sheet consisting essentially of C in an amount less than 0.l percent by weight, Mn in an amount of from 0.1-0.50 percent by weight, W in an amount of from 0.007 percent by weight to 0.15 percent by weight, and the rest Fe and impurities.
  • Steel sheet for press forming having excellent deep drawability and stretchability, and having an excellent nonaging property
  • the steel of said sheet consisting essentially of C in an amount less than 0.] percent by wei ht, Mn in an amount of from 0.0l0.5 percent by weight, in an amount of from 0.007 percent by weight to 0.15 percent by weight, and 0.020.3 percent by weight of at least one element and im wi ss UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Steel (AREA)
US858244A 1965-12-17 1969-08-19 Steel sheet for press forming Expired - Lifetime US3642468A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7731965 1965-12-17

Publications (1)

Publication Number Publication Date
US3642468A true US3642468A (en) 1972-02-15

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US858244A Expired - Lifetime US3642468A (en) 1965-12-17 1969-08-19 Steel sheet for press forming

Country Status (5)

Country Link
US (1) US3642468A (fr)
BE (1) BE691304A (fr)
DE (1) DE1533435B1 (fr)
FR (1) FR1505713A (fr)
GB (1) GB1170950A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4144378A (en) * 1977-09-02 1979-03-13 Inland Steel Company Aluminized low alloy steel
US20060213361A1 (en) * 2005-03-24 2006-09-28 Benteler Automobiltechnik Gmbh Vehicle armor
CN111556907A (zh) * 2017-12-26 2020-08-18 Posco公司 制造超低铁损取向电工钢板的方法

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2021781A (en) * 1931-11-20 1935-11-19 Timken Roller Bearing Co Alloy steel and articles made therefrom
US2021782A (en) * 1931-11-20 1935-11-19 Timken Roller Bearing Co Alloy steel and articles made therefrom
US2021783A (en) * 1931-11-20 1935-11-19 Timken Roller Bearing Co Alloy steel and articles made therefrom
US2266762A (en) * 1939-03-09 1941-12-23 Lincoln Electric Co Welding
US2356450A (en) * 1942-02-28 1944-08-22 Bethlehem Steel Corp Steel
US2375953A (en) * 1942-09-30 1945-05-15 Nat Steel Corp Alloy steel
US2395686A (en) * 1942-09-30 1946-02-26 Nat Steel Corp Alloy steel
US2415078A (en) * 1940-07-17 1947-02-04 Becker Gottfried Process for chroming steel articles
US3069257A (en) * 1960-06-02 1962-12-18 Armco Steel Corp Alloy steel and method
US3183078A (en) * 1961-09-29 1965-05-11 Yawata Iron & Steel Co Vacuum process for producing a steel for nonageing enameling iron sheets
US3303060A (en) * 1962-06-05 1967-02-07 Yawata Iron & Steel Co Atmospheric corrosion-resistant steel sheet for deep drawing

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE945094C (de) * 1949-03-11 1956-06-28 Phoenix Rheinrohr Ag Vereinigt Laugenbestaendiger Stahl

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2021781A (en) * 1931-11-20 1935-11-19 Timken Roller Bearing Co Alloy steel and articles made therefrom
US2021782A (en) * 1931-11-20 1935-11-19 Timken Roller Bearing Co Alloy steel and articles made therefrom
US2021783A (en) * 1931-11-20 1935-11-19 Timken Roller Bearing Co Alloy steel and articles made therefrom
US2266762A (en) * 1939-03-09 1941-12-23 Lincoln Electric Co Welding
US2415078A (en) * 1940-07-17 1947-02-04 Becker Gottfried Process for chroming steel articles
US2356450A (en) * 1942-02-28 1944-08-22 Bethlehem Steel Corp Steel
US2375953A (en) * 1942-09-30 1945-05-15 Nat Steel Corp Alloy steel
US2395686A (en) * 1942-09-30 1946-02-26 Nat Steel Corp Alloy steel
US3069257A (en) * 1960-06-02 1962-12-18 Armco Steel Corp Alloy steel and method
US3183078A (en) * 1961-09-29 1965-05-11 Yawata Iron & Steel Co Vacuum process for producing a steel for nonageing enameling iron sheets
US3303060A (en) * 1962-06-05 1967-02-07 Yawata Iron & Steel Co Atmospheric corrosion-resistant steel sheet for deep drawing

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4144378A (en) * 1977-09-02 1979-03-13 Inland Steel Company Aluminized low alloy steel
US20060213361A1 (en) * 2005-03-24 2006-09-28 Benteler Automobiltechnik Gmbh Vehicle armor
US7357060B2 (en) * 2005-03-24 2008-04-15 Benteler Automobiltechnik Gmbh Vehicle armor
CN111556907A (zh) * 2017-12-26 2020-08-18 Posco公司 制造超低铁损取向电工钢板的方法
US11773490B2 (en) 2017-12-26 2023-10-03 Posco Co., Ltd Method for producing oriented electrical steel sheet with ultra-low iron loss

Also Published As

Publication number Publication date
GB1170950A (en) 1969-11-19
BE691304A (fr) 1967-05-29
FR1505713A (fr) 1967-12-15
DE1533435B1 (de) 1971-07-29

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