• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    PURPOSE: Provided are 45 kg/mm¬2 high strength bake hardening steel sheet with good workability and non aging property at room temperature and a method for manufacturing the same, wherein anisotropic coefficient (r) is greater than 1.6. CONSTITUTION: The method includes the steps of soaking an aluminum killed steel comprising 0.0050 wt.% or less of C, Mn 0.5 to 3.0 wt.%, 0.1 wt.% or less of P, Si 0.1 to 0.3 wt.%, Mo 0.1 to 0.5 wt.%, 0.1 to 0.2 wt.% of one or more than two elements selected from Cr, Ni, V and Zr, a balance of Fe and incidental impurities at 1200 to 1250°C; finish hot rolling the aluminum killed steel at higher than Ar3 transformation temperature, followed by coiling and cold rolling; annealing the cold rolled aluminum killed steel sheet at higher than 800 deg.C; cooling it at a rate of greater than 30 deg.C/sec; and temper rolling.
    公开号:KR20030052349A
    申请号:KR1020010082239
    申请日:2001-12-21
    公开日:2003-06-27
    发明作者:김일영
    申请人:주식회사 포스코；
    IPC主号:
    专利说明:

    High Strength Bake Hardening Steel Sheet With Good Workability and Non Aging Property at Room Temperature and A Method for Manufacturing Thereof}
    [1] The present invention relates to a 45Kg / mm2 high-tensile cold-rolled steel sheet used in automobile interior and exterior plate materials, and more specifically, to manage the C content at an extremely low level, to secure workability, while increasing the hardenability, austenite zone expansion element The present invention relates to a cold-rolled steel sheet and a method for manufacturing the same, which are obtained by adding Mn, Mo, and the like to control the structure after the annealing to form a needle-like ferrite, thereby exhibiting a continuous yielding behavior in terms of tensile properties.
    [2] Recently, the use of high-strength steel sheet in the vehicle body for the purpose of improving the fuel efficiency of the automobile and reducing the weight of the vehicle body has increased the demand for improving the dent resistance and reducing the sheet thickness. In response to these demands, many steelworks have developed and supplied various types of hardened hardened steel. However, hardened hardened steel is a manufacturing feature that utilizes the aging of solid-solution-invasive elements. Therefore, the demand price has a burden of processing the hardened hardened steel within three months or six months, the manufacturer also has a burden of various complaints and claims.
    [3] Most of the prior art is to maintain the solid solution C, or N solid solution to suppress the aging properties at room temperature and to ensure the curing properties by using the aging properties during the baking treatment after coating. However, the aging properties are restored with long-term storage at room temperature, resulting in surface defects of the stretcher-strain during processing, which is not suitable for automotive exterior use.
    [4] Accordingly, the present invention is to solve the above-mentioned conventional problems, to secure the non-aging even at room temperature, the tensile anisotropy coefficient (r value) of 45 Kg / ㎠ class with a tensile hardening type high tensile cold rolled steel sheet of 1.6 or more and its manufacturing method To provide, there is a purpose.
    [5] High tensile cold rolled steel sheet of the present invention for achieving the above object, by weight% C: 0.0050% or less, Mn: 0.5 ~ 3.0%, P: 0.1% or less, Si: 0.1 ~ 0.3%, Mo: 0.1 ~ 0.5%, One or two or more selected from the group of Cr, Ni, V, and Zr: more than 0.1 to 2.0% or less, and is composed of impurities inevitably contained with the remaining Fe.
    [6] In addition, the manufacturing method of the high tensile cold rolled steel sheet of the present invention, by weight% C: 0.0050% or less, Mn: 0.5-3.0%, P: 0.1% or less, Si: 0.1-0.3%, Mo: 0.1-0.5%, Cr 1, or 2 or more selected from the group of Ni, V, and Zr: after homogenization treatment of aluminum-kilted steel composed of more than 0.1% to 0.2% or less of Fe and inevitably contained impurities in a temperature range of 1200 to 1250 ° C. It is composed of hot rolling, winding followed by finishing rolling temperature Ar3 or higher, cold rolling, annealing at 800 ° C or higher, cooling at a rate of 30 ° C / sec or more, and temper rolling.
    [7] Hereinafter, the present invention will be described in detail.
    [8] The present invention controls the C content at a very low level to ensure processability, and increases the hardenability, while controlling the structure after the annealing by adding Mn, Mo, which are elements of the enlarged austenite zone in the Fe state, to an acicular ferrite state. By exhibiting continuous yielding behavior in tensile properties, it ensures the non-aging property of cold rolled steel sheet at room temperature and makes r value 1.6 or more with tensile strength of 45Kg / mm2 or more. The composition range of the steel component of the present invention will be described first.
    [9] · C: 0.005% or less
    [10] In the case of C, since the workability is deteriorated by the carbon precipitate when it exceeds 0.0050%, the upper limit thereof is preferably limited to 0.0050%.
