201211268 六、發明說明： 【發明所屬之技術領域】 本發明係關於-種適合用作電器_心d 一_)、辦 a m &車用構件等之構造構件之冷軋薄鋼板，特別係 關於-種適合用作絲壓製絲後之高尺寸精度之構件的 形狀u優異之冷軋薄鋼板，者，此處所述之「薄鋼板」 係《又為板厚.0.2〜2.〇mm之鋼板，且包含鋼板及鋼帶者。 【先前技術】 近年來於電機領域等領域中，伴隨著原料價格之高漲 為降低成本而強烈要求價格便宜之素材，從而用作素材之: 板之薄壁化正在加速。又，於汽車領域中，除降低成本外 自保護地球環境之觀點考慮，強烈要求改善汽車之油耗，） 汽車車體之輕量化，作為素材之鋼板之薄壁化正在推進。, 右藉由素材之薄魏而減少素材板厚，則存在^ (構件)之剛性下降之問題。針對此種問題，對構件賦予· ㈣或重新修正構件形狀而設法使剖面二次矩㈣⑽ 二=:從而確保所期望之剛性之情況逐㈣ 夕―果為，存在如下之問題：構件形 =成形時所成形之部位增加，使製品(構件)形狀=於 打再讀形H進行制製_會導 致製么成本之増加’因此迫切期望—種難成形後之形狀康 Ϊ00Ι21388 4 201211268 結性優異之鋼板。 對於此種期望’例如於專利文獻1中，記載有一種使{100} <011>〜{223}< 11〇>方位群之x射線無規強度比之平均 值為 3.0 以上，且{554}<225>、{111}< 112>、{111}< 11〇 >之3個晶體方位之X射線無規強度比之平均值為3.5以下 之特定方位之集合組織擴大，此外軋延方向之r值及軋延方 向與直角方向之r值中之至少一者為〇 7以下，以彎曲加工 為主’形狀凍結性優異之肥粒鐵系薄鋼板。專利文獻1中所 記載之鋼板之彎曲成形性顯著提高，回彈量少，以彎曲加工 為主，形狀凍結性優異。 又’於專利文獻2中’記載有一種具有於肥粒鐵(ferrite) 基底中分散有包含麻田散鐵（martensite)之島狀組織之組 織，具有表面平均粗糙度Ha為0.4〜1.8 /zm且PPI (peak to peak intensity，峰·峰強度）值以0.5以爪之計數標準計為80 以上之表面粗糙度，且比例限度應力（proportional limit stress)為20 kg/mm2以下即200 MPa以下之形狀凍結性優異 之高張力鋼板。藉此，壓製成形時之衝壓面與鋼板之緊密性 提高’從而可獲得壓製成形後之形狀凍結性優異之構件（製 品）。 [先行技術文獻] [專利文獻] [專利文獻1]日本專利特開2001_3〇3175公報 100121388 5 201211268 [專利文獻2]日本專利特開昭S8_25456號公報 【發明内容】 (發明所欲解決之問題） i然而，難· I 由 … g由專利文獻1所記載之技術而製造之鋼板中，於 主要接受蠻此j· 妹 曰 加工之製品(構件）中，可確保所期望之形狀凍 ^口仁例如於接受如伸出加工般之彎曲加工以外之加工的 '(冓件）令，則存在未必能確保可滿足之形狀凍結性之問 題又藉由專利文獻2所記載之技術而製造之鋼板係設為 府L田政鐵之島狀組織分散於肥粒鐵基底中之組織，故 易於成為經硬質化之鋼板，於伸出高度高之成形時，存在產 生龜裂之情況較多之問題。 本發明之目的在於解決該習知技術之問題，提出一種形狀 床結性優異之冷軋薄鋼板及其製造方法。 (解決問題之手段） 為達成上述目的，本發明者等人對影響形狀凍結性之各種 因素已進行潛心研究。本發明者等人認為，壓製成形時之製 品（構件）之形狀不良係由於壓製成形時所導入之彈性應變 (elastic strain)於自壓製模具取出製品（構件）時被釋放而產 生，從而著眼於鋼板之比例限度。 所謂比例限度，係指於向彈性體施加外力時，可與應變保 持正比關係之應力之限度。於應力小之期間，虎克定律 (Hooke’s law)成立’因此可看到正比關係。準備具有各種比 100121388 6 201211268 例限度之鋼板，藉由壓製成形而成形特定形狀之零件，對成 形後之形狀;東結性進行5周查。其結果發現，為確保所期望之 優異之形狀凍結性，必需使鋼板之比例限度降至15() MPa 以下。 對成為本發明之基礎之實驗結果進行說明。 對具有各種比例限度之板厚：0.8 mm之薄鋼板(試驗材） 進行壓製成形，形成為圖1所示之尺寸之帽子形狀之零件。 再者，褶皺擠壓壓力設為20 ton。成形後，自模具取出零件， 對帽子形狀之開口量X進行測定。於圖2中，表示鋼板之 比例限度與開口量X之關係。由圖2可知，若鋼板之比例 限度為150 MPa以下，則開口量X之增加少，從而可保持 優異之形狀凍結性，但若鋼板之比例限度超過15〇 Mpa而 變大，則開口量X急遽增大，從而形狀凍結性顯著下降。 其次’本發明者專人為穩定地製造具有上述比例限度之鋼 板，對影響鋼板之比例限度之各種因素已進行潛心研究。其 結果發現’藉由對以具有相對較大之結晶粒徑之肥粒鐵相作 為主體之鋼板，實施使用表面粗繞度小之觀之調質軋延，可 容易地降低比例限度。 其次，對成為上述認知之基礎之實驗結果進行說明。 對具有以質量％計0.040%之〇〇.〇1 %之Si、0.20%之Μη、 0.01%之 Ρ、〇.〇1%4 S、0.04%之 Α1、0.003%之 Ν 及其餘部 分為Fe之組成’且具有由平均結晶粒徑：1〇 #瓜之肥粒鐵 100121388 7 201211268 單相所構成之組織之冷軋退火板(板厚：0 8 mm)，實施軋延 伸長率為1%之調質軋延。於調質軋延時，使用已將表面粗 糙度Ra調整為0.2〜2.5 之各種軋延輥。自已調質軋延 完畢之各鋼板’分別以拉伸方向成為軋延方向之方式提取 JIS (Japanese Industrial Standards，日本工業標準）5 號試驗 片，實施拉伸試驗，求出各鋼板之比例限度。 比例限度係使用在平行部兩面上貼附有長度為5 min之應 變計（strain gauge)之拉伸試驗片，以拉伸速度：1 mm/min 進行拉伸試驗而求出。如圖3所示，比例限度係根據應力_ 應變曲線之傾斜度(Δσ /△ ε )與應力（a )之關係，設為藉由應 力增加而傾斜度開始變小之點。 將所獲得之結果以鋼板之比例限度與所使用之軋延輥之 輥表面粗糙度Ra之關係示於圖4。再者，輥表面粗糙度 係依據JIS B 0601-2001之規定而測定。由圖4可知，若使 用輥表面粗糙度Ra為2.0 以下之軋延輥而實施調質軋 延，則鋼板之比例限度容易達到15〇MPa以下。 對於利用使用上述表面⑽度小之輥之調f軋延之比例 限度減少的機制，迄今為止雖無法充分地闡明其詳細情況， 但本發明者等人作如下推斷。 本發明者等人認為，若對以結晶粒彳f 5〜3G，之粗大 之肥粒鐵作為主體之鋼板，使用^為2()㈣以下之表面 粗Hj、之軋延輥貫施調質軋延，可於板厚方向上導入均句 100121388 8 201211268 之應變，進而可促進向肥粒鐵結晶粒内導入可動差排 (mobile dislocation)，從而可顯著地降低比例限度。另一方 面，本發明者等人認為，於使用表面粗糙度Ra超過2.〇 y m而表面粗糙度大之軋延輥進行調質軋延之情形時，被導入 之應變會集中於鋼板表層，故差排混亂化而可動差排減少， 從而無法獲得比例限度之降低。 本發明係基於上述認知，進而加以研究而完成者。 亦即，本發明之主旨如下。 (1) 一種形狀凍結性優異之冷軋薄鋼板，其係對具有以質 量°/〇計包含 C: 0.10%以下、Si: 0.05%以下、Μη: 0.1 〜1.〇〇/0、 Ρ : 0.05%以下 ' S ·· 0.02%以下、Α1 : 〇.〇2〜〇·ΐ0%、Ν :未 滿0.005%，且其餘部分由Fe及不可避免之雜質所構成之組 成，及以平均結晶粒徑d : 5〜30 // m之肥粒鐵相作為主體 之組織之薄鋼板，實施使用表面粗糙度Ra為2 〇以爪以下 之軋延輥的調質軋延而成之薄鋼板，其中，具有15〇 Mpa 以下之比例限度。 (2) 如（1)之冷軋薄鋼板，其中，除上述組成外，進而以質 量％計含有選自 Ti: 0.005〜〇.〇8%、Nb: 0.010〜〇,_%、B : 0.0003 〜O.〇〇3〇〇/0、Cr : 0.1 〜1.〇%、Mo : 0.1 〜1.〇〇/〇 中之 i 種或2種以上之組成。 (3) 種$狀束結性優異之冷軋薄鋼板，其特徵在於：於 如（1)或（2)之冷軋薄鋼板之至少一表面上，形成熔融鍍辞 100121388 9 201211268 層、合金化熔融鑛鋅層、或電鍍鋅層而成。 (4)一種形狀結性優異之冷軋薄鋼板之製造方法，直传 對鋼素材依序實施熱軋㈣、冷軋料㈣^冷軋板二並 ;:=Γ:火步驟而形成為冷乾退火板之冷軋薄鋼 板之“方法’其特徵在於，上述鋼素材係 包含C : 0.10%以下、Si: 0 05%以下 質里03十 _以下、一一。 及不㈣免之㈣所構成之組成 之鋼素材’上核火步驟鑛上述冷軋板實㈣ 730〜850°C之範圍之溫度加熱30 s以上後，以5t/s 之 平均冷卻速度冷卻至峨以下之溫度為止之退火二二 而形成為具有以平均結晶粒徑d:5〜⑽_之肥_相作 為主體之組織的冷軋退火板之步驟，於上述退火步驟後，對 上述冷㈣該，使絲面祕度⑹為2 G _以下之乾 延輥，實施使調質軋延伸長率對應於該冷軋退火板之平均結 晶粒徑d(em)為d/20〜d/5%之範圍之調質軋延從而形^ 為比例限度為150 MPa以下之冷軋薄鋼板。 (5)如(4)之冷軋薄鋼板之製造方法，其中，代替上述退火 步驟而採如下退火-熔融鍍鋅處理步驟，即，以退火溫度： 730〜850°C之範圍之溫度對上述冷軋板進行退火，且以5它 /s以上之平均冷卻速度冷卻至6〇〇〇c以下之溫度為止，從而 實施熔融鍍鋅。 100121388 10 201211268 (6) 如（5)之冷軋薄鋼板之製造方法，其中，於經過上述退 火-熔融鍍鋅處理步驟後，進而實施對熔融鍍鋅進行合金化 處理之合金化處理步驟。 (7) 如(4)至（6)中任一項之冷軋薄鋼板之製造方法，其中， 除上述鋼素材之組成外，進而以質量％計含有選自Ti: 0.005 〜0.08%、Nb : 0.010〜0.030%、B : 0.0003〜0.0030%、Cr : 0.1〜1.0%、Mo : 0.1〜1.0%中之1種或2種以上之組成。 (發明效果） 根據本發明，可價格便宜且穩定地製造比例限度為150 MPa以下之冷軋薄鋼板，從而成形後之構件之形狀凍結性 顯著提高，於產業上發揮顯著之效果。 【實施方式】 首先，對本發明之薄鋼板之組成限定理由進行說明。以 下，只要未作特別聲明，質量％僅記作％。 C : 0.10%以下 含有超過0.10%之C，係使肥粒鐵粒微細化，促進雪明碳 鐵(cementite)之形成，從而難以使比例限度下降，並且提高 淬火性，促進低溫變態相之生成，從而使強度增加並使延展 性(ductibility)下降。因此，C係限定於0.10%以下。再者， 較佳為0.05%以下。於本發明中，無需限定C含量之下限， 但過度之降低會導致製造成本之高漲，故較佳為設為 0.0010%以上。 100121388 11 201211268201211268 VI. Description of the Invention: [Technical Field] The present invention relates to a cold-rolled steel sheet suitable for use as a structural member of an electric appliance, such as an electric appliance, a vehicle member, etc., particularly - A cold-rolled steel sheet excellent in shape u suitable for use as a member of high-precision precision after silk-pressing, and the "thin steel sheet" described herein is "plate thickness. 0.2 to 2. 〇 mm" Steel plate, including steel plates and steel strips. [Prior Art] In recent years, in the field of electric motors and the like, with the increase in the price of raw materials, in order to reduce costs, materials with low prices have been strongly demanded, and this has been used as a material: The thinning of the board is accelerating. In addition, in the field of the automotive industry, in addition to the reduction of the cost, it is strongly demanded to improve the fuel consumption of the automobile. On the right, by reducing the thickness of the material by the thin material of the material, there is a problem that the rigidity of the (component) is lowered. In response to such a problem, the member is given (4) or the shape of the member is re-corrected, and the second moment of the section is obtained (4) (10) ==: To ensure the desired rigidity, the following problems occur: (Component) = Forming When the shape of the part is increased, the shape of the product (member) = the shape of the re-reading type H will result in the cost of the manufacturing process. Therefore, it is urgently desired - the shape after the formation is difficult. Ϊ Ι 388 388 388 388 388 388 388 388 388 388 388 388 388 388 388 388 388 388 388 388 388 388 388 Steel plate. For example, Patent Document 1 describes that an average