TWI509086B - High carbon steel sheet and manufacturing method thereof - Google Patents

Description

高碳鋼板及其製造方法High carbon steel plate and manufacturing method thereof 發明領域Field of invention

本發明係有關於一種謀求提升成形性之高碳鋼板及其製造方法。The present invention relates to a high carbon steel sheet which is intended to improve formability and a method for producing the same.

發明背景Background of the invention

高碳鋼板係被使用在汽車的鏈條、齒輪及離合器等的驅動系零件、鋸和切削工具等各種鋼鐵製品。在製造該等鋼鐵製品時，係進行高碳鋼板的成形及熱處理。就成形而言，係進行衝孔加工、拉伸加工、壓縮加工、剪切加工等，就熱處理而言，係進行淬火、回火、滲碳(carburization)、氮化、軟氮化等。因為相較於軟鋼板的強度水準，高碳鋼板的強度水準係較高，所以相較於軟鋼板的成形所使用的模具，在高碳鋼板的成形所使用的模具係較容易損耗。又，高碳鋼板在成形中亦比軟鋼板容易產生裂紋。High-carbon steel sheets are used in various steel products such as drive train parts such as chains, gears, and clutches of automobiles, saws, and cutting tools. In the manufacture of such steel products, the forming and heat treatment of high carbon steel sheets are carried out. In the molding, punching, drawing, compression, shearing, and the like are performed, and in the heat treatment, quenching, tempering, carburization, nitriding, soft nitriding, or the like is performed. Since the strength level of the high carbon steel sheet is higher than that of the soft steel sheet, the mold used for forming the high carbon steel sheet is more likely to be worn out than the mold used for forming the soft steel sheet. Moreover, the high carbon steel sheet is more likely to be cracked than the soft steel sheet during molding.

為了抑制模具損耗，提升高碳鋼板表面的潤滑性係有效的，為了抑制在成形中產生裂紋，高碳鋼板的軟質化係有效的。因此，有提案揭示以提升潤滑性和軟質化作為目的之技術(專利文獻1~5)。In order to suppress mold loss, it is effective to improve the lubricity of the surface of the high carbon steel sheet, and it is effective to suppress the occurrence of cracks during molding, and the softening of the high carbon steel sheet is effective. Therefore, there is a proposal to disclose a technique for improving lubricity and softening (Patent Documents 1 to 5).

但是，該等先前技術係帶來成本的顯著增加，乃 是不佳。However, these prior art systems have brought about a significant increase in costs, It is not good.

在專利文獻6係記載一種以提升衝孔性作為目的之碳鋼板，在專利文獻7係記載一種以提升成形性作為目的之高碳鋼板，但是採用該等亦無法得到充分的成形性。Patent Document 6 describes a carbon steel sheet for the purpose of improving the punching property, and Patent Document 7 describes a high-carbon steel sheet for the purpose of improving moldability. However, sufficient formability cannot be obtained by using these.

先前技術文獻Prior technical literature 專利文獻Patent literature

專利文獻1：日本特開2010-174252號公報Patent Document 1: Japanese Laid-Open Patent Publication No. 2010-174252

專利文獻2：日本特開2009-215612號公報Patent Document 2: Japanese Laid-Open Patent Publication No. 2009-215612

專利文獻3：日本特開2011-168842號公報Patent Document 3: Japanese Laid-Open Patent Publication No. 2011-168842

專利文獻4：日本特開2010-255066號公報Patent Document 4: Japanese Laid-Open Patent Publication No. 2010-255066

專利文獻5：日本特開2000-34542號公報Patent Document 5: Japanese Laid-Open Patent Publication No. 2000-34542

專利文獻6：日本特開2000-265240號公報Patent Document 6: Japanese Laid-Open Patent Publication No. 2000-265240

專利文獻7：日本特開平10-147816號公報Patent Document 7: Japanese Patent Laid-Open No. Hei 10-147816

發明概要Summary of invention

本發明之目的係提供一種在避免成本的顯著增加之同時，能夠得到良好的成形性之高碳鋼板及其製造方法。SUMMARY OF THE INVENTION An object of the present invention is to provide a high carbon steel sheet which can attain a good formability while avoiding a significant increase in cost, and a method for producing the same.

為了解決上述課題，本發明者等重複專心研討的結果，得到使高碳鋼板含有預定量的B；使在表面之肥粒鐵的微摩擦係數為預定；及使雪明碳鐵的態樣為預定係重要的之知識。而且，亦得到為了製造此種高碳鋼板，將熱軋 及退火的條件看作所謂的一貫步驟且使該等成為預定係重要的之知識。而且，本申請發明者等係基於該等知識而想出如以下所顯示之本發明的各種態樣。In order to solve the above problems, the inventors of the present invention repeated the results of intensive studies to obtain a high carbon steel sheet containing a predetermined amount of B; the micro-coefficient of ferrite on the surface is predetermined; and the aspect of the ferritic carbon iron is The reservation is important knowledge. Moreover, in order to manufacture such a high carbon steel sheet, hot rolling will be obtained. The conditions of annealing and annealing are regarded as so-called consistent steps and make these knowledge important for the predetermined system. Further, the inventors of the present application have come up with various aspects of the present invention as shown below based on such knowledge.

(1)一種高碳鋼板，其特徵在於具有下述表示之化學組成：以質量%計，C：0.30%~0.70%、Si：0.07%~1.00%、Mn：0.20%~3.00%、Ti：0.010%~0.500%、Cr：0.01%~1.50%、B：0.0004%~0.0035%、P：0.025%以下、Al：0.100%以下、S：0.0100%以下、N：0.010%以下、Cu：0.500%以下、Nb：0.000%~0.500%、Mo：0.000%~0.500%、V：0.000%~0.500%、W：0.000%~0.500%、Ta：0.000%~0.500%、Ni：0.000%~0.500%、Mg：0.000%~0.500%、 Ca：0.000%~0.500%、Y：0.000%~0.500%、Zr：0.000%~0.500%、La：0.000%~0.500%、Ce：0.000%~0.500%，且剩餘部分：Fe及不純物；並且具有下述表示之組織：雪明碳鐵的球狀化率：80%以上，且雪明碳鐵的平均粒徑：0.3μ m~2.2μ m；又在表面的肥粒鐵的微摩擦係數小於0.5。(1) A high carbon steel sheet characterized by having the chemical composition represented by C: 0.30% to 0.70%, Si: 0.07% to 1.00%, Mn: 0.20% to 3.00%, Ti: 0.010%~0.500%, Cr: 0.01%~1.50%, B: 0.0004%~0.0035%, P: 0.025% or less, Al: 0.100% or less, S: 0.0100% or less, N: 0.010% or less, Cu: 0.500% Hereinafter, Nb: 0.000% to 0.500%, Mo: 0.000% to 0.500%, V: 0.000% to 0.500%, W: 0.000% to 0.500%, Ta: 0.000% to 0.500%, Ni: 0.000% to 0.500%, Mg: 0.000% to 0.500%, Ca: 0.000% to 0.500%, Y: 0.000% to 0.500%, Zr: 0.000% to 0.500%, La: 0.000% to 0.500%, Ce: 0.000% to 0.500%, and remaining Part: Fe and impurities; and has the following structure: spheroidization rate of sedum carbon iron: 80% or more, and average particle diameter of ferritic carbon iron: 0.3 μ m to 2.2 μ m; The micro-coefficient of ferrite is less than 0.5.

(2)如(1)之高碳鋼板，其中前述化學組成中：Nb：0.001%~0.500%、Mo：0.001%~0.500%、V：0.001%~0.500%、W：0.001%~0.500%、Ta：0.001%~0.500%、Ni：0.001%~0.500%、Mg：0.001%~0.500%、Ca：0.001%~0.500%、Y：0.001%~0.500%、Zr：0.001%~0.500%、La：0.001%~0.500%、或Ce：0.001%~0.500%，或是該等的任意組合成立。(2) The high carbon steel sheet of (1), wherein the chemical composition: Nb: 0.001% to 0.500%, Mo: 0.001% to 0.500%, V: 0.001% to 0.500%, W: 0.001% to 0.500%, Ta: 0.001% to 0.500%, Ni: 0.001% to 0.500%, Mg: 0.001% to 0.500%, Ca: 0.001% to 0.500%, Y: 0.001% to 0.500%, Zr: 0.001% to 0.500%, La: 0.001% to 0.500%, or Ce: 0.001% to 0.500%, or any combination of these is established.

(3)一種高碳鋼板之製造方法，其特徵在於具有以下步驟：進行鋼胚的熱軋而製得熱軋鋼板之步驟；及進行前述熱軋鋼板的酸洗，且在前述酸洗之後，進行前述熱軋鋼板的退火之步驟；其中前述鋼胚具有下述表示之化學組成：以質量%計，C：0.30%~0.70%、Si：0.07%~1.00%、Mn：0.20%~3.00%、Ti：0.010%~0.500%、Cr：0.01%~1.50%、B：0.0004%~0.0035%、P：0.025%以下、Al：0.100%以下、S：0.0100%以下、N：0.010%以下、Cu：0.500%以下、Nb：0.000%~0.500%、Mo：0.000%~0.500%、V：0.000%~0.500%、W：0.000%~0.500%、Ta：0.000%~0.500%、Ni：0.000%~0.500%、 Mg：0.000%~0.500%、Ca：0.000%~0.500%、Y：0.000%~0.500%、Zr：0.000%~0.500%、La：0.000%~0.500%、Ce：0.000%~0.500%，且剩餘部分：Fe及不純物；又前述進行熱軋之步驟中，係將鋼胚加熱溫度設為1000℃以上且小於1150℃，將精加工輥軋溫度設為830℃以上且950℃以下，且將捲取溫度設為450℃以上且700℃以下；又前述進行退火之步驟具有以下步驟：將前述熱軋鋼板保持在730℃以上且770℃以下的溫度3小時以上且60小時以下之步驟；其次，將前述熱軋鋼板以1℃/hr以上且60℃/hr以下的冷卻速度冷卻至650℃為止之步驟。(3) A method for producing a high carbon steel sheet, comprising the steps of: performing hot rolling of a steel blank to obtain a hot rolled steel sheet; and performing pickling of the hot rolled steel sheet, and after the pickling, a step of annealing the hot-rolled steel sheet; wherein the steel embryo has a chemical composition represented by C: 0.30% to 0.70%, Si: 0.07% to 1.00%, and Mn: 0.20% to 3.00% by mass% Ti: 0.010% to 0.500%, Cr: 0.01% to 1.50%, B: 0.0004% to 0.0035%, P: 0.025% or less, Al: 0.100% or less, S: 0.0100% or less, N: 0.010% or less, Cu : 0.500% or less, Nb: 0.000% to 0.500%, Mo: 0.000% to 0.500%, V: 0.000% to 0.500%, W: 0.000% to 0.500%, Ta: 0.000% to 0.500%, Ni: 0.000%~ 0.500%, Mg: 0.000% to 0.500%, Ca: 0.000% to 0.500%, Y: 0.000% to 0.500%, Zr: 0.000% to 0.500%, La: 0.000% to 0.500%, Ce: 0.000% to 0.500%, and remaining Part: Fe and impurities; in the step of performing hot rolling, the steel slab heating temperature is set to 1000 ° C or more and less than 1150 ° C, and the finishing rolling temperature is set to 830 ° C or more and 950 ° C or less, and the roll is rolled. The temperature is set to 450° C. or higher and 700° C. or lower; and the step of annealing is performed by the step of maintaining the hot-rolled steel sheet at a temperature of 730° C. or more and 770° C. or lower for 3 hours or more and 60 hours or less; secondly, The hot-rolled steel sheet is cooled to a temperature of 650 ° C at a cooling rate of 1 ° C / hr or more and 60 ° C / hr or less.