    [11] · Mn: 0.5 ~ 3.0%
    [12] In the case of Mn, it is an element with high hardenability and is added to secure continuous yield behavior during tensile test, which is a characteristic of the developed steel, and to secure room temperature aging. When Mn is added less than 0.5%, it is difficult to form acicular ferrite in the tissue, so continuous yielding behavior is difficult, and when it exceeds 3.0%, ductility decreases rapidly due to solid solution strengthening. Therefore, limiting the addition amount to 0.5 ~ 3.0% desirable.
    [13] · P: 0.1% or less
    [14] The case of P serves to improve in-plane anisotropy and improve strength as a substituted alloy element having the greatest solid solution strengthening effect. However, if the content exceeds 0.1%, it is preferable to limit the addition amount to 0.1% or less since the ductility decrease is inevitable such that P is segregated at the grain boundary due to the excessive addition of P to drop the material.
    [15] · Si: 0.1 ~ 0.3%
    [16] In the case of Si, the effect is that when the content is less than 0.1% as a strong reinforcing element, the effect is negligible when the content is less than 0.1%, the ductility decrease when the addition is more than 0.3%, and the adhesion to the plating is caused by the Si oxide during the hot dip plating process. It is preferable to limit it to 0.1 to 0.3%.
    [17] · Mo: 0.1 ~ 0.5%
    [18] In the case of Mo, as an element to improve the hardenability and toughness, it is added to secure continuous yield behavior during tensile test, which is a characteristic of the developed steel, and to secure room temperature aging. When Mo is less than 0.1%, it is difficult to continuously form needle-like ferrite in the structure, and when it exceeds 0.5%, it is preferable to limit the amount to 0.1 to 0.5% due to the rapid ductility decrease due to solid solution strengthening.
    [19] · Cr, Ni, V, 1 or more kinds selected from the group of Zr: more than 0.1% to 0.2% or less
    [20] The Cr, Ni, V, Zr is added to secure the strength, when one or two or more of these addition amount is less than 0.10%, it is difficult to secure the strength, if it exceeds 0.2% the strength is increased but the target Hard to secure ductility
    [21] The slabs formed as described above are obtained by ingot or continuous casting process after obtaining molten steel through steelmaking process. The slab is produced by hot rolling, cold rolling, and annealing to produce high tensile steel sheets having the desired mechanical properties. The manufacturing conditions for each process will be described in detail.
    [22] · Hot rolling
    [23] The slab is heated at 1200 to 1250 ° C., where the austenite structure can be sufficiently homogenized before hot rolling, followed by finishing hot rolling above the Ar 3 temperature. If the hot finish rolling temperature is less than Ar 3 transformation point, it is rolled in the ferrite + pearlite two-phase structure, which causes abnormal coarse grains, which in turn causes defects in product processing. Therefore, it is preferable that the hot finish rolling temperature is higher than the Ar 3 transformation point.
    [24] The hot rolled sheet hot rolled as described above is wound into a hot rolled sheet according to a conventional method to obtain a coiling coil.
    [25] - cold rolling
    [26] The wound hot rolled sheet is cold rolled, in which case the cold rolling may be appropriately set to a rolling condition so as to obtain a cold rolled sheet at a desired final thickness. Therefore, since cold rolling conditions are not specifically limited, normal conditions are possible.
    [27] · Annealing Process
    [28] Next, the cold rolled sheet is annealed, and the annealing at this time is preferably continuous annealing. If the continuous annealing temperature is less than 800 ℃, sufficient annealing is not achieved, it is better to continuously annealing at 800 ℃ or more. If the cooling rate at this time is less than 30 ° C / sec, it is difficult to secure the target needle-like ferrite structure, it is preferable to cool at a rate of 30 ° C / sec or more.
    [29] The annealed cold rolled steel sheet is temper rolled under normal conditions.
    [30] The high tensile strength steel sheet manufactured according to the present invention has a tensile strength of 45 Kg / mm 2 or more and a cold rolled steel sheet having an r value (aqueous anisotropy coefficient) of 1.6 or more. In addition, the high tensile strength steel sheet provided in accordance with the present invention is applied to the conventional electroplating or hot-dip plating in accordance with the required characteristics of the product.
    [31] Hereinafter, the present invention will be described in more detail with reference to Examples.
    [32] EXAMPLE
    [33] The ultra-low carbon Al-Killed steel is melted in a converter to have a composition as shown in Table 1 below.
    [34] After the refining treatment, a continuous casting to produce a steel slab. At this time
    [35] The invented steel (1-4) and the comparative steel (5-13) are both final steel components after out-of-furnace refining. Invented steel (1-4) was added within the range of components limited in the present invention, the comparative steel (5, 6) was Mn exceeded the range, the comparative steel (7) was added in excess of Si. The comparative steels (8, 9) were added with Mo exceeding the range, the comparative steel (10) exceeded the range Cr + Ni + V + Zr, and the comparative steel (11) was Cr + Ni + V + Zr It is less than this range. Comparative steel (12) satisfies the composition range of the present invention but less than the annealing temperature, Comparative steel (13) also satisfies the composition range of the present invention, but the cooling rate after annealing was less than.