value of the x-ray random intensity ratio of the {100} <011>~{223}<11〇> orientation group is 3.0 or more, and {554}<225>, {111}<112>, {111}<11〇> The crystallographic intensity of the three crystal orientations is larger than the average of the specific orientation of 3.5 or less. Further, at least one of the r value in the rolling direction and the r value in the rolling direction and the right direction is 〇7 or less, and the bending process is mainly a ferrite-type iron-based steel sheet excellent in shape freezing property. The steel sheet described in Patent Document 1 has a markedly improved bend formability, and has a small amount of springback, and is mainly subjected to bending processing, and is excellent in shape freezeability. Further, 'Patent Document 2' describes a structure having an island-like structure containing martensite dispersed in a ferrite base having a surface average roughness Ha of 0.4 to 1.8 /zm and The PPI (peak to peak intensity) value is a surface roughness of 80 or more in terms of a claw count standard, and the proportional limit stress is 20 kg/mm 2 or less, that is, a shape of 200 MPa or less. High tensile steel sheet with excellent freezing properties. Thereby, the tightness of the press surface and the steel sheet at the time of press forming is improved, and a member (product) excellent in shape freezeability after press forming can be obtained. [PRIOR ART DOCUMENT] [Patent Document 1] Japanese Patent Laid-Open Publication No. 2001-3〇3175 Publication No. 100121388 5 201211268 [Patent Document 2] Japanese Patent Laid-Open Publication No. S8-25456 (Summary of the Invention) i. However, in the steel sheet manufactured by the technique described in Patent Document 1, it is possible to ensure the desired shape of the product in the product (member) which is mainly processed by the j. For example, a steel plate system manufactured by the technique described in Patent Document 2 has a problem that it is not necessary to ensure the shape freezeability which can be satisfied by the processing of the bending process. It is a structure in which the island-like structure of the house L-Tian-Iron is dispersed in the base of the ferrite-grained iron. Therefore, it is easy to become a hardened steel plate, and there is a problem that cracks are often generated at the time of forming a high protrusion height. SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and to provide a cold rolled steel sheet having excellent shape bedability and a method for producing the same. (Means for Solving the Problem) In order to achieve the above object, the inventors of the present invention have conducted intensive studies on various factors affecting the shape freezing property. The present inventors have considered that the shape of the product (member) at the time of press forming is caused by the elastic strain introduced during press forming being released when the article (member) is taken out from the press mold, thereby focusing on The proportion limit of the steel plate. The proportional limit refers to the limit of the stress that can be proportional to the strain when an external force is applied to the elastic body. During the period of small stress, Hooke’s law was established, so a positive relationship can be seen. A steel plate having various ratios of 100121388 6 201211268 was prepared, and a part of a specific shape was formed by press forming, and the shape after forming was formed; the east knot was examined for 5 weeks. As a result, it has been found that in order to secure the desired shape freezeability, it is necessary to reduce the ratio of the steel sheet to 15 () MPa or less. The experimental results which are the basis of the present invention will be described. A steel sheet (test material) having a plate thickness of various scales and a thickness of 0.8 mm was press-formed to form a hat-shaped part of the size shown in Fig. 1. Furthermore, the pleat extrusion pressure was set to 20 ton. After the molding, the parts were taken out from the mold, and the opening amount X of the hat shape was measured. In Fig. 2, the relationship between the proportional limit of the steel sheet and the opening amount X is shown. As can be seen from Fig. 2, when the ratio of the steel sheet is 150 MPa or less, the increase in the amount of opening X is small, and excellent shape freezeability can be maintained. However, if the ratio of the steel sheet exceeds 15 〇Mpa, the opening amount X is increased. The sharp increase increases, and the shape freezeability drops significantly. Next, the inventors of the present invention have steadily manufactured steel sheets having the above-mentioned ratio limits, and have conducted intensive studies on various factors affecting the scale limit of the steel sheets. As a result, it has been found that by using a steel sheet mainly composed of a ferrite-grained iron phase having a relatively large crystal grain size, it is possible to easily reduce the scale limit by performing a temper rolling with a small surface roughness. Next, the experimental results that form the basis of the above cognition will be described. For example, there are 0.040% by mass of 〇〇.〇1% of Si, 0.20% of Μ, 0.01% of Ρ, 〇.〇1%4 S, 0.04% of Α1, 0.003% of Ν and the remainder of Fe The cold rolled annealed sheet (sheet thickness: 0 8 mm) of the composition consisting of the average crystal grain size: 1 〇 #瓜#肥的粒铁100121388 7 201211268 single phase, the rolling elongation rate is 1% Tempering and rolling. For the temper rolling delay, various rolling rolls having a surface roughness Ra of 0.2 to 2.5 were used. JIS (Japanese Industrial Standards) No. 5 test piece was extracted from each steel sheet which had been subjected to the tempering and rolling, and the tensile test was carried out to obtain the ratio limit of each steel sheet. The proportional test was carried out by using a tensile test piece having a strain gauge of 5 min on both sides of the parallel portion and performing a tensile test at a tensile speed of 1 mm/min. As shown in Fig. 3, the proportional limit is based on the relationship between the inclination (Δσ / Δ ε ) of the stress-strain curve and the stress (a), and the inclination becomes smaller as the stress increases. The relationship between the obtained results and the surface roughness Ra of the rolling rolls used is shown in Fig. 4. Further, the surface roughness of the roll was