(4)如(3)之高碳鋼板之製造方法，其中前述化學組成中：Nb：0.001%~0.500%、Mo：0.001%~0.500%、V：0.001%~0.500%、W：0.001%~0.500%、Ta：0.001%~0.500%、Ni：0.001%~0.500%、 Mg：0.001%~0.500%、Ca：0.001%~0.500%、Y：0.001%~0.500%、Zr：0.001%~0.500%、La：0.001%~0.500%、或Ce：0.001%~0.500%，或是該等的任意組合成立。(4) The method for producing a high carbon steel sheet according to (3), wherein the chemical composition: Nb: 0.001% to 0.500%, Mo: 0.001% to 0.500%, V: 0.001% to 0.500%, W: 0.001% 0.500%, Ta: 0.001% to 0.500%, Ni: 0.001% to 0.500%, Mg: 0.001% to 0.500%, Ca: 0.001% to 0.500%, Y: 0.001% to 0.500%, Zr: 0.001% to 0.500%, La: 0.001% to 0.500%, or Ce: 0.001% to 0.500%, or Any combination of these is true.

依照本發明，因為將B含量、在表面的肥粒鐵的微摩擦係數等設為適當者，所以在避免成本的顯著增加之同時，能夠得到良好的成形性。According to the present invention, since the B content, the micro-coefficient of the ferrite iron on the surface, and the like are made appropriate, it is possible to obtain a good formability while avoiding a significant increase in cost.

11、31‧‧‧肥粒鐵11, 31‧‧‧ ferrite iron

12‧‧‧沃斯田鐵12‧‧‧Worthian Iron

13‧‧‧B原子13‧‧‧B atom

14‧‧‧共價鍵14‧‧‧ covalent bond

15‧‧‧鋼板表面15‧‧‧ steel surface

16‧‧‧O原子16‧‧‧O atom

32‧‧‧雪明碳鐵32‧‧‧ Xueming Carbon Iron

33‧‧‧瑕疵33‧‧‧瑕疵

圖1係顯示肥粒鐵的微摩擦係數與B含量之關係之圖。Figure 1 is a graph showing the relationship between the micro-coefficient of fermented iron and the B content.

圖2係顯示肥粒鐵的微摩擦係數與在模具或高碳鋼板產生瑕疵為止的沖壓次數之關係之圖。Fig. 2 is a graph showing the relationship between the micro-coefficient of ferrite iron and the number of times of punching in a mold or a high-carbon steel sheet.

圖3A係顯示測定微摩擦係數前之高碳鋼板表面之顯微鏡照片。Fig. 3A is a photomicrograph showing the surface of a high carbon steel sheet before the measurement of the micro friction coefficient.

圖3B係顯示測定微摩擦係數後之高碳鋼板表面之顯微鏡照片。Fig. 3B is a photomicrograph showing the surface of a high carbon steel sheet after measuring the micro friction coefficient.

圖4係顯示從熱軋至冷卻為止之間的溫度變化之示意圖。Fig. 4 is a view showing the temperature change from hot rolling to cooling.

圖5A係顯示在時點tA之組織之示意圖。Fig. 5A is a schematic view showing the structure at time point tA.

圖5B係顯示在時點tB之組織之示意圖。Fig. 5B is a schematic view showing the structure at time point tB.

圖5C係顯示在時點tC之組織之示意圖。Figure 5C is a schematic diagram showing the organization at time tC.

圖5D係顯示在時點tD之組織之示意圖。Figure 5D is a schematic diagram showing the organization at time tD.

圖5E係顯示在時點tE之組織之示意圖。Figure 5E is a schematic diagram showing the organization at time tE.

圖6A係顯示鋼胚加熱溫度為大於1150℃時之組織之圖。Fig. 6A is a view showing the structure of the steel embryo heating temperature of more than 1150 °C.

圖6B係顯示鋼胚加熱溫度為小於1000℃時之組織之圖。Fig. 6B is a view showing the structure when the steel embryo heating temperature is less than 1000 °C.

圖6C係顯示退火保持溫度為小於730℃時之組織之圖。Fig. 6C is a view showing the structure when the annealing holding temperature is less than 730 °C.

圖6D係顯示退火保持溫度為大於770℃時或退火保持時間為大於60小時時之組織之圖。Fig. 6D is a view showing the structure when the annealing holding temperature is more than 770 ° C or the annealing holding time is more than 60 hours.

圖6E係顯示退火保持溫度為小於3小時的情況之組織之圖。Fig. 6E is a view showing the structure of the case where the annealing holding temperature is less than 3 hours.

圖6F係顯示冷卻速度為小於1℃/hr的情況之組織之圖。Fig. 6F is a view showing the structure of the case where the cooling rate is less than 1 °C / hr.

圖6G係顯示冷卻速度為大於60℃/hr的情況之組織之圖。Fig. 6G is a diagram showing the structure of a case where the cooling rate is more than 60 °C / hr.

圖7係針對在第1實驗或第3實驗之實施例的一部分之肥粒鐵的微摩擦係數與B含量的關係之圖。Fig. 7 is a graph showing the relationship between the micro-coefficient of fermented iron and the B content of a part of the examples of the first experiment or the third experiment.

用以實施發明之形態Form for implementing the invention

以下，說明本發明的實施形態。Hereinafter, embodiments of the present invention will be described.

首先，說明在本發明的實施形態之高碳鋼板及其製造所所使用的鋼胚(鋼塊)之化學組成。詳細係後述，本發 明的實施形態之高碳鋼板係經過鋼胚的熱軋及退火等而製造。因此，高碳鋼板及鋼胚的化學組成，係不僅是考慮高碳鋼板的特性，而且亦考慮該等的處理。在以下的說明，在高碳鋼板及其製造所使用的鋼胚所含有的各元素之含量單位之「%」，係只要是未預先告知，就意味著「質量%」。 在本實施形態之高碳鋼板及其製造所使用之鋼胚，係具有下述表示之化學組成：C：0.30%~0.70%、Si：0.07%~1.00%、Mn：0.20%~3.00%、Ti：0.010%~0.500%、Cr：0.01%~1.50%、B：0.0004%~0.0035%、P：0.025%以下、Al：0.100%以下、S：0.0100%以下、N：0.010%以下、Cu：0.500%以下、Nb：0.000%~0.500%、Mo：0.000%~0.500%、V：0.000%~0.500%、W：0.000%~0.500%、Ta：0.000%~0.500%、Ni：0.000%~0.500%、Mg：0.000%~0.500%、Ca：0.000%~0.500%、Y：0.000%~0.500%、Zr：0.000%~0.500%、La：0.000%~0.500%、及Ce：0.000%~0.500%，且剩餘部分：Fe及不純物。作為不純物，能夠例示在礦石、廢料等的原材料所含有者、及在製造步驟所者。例如在使用廢料作為原材料時，Sn、Sb或是As或該等的任意組合係有混入0.003%以上之情況。但是任一含量為0.03%以下時，因為不阻礙本實施形態的效果，所以能夠容許作為不純物。又，O係能夠容許以0.0025%為限度的方式作為不純物。O係形成氧化物，氧化物凝聚而粗大化時，無法得到充分的成形性。因此，O含量係越低越佳，但是將O含量減低至小於0.0001%為止係在技術上有困難。First, the chemical composition of the steel billet (steel block) used in the high carbon steel sheet according to the embodiment of the present invention and its production will be described. The details are described later, this issue The high carbon steel sheet according to the embodiment of the present invention is produced by hot rolling and annealing of a steel preform. Therefore, the chemical composition of the high carbon steel sheet and the steel embryo is not only considering the characteristics of the high carbon steel sheet, but also considering such treatment. In the following description, the "%" of the content unit of each element contained in the steel embryo used in the high carbon steel sheet and its production means "% by mass" unless otherwise notified. The high carbon steel sheet of the present embodiment and the steel embryo used for the production thereof have the chemical composition shown below: C: 0.30% to 0.70%, Si: 0.07% to 1.00%, and Mn: 0.20% to 3.00%, Ti: 0.010% to 0.500%, Cr: 0.01% to 1.50%, B: 0.0004% to 0.0035%, P: 0.025% or less, Al: 0.100% or less, S: 0.0100% or less, N: 0.010% or less, Cu: 0.500% or less, Nb: 0.000% to 0.500%, Mo: 0.000% to 0.500%, V: 0.000% to 0.500%, W: 0.000% to 0.500%, Ta: 0.000% to 0.500%, Ni: 0.000% to 0.500 %, Mg: 0.000% to 0.500%, Ca: 0.000% to 0.500%, Y: 0.000% to 0.500%, Zr: 0.000% to 0.500%, La: 0.000% to 0.500%, and Ce: 0.000% to 0.500% And the rest: Fe and impurities. Examples of the impurities include those included in raw materials such as ore and scrap, and those in the production steps. For example, when scrap is used as a raw material, Sn, Sb or As or any combination of these may be mixed in a ratio of 0.003% or more. However, when any content is 0.03% or less, since the effect of the embodiment is not inhibited, it can be allowed to be an impurity. Further, the O system can be used as an impurity with a limit of 0.0025%. When O forms an oxide and the oxide aggregates and coarsens, sufficient formability cannot be obtained. Therefore, the lower the O content, the better, but it is technically difficult to reduce the O content to less than 0.0001%.

(C：0.30%~0.70%)(C: 0.30%~0.70%)

因為C係與Fe鍵結而形成摩擦係數較小的雪明碳鐵，所以是用以確保高碳鋼板的大潤滑性之重要元素。C含量小於0.30%時，雪明碳鐵的量不足而無法得到充分的潤滑性，致使在成形中與模具產生黏附。因此，C含量係設為0.30%以上，較佳是設為0.35%以上。C含量大於0.70%時，雪明碳鐵的量變為過剩，在成形中容易產生以雪明碳鐵作為起點之裂紋。因此，C含量係設為0.70%以下，較佳是設為0.65%以下。Since the C system is bonded to Fe to form ferritic carbon iron having a small friction coefficient, it is an important element for ensuring high lubricity of the high carbon steel sheet. When the C content is less than 0.30%, the amount of ferritic carbon iron is insufficient, and sufficient lubricity cannot be obtained, resulting in adhesion to the mold during molding. Therefore, the C content is set to 0.30% or more, preferably 0.35% or more. When the C content is more than 0.70%, the amount of ferritic carbon iron becomes excessive, and cracks with stellite carbon iron as a starting point are likely to occur during molding. Therefore, the C content is set to 0.70% or less, preferably 0.65% or less.

(Si：0.07%~1.00%)(Si: 0.07%~1.00%)

Si係具有作為脫氧劑之作用，又，係抑制雪明碳鐵在退火中過剩的粗大化之有效的元素。Si含量小於0.07%時，無法充分地得到利用上述作用之效果。因此，Si含量係設為0.07%以上，較佳是設為0.10%以上。Si含量大於1.00%時，肥粒鐵的延展性低，在成形中容易產生以肥粒鐵的粒內裂紋作為起點之裂紋。因此，Si含量係設為1.00%以下，較佳是設為0.80%以下。The Si system functions as a deoxidizing agent and is an effective element for suppressing excessive coarsening of the sulphur carbon iron during annealing. When the Si content is less than 0.07%, the effect of utilizing the above effects cannot be sufficiently obtained. Therefore, the Si content is set to 0.07% or more, preferably 0.10% or more. When the Si content is more than 1.00%, the ductile iron of the ferrite is low, and cracks in which the intragranular crack of the ferrite iron is used as a starting point are likely to occur during molding. Therefore, the Si content is 1.00% or less, preferably 0.80% or less.

(Mn：0.20%~3.00%)(Mn: 0.20% to 3.00%)

Mn係控制波來鐵變態之重要元素。Mn含量小於0.20%時，利用上述作用之效果係無法充分地得到。亦即，Mn含量小於0.20%時，在二相區域退火後之冷卻過程產生波來鐵變態致使雪明碳鐵的球狀化率。因此，Mn含量係設為0.20%以上，較佳是設為0.25%以上。Mn含量大於3.00%時，肥粒鐵的延展性低，在成形中容易產生以肥粒鐵的粒內裂紋作 為起點之裂紋。因此，Mn含量係設為3.00%以下，較佳是設為2.00%以下。Mn is an important element in controlling the wave metamorphosis. When the Mn content is less than 0.20%, the effect by the above action cannot be sufficiently obtained. That is, when the Mn content is less than 0.20%, the cooling process after annealing in the two-phase region generates a spheroidization rate of the ferritic carbon iron. Therefore, the Mn content is set to 0.20% or more, preferably 0.25% or more. When the Mn content is more than 3.00%, the ferrite iron has low ductility, and it is easy to produce intragranular cracks of ferrite iron during forming. Crack as the starting point. Therefore, the Mn content is set to 3.00% or less, preferably 2.00% or less.