    [36]
    [37] The steel slab having the composition shown in Table 1 was homogenized at a temperature of 1250 ℃
    [38] After finishing hot rolling to the thickness of 4.0 mm in the vicinity of 910 degreeC which is a direct temperature of Ar <3>, it wound up and pickled by the normal method. The pickled hot rolled steel sheet was obtained by cold rolled steel sheet having a final thickness of 0.8 mm after cold rolling under normal conditions, and then annealed under the conditions of Table 1, and then measured by mechanical properties.
    [39]
    [40] As shown in Tables 1 and 2, in the case of the comparative steel (5), Mn was not within the limited range, and thus, needle-like ferrite was not generated in the tissue, and YP-El was generated after baking, thereby preventing inaging. In the case of the comparative steel (6), Mn exceeded the limit and was poor due to the r value of 1.5 due to the decrease in the ductility. In the case of the comparative steel 7, the Si value was poor due to the decrease in ductility due to the Si exceeding the limit. In the case of Comparative steel (8), Mo was not within the limited range, and thus, needle-like ferrite was not generated in the tissue, and YP-El was generated after baking, thereby preventing inaging. In the case of the comparative steel (9), Mn exceeded the limit and was poor as the r value 1.4 due to the ductility deterioration. In the case of the comparative steel 10, the sum of Cr + Ni + V + Zr exceeded the limit and was poor due to the r value 1.3 due to the ductility deterioration. In the case of the comparative steel (11), the sum of Cr + Ni + V + Zr was less than the limit and the tensile strength was poor at 42 Kg. In the case of the comparative steel (12), the annealing temperature was lower due to the ductility deterioration due to the limit of the ductility. Was poor at a value of 1.5. In the case of the comparative steel 13, the cooling rate after annealing was not within the limited range, so that sufficient needle-like ferrite was not generated in the tissue, and YP-El was generated after the quenching treatment, thereby preventing inaging.
    [41] In contrast, in the case of the inventive steel (1-4), the target strength, r value, and non-aging property were secured by working the components and the manufacturing conditions within the limits of the present invention.
    [42] As described above, according to the present invention, the C content is extremely controlled to ensure workability, the hardenability is increased, and the structure is brought to an acicular ferrite state by adding Mn, Mo, or the like, which is an austenite expansion element in the Fe state. By controlling and exhibiting continuous yielding behavior in terms of tensile properties, it has a useful effect of securing an unaging property at room temperature and providing a non-aging small hardened high tensile steel sheet having excellent machinability with a tensile strength of 45Kg / mm2 or more and an r value of 1.6 or more.
    权利要求:
    Claims (3)
    [1" claim-type="Currently amended] By weight% C: 0.0050% or less, Mn: 0.5-3.0%, P: 0.1% or less, Si: 0.1-0.3%, Mo: 0.1-0.5%, 1 type selected from the group of Cr, Ni, V, Zr or 2 or more kinds: non-aging small hardened type 45Kg / mm2 grade cold rolled steel sheet having a processability of 0.1% to 0.2% or less and composed of remaining Fe and impurities inevitable.
    [2" claim-type="Currently amended] According to claim 1, wherein the cold-rolled steel sheet has an aging anisotropy coefficient (r value) of 1.6 or more non-aging small hardening type 45Kg / ㎜ grade cold rolled steel sheet excellent in formability.
    [3" claim-type="Currently amended] By weight% C: 0.0050% or less, Mn: 0.5-3.0%, P: 0.1% or less, Si: 0.1-0.3%, Mo: 0.1-0.5%, 1 type selected from the group of Cr, Ni, V, Zr or 2 or more types: aluminum-killed steel, which is composed of more than 0.1 to 0.2% or less, and the remaining Fe and inevitably contained impurities, is homogenized at a temperature range of 1200 to 1250 ° C, and then hot-rolled by hot rolling under the condition of the finish rolling temperature Ar3 or higher. Next, cold rolling, annealing at 800 ℃ or more, and then cooled at a rate of 30 ℃ / sec or more, followed by temper rolling, the production method of the non-aging small hardening type 45Kg / mm2 cold rolled steel sheet excellent in formability.
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    同族专利:
    公开号 | 公开日
    KR100544538B1|2006-01-24|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2001-12-21|Application filed by 주식회사 포스코
    2001-12-21|Priority to KR20010082239A
    2003-06-27|Publication of KR20030052349A
    2006-01-24|Application granted
    2006-01-24|Publication of KR100544538B1
    优先权:
    申请号 | 申请日 | 专利标题
    KR20010082239A|KR100544538B1|2001-12-21|2001-12-21|High Strength Bake Hardening Steel Sheet With Good Workability and Non Aging Property at Room Temperature and A Method for Manufacturing Thereof|
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