measured in accordance with the regulations of JIS B 0601-2001. As can be seen from Fig. 4, when the temper rolling is performed using a rolling roll having a roll surface roughness Ra of 2.0 or less, the ratio of the steel sheet is easily 15 MPa or less. The mechanism for reducing the limit of the rolling ratio of the roll using the above-mentioned surface (10) is not sufficiently clarified, but the inventors of the present invention have inferred as follows. The inventors of the present invention have considered that the steel sheet having the coarse grain ferrite as the crystal grain 彳f 5 to 3G as the main body is subjected to the tempering of the surface roughness Hj of 2 () (4) or less. Rolling can introduce the strain of the uniform sentence 100121388 8 201211268 in the thickness direction, and further promote the introduction of the mobile dislocation into the ferrite iron crystal grain, thereby significantly reducing the scale limit. On the other hand, the inventors of the present invention thought that when a rolling roll having a surface roughness Ra of more than 2. 〇m and a large surface roughness is used for temper rolling, the introduced strain is concentrated on the surface of the steel sheet. Therefore, the difference is chaotic and the movable difference is reduced, so that the reduction of the proportional limit cannot be obtained. The present invention has been completed based on the above findings and further research. That is, the gist of the present invention is as follows. (1) A cold-rolled steel sheet excellent in shape freezeability, which has a mass of C: 0.10% or less, Si: 0.05% or less, Μη: 0.1 〜1.〇〇/0, Ρ: 0.05% or less 'S ·· 0.02% or less, Α1 : 〇.〇2~〇·ΐ0%, Ν: less than 0.005%, and the rest consists of Fe and unavoidable impurities, and the average crystal grain The thin steel plate having the diameter d: 5 to 30 // m of the ferrite-grained iron phase as the main structure, is formed by using a tempering rolling mill having a surface roughness Ra of 2 〇 and a rolling roll below the claw, wherein , with a limit of 15 〇 Mpa or less. (2) The cold-rolled steel sheet according to (1), which, in addition to the above composition, further contains, in mass%, selected from the group consisting of Ti: 0.005 to 〇.〇8%, Nb: 0.010 〇, _%, B: 0.0003 〜O.〇〇3〇〇/0, Cr: 0.1 〜1.〇%, Mo: 0.1 〜1. i/〇 of the i species or two or more components. (3) A cold-rolled steel sheet excellent in $-bundling property, characterized in that on at least one surface of a cold-rolled steel sheet such as (1) or (2), a layer of molten plating is formed 100121388 9 201211268, an alloy It is formed by melting a zinc ore layer or an electroplated zinc layer. (4) A method for manufacturing a cold-rolled steel sheet having excellent shape and joint properties, which is directly subjected to hot rolling (four), cold-rolled material (four), cold-rolled sheet, and cold-rolled material; The "method" of the cold-rolled steel sheet of the dry-annealed sheet is characterized in that the steel material includes C: 0.10% or less, Si: 0 05% or less, and the mass is less than or equal to 03, and is not one (four). The composition of the steel material 'on the nuclear fire step mine, the above-mentioned cold-rolled plate (4) 730 ~ 850 ° C temperature after heating for more than 30 s, after cooling at an average cooling rate of 5t / s to the temperature below 峨 annealing a step of forming a cold-rolled annealed sheet having a structure in which a fat_phase of the average crystal grain size d: 5 to (10)_ is used as a main body, and after the annealing step, the coldness (four) is used to make the surface roughness (6) For the dry roll of 2 G _ or less, the temper rolling is performed so that the elongation rate of the temper rolling is corresponding to the average crystal grain size d (em) of the cold-rolled annealed sheet in the range of d/20 to d/5%. A method of manufacturing a cold-rolled steel sheet having a ratio of 150 MPa or less. (5) A method for producing a cold-rolled steel sheet according to (4), wherein The annealing step is performed by an annealing-melting galvanizing treatment step of annealing the cold-rolled sheet at a temperature ranging from 730 to 850 ° C and cooling to an average cooling rate of 5 s or more. (6) The method for producing a cold-rolled steel sheet according to (5), after the annealing-melting galvanizing treatment step, and further, the method of producing the cold-rolled steel sheet according to (5) (7) The method for producing a cold-rolled steel sheet according to any one of (4) to (6), wherein, in addition to the composition of the steel material, One or more selected from the group consisting of Ti: 0.005 to 0.08%, Nb: 0.010 to 0.030%, B: 0.0003 to 0.0030%, Cr: 0.1 to 1.0%, and Mo: 0.1 to 1.0% by mass% (Effect of the Invention) According to the present invention, a cold-rolled steel sheet having a ratio limit of 150 MPa or less can be produced inexpensively and stably, and the shape freezeability of the formed member is remarkably improved, and the industrial effect is remarkable. Implementation method] First, the hair The reason for the limitation of the composition of the thin steel sheet is described below. Unless otherwise stated, the mass % is only referred to as %. C : 0.10% or less contains more than 0.10% of C, which is to refine the ferrite particles and promote the snow The formation of iron (cementite) makes it difficult to reduce the ratio limit, and improves the hardenability, promotes the formation of a low-temperature metamorphic phase, and increases the strength and decreases the ductility. Therefore, the C system is limited to 0.10% or less. Further, it is preferably 0.05% or less. In the present invention, the lower limit of the C content is not necessarily limited, but an excessive decrease causes an increase in the production cost, and therefore it is preferably made 0.0010% or more. 100121388 11 201211268
Si ·· 0.05%以下 Si係肥粒鐵穩定化 r f ’且純進肥粒鐵t之C變濃， =雪^^麻田散鱗易於生成而有助於促進硬質化之 加工性之觀點而言，較佳為儘可能地降低。又， Si於退火時會在表面 狀、化赤虛㈣ 场成S1氧化物，從而會對表面性 狀、化成處理性、雷赫，， A性荨這成不良影響。由此，Si係限 定於0.05%以下。再本 ^ ^ 丹者，更佳為0.03%以下。 Μη : 0.1 〜1.0% Μη係形成MnS，ρ大μ m 0 ^ 防止因S而產生之熱龜裂之有效元素，Si ·· 0.05% or less Si-based ferrite-iron stabilized rf′ and purely fermented-grain iron t-C becomes thicker, and snow=^Matian scales are easy to form and contribute to the workability of hardening. Preferably, it is reduced as much as possible. Further, when Si is annealed, it forms a S1 oxide in the surface and in the red (4) field, which adversely affects the surface properties, chemical conversion properties, Reich, and A-type enthalpy. Therefore, the Si system is limited to 0.05% or less. Again, ^ ^ Dan, better than 0.03%. Μη : 0.1 ～1.0% Μη forms MnS, ρ is large μ m 0 ^ The effective element for preventing thermal cracking due to S,