(Ti：0.010%~0.500%)(Ti: 0.010%~0.500%)

Ti係在熔鋼階段形成氮化物，來防止形成BN之有效的元素。Ti含量小於0.010%時，無法充分地得到利用上述作用之效果。因此，Ti含量係設為0.010%以上，較佳是設為0.040%以上。Ti含量大於0.500%時，在成形中容易產生以粗大的Ti氧化物作為起點之裂紋。這是因為在連續鑄造中形成粗大的Ti氧化物且被捲入鋼胚的內部之緣故。因此，Ti含量係設為0.500%以下，較佳是設為0.450%以下。The Ti system forms a nitride at the molten steel stage to prevent the formation of an effective element of BN. When the Ti content is less than 0.010%, the effect of utilizing the above effects cannot be sufficiently obtained. Therefore, the Ti content is set to 0.010% or more, preferably 0.040% or more. When the Ti content is more than 0.500%, cracks with coarse Ti oxide as a starting point are likely to occur during molding. This is because coarse Ti oxide is formed in the continuous casting and is caught inside the steel embryo. Therefore, the Ti content is set to 0.500% or less, preferably 0.450% or less.

(Cr：0.01%~1.50%)(Cr: 0.01%~1.50%)

Cr係與N的親和力高且是抑制BN的形成之有效的元素，又，亦是對於控制波來鐵變態之有效的元素。Cr含量小於0.01%時，無法充分地得到利用上述作用之效果。因此，Cr含量係設為0.01%以上，較佳是設為0.05%以。Cr含量大於1.50%時，退火中之雪明碳鐵的球狀化係受到阻礙且雪明碳鐵的粗大化係大幅度地受到抑制。因此，Cr含量係設為1.50%以下，較佳是設為0.90%以下。The Cr system has a high affinity with N and is an effective element for suppressing the formation of BN, and is also an element effective for controlling the wave transition state. When the Cr content is less than 0.01%, the effect of utilizing the above effects cannot be sufficiently obtained. Therefore, the Cr content is set to 0.01% or more, preferably 0.05%. When the Cr content is more than 1.50%, the spheroidization of the stellite in the annealing is hindered, and the coarsening of the swarf carbon is greatly suppressed. Therefore, the Cr content is set to 1.50% or less, preferably 0.90% or less.

(B：0.0004%~0.0035%)(B: 0.0004%~0.0035%)

B係使在高碳鋼板的表面的肥粒鐵的微摩擦係數降低之元素。後述的退火中，B亦是在肥粒鐵與雪明碳鐵之界面的偏析及濃化，而抑制成形中在該界面之剝離且防止產生裂紋之有效的元素。B含量小於0.0004%時，無法充分地得到利用上述作用之效果。因此，B含量係設為0.0004%以上， 較佳是設為0.0008%以上。B含量大於0.0035%時，在成形中容易產生以Fe和B的碳化物等的硼化物作為起點之裂紋。 因此，B含量係設為0.0035%以下，較佳是設為0.0030%以下。B is an element which reduces the micro-coefficient of ferrite iron on the surface of a high carbon steel sheet. In the annealing to be described later, B is also an element which is segregated and concentrated at the interface between the ferrite iron and the ferritic carbon iron, and is effective for suppressing peeling at the interface during molding and preventing cracking. When the B content is less than 0.0004%, the effect of utilizing the above effects cannot be sufficiently obtained. Therefore, the B content is set to 0.0004% or more. It is preferably set to 0.0008% or more. When the B content is more than 0.0035%, cracks using boride such as Fe and B carbides as a starting point are likely to occur during molding. Therefore, the B content is set to 0.0035% or less, preferably 0.0030% or less.

圖1係顯示肥粒鐵的微摩擦係數與B含量之關係 之圖。如圖1所顯示，相較於B含量小於0.0004%時，B含量為0.0004%以上時之肥粒鐵的微摩擦係數係顯著地較低。作為肥粒鐵的微摩擦係數越低，能夠抑制模具的損耗之理由，係如後述，能夠推測係因為在高碳鋼板的表面形成較硬的B膜之緣故。又，能夠推測在肥粒鐵與雪明碳鐵之界面偏析及濃化後的B亦是使該界面的強度提升而能夠抑制高碳鋼板產生裂紋且抑制裂紋所帶來的模具損耗之原因之一。Figure 1 shows the relationship between the micro-coefficient of fermented iron and B content. Picture. As shown in Fig. 1, the micro-coefficient of ferrite iron is significantly lower when the B content is less than 0.0004% and the B content is 0.0004% or more. The reason why the micro-coefficient of ferrite iron is lower and the loss of the mold can be suppressed is as follows, and it is estimated that a hard B film is formed on the surface of the high-carbon steel sheet. In addition, it is presumed that the segregation and concentration of B at the interface between the ferrite iron and the smear carbon iron is also the reason for suppressing the occurrence of cracks in the high carbon steel sheet and suppressing the mold loss due to the crack. One.

(P：0.025%以下)(P: 0.025% or less)

P不是必要元素，例如在鋼板中以不純物的方式含有。P係在肥粒鐵與雪明碳鐵之界面強烈地產生偏析，而阻礙B在該界面的偏析且在該界面引起剝離。因此，P含量係越低越佳。特別是P含量大於0.025%時，不良影響係變為顯著。 因此，P含量係設為0.025%。又，P含量減低係花費精煉成本，欲減低至小於0.0001%為止時，精煉成本係顯著地上升。 因此，P含量亦可設為0.0001%以上。P is not an essential element, for example, it is contained as an impurity in a steel sheet. P is strongly segregated at the interface between ferrite iron and ferritic carbon iron, and hinders the segregation of B at the interface and causes peeling at the interface. Therefore, the lower the P content, the better. In particular, when the P content is more than 0.025%, the adverse effect becomes remarkable. Therefore, the P content is set to 0.025%. Further, when the P content is reduced, the refining cost is required, and when it is desired to reduce it to less than 0.0001%, the refining cost is remarkably increased. Therefore, the P content can also be made 0.0001% or more.

(Al：0.100%以下)(Al: 0.100% or less)

Al係具有在製鋼階段作為脫氧劑之作用且是N的固定之有效的元素，但不是高碳鋼板的必要元素，例如鋼板中以不純物的方式含有。Al含量大於0.100%時，肥粒鐵的延 展性低，在成形中容易產生以肥粒鐵的粒內裂紋作為起點之裂紋，又，強度係變為過剩且引起成形荷重的增加。因此，Al含量係設為0.100%以下。高碳鋼板的Al含量小於0.001%時，亦有N的固定不充分之情形。因此，Al含量亦可設為0.001%以上。The Al system has an action as a deoxidizing agent in the steel making stage and is an effective element for fixing N. However, it is not an essential element of a high carbon steel sheet, and for example, it is contained as an impurity in a steel sheet. When the Al content is more than 0.100%, the elongation of the ferrite iron The exhibitability is low, and cracks starting from the intragranular crack of the ferrite iron are likely to occur in the forming, and the strength is excessive and the forming load is increased. Therefore, the Al content is set to be 0.100% or less. When the Al content of the high carbon steel sheet is less than 0.001%, the fixation of N may be insufficient. Therefore, the Al content may be 0.001% or more.

(S：0.0100%以下)(S: 0.0100% or less)

S不是必要元素，例如在鋼板中以不純物的方式含有。S係形成MnS等的粗大的非金屬夾雜物且使成形性變差。因此，S含量係越低越佳。特別是S含量大於0.0100%時，不良影響係變為顯著。因此，S含量係設為0.0100%以下。又，S含量的減低係花費精煉成本，欲小於至0.0001%為止時，精煉成本係顯著地上升。因此，S含量亦可設為0.0001%以上。S is not an essential element, for example, it is contained as an impurity in a steel sheet. S forms coarse non-metallic inclusions such as MnS and deteriorates formability. Therefore, the lower the S content, the better. In particular, when the S content is more than 0.0100%, the adverse effect becomes remarkable. Therefore, the S content is set to 0.0100% or less. Further, the reduction in the S content is a refining cost, and when it is intended to be less than 0.0001%, the refining cost is remarkably increased. Therefore, the S content can also be made 0.0001% or more.

(N：0.010%以下)(N: 0.010% or less)

N不是必要元素，例如在鋼板中以不純物的方式含有。N係由於形成BN而使B的固熔量低落且引起模具的黏附及在成形中產生裂紋等。因此，N含量係越低越佳。特別是N含量大於0.010%時，不良影響係變為顯著。因此，N含量係設為0.010%以下。又，N含量減低係花費精煉成本，欲減低至小於0.001%為止時、精煉成本係顯著地。因此，N含量亦可設為0.001%以上。N is not an essential element, for example, it is contained as an impurity in a steel sheet. N forms a BN, and the amount of solid solution of B is lowered, causing adhesion of a mold, generation of cracks during molding, and the like. Therefore, the lower the N content, the better. In particular, when the N content is more than 0.010%, the adverse effect becomes remarkable. Therefore, the N content is set to 0.010% or less. Further, when the N content is reduced, the refining cost is required, and when it is desired to reduce it to less than 0.001%, the refining cost is remarkable. Therefore, the N content may be 0.001% or more.

(Cu：0.000%~0.500%)(Cu: 0.000%~0.500%)

Cu不是必要元素，例如從廢料等混入且在鋼板中以不純物的方式含有。Cu係引起強度上升及熱脆性。因此，Cu含量係越低越佳。特別是Cu含量大於0.500%時，不良影響 係變為顯著。因此，Cu含量係設為0.500%以下。又，為了減低Cu含量係花費精煉成本，欲減低至小於0.001%為止時，精煉成本係顯著地上升。因此，Cu含量亦可設為0.001%以上。Cu is not an essential element, and is, for example, mixed from waste or the like and contained as an impurity in a steel sheet. Cu causes an increase in strength and hot brittleness. Therefore, the lower the Cu content, the better. Especially when the Cu content is more than 0.500%, the adverse effect The system becomes significant. Therefore, the Cu content is set to 0.500% or less. Further, in order to reduce the Cu content, it takes a refining cost, and when it is desired to reduce it to less than 0.001%, the refining cost is remarkably increased. Therefore, the Cu content may be 0.001% or more.

Nb、Mo、V、W、Ta、Ni、Mg、Ca、Y、Zr、 La及Ce不是必要元素，而是在高碳鋼板及鋼胚中亦可有限度地適當地含有預定量之任意元素。Nb, Mo, V, W, Ta, Ni, Mg, Ca, Y, Zr, La and Ce are not essential elements, but a predetermined amount of any element may be appropriately contained in a high carbon steel sheet and a steel embryo.

(Nb：0.000%~0.500%)(Nb: 0.000%~0.500%)

Nb係形成氮化物且是抑制BN的形成之有效的元素。因此，亦可含有Nb。但是，Nb含量大於0.500%時，肥粒鐵的延展性低且無法得到充分的成形性。因此，Nb含量係設為0.500%以下。為了確實地利用上述作用之效果，Nb含量係較佳為0.001%以上。Nb forms a nitride and is an effective element for suppressing the formation of BN. Therefore, it is also possible to contain Nb. However, when the Nb content is more than 0.500%, the ductile iron of the ferrite is low and sufficient formability cannot be obtained. Therefore, the Nb content is set to 0.500% or less. In order to reliably utilize the effects of the above effects, the Nb content is preferably 0.001% or more.

(Mo：0.000%~0.500%)(Mo: 0.000%~0.500%)

Mo係提升淬火性之有效的元素。因此，亦可含有Mo。但是，Mo含量大於0.500%時，肥粒鐵的延展性低且無法得到充分的成形性。因此，Mo含量係設為0.500%以下。為了確實地得到利用上述作用之效果Mo含量係較佳為0.001%以上。Mo is an effective element for improving hardenability. Therefore, it is also possible to contain Mo. However, when the Mo content is more than 0.500%, the ductility of the ferrite iron is low and sufficient formability cannot be obtained. Therefore, the Mo content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, the Mo content is preferably 0.001% or more.

(V：0.000%~0.500%)(V: 0.000%~0.500%)

V係與Nb同樣地形成氮化物且是抑制BN的形成之有效的元素。因此，亦可含有V。但是，V含量大於0.500%時，肥粒鐵的延展性低且無法得到充分的成形性。因此，V含量係設為0.500%以下。為了確實地得到利用上述作用之效果， V含量係較佳為0.001%以上。The V system forms a nitride similarly to Nb and is an effective element for suppressing the formation of BN. Therefore, it is also possible to contain V. However, when the V content is more than 0.500%, the ductility of the ferrite iron is low and sufficient formability cannot be obtained. Therefore, the V content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, The V content is preferably 0.001% or more.

(W：0.000%~0.500%)(W: 0.000%~0.500%)

W係與Mo同樣地是提升淬火性之有效的元素。因此，亦可含有W。但是，W含量大於0.500%時，肥粒鐵的延展性低且無法得到充分的成形性。因此，W含量係設為0.500%以下。為了確實地得到利用上述作用之效果，W含量係較佳為0.001%以上。Like the Mo, the W system is an effective element for improving the hardenability. Therefore, it is also possible to contain W. However, when the W content is more than 0.500%, the ductility of the ferrite iron is low and sufficient formability cannot be obtained. Therefore, the W content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, the W content is preferably 0.001% or more.

(Ta：0.000%~0.500%)(Ta: 0.000%~0.500%)

Ta係與Nb及V同樣地形成氮化物且是抑制BN的形成之有效的元素。因此，亦可含有Ta。但是，Ta含量大於0.500%時，肥粒鐵的延展性低且無法得到充分的成形性。因此，Ta含量係設為0.500%以下。為了確實地得到利用上述作用之效果，Ta含量係較佳為0.001%以上。The Ta system forms a nitride similarly to Nb and V and is an effective element for suppressing the formation of BN. Therefore, it is also possible to contain Ta. However, when the Ta content is more than 0.500%, the ductility of the ferrite iron is low and sufficient formability cannot be obtained. Therefore, the Ta content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, the Ta content is preferably 0.001% or more.

(Ni：0.000%~0.500%)(Ni: 0.000%~0.500%)

Ni係提升韌性及提升淬火性之有效的元素。因此，亦可含有Ni。但是，Ni含量大於0.500%時，肥粒鐵的微摩擦係數變高，致使與模具容易產生黏附。因此，Ni含量係設為0.500%以下。為了確實地得到利用上述作用之效果、Ni含量係較佳為0.001%以上。Ni is an effective element for improving toughness and improving hardenability. Therefore, Ni may also be contained. However, when the Ni content is more than 0.500%, the micro-coefficient of ferrite iron becomes high, which tends to cause adhesion to the mold. Therefore, the Ni content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, the Ni content is preferably 0.001% or more.

(Mg：0.000%~0.500%)(Mg: 0.000%~0.500%)

Mg係控制硫化物的形態之有效的元素。因此，亦可含有Mg。但是，Mg係容易形成氧化物，Mg含量大於0.500%時，以氧化物作為起點之裂紋致使無法得到更充分的成形性。因此，Mg含量係設為0.500%以下。為了確實地得到利 用上述作用之效果，Mg含量係較佳為0.001%以上。The Mg system is an effective element for controlling the form of sulfide. Therefore, it is also possible to contain Mg. However, Mg is likely to form an oxide, and when the Mg content is more than 0.500%, cracks using an oxide as a starting point fail to obtain more sufficient formability. Therefore, the Mg content is set to 0.500% or less. In order to get the benefits With the effect of the above action, the Mg content is preferably 0.001% or more.

(Ca：0.000%~0.500%)(Ca: 0.000%~0.500%)

Ca係與Mg同樣地是控制硫化物的形態之有效的元素。因此，亦可含有Ca。但是，Ca係容易形成氧化物，Ca含量大於0.500%時，以氧化物作為起點之裂紋致使無法得到更充分的成形性。因此，Ca含量係設為0.500%以下。為了確實地得到利用上述作用之效果、Ca含量係較佳為0.001%以上。The Ca system is an effective element for controlling the form of the sulfide as in the case of Mg. Therefore, it is also possible to contain Ca. However, Ca is likely to form an oxide, and when the Ca content is more than 0.500%, cracks using an oxide as a starting point fail to obtain more sufficient moldability. Therefore, the Ca content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, the Ca content is preferably 0.001% or more.

(Y：0.000%~0.500%)(Y: 0.000%~0.500%)

Y係與Mg及Ca同樣地是控制硫化物的形態之有效的元素。因此，亦可含有Y。但是，Y係容易形成氧化物、Y含量大於0.500%時，以氧化物作為起點之裂紋致使無法得到更充分的成形性。因此，Y含量係設為0.500%以下。為了確實地得到利用上述作用之效果、Y含量係較佳為0.001%以上。Like the Mg and Ca, the Y system is an effective element for controlling the form of the sulfide. Therefore, it is also possible to contain Y. However, when the Y system is likely to form an oxide and the Y content is more than 0.500%, cracks using an oxide as a starting point fail to obtain more sufficient moldability. Therefore, the Y content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, the Y content is preferably 0.001% or more.

(Zr：0.000%~0.500%)(Zr: 0.000%~0.500%)

Zr係與Mg、Ca及Y同樣地是控制硫化物的形態之有效的元素。因此，亦可含有Zr。但是，Zr係容易形成氧化物，Zr含量大於0.500%時，以氧化物作為起點之裂紋致使無法得到更充分的成形性。因此，Zr含量係設為0.500%以下。 為了確實地得到利用上述作用之效果，Zr含量係較佳為0.001%以上。Like the Mg, Ca, and Y, the Zr system is an effective element for controlling the form of the sulfide. Therefore, it is also possible to contain Zr. However, Zr is likely to form an oxide, and when the Zr content is more than 0.500%, cracks using an oxide as a starting point fail to obtain more sufficient formability. Therefore, the Zr content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, the Zr content is preferably 0.001% or more.

(La：0.000%~0.500%)(La: 0.000%~0.500%)

La係與Mg、Ca、Y及Zr同樣地是控制硫化物的形態之 有效的元素。因此，亦可含有La。但是，La係容易形成氧化物、La含量大於0.500%時，以氧化物作為起點之裂紋致使無法得到更充分的成形性。因此，La含量係設為0.500%以下。為了確實地得到利用上述作用之效果，La含量係較佳為0.001%以上。La is the same as Mg, Ca, Y and Zr in controlling the form of sulfides. A valid element. Therefore, it is also possible to contain La. However, when La is likely to form an oxide and the La content is more than 0.500%, cracks using an oxide as a starting point fail to obtain more sufficient formability. Therefore, the La content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, the La content is preferably 0.001% or more.

(Ce：0.000%~0.500%)(Ce: 0.000%~0.500%)

Ce係與Mg、Ca、Y、Z及rLa同樣地是控制硫化物的形態之有效的元素。因此，亦可含有Ce。但是，Ce係容易形成氧化物，Ce含量大於0.500%時，以氧化物作為起點之裂紋致使無法得到更充分的成形性。因此，Ce含量係設為0.500%以下。為了確實地得到利用上述作用之效果，Ce含量係較佳為0.001%以上。Similarly to Mg, Ca, Y, Z, and rLa, the Ce system is an effective element for controlling the form of sulfide. Therefore, Ce can also be contained. However, Ce is likely to form an oxide, and when the Ce content is more than 0.500%, cracks using an oxide as a starting point fail to obtain more sufficient moldability. Therefore, the Ce content is set to 0.500% or less. In order to surely obtain the effect of utilizing the above effects, the Ce content is preferably 0.001% or more.

如此，Nb、Mo、V、W、Ta、Ni、Mg、Ca、Y、 Zr、La及Ce係任意元素，以滿足「Nb：0.001%~0.500%」、「Mo：0.001%~0.500%」、「V：0.001%~0.500%」、「W：0.001%~0.500%」、「Ta：0.001%~0.500%」、「Ni：0.001%~0.500%」、「Mg：0.001%~0.500%」、「Ca：0.001%~0.500%」、「Y：0.001%~0.500%」、「Zr：0.001%~0.500%」、「La：0.001%~0.500%」、或「Ce：0.001%~0.500%」、或是該等的任意組合為佳。Thus, Nb, Mo, V, W, Ta, Ni, Mg, Ca, Y, Zr, La, and Ce are arbitrary elements to satisfy "Nb: 0.001% to 0.500%", "Mo: 0.001% to 0.500%", "V: 0.001% to 0.500%", and "W: 0.001% to 0.500%" "Ta: 0.001% to 0.500%", "Ni: 0.001% to 0.500%", "Mg: 0.001% to 0.500%", "Ca: 0.001% to 0.500%", "Y: 0.001% to 0.500%" "Zr: 0.001% to 0.500%", "La: 0.001% to 0.500%", or "Ce: 0.001% to 0.500%", or any combination of these is preferable.

其次，說明在本實施形態的高碳鋼板表面的肥粒 鐵的微摩擦係數。在本實施形態的高碳鋼板表面的肥粒鐵的微摩擦係數係小於0.5。Next, the fertilizer particles on the surface of the high carbon steel sheet of the present embodiment will be described. The micro-coefficient of iron. The micro-coefficient of ferrite iron on the surface of the high carbon steel sheet of the present embodiment is less than 0.5.

(在表面的肥粒鐵的微摩擦係數：小於0.5)(Micro-friction coefficient of ferrite iron on the surface: less than 0.5)

在表面的肥粒鐵的微摩擦係數，係與模具在成形中與高碳鋼板產生黏附有密切的關係。肥粒鐵的微摩擦係數為0.5以上時，在使用模具之成形中，在高碳鋼板與模具之間產生微黏附。該結果，使用該模具而進行從數千至達到數萬次之衝孔等的成形時，黏附物係在該期間蓄積模具上且在模具或是高碳鋼板或其雙方產生瑕疵，致使成形性低落。 因此，肥粒鐵的微摩擦係數係設為小於0.5。從成形性的觀點而言，微摩擦係數係以盡可能較低為佳。雖然亦依存於高碳鋼板的製造方法等，微摩擦係數係多半為0.35以上。The micro-coefficient of ferrite on the surface is closely related to the adhesion of the mold to the high-carbon steel sheet during forming. When the micro-coefficient of ferrite iron is 0.5 or more, micro-adhesion occurs between the high-carbon steel sheet and the mold in the molding using the mold. As a result, when the mold is used to form a punch or the like from several thousands to tens of thousands of times, the adhesive is accumulated in the mold during the period, and flaws are generated in the mold or the high carbon steel sheet or both, resulting in formability. low. Therefore, the micro-coefficient of fermented iron is set to be less than 0.5. From the viewpoint of formability, the micro-coefficient of friction is preferably as low as possible. Although depending on the manufacturing method of the high carbon steel sheet, etc., the micro friction coefficient is mostly 0.35 or more.

圖2係顯示在高碳鋼板的衝孔成形之肥粒鐵的微 摩擦係數與模具或高碳鋼板至產生瑕疵為止的沖壓次數(shot)之關係之圖。如圖2所顯示，相較於微摩擦係數為0.5以上時，微摩擦係數小於0.5時，至產生瑕疵為止之沖壓次數係顯著地較高。Figure 2 shows the micro-featured iron in the punching of high carbon steel sheets. The relationship between the coefficient of friction and the number of shots from the mold or high carbon steel sheet to the occurrence of flaws. As shown in Fig. 2, when the micro-coefficient of friction is 0.5 or more and the micro-coefficient of friction is less than 0.5, the number of times of pressing until the occurrence of enthalpy is remarkably high.