較佳為根據所含有$ qI 胥之S量而含有。為獲得此種效果，必需含 有0.1/。以上。又’ Mn係經固溶而使鋼之強度增加，並且使 /卒火f生提N而有助於結晶粒之微細化之元素，其大量含有會 促進麻田散鐵等低溫變態相之生成，或使肥粒鐵粒微細化而 難以使比例限度下降，並且使延展性顯著下降而使加工性劣 化。此種傾向於含有超過1.0%之情形時變得顯著。因此， Μη係限定於〇1〜1〇%之範圍内。再者，於要求更良好之 加工性之用途中，較理想的是設為0.5%以下。 Ρ : 0.05%以下 Ρ係於鋼中作為不可避免之雜質而含有，具有在晶界偏析 而使晶界強度下降之作用。因此，於本發明中，較佳為儘可 能地減少’但可容許至0.05%為止。因此，Ρ係限定於0 05〇/〇 以下。再者，較佳為〇.〇3%以下。 100121388 12 201211268 S : 0.02%以下 S係使熱狀態下之鋼之延展賴著下降，誘發熱龜裂而使 表面性狀顯著劣化之元素。又，S _成粗大之硫化物，使 鋼之延展性、她下降。@此，s較佳為儘可能地減少，但 "要為0.02/。左右為止，即可容許。由此，$係限定於㈣％ 以下。再者，較佳為〇〇1%以下。 A1 : 0.02〜〇·1〇〇/0 Α1係作為鋼之去氧劑膽揮作用，具有提高鋼之清潔度 之作用並且具有強有力地固定Ν，抑制因Ν所引起之時 效硬。化(age hardness)之作用。為獲得此種效果，必需含有 0.02%以上。另一方面，含有超過_%，會導致因氧化紹 之生成所引起之夾雜物量之增加等表面性狀之惡化。因此， A1係限定於0.02〜〇.1〇%之範圍内。再者，較佳為〇 〇5%以 下。 N :未滿 〇.〇〇5〇/0 N係經固溶而有助於增加鋼之強度，具有使比例限度增加 之傾向，並且若大量地含有，則會產生鋼坯之熱龜裂，而具 有使鋼堪之表面性狀惡化之傾向之元素；於本發明中，較理 想的是儘可能地減少，但只要未滿0.005%，即可容許。因 此，N係限定於未滿〇 〇〇5〇/〇。 上述成分為基本成分，但除基本組成以外，可進而視需要 選擇含有選自 Ti: 0.005〜〇.〇8〇/0、Nb : 0.010〜0.030%、B : 100121388 13 201211268 0.0003 〜0.0030〇/〇、Cr : 0.1 〜1.0%、Mo : 0.1 〜1.0% 中之 1 種或2種以上。 選自 Τι : 0.005 〜〇 〇8〇/〇、Nb : 〇 〇1〇〜〇 〇3〇0/〇、b : 〇 〇〇〇3 〜0·〇〇3〇%、Cr : 0.1 〜1.0%、Mo : 0·1 〜1.0%中之 1 種或 2 種以上Preferably, it is contained in accordance with the amount of S contained in $ qI 胥. In order to achieve this effect, it must be 0.1/. the above. In addition, Mn is an element which increases the strength of steel by solid solution, and contributes to the precipitation of N, which contributes to the refinement of crystal grains. The large amount of Mn promotes the formation of low-temperature metamorphic phases such as granulated iron. Or it is difficult to reduce the scale limit by making the ferrite iron particles fine, and the ductility is remarkably lowered to deteriorate the workability. This tends to become significant when it tends to contain more than 1.0%. Therefore, Μη is limited to the range of 〇1 to 1%. Further, in applications requiring better processability, it is preferably set to 0.5% or less. Ρ : 0.05% or less Lanthanum is contained in steel as an unavoidable impurity, and has a function of segregating at the grain boundary to lower the grain boundary strength. Therefore, in the present invention, it is preferable to reduce as much as possible but to allow it to be 0.05%. Therefore, the tether is limited to 0 05〇/〇. Further, it is preferably 〇.〇3% or less. 100121388 12 201211268 S : 0.02% or less S is an element which causes the steel in a hot state to be lowered, and which causes thermal cracking and causes deterioration of surface properties. In addition, S _ becomes a coarse sulfide, which makes the ductility of steel and her decline. @这, s is preferably reduced as much as possible, but " is 0.02/. It can be tolerated until left and right. Therefore, the $ is limited to (four)% or less. Further, it is preferably 〇〇1% or less. A1: 0.02~〇·1〇〇/0 Α1 is a desulfurizing agent for steel. It has the effect of improving the cleanliness of steel and has a strong fixed enthalpy to suppress the aging caused by bismuth. The role of age hardness. In order to achieve this effect, it is necessary to contain 0.02% or more. On the other hand, when the content exceeds _%, surface properties such as an increase in the amount of inclusions due to the formation of oxidation may be deteriorated. Therefore, A1 is limited to the range of 0.02 to 〇.1〇%. Further, it is preferably 〇 5% or less. N: not full 〇.〇〇5〇/0 N is solid solution to help increase the strength of the steel, and has a tendency to increase the ratio limit, and if it is contained in a large amount, it will cause thermal cracking of the slab, and It is an element which has a tendency to deteriorate the surface properties of the steel; in the present invention, it is preferable to reduce as much as possible, but it is acceptable as long as it is less than 0.005%. Therefore, the N series is limited to less than 〇5〇/〇. The above components are basic components, but may be selected from the group consisting of Ti: 0.005~〇.〇8〇/0, Nb: 0.010~0.030%, B: 100121388 13 201211268 0.0003 to 0.0030〇/〇, in addition to the basic composition. One or two or more of Cr: 0.1 to 1.0% and Mo: 0.1 to 1.0%. From Τι : 0.005 ~ 〇〇 8 〇 / 〇, Nb : 〇〇 1 〇 ~ 〇〇 3 〇 0 / 〇, b : 〇〇〇〇 3 〜 0 · 〇〇 3 〇 %, Cr : 0.1 〜 1.0% One or more of Mo: 0·1 to 1.0%
Tl ' Nb ' B ' Cr、Mo均係形成氮化物及/或碳化物，立有 助於減少使耐時效性劣化之固溶C、N之元素，可視需要選 擇3有1種或2種以上。為獲得此種效果，較理想的是分別 3 有 Τι. 〇.〇〇5〇/〇以上、_ : 〇 〇1〇0/〇以上、B : 〇 〇〇〇3%以上、 Cr . 0.1/。以上、M〇 : 〇 以上，但分別超過η : 〇 〇8〇/〇、Tl ' Nb ' B ' Cr and Mo are all formed into nitrides and/or carbides, and contribute to the reduction of the elements of solid solution C and N which deteriorate the aging resistance, and may be selected as one or more than three or more. . In order to obtain such an effect, it is preferable that 3 has Τι. 〇.〇〇5〇/〇 or more, _: 〇〇1〇0/〇 or more, B: 〇〇〇〇3% or more, Cr. 0.1/ . Above, M〇 : 〇 above, but exceeds η: 〇 〇8〇/〇,
Nb . 0.030%、b : 〇,〇〇3〇%、Cr : 10%、M。： 1()%之含有， 係由析出物之增加、或淬火性之提高而促進低溫變態相之 &加等’從而使鋼硬質化而使延展性下降。因此，於含有之 清形時’較佳為分別限定於Ti : 0.005〜0.08%、Nb : 0.010 O-030/o > B ： 0.0003-〇.〇〇3〇〇/0. Cr ： 0.1-1.0% ' Mo ： 0·1 〜1.0%之範圍内。 上述成分以外之其餘部分係由Fe及不可避免之雜質所構 成。 又’本發明之薄鋼板具有上述組成，進而具有以平均蛣晶 粒裣.5〜3〇 之肥粒鐵相作為主體之組織。此處所述之 作為主體」，係指以相對於組織整體之體積率計為95%以 上佳為98%以上，更佳為1〇〇%之情況。除作為主體之 100121388 201211268 相以外之第二相為雪明碳鐵、絲鐵(pea伽）、變韌鐵 (bamite)等。第二相係以體積率計設為以下。若第二相超 過5%而變多，則鋼板會硬質化，成形性(加工性)下降。 又，若肥粒鐵相之平均結晶粒徑未滿5 //m，則晶界變 多，因此調質軋延時之應變會特別集中於晶界三重點，使差 排變得易於混亂化，故成為比例限度增加之傾向。另一方 面，若肥粒鐵相之平均結晶粒徑超過3〇 而結晶粒粗大 化則於壓製成形時’被稱為橘皮(orange peel)之凹凸邊變 得顯著，從而構件之表面性狀下降，並且難以將比例限度之 降低所需之可動差排導入至晶界附近。由此，肥粒鐵相之平 均結晶粒徑限定於5〜30 ym。 此外’本發明之冷軋薄鋼板係對具有上述組成與上述組織 之薄鋼板，實施使用表面粗糙度Ra為2.0 //m以下之軋延 輥之調質軋延而成之薄鋼板。於調質軋延時所使用之軋延輥 之表面粗糙度Ra超過2.0 之情形時，調質軋延時所導 入之應變集中於鋼板表層，無法於板厚方向上導入均勻之應 變’從而無法獲得所期望之比例限度之降低。因此，於本發 明中，係對具有上述組成與上述組織之薄鋼板，實施使用表 面粗糙度Ra為2.0 /im以下之軋延輥之調質軋延。 其次’對本發明之薄鋼板之較佳製造方法進行說明。 於本發明之薄鋼板之製造方法中，首先對鋼素材依序實施 熱軋步驟、冷軋步驟、以及退火步驟而形成為冷軋退火板。 100121388 15 201211268 所使用之鋼素材係與上述鋼板之組成同樣地，形成為具有 如下之組成之鋼素材：以質量％計包含c : 〇 1〇%以下/si: 0.05%以下、Mn : 0.K0%、P :⑽5%以下、s° : 〇 〇2%以 下、A1 : 0.02〜(U0%、N :未滿〇.〇〇5%，或者更包含選自 Ti : 0.005 〜0.08%、Nb : 〜〇 〇3〇%、b : 〇 〇〇〇3〜 0.0030%、Cr : 0.1 〜1.0%、Mo : 〇]〜1 〇%中之 i 種或 2 種 以上，且其餘部分由Fe及不可避免之雜質所構成。 鋼素材之製造方法無需特別限定，但較佳為利用轉爐等常 用之溶製方法對上述組成之熔鋼進贿製，並彻連續禱造 法等常用之鑄造方法形成為鋼Ji(slab)等鋼素材。為防止成 分之大量偏析’鋼素材之鑄造方法較理想的是連續禱造法， 但即便利用造塊法、薄鋼堪鑄造法，亦不存在任何問題。 首先’根據常用方法，對上述级成之鋼素材依序實施熱札 步驟及冷軋步驟而形成為冷軋板。 於本發明中，熱軋步鄉只要_㈣進行 札，其後實祕繞步·可製造_望之尺寸.之熱札板 即可，無需特別限定其條件。 繼二對所獲得之熱氣板實施冷乳步驟而形成為冷錢。 :對賴洗，繼繼料而形成為 乾，只要可軸騎J之酸洗方料可制1,關於冷 乳條件均可適^ 尺寸形狀之冷軋板即可’常用之冷 100121388 201211268 繼而，對所獲得之冷軋板實施退火步驟，形成為冷軋退火 板。 退火步驟係對冷軋板實施以退火溫度：730〜85〇t之範圍 之溫度加熱30s以上後’以5C/s以上之平均冷卻速度冷卻 至600°C以下之溫度為止之退火處理的步驟。藉此，形成為 具有以平均結晶粒徑d: 5〜30 之肥粒鐵相作為主體之 組織之冷軋退火板。 若退火溫度未滿730°C，則藉由冷軋而加工之肥粒鐵之再 結晶之完成變得困難，此外無法確保平均結晶粒徑：5 以上之粗大肥粒鐵粒。另一方面，若退火溫度超過謂。c而 成為南溫，則向沃斯田鐵(austenite)之變態行進，於冷卻時， 變態為微細之肥粒鐵、或者向低溫㈣相變態，肥粒鐵分率 ^小。。因此’退火溫度較佳為限定於730〜85(rc之範圍之 4 2者’退火溫度下之保持(加熱)時間較佳為設為30s 鐵粒。再者，純㈣無法確保所㈣之粗大肥粒 1之上限並無特觀定，但自生產性之 觀點而5較理想的是大致21以下。 又’退火步驟中之退火後 °C/s以上之平始太,、、 丨权佳馮自退火溫度起以5 卻速度平均小於^逮度冷卻至6〇〇t以下。若退火後之冷 無法形成騎敏则味齡之錢㈣促進，從而 斤㈣之粒徑範圍之肥粒鐵組織。另一方面，退 100121388 17 201211268 火後冷軋速度之上限無需特別限定，但於以超過3〇<t/s之 急速冷卻而驟冷之情形時，需要特別之冷卻設備，故較佳為 以30°C/s以下之冷卻速度進行冷卻。再者，若冷卻停止溫 度超過600°C而成為高溫’則存在於此後之冷卻中形成低溫 變態相之虞。因此，退火後之冷卻係設為以5t/s以上之平 均冷卻速度冷卻至600t：以下為止。再者，6〇〇它以下之冷 卻速度無需特別規定。 再者，亦可於所獲得之薄冷軋退火板上形成電鍛辞、化成 處理膜。 又，於本發明中，亦可取代上述退火步驟而設為如下退3 -熔融鍍鋅處理步驟，即，對上述冷軋板以退火溫度：73 〜85〇<t之範11之溫度進行退火，以5°C/S以上之平均冷名 速度冷卻至6G(rc以下之溫度為止，從而實雜融錢辞。^ 火-熔融_處理步㈣可綱連續㈣料生產線，於$ 火後’進行連續輯於通f之·。c附近之炼_辞洛^ 炫融鍍鋅處理。再者，亦可進而實施贿融鍍鋅層設為^ 化熔融_層之電㈣之合金化處理H合金化處理^ 设為根據常用方法 ’、 進行再,：！ 00t之溫度_ 進订再加熱之處理即可。 經過此種熱軋步驟、冷軋步驟、退火步驟或者退火 =步驟之冷軋退火板(電锻板)成為具有以平均結 .、、'㈣以上30 μ m以下之肥粒鐵相作為主體之紹 100121388 18 201211268 之冷軋退火板(㈣板）。再者，亦可於所獲得之冷軋退火板 (電鍍板）上進而形成化成處理膜。 於本發明中，繼而使用表面粗链度^為2〇 _以下之 軋延輥對冷軋退火板（電鍍板)實施調質軋延。 如圖4所示，若所使用之軋延輕之表面粗糖度以超過Μ ㈣而變粗’則無法穩定地確们5請以以下之比例限度。 2使用之軋延親之表面崎度Ra之下限無需特別限定，但 若所使用之軋延歡表面粗妓Ra變小，則所獲得之鋼板 之表面粗縫度亦變小，鋼板之摩擦阻力過度變小，從而於捲 繞成線圈狀時，於線圈上會出現繞偏而易於鬆散。因此，、所 使用之軋延輥之表面㈣度以較佳為設為Q2 _以上。 再者，表面粗糙度Ra係使用依據JIS B 〇6〇12〇〇1之規定所 測定之值。 此外’若㈣為㈣賴叙冷軋社板之平均結晶粒徑 設為d(㈣’則調質軋延時之伸長率(調質軋延伸長修㈨ 車交佳為設為（0.05〜0.20)d。其理由如下。藉由實施調質札 延’導人可動差排，從而比例限度降低。然而，藉由調質乳 延而導入之可動差排易於導人至晶界附近，故為將所期望之 比例限度之降低所需之可動差排有效地導入至晶界附近，必 需隨著肥粒鐵粒徑增大而增大調質札延伸長率。即，根據肥 粒鐵平均粒徑“以爪丨而調整調質軋延伸長率變得重 要。將已凋質軋延完畢之鋼板之比例限度(]^1>幻與R/d之關 100121388 19 201211268 係不於圖5。再者，圖5係使用肥粒鐵平均結晶粒徑d為$ 〜2〇 之鋼板，並使用表面粗糙度1^為〇 2〜18以泔 之軋延輥進行調質軋延之結果。根據圖5可知，R/d處於〇.的 〜0.20之間且鋼板之比例限度成為15〇Mpa以下。 若調質軋延伸長率R(%)未滿〇.〇5d，則調質軋延之軋縮量 不足’且無法導人所期望之可動差排，從而無法確保所期望 之低比例限度。另-方面，若超過Q遷而軋縮量變多，則 所導入之差排混亂化’且有效地幫助比例限度降低之可動差 排不足’從而無法確保所期望之低比例限度。由此，調質札 延伸長率R(%)係根據肥粒鐵平均結晶粒徑d，限定於(〇〇5 〜〇.20)d之範圍内。 以下，基於實施例，進一步對本發明進行說明。 [實施例] 對表1所不之組成之鋼素材實施如下熱軋步驟：實施加熱 至1200Ϊ而將最終通路之出料侧溫度設為9〇〇β(：之熱軋，益 於550 C進行捲繞，形成為板厚：2 6職之薄熱軋板。對所 獲得之薄熱軋板實㈣洗後，實施如下之冷軋步驟：實施冷 軋，形成為板厚0.8 mm之冷軋板。繼而，對所獲得之冷軋 板，實施於表2所示之退火溫度、保持時間及冷卻速度之條 件下進行退火處理之退火步驟，形成為薄冷乳退火板。再 者，冷卻速度係設為自退火溫度至6〇〇<t為止之平均。 於一部分鋼板中，在表2所示之條件下’實施退火_溶融 100121388 20 201211268 鍍鋅處理步驟來取代退火處理。退火熔崎理 。中，繼料處理錢，實减續錢於電麟之溫度步4= C之炼融鍵鋅浴中之炫融鍍鋅處理。再者，對-部分之铜 板，於熔融鍍鈕夂綱 。，辞處理後，以表2所权溫度實施合金化處理。 所獲彳于之薄冷軋退火板（薄電鍍板），以平行於軋延方向 之』面成為觀察面之方式提取組織觀察料驗#，進行研 磨並進行ί肖I魏液恤⑽# ’求出肥粒鐵相之平均纤 晶粒控、M、織分率。肥粒鐵相之平均結晶粒徑係使用光學顯 微鏡(倍率：_倍），對2_·，之區域藉由切斷法而 求出。又’肥粒鐵相之組織分率係使用光學顯微鏡(倍率： 100倍）’拍攝2張200x200 之區域，使用圖像解析裝 置而算出。再者，亦對肥粒鐵以外之第二相進行觀察。將組 織觀察結果一併揭示於表2。 繼而’對所獲得之冷軋退火板(電鍍板），使用表2所示之 表面粗縫度Ra("m)之軋延幸昆，以表2所示之調質軋延伸長 率R(%)實施調質軋延，魏之表面祕度Ra係依據JIS B 0601-2001之規定而敎4者，對未實施熔賴鋅處理之 一部分鋼板，於調質軋延後實施電鍍辞處理。 自已調質軋延完畢之薄鋼板（薄電鍍鋼板），以試驗方向成 為軋延方向之方式提取JIS 5號試驗片（標距（GL，gauge length) : 50 mm)，依據JIS Z 2241之規定進行拉伸試驗，求 出拉伸特性（降伏強度（YS ’ Yield strength)、拉伸強度 100121388 21 201211268 (Tension Strength，TS)、伸長率（E卜 Elongation))。又，自 所獲得之薄鋼板’以試驗方向成為軋延方向之方式提取jIS 5號試驗片，實施拉伸試驗，求出比例限度。 比例限度係使用在平行部兩面上貼附有應變計（計量長 度· 5 mm)之拉伸試驗片，以拉伸速度：1 進行拉伸 試驗，根據應力-應變曲線之傾斜度(Δσ/Δε)與應力（(7)之 關係’以圖3所示之要領而求出。 再者，對已調質軋延完畢之薄鋼板亦進行組織觀察，確認 出具有與冷軋退火板（電鍍板)相同之組織。將所獲得之結果 示於表3。 [表1]Nb . 0.030%, b : 〇, 〇〇 3〇%, Cr: 10%, M. The content of 1%) is promoted by the increase in precipitates or the increase in hardenability to promote the low-temperature metamorphic phase, thereby hardening the steel and lowering the ductility. Therefore, when it is contained, it is preferably limited to Ti: 0.005 to 0.08%, Nb: 0.010 O-030/o > B: 0.0003-〇.〇〇3〇〇/0. Cr : 0.1- 1.0% ' Mo : 0·1 to 1.0%. The rest of the above components are composed of Fe and unavoidable impurities. Further, the steel sheet of the present invention has the above composition, and further has a structure mainly composed of a ferrite-grained iron phase of an average of 蛣 granules 55 to 3 。. The term "subject" as used herein refers to a case where the volume ratio with respect to the entire structure is 95% or more, preferably 98% or more, more preferably 1% by weight. The second phase other than the main body of the 100121388 201211268 phase is ferritic carbon iron, silk iron (pea gamma), toughened iron (bamite) and the like. The second phase system is set to the following in terms of volume ratio. When the second phase is increased by more than 5%, the steel sheet is hardened and the formability (processability) is lowered. Moreover, if the average crystal grain size of the ferrite grain iron phase is less than 5 //m, the grain boundary is increased, so the strain of the quenching and rolling rolling time is particularly concentrated on the grain boundary three key points, so that the difference row becomes easy to be confused, so Become a tendency to increase the percentage limit. On the other hand, if the average crystal grain size of the ferrite-grained iron phase exceeds 3 〇 and the crystal grains are coarsened, the unevenness of the orange peel is remarkable at the time of press forming, and the surface properties of the member are lowered. And it is difficult to introduce the movable difference row required for the reduction of the proportional limit to the vicinity of the grain boundary. Thus, the average grain size of the ferrite iron phase is limited to 5 to 30 μm. Further, the cold-rolled steel sheet according to the present invention is a steel sheet obtained by rolling and rolling a steel sheet having the above-described composition and the above-mentioned structure, using a rolling roll having a surface roughness Ra of 2.0 / m or less. When the surface roughness Ra of the rolling roll used in the temper rolling delay is more than 2.0, the strain introduced by the temper rolling delay is concentrated on the surface of the steel sheet, and it is impossible to introduce a uniform strain in the thickness direction. The reduction in the expected ratio limit. Therefore, in the present invention, the steel sheet having the above-described composition and the above-described structure is subjected to temper rolling with a rolling roll having a surface roughness Ra of 2.0 / im or less. Next, a preferred method of producing the steel sheet of the present invention will be described. In the method for producing a thin steel sheet according to the present invention, first, a hot rolling step, a cold rolling step, and an annealing step are sequentially applied to the steel material to form a cold rolled annealed sheet. 