微摩擦係數係能夠使用奈米壓痕儀而測定。亦即， 使用鑽石壓頭且在高碳鋼板表面負荷10μ N的垂直荷重P，來取得使其在水平方向移動時所產生的動摩擦力F。此時的移動速度係例如設為1μ m/秒。然後，從下述(1)式算出微摩擦係數μ (動摩擦係數)。作為奈米壓痕儀，例如能夠使用Omicron公司製的「TI-900 TriboIndenter」。The micro-coefficient of friction can be measured using a nanoindenter. That is, the dynamic friction force F generated when moving in the horizontal direction is obtained by using a diamond indenter and a vertical load P of 10 μN on the surface of the high carbon steel sheet. The moving speed at this time is, for example, 1 μ m/sec. Then, the micro friction coefficient μ (dynamic friction coefficient) is calculated from the following formula (1). As the nano indenter, for example, "TI-900 TriboIndenter" manufactured by Omicron Co., Ltd. can be used.

F=μP．．．(1)式F=μP. . . (1)

圖3A係顯示測定微摩擦係數前之高碳鋼板表面之顯微鏡照片，圖3B係顯示測定微摩擦係數後之高碳鋼板表面之顯微鏡照片。圖3A及圖3B係顯示10μ m×10μ m的視 野例。如圖3A及圖3B所顯示，該視野例係存在有肥粒鐵31及雪明碳鐵32。又，如圖3B所顯示，在測定後，係存在有伴隨著鑽石壓頭在水平方向的移動所產生的測定瑕疵33。 又，雪明碳鐵的微摩擦係數係0.4以下。Fig. 3A is a micrograph showing the surface of a high carbon steel sheet before the measurement of the micro friction coefficient, and Fig. 3B is a micrograph showing the surface of the high carbon steel sheet after the measurement of the micro friction coefficient. 3A and 3B show the View-based embodiment of the 10 μ m 10 μ m ×. As shown in FIG. 3A and FIG. 3B, the field of view is characterized by the presence of the ferrite iron 31 and the swarf carbon iron 32. Further, as shown in Fig. 3B, after the measurement, there is a measurement enthalpy 33 which is caused by the movement of the diamond indenter in the horizontal direction. Further, the micro-coefficient of the sulphur carbon iron is 0.4 or less.

其次，說明本實施形態之高碳鋼板的組織。本實 施形態之高碳鋼板係具有下述表示的組織，雪明碳鐵的球狀化率：80%以上，且雪明碳鐵的平均粒徑：0.3μ m~2.2μ m。Next, the structure of the high carbon steel sheet of the present embodiment will be described. The high carbon steel sheet according to the present embodiment has a structure represented by the following: the spheroidization ratio of the stellite carbon iron is 80% or more, and the average particle diameter of the stellite carbon iron is 0.3 μm to 2.2 μm .

(雪明碳鐵的球狀化率：80%以上)(Spheroidization rate of Xueming carbon iron: 80% or more)

雪明碳鐵係在成形中有成為應力集中的起點之情形，特別是在針狀雪明碳鐵，應力係容易局部地產生集中。雪明碳鐵的球狀化率小於80%時，因為大量地含有應力容易集中的針狀雪明碳鐵，所以容易產生應力集中且在肥粒鐵與雪明碳鐵之界面產生剝離，而無法得到充分的成形性。 因此，雪明碳鐵的球狀化率係設為80%以上，較佳是設為85%以上。從成形性的觀點而言，雪明碳鐵的球狀化率係以盡可能較高為佳，亦可為100%。但是，卻使雪明碳鐵的球狀化率為100%時，生產性有可能低落，從生產性的觀點而言，雪明碳鐵的球狀化率係較佳為80%以上且小於100%。The Xueming carbon-iron system has a tendency to become a stress concentration in the forming, and particularly in the acicular stellite, the stress system is likely to locally concentrate. When the spheroidization rate of the stellite carbon iron is less than 80%, since a large amount of acicular stellite carbon iron which is easily concentrated in stress is contained, stress concentration tends to occur and peeling occurs at the interface between the ferrite iron and the ferritic carbon iron. Insufficient formability is not obtained. Therefore, the spheroidization ratio of Xueming carbon iron is 80% or more, and preferably 85% or more. From the viewpoint of formability, the spheroidization ratio of stellite carbon iron is preferably as high as possible, and may be 100%. However, when the spheroidization ratio of stellite carbon is 100%, the productivity may be lowered, and from the viewpoint of productivity, the spheroidization ratio of ferritic carbon iron is preferably 80% or more and less than 100%.

(雪明碳鐵的平均粒徑：0.3μ m~2.2μ m)(average particle size of Xueming carbon iron: 0.3 μ m~2.2 μ m)

雪明碳鐵的平均粒徑係與在雪明碳鐵之應力集中的程度有密切的關係。雪明碳鐵的平均粒徑小於0.3μm時，在成形中所產生的差排(dislocation)係對雪明碳鐵形成差排環 (Orowan loop)且雪明碳鐵周邊的差排密度增加而產生裂紋(空隙)。因此，雪明碳鐵的平均粒徑係設為0.3μm以上，較佳是設為0.5μm以上。雪明碳鐵的平均粒徑大於2.2μm時，在成形中所產生的差排係大量地堆積且產生局部的應力集中，致使產生裂紋。因此，雪明碳鐵的平均粒徑係設為2.2μm以下，較佳是設為2.0μm以下。The average particle size of Xueming carbon iron is closely related to the degree of stress concentration in Xueming carbon iron. When the average particle diameter of Xueming carbon iron is less than 0.3 μm, the dislocation generated during the forming is a poorly arranged ring for the ferritic carbon iron. (Orowan loop) and the difference in density at the periphery of the swarf carbon iron increases to cause cracks (voids). Therefore, the average particle diameter of the Xueming carbon iron is 0.3 μm or more, and preferably 0.5 μm or more. When the average particle diameter of the stellite carbon iron is more than 2.2 μm, the difference in the formation during the formation is largely deposited and local stress concentration occurs, causing cracks to occur. Therefore, the average particle diameter of the Xueming carbon iron is 2.2 μm or less, and preferably 2.0 μm or less.

雪明碳鐵的球狀化率及平均粒徑，係能夠藉由使 用掃描型電子顯微鏡組織觀察來進行。製造組織觀察用試樣，係藉由使用砂紙之濕式研磨及使用粒子尺寸為1μm的鑽石砥粒之研磨將觀察面精加工成為鏡面之後，使用3體積%硝酸及97體積%酒精的蝕刻液進行蝕刻。觀察倍率係設為3000倍~10000倍，例如設為10000倍且在觀察面選擇16處之含有明碳鐵為500個以上的視野，而且取得該等的組織影像。 然後，使用影像處理軟體而測定組織影像中之各雪明碳鐵的面積。作為影像處理軟體，例如能夠使用三谷商事股份公司製的「Win ROOF」。此時，為了抑制雜訊引起的測定誤差之影響，係將面積為0.01μm2以下的雪明碳鐵從評價對象除去。然後，求取評價對象的雪明碳鐵之平均面積且求取該平均面積所得到的圓之直徑，將該直徑設作雪明碳鐵的平均粒徑。雪明碳鐵的平均面積係將評價對象的雪明碳鐵之總面積除以該雪明碳鐵的個數而得到的值。又，將長軸長度與短軸長度之比為3以上的雪明碳鐵設作針狀雪明碳鐵，將小於3的雪明碳鐵設作球狀雪明碳鐵，且將球狀雪明碳鐵的個數除以總雪明碳鐵的個數所得到的值設作雪明 碳鐵的球狀化率。The spheroidization rate and average particle size of Xueming carbon iron can be It was carried out by observation with a scanning electron microscope. A sample for observation of a tissue was prepared by wet-grinding using a sandpaper and polishing the observation surface into a mirror surface by grinding using a diamond granule having a particle size of 1 μm, and then using an etchant of 3 vol% nitric acid and 97 vol% alcohol. Etching is performed. The observation magnification ratio is set to 3,000 times to 10,000 times, for example, 10,000 times, and the field of view containing the carbon carbon in the 16th place on the observation surface is 500 or more, and the tissue images are obtained. Then, using the image processing software, the area of each smectite in the tissue image was measured. As the image processing software, for example, "Win ROOF" manufactured by Sangu Trading Co., Ltd. can be used. At this time, in order to suppress the influence of the measurement error caused by the noise, the stellite carbon having an area of 0.01 μm 2 or less is removed from the evaluation target. Then, the average area of the smectite carbon to be evaluated is obtained, and the diameter of the circle obtained by obtaining the average area is determined, and the diameter is set as the average particle diameter of ferritic carbon iron. The average area of the smectite carbon iron is a value obtained by dividing the total area of the ferritic carbon iron to be evaluated by the number of the stellite carbon iron. Further, a stellite carbon iron having a ratio of a major axis length to a minor axis length of 3 or more is used as a needle-shaped stellite carbon iron, and a stellite carbon iron having a length of less than 3 is used as a spherical stellite carbon iron, and a spherical shape is obtained. The value obtained by dividing the number of Xueming carbon iron by the total number of ferritic carbon iron is set as Xueming The spheroidization rate of carbon iron.

其次，說明本實施形態的高碳鋼板之製造方法。 在該製造方法，係進行上述化學組成的鋼胚之熱軋而製得熱軋鋼板，而且進行該熱軋鋼板的酸洗，隨後進行熱軋鋼板的退火。在熱軋，係將鋼胚加熱溫度設為1000℃以上且小於1150℃，將精加工輥軋溫度設為830℃以上且950℃以下，而且將捲取溫度設為450℃以上且700℃以下。在退火時，係將熱軋鋼板保持在730℃以上且770℃以下的溫度3小時以上且60小時以下，其次，以1℃/hr以上且60℃/hr以下的冷卻速度將熱軋鋼板冷卻至650℃為止。又，退火環境係例如設為在至少環境溫度為大於400℃之溫度區域，含有75體積%以上的氫之環境，但是不被此限定。Next, a method of producing the high carbon steel sheet of the present embodiment will be described. In this production method, a hot-rolled steel sheet is obtained by hot rolling of a steel preform having the above chemical composition, and pickling is performed on the hot-rolled steel sheet, followed by annealing of the hot-rolled steel sheet. In hot rolling, the steel slab heating temperature is set to 1000 ° C or more and less than 1150 ° C, and the finishing rolling temperature is set to 830 ° C or more and 950 ° C or less, and the coiling temperature is set to 450 ° C or more and 700 ° C or less. . At the time of annealing, the hot-rolled steel sheet is maintained at a temperature of 730 ° C or more and 770 ° C or less for 3 hours or more and 60 hours or less, and secondly, the hot-rolled steel sheet is cooled at a cooling rate of 1 ° C / hr or more and 60 ° C / hr or less. Up to 650 ° C. Further, the annealing environment is, for example, an environment containing at least 75% by volume of hydrogen in a temperature region where the ambient temperature is greater than 400 ° C, but is not limited thereto.

在此，概略地說明從熱軋至冷卻為止之間的鋼板 變化。圖4係顯示溫度的變化之示意圖。圖5A至圖5E係顯示組織的變化之示意圖。Here, the steel sheet from hot rolling to cooling will be roughly described. Variety. Figure 4 is a schematic diagram showing changes in temperature. 5A to 5E are schematic views showing changes in tissue.

圖4所顯示的例子，係在熱軋S1含有鋼胚加熱S11、 精加工輥軋S12及捲取S13，在退火S3含有高溫保持S31及冷卻S32。在熱軋S1與退火S3之間有酸洗S2，在退火S3之後有冷卻S4。The example shown in Figure 4 is based on hot rolling S1 containing steel embryo heating S11, Finishing roll S12 and winding S13, and annealing S3 contains high temperature holding S31 and cooling S32. There is pickling S2 between hot rolling S1 and annealing S3, and cooling S4 after annealing S3.