100121388 15 201211268 The steel material used is formed into a steel material having the following composition in the same manner as the above-described steel sheet: c: 〇1〇% or less/si: 0.05% or less, Mn: 0. K0%, P: (10)5% or less, s°: 〇〇2% or less, A1: 0.02~(U0%, N: less than 〇.〇〇5%, or more including Ti: 0.005 to 0.08%, Nb : ~〇〇3〇%, b: 〇〇〇〇3~ 0.0030%, Cr: 0.1 ～1.0%, Mo: 〇]~1 〇% of i or more, and the rest is Fe and not The manufacturing method of the steel material is not particularly limited, but it is preferable to use a common melting method such as a converter to make a bribe for the above-mentioned composition, and to form a common casting method such as a continuous prayer method. Steel material such as steel Ji (slab). In order to prevent a large amount of segregation of components, the casting method of steel material is ideally continuous praying method, but even if it uses the agglomeration method and the thin steel casting method, there is no problem. 'According to the usual method, the steel material of the above grade is sequentially subjected to a hot step and a cold rolling step to form In the present invention, the hot rolling step is carried out as long as the _(four) is carried out, and then the actual step is swept. The hot plate of the size can be manufactured, and the condition is not particularly limited. The hot air plate is formed into a cold milk step to form a cold money. The dry heat is formed into a dry material, as long as it can be made by picking up the pickling material of the J, and the cold milk condition can be suitable for the size and shape. The cold-rolled sheet can be used as a common cold 100121388 201211268. Then, the obtained cold-rolled sheet is subjected to an annealing step to form a cold-rolled annealed sheet. The annealing step is performed on the cold-rolled sheet at an annealing temperature of 730 to 85 〇t. After the temperature of the range is heated for 30 sec or more, the step of annealing is performed until the temperature is cooled to 600 ° C or lower at an average cooling rate of 5 C/s or more. Thereby, it is formed to have an average crystal grain size d: 5 to 30. The cold-rolled annealed sheet having the granular iron phase as the main structure. If the annealing temperature is less than 730 ° C, the completion of recrystallization of the ferrite iron processed by cold rolling becomes difficult, and the average crystal grain size cannot be ensured: 5 or more coarse fat iron particles. On the other hand, if retired When the temperature of the fire exceeds the value of c. It becomes the south temperature, and it travels to the metamorphosis of the austenite. When it cools, it is transformed into a fine ferrite iron or a low-temperature (four) phase transformation state, and the ferrite particle fraction is small. Therefore, the 'annealing temperature is preferably limited to 730 to 85 (the range of rc is 4 2 'the holding (heating) time at the annealing temperature is preferably set to 30 s iron particles. Furthermore, pure (four) cannot ensure that (4) The upper limit of the coarse fat grain 1 is not particularly limited, but it is preferably about 21 or less from the viewpoint of productivity. In addition, after annealing in the annealing step, the temperature above °C/s is too low, and 丨 佳 冯 feng is cooled from the annealing temperature by 5, but the average speed is less than the catching degree and cooled to 6 〇〇t or less. If the cold after annealing can not form the sensation of the sensation, then the money of the age of the taste (4) promotes, and thus the particle size range of the granules of the granules. On the other hand, the upper limit of the cold rolling speed after the fire is not particularly limited, but in the case of rapid cooling with a rapid cooling of more than 3 〇 < t/s, special cooling equipment is required, so it is preferably The cooling was carried out at a cooling rate of 30 ° C / s or less. Further, if the cooling stop temperature exceeds 600 °C and becomes a high temperature, there is a possibility that a low-temperature metamorphic phase is formed during the subsequent cooling. Therefore, the cooling system after annealing is cooled to 600 t: or less at an average cooling rate of 5 t/s or more. Furthermore, there is no need to specify the speed of the cooling below 6 。. Further, an electric forging and chemical conversion treatment film can be formed on the obtained thin cold rolled annealed sheet. Further, in the present invention, in place of the above annealing step, the following 3-de-melting galvanizing treatment step may be employed, that is, the cold-rolled sheet is subjected to annealing at a temperature of 73 to 85 Å < t. Annealing, cooling to 6G (average temperature below rc) at an average cold speed of 5 ° C / S or more, so that the money is mixed. ^ Fire - melting _ processing step (four) can be continuous (four) material production line, after $ fire 'Continue the series in the vicinity of the f. · C near the refining _ _ Luo ^ smelting galvanizing treatment. In addition, can also be implemented in the brittle galvanized layer to ^ melting _ layer of electricity (four) alloying treatment H alloying treatment ^ is set according to the usual method ', and then: 00t temperature _ order reheating treatment. After such hot rolling step, cold rolling step, annealing step or annealing = step cold rolling The annealed sheet (electrically forged sheet) is a cold-rolled annealed sheet ((four) board) having a ferrite-grained iron phase of an average of ., ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, The obtained cold-rolled annealed sheet (plated plate) is further formed into a chemical conversion treatment film. In the present invention, The cold-rolled annealed sheet (plated sheet) is subjected to temper rolling and rolling using a rolling roll having a surface roughness of 2 〇 or less. As shown in Fig. 4, if the surface roughness of the rolled surface is more than Μ (4) If it becomes thicker, it cannot be steadily determined. Please limit the ratio of the following. 2 The lower limit of the surface roughness Ra of the rolling contact is not limited, but if the rolling surface used is rough, the Ra becomes small. The surface roughness of the steel sheet obtained is also small, and the frictional resistance of the steel sheet is excessively small, so that when wound into a coil shape, the coil is twisted and easily loosened. Therefore, the rolling used is used. The surface (four) degree of the roll is preferably set to Q2 _ or more. Further, the surface roughness Ra is a value measured in accordance with JIS B 〇 6〇12〇〇1. Further, if (4) is (4) The average crystal grain size of the cold-rolled plate is set to d ((4)', and the elongation of the quenching and rolling time is delayed (the tempering rolling extension is long (9). The car is preferably set to (0.05 to 0.20) d. The reason is as follows. The implementation of the tempering zhayan 'guided movable row, so the proportion limit is reduced. However, guided by the tempering emulsion The movable difference row is easy to lead to the vicinity of the grain boundary, so that the movable difference row required to reduce the desired ratio limit is effectively introduced into the vicinity of the grain boundary, and must be increased as the particle size of the ferrite iron increases. According to the average grain size of the fertilized iron, it is important to adjust the elongation rate of the quenched and tempered rolling with the claws. The proportion limit of the steel plate that has been withered has been reduced (]^1> R/d of 100121388 19 201211268 is not shown in Fig. 5. In addition, Fig. 5 is a steel plate with a ferrite grain average crystal grain size d of 〜2〇, and a surface roughness of 1^ is 〇2~18 As a result of the temper rolling and rolling, the R/d is between 0.25 and 0.20 and the ratio of the steel sheet is 15 〇Mpa or less. If the elongation rate R (%) of the tempering rolling is less than 〇5 ,, the rolling reduction of the temper rolling is insufficient, and the desired moving difference is not obtained, so that the desired low ratio limit cannot be ensured. On the other hand, if the amount of rolling is increased in excess of Q, the introduced difference is disordered and the movable difference is effectively insufficient to reduce the proportional limit, and the desired low ratio limit cannot be secured. Therefore, the elongation rate R (%) of the quenching and tempering is limited to the range of (〇〇5 to 〇.20)d according to the average crystal grain size d of the ferrite. Hereinafter, the present invention will be further described based on examples. [Examples] The steel material having the composition shown in Table 1 was subjected to the following hot rolling step: heating to 1200 Torr and setting the discharge side temperature of the final passage to 9 〇〇β (: hot rolling, benefiting from 550 C) Winding, formed into a sheet thickness: a thin hot-rolled sheet of 26 grades. After the thin hot-rolled sheet obtained (4), the following cold-rolling step is carried out: cold rolling is performed to form a cold-rolled sheet having a thickness of 0.8 mm. Then, the obtained cold-rolled sheet is subjected to an annealing step of annealing treatment under the conditions of annealing temperature, holding time and cooling rate shown in Table 2 to form a thin cold-ward-annealed sheet. Further, the cooling rate The average is from the annealing temperature to 6 〇〇 < t. In some steel sheets, under the conditions shown in Table 2, 'annealing_melting 100121388 20 201211268 galvanizing treatment step instead of annealing treatment. Annealing saki In the middle, the material is processed and the money is reduced. The temperature is reduced in the temperature of step 4 = C. The smelting and galvanizing treatment in the zinc bath of the smelting key. In addition, the copper plate of the part is melted and plated. After the treatment, the alloying treatment is carried out at the temperature given in Table 2. The thin cold-rolled annealed sheet (thin-plated plate) obtained by the thin-rolled cold-rolled sheet (the thin plated plate) is extracted in parallel with the surface of the rolling direction to form the observation surface, and is ground and ф 肖 I魏液(10)# The average grain size, M, and weaving rate of the iron phase of the fertilized grain. The average crystal grain size of the ferrite phase is determined by an optical microscope (magnification: _ times), and the area of 2_· is cut by the method. In addition, the tissue fraction of the ferrite phase is measured by using an optical microscope (magnification: 100 times) to capture two areas of 200x200, and is calculated using an image analysis device. The two phases were observed. The results of the observation of the structure are also shown in Table 2. Then, for the obtained cold rolled annealed sheet (plated sheet), the surface roughness Ra ("m) shown in Table 2 was used. Kun, with the tempering and rolling elongation rate R (%) shown in Table 2 to carry out quenching and tempering rolling, Wei surface roughness Ra according to the provisions of JIS B 0601-2001 敎 4, for the implementation of melting zinc One part of the steel plate is treated, and the electroplating process is carried out after the quenching and tempering rolling. The thin steel plate has been tempered and rolled. The plated steel plate was subjected to a JIS No. 5 test piece (gauge length: 50 mm) in such a manner that the test direction became the rolling direction, and the tensile test was carried out in accordance with JIS Z 2241 to determine the tensile properties ( YS ' Yield strength, tensile strength 100121388 21 201211268 (Tension Strength, TS), elongation (E E Elongation). Further, the obtained steel sheet 'is extracted in the direction in which the test direction becomes the rolling direction The jIS No. 5 test piece was subjected to a tensile test to determine the ratio limit. The proportional limit is a tensile test piece to which a strain gauge (meter length·5 mm) is attached on both sides of the parallel portion, and the tensile test is performed at a tensile speed of 1 according to the inclination of the stress-strain curve (Δσ/Δε). The relationship between stress and stress ((7) is obtained by the method shown in Fig. 3. Furthermore, the microstructure of the thin steel sheet which has been tempered and rolled is also observed, and it is confirmed that it has a cold rolled sheet (plated sheet). The same organization. The results obtained are shown in Table 3. [Table 1]