在鋼胚加熱S11的結束之時點tA，係如圖5A所顯示，B原子13係在沃斯田鐵12與沃斯田鐵12之界面的偏析。在高溫保持S31的結束之時點tB，係如圖5B所顯示，鋼板的組織係含有肥粒鐵11及沃斯田鐵12。又，B原子13係在肥粒鐵11與沃斯田鐵12之界面的偏析。B原子13的一部分亦存在 鋼板表面15且在鋼板表面所存在的B原子13係藉由共價鍵14而互相鍵結著。圖5B係未顯示，在鋼板組織亦含有雪明碳鐵，B原子13的一部分亦在肥粒鐵11與雪明碳鐵之界面的偏析。冷卻S32的途中之時點tC，相較於圖5B所顯示的組織，如圖5C所顯示，肥粒鐵11的比例係增加且沃斯田鐵12的比例減少，伴隨著該情形，該等二相的界面係移動。而且，伴隨著界面移動，在鋼板表面所存在的B原子13係增加。然後，進行冷卻S32後之時點tD，相較於圖5C所顯示的組織，如圖5D所顯示，肥粒鐵11的比例係增加且沃斯田鐵12的比例減少且在鋼板表面存在的B原子13係增加。然後，在鋼板的溫度達到650℃之時點tE，如圖5E所顯示，沃斯田鐵12消失且鋼板表面15係被許多B原子13覆蓋。因為B原子13係藉由共價鍵14而互相鍵結著之緣故，所以結晶化。圖5E所顯示的組織，係冷卻S4之間亦無變化且在鋼板的溫度達到室溫左右、例如小於60℃的溫度時亦能夠維持。At the point tA at the end of the steel embryo heating S11, as shown in Fig. 5A, the B atom 13 is segregated at the interface between the Vostian iron 12 and the Vostian iron 12. At the point tB at which the high temperature is maintained at the end of S31, as shown in Fig. 5B, the structure of the steel sheet contains the ferrite iron 11 and the Vostian iron 12. Further, the B atom 13 is a segregation at the interface between the ferrite iron 11 and the Vostian iron 12. Part of B atom 13 also exists The B atoms 13 present on the steel sheet surface 15 and on the surface of the steel sheet are bonded to each other by a covalent bond 14. Fig. 5B is not shown, and the steel sheet structure also contains ferritic carbon iron, and a part of the B atom 13 is also segregated at the interface between the ferrite iron 11 and the swarf carbon iron. At the time point tC at the middle of cooling S32, as compared with the structure shown in FIG. 5B, as shown in FIG. 5C, the ratio of the ferrite iron 11 is increased and the proportion of the Worth iron 12 is decreased, which is accompanied by the situation. The interface of the phase moves. Further, along with the movement of the interface, the B atom 13 system existing on the surface of the steel sheet increases. Then, at time tD after cooling S32, as compared with the structure shown in FIG. 5C, as shown in FIG. 5D, the ratio of the ferrite iron 11 is increased and the proportion of the Worth iron 12 is decreased and B is present on the surface of the steel sheet. The atom 13 system is increased. Then, at a point tE when the temperature of the steel sheet reaches 650 ° C, as shown in FIG. 5E, the Worth iron 12 disappears and the surface 15 of the steel sheet is covered by a plurality of B atoms 13 . Since the B atoms 13 are bonded to each other by the covalent bond 14, they are crystallized. The structure shown in Fig. 5E is also unchanged between cooling S4 and can be maintained even when the temperature of the steel sheet reaches about room temperature, for example, less than 60 °C.

依照該製造方法，因為藉由共價鍵14而互相鍵結 的許多B原子13係將鋼板表面15覆蓋，所以能夠使在表面15之肥粒鐵的微摩擦係數小於0.5。According to the manufacturing method, since they are bonded to each other by the covalent bond 14 Many of the B atoms 13 are covered by the steel sheet surface 15, so that the micro-coefficient of the ferrite iron on the surface 15 can be made smaller than 0.5.

(鋼胚加熱溫度：1000℃以上且小於1150℃)(steel embryo heating temperature: 1000 ° C or more and less than 1150 ° C)

鋼胚加熱溫度大於1150℃時，氧容易從鋼胚表面擴散至鋼胚內部且與鋼胚中的B鍵結。亦即，如圖6A所顯示，因為B原子13係與O原子16鍵結而被消耗。因此，即便隨後適當地進行處理，亦無法得到被B的結晶覆蓋之良好的表面且無法使在表面之肥粒鐵的微摩擦係數小於0.5。因此， 鋼胚加熱溫度係設為1150℃以下，較佳是設為1140℃以下。 鋼胚加熱溫度為小於1000℃時，係無法消在鑄造中所形成的微偏析及/或大偏析，如圖6B所顯示，B原子13凝固偏析係殘留。B原子13的凝固偏析，因為即便隨後適當地進行處理亦無法消除，所以無法得到被B的結晶覆蓋之良好的表面且無法使在表面之肥粒鐵的微摩擦係數小於0.5。又，鋼胚加熱溫度為小於1000℃時，在高碳鋼板中亦殘留Cr及/或Mn等偏析及濃化之區域。因此，即便隨後適當地進行處理，在成形中亦從該區域產生裂紋且無法得到充分的成形性。 因此，鋼胚加熱溫度係設為1000℃以上，較佳是設為1030℃以上。When the steel embryo heating temperature is greater than 1150 ° C, oxygen easily diffuses from the surface of the steel embryo into the interior of the steel embryo and bonds with B in the steel embryo. That is, as shown in FIG. 6A, since the B atom 13 is bonded to the O atom 16, it is consumed. Therefore, even if the treatment is appropriately performed, a good surface covered with the crystal of B cannot be obtained, and the micro-coefficient of the ferrite on the surface cannot be made smaller than 0.5. therefore, The steel embryo heating temperature is set to 1150 ° C or lower, preferably 1140 ° C or lower. When the steel embryo heating temperature is less than 1000 ° C, microsegregation and/or large segregation formed in the casting cannot be eliminated, and as shown in Fig. 6B, the solidification segregation of the B atom 13 remains. The solidification segregation of the B atom 13 cannot be eliminated even if it is appropriately treated later, so that a good surface covered with the crystal of B cannot be obtained, and the micro-coefficient of the ferrite iron on the surface cannot be made smaller than 0.5. Further, when the steel embryo heating temperature is less than 1000 ° C, a region where segregation and concentration such as Cr and/or Mn remain in the high carbon steel sheet remains. Therefore, even if the treatment is appropriately performed, cracks are generated from the region during the molding and sufficient formability cannot be obtained. Therefore, the steel embryo heating temperature is set to 1000 ° C or higher, preferably 1030 ° C or higher.

(精加工輥軋溫度：830℃以上且950℃以下)(finishing rolling temperature: 830 ° C or more and 950 ° C or less)

精加工輥軋溫度大於950℃時，係例如在至捲取完成為止之期間，在輸出台(ROT：run out table)上產生粗大的鏽垢。雖然藉由酸洗而能夠將粗大的鏽垢除去，但是會產生大的凹凸痕跡，且起因於該痕跡而有在成形中與模具產生黏附之情形。又，產生粗大的鏽垢時，捲取時在鋼板表面產生凹凸瑕疵，且起因於該瑕疵而有在成形中與模具產生黏附之情形。因此，精加工輥軋溫度係設為950℃以下，較佳是設為940℃以下。精加工輥軋溫度小於830℃時，在至捲取完成為止之期間所產生的鏽垢與鋼板之密著性係非常高且難以藉由酸洗而除去。雖然進行強酸洗時能夠除去，但是進行強酸洗時，因為鋼板表面係粗糙化，所以在成形中有與模具產生黏附之情形。又，精加工輥軋溫度小於830 ℃時，因為在至捲取之期間沃斯田鐵的再結晶係未完成，所以熱軋鋼板的各向異性提高。因為熱軋鋼板的各向異性係即便退火後亦持續，所以無法得到充分的成形性。因此，精加工輥軋溫度係設為830℃以上，較佳是設為840℃以上。When the finishing rolling temperature is more than 950 ° C, coarse rust is generated on the output table (ROT: run out table), for example, until the winding up is completed. Although coarse rust can be removed by pickling, a large unevenness is generated, and the trace is caused by adhesion to the mold during molding. Further, when coarse rust is generated, irregularities are generated on the surface of the steel sheet during winding, and the ruthenium may be adhered to the mold during molding. Therefore, the finishing rolling temperature is 950 ° C or lower, preferably 940 ° C or lower. When the finishing rolling temperature is less than 830 ° C, the adhesion between the rust and the steel sheet generated during the winding up is extremely high and it is difficult to remove by pickling. Although it can be removed at the time of strong pickling, when the strong pickling is performed, since the surface of the steel sheet is roughened, there is a case where it adheres to the mold during molding. Also, the finishing rolling temperature is less than 830 At ° C, the anisotropy of the hot rolled steel sheet is improved because the recrystallization system of the Worth iron is not completed during the winding up. Since the anisotropy of the hot-rolled steel sheet continues even after annealing, sufficient formability cannot be obtained. Therefore, the finishing rolling temperature is 830 ° C or higher, preferably 840 ° C or higher.

(捲取溫度：450℃以上且700℃以下)(Winding temperature: 450 ° C or more and 700 ° C or less)

捲取溫度大於700℃時，係在熱軋鋼板中生成具有粗大的板層之波來鐵且退火中的雪明碳鐵之球狀化係受到阻礙，致使無法得到80%以上的球狀化率。因此，捲取溫度係設為700℃以下。又，捲取溫度大於570℃時，至捲取完成為止之期間產生粗大的鏽垢。因此，基於與精加工輥軋溫度為大於950℃時之同樣的理由，而有在成形中與模具產生黏附之情形。因此，捲取溫度係較佳是設為570℃以下，更佳是設為550℃以下。捲取溫度小於450℃時，在至捲取完成為止之期間所產生的鏽垢與鋼板之密著性係非常高且難以藉由酸洗而除去。雖然進行強酸洗時能夠除去，但是進行強酸洗時，因為鋼板表面係粗糙化，所以在成形中有與模具產生黏附之情形。又，捲取溫度小於450℃時，熱軋鋼板係脆化且在酸洗之鋼捲退捲時，熱軋鋼板產生裂紋且無法得到充分的產率。因此，捲取溫度係設為450℃以上，較佳是設為460℃以上。When the coiling temperature is more than 700 ° C, the spheroidal system of the stellite carbon having a coarse slab is formed in the hot-rolled steel sheet, and the spheroidization of the stellite in the annealing is hindered, so that spheroidization of 80% or more cannot be obtained. rate. Therefore, the coiling temperature is set to 700 ° C or lower. Further, when the coiling temperature is more than 570 ° C, coarse rust is generated during the period until the winding is completed. Therefore, for the same reason as when the finishing rolling temperature is more than 950 ° C, there is a case where adhesion to the mold occurs during molding. Therefore, the coiling temperature is preferably 570 ° C or lower, more preferably 550 ° C or lower. When the coiling temperature is less than 450 ° C, the adhesion between the scale and the steel sheet generated during the winding up is extremely high and it is difficult to remove it by pickling. Although it can be removed at the time of strong pickling, when the strong pickling is performed, since the surface of the steel sheet is roughened, there is a case where it adheres to the mold during molding. Further, when the coiling temperature is less than 450 ° C, the hot-rolled steel sheet is embrittled, and when the pickled steel coil is unwound, the hot-rolled steel sheet is cracked and a sufficient yield cannot be obtained. Therefore, the coiling temperature is set to 450 ° C or higher, preferably 460 ° C or higher.

為了確保藉由捲取而得到的熱軋鋼捲在長度方 向及寬度方向之品質(減低材質的偏差等)，亦可在精加工輥軋機之入側跟前將粗軋件(rough bar)升溫。在該升溫所使用 的裝置及該升溫的方法係沒有特別限定，以藉由高頻感應加熱來進行升溫為佳。升溫後的粗軋件之較佳溫度範圍係850℃~1100℃。因為小於850℃的溫度係接近從沃斯田鐵變態成為肥粒鐵之溫度，升溫後的粗軋件之溫度小於850℃時，有在變態及逆變態產生發熱及吸熱之情形，致使溫度控制變為不穩定且熱軋鋼捲的長度方向及寬度方向的溫度係難以均勻化。因此，進行粗軋件升溫時，升溫之溫度係較佳是設為850℃以上。為了使粗軋件的溫度大於1100℃，係花費太多的時間且生產性低落。因此，進行粗軋件升溫時，升溫之溫度係較佳是設為1100℃以下。In order to ensure that the hot rolled steel coil obtained by coiling is in the length In the direction of the width and the width (reducing the deviation of the material, etc.), the rough bar can be heated before the entry side of the finishing roll mill. Used in this warming The apparatus and the method of raising the temperature are not particularly limited, and it is preferred to carry out the temperature increase by high-frequency induction heating. The preferred temperature range for the roughened steel after heating is 850 ° C to 1100 ° C. Because the temperature less than 850 °C is close to the temperature from the Worthite iron to the ferrite iron, and the temperature of the roughened steel after the temperature rise is less than 850 °C, there is a situation of heat generation and heat absorption in the metamorphic and inverting states, resulting in temperature control. The temperature becomes unstable and the temperature in the longitudinal direction and the width direction of the hot-rolled steel coil is difficult to be uniformized. Therefore, when the temperature of the rough-rolled material is raised, the temperature at which the temperature rises is preferably 850 ° C or higher. In order to make the temperature of the roughed piece larger than 1100 ° C, it takes too much time and productivity is low. Therefore, when the temperature of the rough rolling material is raised, the temperature at which the temperature rises is preferably 1100 ° C or lower.

(退火保持溫度：730℃以上且770℃以下)(annealing temperature: 730 ° C or more and 770 ° C or less)

退火保持溫度小於730℃時，係無法充分地生成沃斯田鐵12，如圖6C所顯示，會存在許多肥粒鐵11與肥粒鐵11之界面，而B原子13產生偏析的位置不足。因此，即便隨後適當地進行處理，亦無法得到被B的結晶覆蓋之良好的表面且無法使在表面之肥粒鐵的微摩擦係數小於0.5。又，退火保持溫度小於730℃時，B原子13係不容易在肥粒鐵11與雪明碳鐵之界面的偏析，為了使其充分地偏析，需要100小時左右之非常長的時間，致使生產性低落。因此，退火保持溫度係設為730℃以上，較佳是設為735℃以上。退火保持溫度大於770℃時，如圖6D所顯示，B原子13係集中肥粒鐵11、沃斯田鐵12及鋼板表面之三態點(triple point)附近且生成粗大的B結晶。生成粗大的B結晶時，即便隨後適當地進行處理，B結晶的膜厚度偏差變大且無法使在表面之肥粒鐵的微 摩擦係數小於0.5。又，退火保持溫度大於770℃時，被捲取成為鋼捲狀之熱軋鋼板係熱膨脹大，熱軋鋼板之間在退火中有產生摩擦，致使在表面產生擦痕之情形。擦痕引起表面美觀受到損害、或產率低落。因此，退火保持溫度係設為770℃以下，較佳是設為765℃以下。When the annealing temperature is less than 730 ° C, the Wolster iron 12 cannot be sufficiently formed. As shown in Fig. 6C, there are many interfaces between the ferrite iron 11 and the ferrite iron 11, and the position where the B atom 13 is segregated is insufficient. Therefore, even if the treatment is appropriately performed, a good surface covered with the crystal of B cannot be obtained, and the micro-coefficient of the ferrite on the surface cannot be made smaller than 0.5. Further, when the annealing temperature is less than 730 ° C, the B atom 13 is less likely to segregate at the interface between the ferrite iron 11 and the stellite carbon, and in order to sufficiently segregate it, it takes about 100 hours for a very long time, resulting in production. Sexually low. Therefore, the annealing holding temperature is 730 ° C or higher, and preferably 735 ° C or higher. When the annealing retention temperature is higher than 770 ° C, as shown in FIG. 6D, the B atom 13 is concentrated near the triple point of the ferrite iron 11, the Vostian iron 12, and the surface of the steel sheet to form a coarse B crystal. When a coarse B crystal is formed, even if it is appropriately treated later, the film thickness deviation of the B crystal becomes large and the ferrite of the surface is not made fine. The coefficient of friction is less than 0.5. Further, when the annealing holding temperature is higher than 770 ° C, the hot-rolled steel sheet wound into a steel coil has a large thermal expansion, and friction between the hot-rolled steel sheets during annealing causes scratches on the surface. Scratches cause damage to the aesthetic appearance of the surface, or a low yield. Therefore, the annealing holding temperature is 770 ° C or lower, preferably 765 ° C or lower.

(退火保持時間：3小時以上且60小時以下)(annealing retention time: 3 hours or more and 60 hours or less)

退火保持時間小於3小時之情況，係如圖6E所顯示，因為B原子13係未在肥粒鐵11與沃斯田鐵12之界面充分地產生偏析，即便隨後適當地進行處理亦無法得到被B結晶覆蓋之良好的表面，且無法使在表面之肥粒鐵的微摩擦係數小於0.5。又，退火保持時間小時3小時之情況，雪明碳鐵係未充分地粗大化且無法得到使雪明碳鐵的平均粒徑為0.3μ m以上。因此，退火保持時間係設為3小時以上，較佳是設為5小時以上。退火保持時間大於60小時之情況，基於與退火保持溫度大於770℃時同樣的理由，無法使在表面之肥粒鐵的微摩擦係數小於0.5。又，退火保持時間大於60小時之情況，雪明碳鐵係過剩地粗大化且無法使雪明碳鐵的平均粒徑為2.2μ m以下。因此，退火保持時間係設為60小時以下，較佳是設為40小時以下。When the annealing retention time is less than 3 hours, as shown in Fig. 6E, since the B atom 13 system is not sufficiently segregated at the interface between the ferrite iron 11 and the Vostian iron 12, even if it is appropriately treated later, it cannot be obtained. B crystal covers a good surface and does not allow the micro-coefficient of ferrite on the surface to be less than 0.5. Further, in the case where the annealing retention time was 3 hours, the smectite carbon steel was not sufficiently coarsened, and the average particle diameter of the ferritic carbon iron was not obtained to be 0.3 μm or more. Therefore, the annealing retention time is set to 3 hours or longer, preferably 5 hours or longer. When the annealing holding time is longer than 60 hours, the micro-coefficient of the ferrite iron on the surface cannot be made smaller than 0.5 for the same reason as when the annealing holding temperature is more than 770 °C. Further, when the annealing retention time is longer than 60 hours, the smectite carbon steel is excessively coarsened, and the average particle diameter of the swarf carbon iron cannot be made 2.2 μm or less. Therefore, the annealing retention time is set to 60 hours or less, preferably 40 hours or less.

(至650℃為止之冷卻速度：1℃/hr以上且60℃/hr以下)(Cooling speed up to 650 ° C: 1 ° C / hr or more and 60 ° C / hr or less)

至650℃為止之冷卻速度小於1℃/hr之情況，如圖6F所顯示，B結晶在冷卻中係過剩地產生且B結晶係在高碳鋼板表面形成凸部。形成凸部時，B結晶的膜厚度偏差大且在成 形中與模具產生黏附、或在模具產生瑕疵。又，至650℃為止之冷卻速度小於1℃/hr之情況，無法得到充分的生產性。 因此，至650℃為止之冷卻速度係設為1℃/hr以上，較佳是設為2℃/hr以上。至650℃為止之冷卻速度大於60℃/hr之情況，沃斯田鐵12的減少速度係變為過剩，如圖6G所顯示，無法使B原子13之間產生充分的共價鍵14且無法使在表面之肥粒鐵的微摩擦係數小於0.5。又，至650℃為止之冷卻速度大於60℃/hr之情況，在冷卻中係從沃斯田鐵12生成波來鐵，致使雪明碳鐵的球狀化受到阻礙且無法得到80%以上的球狀化率。因此，至650℃為止之冷卻速度係設為60℃/hr以下，較佳是設為50℃/hr以下。When the cooling rate to 650 ° C is less than 1 ° C / hr, as shown in Fig. 6F, the B crystal is excessively generated during cooling and the B crystal forms a convex portion on the surface of the high carbon steel sheet. When the convex portion is formed, the film thickness of the B crystal is largely deviated and is in progress Adhesion in the form with the mold or flaws in the mold. Moreover, when the cooling rate until 650 ° C is less than 1 ° C / hr, sufficient productivity cannot be obtained. Therefore, the cooling rate up to 650 ° C is set to 1 ° C / hr or more, preferably 2 ° C / hr or more. When the cooling rate to 650 ° C is more than 60 ° C / hr, the rate of decrease of the Worthite 12 is excessive, and as shown in Fig. 6G, a sufficient covalent bond 14 cannot be generated between the B atoms 13 and cannot be obtained. The micro-coefficient of ferrite on the surface is less than 0.5. Further, when the cooling rate to 650 ° C is more than 60 ° C / hr, the formation of the pulverized iron from the Worthite iron 12 during cooling causes the spheroidization of the stellite carbon to be hindered and the spheroidization of the stellite carbon is not obtained. Spheroidization rate. Therefore, the cooling rate up to 650 ° C is 60 ° C / hr or less, preferably 50 ° C / hr or less.

依照本實施形態，因為能夠得到優異的潤滑性，所以能夠抑制高碳鋼板與模具之黏附而抑制模具的損耗。又，依照本實施形態，亦能夠抑制在成形中產生裂紋。According to the present embodiment, since excellent lubricity can be obtained, adhesion of the high carbon steel sheet to the mold can be suppressed, and the loss of the mold can be suppressed. Moreover, according to this embodiment, it is also possible to suppress the occurrence of cracks during molding.

又，上述實施形態係任一者均只不過在實施本發明時揭示作為具體化的例子，本發明的技術的範圍係不可因該等而被限定地解釋。亦即，本發明係不從其技術思想、或其主要的特徵脫離而能夠以各式各樣的形式來實施。Further, any of the above-described embodiments is merely an example of the embodiment when the present invention is implemented, and the scope of the technology of the present invention is not to be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the technical idea or its main features.

實施例Example

其次，說明本發明的實施例。在實施例的條件，係為了確認本發明的實施可能性及效果而採用之一條件例，本發明係不被該一條件例限定。本發明係只要不脫離本發明的要旨而達成本發明的目的，能夠採用各種條件而得者。Next, an embodiment of the present invention will be described. The conditions of the examples are based on one of the conditional examples in order to confirm the implementation possibilities and effects of the present invention, and the present invention is not limited by the one conditional example. The present invention can achieve the object of the present invention without departing from the gist of the present invention, and can be obtained by various conditions.

(第1實驗)(first experiment)

在第1實驗，係進行表1所顯示的化學組成的鋼胚(鋼種A~Y、BK)之熱軋而取得厚度為4mm的熱軋鋼板。在熱軋係將鋼胚加熱溫度設為1130℃，將其時間設為1小時，將精加工輥軋溫度設為850℃且將捲取溫度設為520℃。其次，冷卻至小於60℃的溫度為止且進行使用硫酸之酸洗。隨後，進行熱軋鋼板的退火而取得熱軋退火鋼板。在退火係將熱軋鋼板於750℃保持15小時之後，以30℃/hr的冷卻速度冷卻至650℃為止。接著，冷卻至小於60℃的溫度為止。如此進行而製造各種高碳鋼板。表1中的空欄係顯示該元素的含量為小於檢出界限且剩餘部分係Fe及不純物。例如鋼種BK的Cr含量係能夠視為0.00%。表1中的底線係表示該數值為從本發明的範圍脫離。In the first experiment, hot-rolled steel sheets having a chemical composition of the chemical composition shown in Table 1 (steel types A to Y, BK) were hot rolled to obtain a hot-rolled steel sheet having a thickness of 4 mm. In the hot rolling system, the slab heating temperature was set to 1,130 ° C, the time was set to 1 hour, the finishing rolling temperature was set to 850 ° C, and the coiling temperature was set to 520 ° C. Next, it was cooled to a temperature of less than 60 ° C and subjected to pickling using sulfuric acid. Subsequently, the hot rolled steel sheet is annealed to obtain a hot rolled annealed steel sheet. After the hot-rolled steel sheet was held at 750 ° C for 15 hours in the annealing system, it was cooled to 650 ° C at a cooling rate of 30 ° C / hr. Next, it is cooled to a temperature of less than 60 °C. In this way, various high carbon steel sheets are produced. The empty bars in Table 1 show that the content of the element is less than the detection limit and the remainder is Fe and impurities. For example, the Cr content of the steel type BK can be regarded as 0.00%. The bottom line in Table 1 indicates that the value is deviated from the scope of the present invention.