100121388 22 201211268 鬥3<】 備註 1本發明例I 1本發明例1 |本發明例I |本發明例I 本發明例 1本發明例1 |本發明例| |本發明例| 1本發明例1 i本發明例1 1本發明例1 1本發明例 比較例 比較例| 比較例 比較例 比較例 比較例 比較例 調質軋延 R/d 0.10 0.13 0.17 0.10 0.06 0.18 0.09 0.10 0.08 0.13 0.11 b-12 m 0.04 0.15 0.20 0.09 0.10 0.10 伸長率R (%) q 00 Ο in 00 ο <N 1-H (N 00 〇 d 寸 〇 00 d q <N vn cs VO o (N 00 o o ro q q 報表面粗 縫度Ra (以m) (N 1—Η yr\ Ο d <N Ο 00 〇\ d vn d CN 〇 寸 d in ο q cn CN CN 鋼板組織 肥粒鐵平 均粒徑d ("m) 〇 Os 00 〇\ VO 〇\ o cs 寸 00 寸1 寸1 寸1 其他電鍍處理 (調質軋延後) 1 1 1 電辞 1 電鋅 電鋅 1 1 1 電鋅 電鋅 1 電鋅 1 1 1 1 1 熔融鍍鋅處理 合金化溫度 P 1 1 1 1 540 1 1 1 1 1 1 1 1 1 1 1 1 1 1 炫融鐘鋅處 理之有無 1 1 1 1 1 1 1 1 1 1 1 1 枇 1 1 1 退火處理 冷卻速度=·= rc/s) 1-H V〇 (N <n kn 1—< CN (N 寸丨 〇 oo 保持時間 ⑻ 〇 m o 180 200 120 丨150 100 ο 00 丨 150 1 1 !3〇 1 § 120 120 I 150 200 120 退火溫度 CC) 760 790 800 730 800 820 790 1 830 820 840 780 800 750 790 770 820 830 800 780 0Γ 6 < m υ Q 〇 w KH Μ o pLn ο 001 鋼板 (N m 寸 iTi \〇 卜 00 ON ο 1-Η CN ΓΟ 2 VO 卜 00 〇\ 1-H 贫牛>7·成 Ρ0091·* ιταοοοπίΝιοοι 201211268 ted 備註 本發明例 i本發明例 本發明例 本發明例 本發明例 本發明例 |本發明例1 |本發明例1 |本發明例1 |本發明例I 1本發明例1 I本發明例I 比較例 比較例 |比較例| 比較例 比較例 比較例 比較例 板厚I 1 00 〇 00 〇 00 〇 〇〇 d 00 〇 00 d 00 d 00 d 00 ο 00 Ο 00 d 00 Ο 00 ο 00 c5 00 〇 00 d 00 ο 00 c5 00 d 拉伸特性 比例限度 (MPa) § g L 120 —I 〇 o m ο Ο VO Ο 00 ο ο 160 ο 卜 180 160 160 ο \〇 170 伸長率 El(%) σ\ ro 〇 ο ο CO Ο] οι 〇 On m Ο 00 CO 拉伸強度 TS(MPa) 340 360 350 350 330 340 310 350 360 340 300 310 330 320 350 350 360 360 370 降伏強度 YS(MPa) 220 240 230 200 Ο 00 220 150 250 260 230 s 170 220 220 240 250 230 270 280 組織 j 1 1 u 2nS 〇 〇 ON 00 Cj On ο 2 〇〇 寸1 寸1 寸1 肥粒鐵相 (面積率） 100 00 〇\ 〇\ 〇\ 100 100 100 100 yn 〇\ Os 00 Os 100 ο Os Ο 00 〇\ IT) σ\ 100 〇\ 種類* F+B F+B 1 Uh F+p 1 F+P 1 F+p 1 U-i 1 F+p 1 1 F+p | 1 F+p 1 1¾ 丨F+P 丨 F+Ρ | 鋼板種類 冷軋退火板 電鍍板 冷軋退火板 電鍍板 電鍍板 電鍍板 電鍍板 電鍍板 冷軋退火板 冷軋退火板 電鍍板 電鍍板 冷軋退火板 電鍍板 冷軋退火板 電鍍板 冷軋退火板 冷軋退火板 冷軋退火板 ! 鋼 No. C ffl U Q m o K s 〇 Ph ο 001 鋼板 No. (N 寸 iT) 卜 00 Os ο »-Η <Ν 寸 00 Os ί-Η 鲅^^:3,黎蕊粼：a,黎芻契：dr 寸 Z 88--001 201211268 本發明例均係形成為具有以平均結晶粒徑：5〜3 0 # m之 肥粒鐵相作為主體之組織，且具有150 MPa以下之低比例 限度之薄鋼板。另一方面，脫離本發明之範圍之比較例中， 比例限度超過150 MPa。 【圖式簡單說明】 圖1係模式性地表示帽狀零件之形狀尺寸之說明圖。 ' 圖2係表示鋼板之比例限度對帽狀零件之開口量X所造 成之影響之圖表。 圖3係根據應力-應變曲線之傾斜度(Δσ/Δε)與應力（σ) 之關係，表示決定比例限度之一例的圖表。 圖4係表示輥表面粗糙度Ra對比例限度所造成之影響之 圖表。 圖5係表示已調質軋延完畢之鋼板之比例限度(MPa)與 R/d之關係。 【主要元件符號說明】 X 開口量 100121388 25100121388 22 201211268 Buck 3<1> Remark 1 Inventive Example I 1 Inventive Example 1 | Inventive Example I | Inventive Example I Inventive Example 1 Inventive Example 1 | Inventive Example | | Inventive Example | 1 Inventive Example 1 i Inventive Example 1 1 Inventive Example 1 1 Inventive Example Comparative Example Comparative Example | Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Tempering Rolling R/d 0.10 0.13 0.17 0.10 0.06 0.18 0.09 0.10 0.08 0.13 0.11 b- 12 m 0.04 0.15 0.20 0.09 0.10 0.10 Elongation R (%) q 00 Ο in 00 ο <N 1-H (N 00 〇d inch 〇 00 dq <N vn cs VO o (N 00 oo ro qq surface Roughness Ra (in m) (N 1—Η yr\ Ο d <N Ο 00 〇\ d vn d CN 〇 inch d in ο q cn CN CN Steel plate structure Fertilizer iron average particle size d ("m ) 〇Os 00 〇\ VO 〇\ o cs inch 00 inch 1 inch 1 inch 1 other plating treatment (after quenching and tempering) 1 1 1 electrogram 1 electric zinc electric zinc 1 1 1 electric zinc electric zinc 1 electric zinc 1 1 1 1 1 Melting galvanizing treatment alloying temperature P 1 1 1 1 540 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Whether or not the smelting bell is treated with zinc 1 1 1 1 1 1 1 1 1 1 1 1枇1 1 1 Annealing cooling rate =·= Rc/s) 1-HV〇(N <n kn 1—< CN (N inch 丨〇oo hold time (8) 〇mo 180 200 120 丨150 100 ο 00 丨150 1 1 !3〇1 § 120 120 I 150 200 120 Annealing temperature CC) 760 790 800 730 800 820 790 1 830 820 840 780 800 750 790 770 820 830 800 780 0Γ 6 < m υ Q 〇w KH Μ o pLn ο 001 Steel plate (N m inch iTi \〇 00 00 ON ο 1-Η CN ΓΟ 2 VO 卜 〇 1- 1- 1- 1- 1- 1- 1- 1- 1- 1- 1- 1- 1- Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ Ρ 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 EXAMPLES: Inventive Example 1 | Inventive Example 1 | Inventive Example 1 | Inventive Example I 1 Inventive Example 1 I Inventive Example I Comparative Example Comparative Example | Comparative Example | Comparative Example Comparative Example Comparative Example Comparative Example Sheet Thickness I 1 00 〇00 〇00 〇〇〇d 00 〇00 d 00 d 00 d 00 ο 00 Ο 00 d 00 Ο 00 ο 00 c5 00 〇00 d 00 ο 00 c5 00 d Tensile characteristic ratio limit (MPa) § g L 120 —I 〇om ο Ο VO Ο 00 ο ο 160 ο 卜 180 160 160 ο \〇170 Elongation El(%) σ\ ro 〇ο ο CO Ο] Οι 〇On m Ο 00 CO Tensile strength TS(MPa) 340 360 350 350 330 340 310 350 360 340 300 310 330 320 350 350 360 360 370 Falling strength YS(MPa) 220 240 230 200 Ο 00 220 150 250 260 230 s 170 220 220 240 250 230 270 280 Organization j 1 1 u 2nS 〇〇ON 00 Cj On ο 2 inch 1 inch 1 inch 1 fat iron phase (area ratio) 100 00 〇\ 〇\ 〇\ 100 100 100 100 yn 〇\ Os 00 Os 100 ο Os Ο 00 〇\ IT) σ\ 100 〇\ Category* F+B F+B 1 Uh F+p 1 F+P 1 F+p 1 Ui 1 F+p 1 1 F+p | 1 F+p 1 13⁄4 丨F+P 丨F+Ρ | Steel plate type cold rolled annealed plate plated plate cold rolled annealed plate plated plate plated plate plated plate plated plate cold rolled annealed sheet cold rolled annealed plate plating Plate plating plate cold rolled annealed plate plated plate cold rolled annealed plate plated plate cold rolled annealed sheet cold rolled annealed sheet cold rolled annealed sheet! Steel No. C ffl UQ mo K s 〇Ph ο 001 steel plate No. (N inch iT) 00 Os ο »-Η <Ν inch 00 Os ί-Η 鲅^^:3, 黎蕊粼: a, 黎刍契: dr inch Z 88--001 201211268 The inventive examples are all formed to have an average knot Crystal grain size: 5 to 3 0 # m The ferrite grain iron phase is the main structure, and has a low proportion of thin steel sheets of 150 MPa or less. On the other hand, in the comparative example which deviated from the scope of the present invention, the ratio limit exceeded 150 MPa. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an explanatory view schematically showing the shape and size of a cap-shaped member. Fig. 2 is a graph showing the effect of the proportional limit of the steel plate on the opening amount X of the cap-shaped member. Fig. 3 is a graph showing an example of determining the proportional limit based on the relationship between the inclination (Δσ/Δε) of the stress-strain curve and the stress (σ). Fig. 4 is a graph showing the influence of the roller surface roughness Ra on the scale limit. Fig. 5 is a graph showing the relationship between the ratio limit (MPa) and the R/d of the steel sheet which has been subjected to the temper rolling. [Main component symbol description] X opening amount 100121388 25