然後，針對各高碳鋼板，測定肥粒鐵的微摩擦係 數和雪明碳鐵的球狀化率及平均粒徑。在測定肥粒鐵的微摩擦係數時，亦進行測定雪明碳鐵的摩擦係數。將該等的結果顯示在表2。表2中的底線係表示該項目係從本發明的範圍脫離。Then, for each high carbon steel plate, the micro-friction system of the ferrite iron was measured. The number and the spheroidization rate and average particle size of ferritic carbon iron. When determining the micro-coefficient of ferrite iron, the coefficient of friction of Xueming carbon iron was also measured. The results of these are shown in Table 2. The bottom line in Table 2 indicates that the item is detached from the scope of the present invention.

而且，針對各高碳鋼板，進行黏附抑制性的評價及裂紋敏感性(crack sensitivity)的評價作為成形性的評價。在黏附抑制性的評價係進行引伸珠試驗(drawbead test)。亦即，將前端之半徑R為20mm的壓入珠粒以10kN的荷重加壓接觸高碳鋼板而拔出。然後，觀察在壓入珠粒的前端有無黏附物，將有黏附物存在者評定為×，而將不存在者評定為○。又，在該試驗之存在黏附物，係表示在從數千至達到數萬次之沖壓成形，黏附物係早期在模具產生且使成形性低落。在裂紋敏感性的評價係進行壓縮加工試驗。亦即，從高碳鋼板以試片高度方向係與板厚方向平行的方式切取直徑為10mm、高度為4mm的圓柱試片，將其進行壓縮加工至高度成為1mm為止。然後，進行外觀觀察及剖面組織觀察，將壓縮中或壓縮後在外觀存在有裂紋者以及在剖面組織觀察存在有1mm以上的龜裂者評定為評點×，而將除此以外者評定為○。將該等的結果亦顯示在表2。In addition, evaluation of adhesion inhibition property and evaluation of crack sensitivity were performed for each high carbon steel sheet as evaluation of moldability. The evaluation of the adhesion inhibition was carried out by a drawbead test. That is, the press-in beads having a radius R of 20 mm at the front end were press-contacted with a high-carbon steel sheet under a load of 10 kN to be pulled out. Then, it was observed whether or not there was an adhesive at the front end of the pressed beads, and the presence of the adherent was evaluated as ×, and the non-existent was evaluated as ○. Further, the presence of the adherend in the test indicates that the press is formed from thousands to tens of thousands of times, and the adhesive is produced in the mold early and the formability is lowered. The evaluation of the crack sensitivity was carried out by a compression processing test. In other words, a cylindrical test piece having a diameter of 10 mm and a height of 4 mm was cut out from the high carbon steel plate so that the height direction of the test piece was parallel to the thickness direction of the test piece, and the test piece was compressed until the height became 1 mm. Then, the appearance observation and the cross-sectional structure observation were carried out, and those who had cracks in the appearance after compression or compression and those having a crack of 1 mm or more in the cross-sectional structure were evaluated as the evaluation ×, and the others were evaluated as ○. The results of these are also shown in Table 2.

如表2所顯示，在試料No.1~No.9，因為在本發明 範圍內，所以能夠得到良好的黏附抑制性及裂紋敏感性。As shown in Table 2, in samples No. 1 to No. 9, because in the present invention Within the range, good adhesion inhibition and crack sensitivity can be obtained.

另一方面，在試料No.10，因為鋼種J的C含量太 低，所以雪明碳鐵的量不足而無法得到充分的潤滑性，致 使在成形中與模具產生黏附。在試料No.11，因為鋼種K的N含量太高，所以BN析出且B的固熔量不足，而且肥粒鐵的微摩擦係數低，致使產生黏附及在壓縮試驗中產生裂紋。 在試料No.12，因為鋼種L的Al含量太高，所以肥粒鐵的延展性低，致使在壓縮試驗中產生以肥粒鐵的粒內裂紋作為起點之裂紋。在試料No.13，因為鋼種M的B含量太高，所以形成硼化物，致使在壓縮試驗中產生以此作為起點之裂紋。在試料No.14，因為鋼種N的Mn含量為太低，所以在退火的冷卻中產生波來鐵變態且雪明碳鐵的球狀化率低，致使在壓縮試驗中產生以針狀雪明碳鐵作為起點之裂紋。在試料No.15，因為鋼種O的P含量太高，所以B在肥粒鐵與雪明碳鐵之界面的偏析係受到阻礙，致使在壓縮試驗中產生裂紋。在試料No.16，因為鋼種P的Si含量太高，所以肥粒鐵的延展性低，致使在壓縮試驗中產生以肥粒鐵的粒內裂紋作為起點之裂紋。在試料No.17及試料No.18，因為各自鋼種Q、鋼種R的B含量太低，所以肥粒鐵的微摩擦係數低，致使產生黏附及在壓縮試驗中產生裂紋。在試料No.19，因為鋼種S的Si含量太低，所以雪明碳鐵在退火中過剩地粗大，致使在壓縮試驗中產生以粗大的雪明碳鐵作為起點之裂紋。 在試料No.20，因為鋼種T的S含量太高，所以形成非金屬夾雜物之粗大的硫化物，致使在壓縮試驗中產生以粗大的硫化物作為起點之裂紋。在試料No.21，因為鋼種U的Mn含量為太高，所以肥粒鐵的延展性低，致使在壓縮試驗中產生以肥粒鐵的粒內裂紋作為起點之裂紋。在試料No.22，因為 鋼種V的Cr含量太高，所以退火中之雪明碳鐵的球狀化係受到阻礙且雪明碳鐵的粗大化係受到抑制，致使在壓縮試驗中產生以微細的針狀雪明碳鐵作為起點之裂紋。在試料No.23，因為鋼種W的C含量太高，所以雪明碳鐵的量過剩，致使在壓縮試驗中產生以雪明碳鐵作為起點之裂紋。在試料No.24，因為鋼種X的Ti含量太低，所以BN析出且B的固熔量不足，而且肥粒鐵的微摩擦係數低，致使產生黏附及在壓縮試驗中產生裂紋。在試料No.25，因為鋼種Y的Ti含量太高，所以形成粗大的Ti氧化物，致使在壓縮試驗中產生以粗大的Ti氧化物作為起點之裂紋。在試料No.26，因為鋼種BK的Cr含量太低，所以BN析出且B的固熔量不足，而且肥粒鐵的微摩擦係數低，致使在成形中與模具產生黏附。On the other hand, in sample No. 10, because the C content of steel type J is too Low, so the amount of Xueming carbon iron is insufficient to obtain sufficient lubricity, resulting in Adhesion to the mold during forming. In sample No. 11, since the N content of the steel species K was too high, BN precipitated and the amount of solid solution of B was insufficient, and the micro-coefficient of ferrite iron was low, causing adhesion and cracking in the compression test. In sample No. 12, since the Al content of the steel species L was too high, the ductility of the ferrite iron was low, and cracks originating from the intragranular crack of the ferrite iron were generated in the compression test. In sample No. 13, since the B content of the steel species M was too high, boride was formed, so that cracks as a starting point were generated in the compression test. In sample No. 14, since the Mn content of the steel species N was too low, the wave-forming iron was deformed during the cooling of the annealing and the spheroidization rate of the stellite carbon was low, resulting in the needle-like snowing in the compression test. Carbon iron as a starting point crack. In sample No. 15, since the P content of the steel species O was too high, the segregation of B at the interface between the ferrite iron and the swarf carbon iron was hindered, resulting in cracks in the compression test. In sample No. 16, since the Si content of the steel species P was too high, the ductility of the ferrite iron was low, and cracks originating from the intragranular crack of the ferrite iron were generated in the compression test. In sample No. 17 and sample No. 18, since the B content of each steel type Q and steel type R was too low, the micro-coefficient of ferrite iron was low, causing adhesion and cracking in the compression test. In sample No. 19, since the Si content of the steel species S was too low, the swarf carbon iron was excessively coarsened in the annealing, so that cracks with coarse stellite carbon iron as a starting point were generated in the compression test. In sample No. 20, since the S content of the steel species T was too high, coarse sulfides of non-metallic inclusions were formed, resulting in cracks starting from coarse sulfides in the compression test. In sample No. 21, since the Mn content of the steel species U was too high, the ductility of the ferrite iron was low, and cracks originating from the intragranular crack of the ferrite iron were generated in the compression test. In sample No. 22, because The Cr content of the steel species V is too high, so the spheroidization of the stellite in the annealing is hindered and the coarsening of the ferritic carbon iron is suppressed, resulting in the formation of fine needle-like ferritic carbon iron in the compression test. Crack as a starting point. In sample No. 23, since the C content of the steel species W was too high, the amount of the sulphur carbon iron was excessive, so that cracks starting from swarf carbon iron were generated in the compression test. In sample No. 24, since the Ti content of the steel type X was too low, BN precipitated and the amount of solid solution of B was insufficient, and the micro-coefficient of ferrite iron was low, causing adhesion and cracking in the compression test. In sample No. 25, since the Ti content of the steel species Y was too high, coarse Ti oxide was formed, resulting in cracking with coarse Ti oxide as a starting point in the compression test. In sample No. 26, since the Cr content of the steel type BK was too low, BN precipitated and the amount of solid solution of B was insufficient, and the micro-coefficient of ferrite iron was low, causing adhesion to the mold during molding.

(第2實驗)(2nd experiment)

在第2實驗，係進行表3所顯示的化學組成的鋼胚(鋼種Z~BJ)之熱軋而取得厚度為4mm的熱軋鋼板。在熱軋係將鋼胚加熱溫度設為1130℃，將其時間設為1小時，將精加工輥軋溫度設為850℃且將捲取溫度設為520℃。其次，冷卻至小於60℃的溫度為止且進行使用硫酸之酸洗。隨後，進行熱軋鋼板的退火而取得熱軋退火鋼板。在退火係將熱軋鋼板於750℃保持15小時之後，以30℃/hr的冷卻速度冷卻至650℃為止。接著，冷卻至小於60℃的溫度為止。如此進行而製造各種高碳鋼板。表3中的空欄係顯示該元素的含量為小於檢出界限且剩餘部分係Fe及不純物。表3中的底線係表 示該數值為從本發明的範圍脫離。In the second experiment, hot-rolled steel sheets having a chemical composition (steel type Z to BJ) shown in Table 3 were hot-rolled to obtain a hot-rolled steel sheet having a thickness of 4 mm. In the hot rolling system, the slab heating temperature was set to 1,130 ° C, the time was set to 1 hour, the finishing rolling temperature was set to 850 ° C, and the coiling temperature was set to 520 ° C. Next, it was cooled to a temperature of less than 60 ° C and subjected to pickling using sulfuric acid. Subsequently, the hot rolled steel sheet is annealed to obtain a hot rolled annealed steel sheet. After the hot-rolled steel sheet was held at 750 ° C for 15 hours in the annealing system, it was cooled to 650 ° C at a cooling rate of 30 ° C / hr. Next, it is cooled to a temperature of less than 60 °C. In this way, various high carbon steel sheets are produced. The empty bars in Table 3 show that the content of the element is less than the detection limit and the remainder is Fe and impurities. The bottom line in Table 3 This numerical value is shown to be depart from the scope of the present invention.

然後，與第1實驗同樣地進行且針對各高碳鋼板， 測定肥粒鐵的微摩擦係數和雪明碳鐵的球狀化率及平均粒徑，而且，進行黏附抑制性的評價及裂紋敏感性的評價。 將該等結果顯示在表4。表4的底線係表示其項目係從本發明的範圍脫離。Then, in the same manner as in the first experiment, and for each high carbon steel sheet, The micro-coefficient of ferrite iron and the spheroidization rate and average particle diameter of the stellite carbon were measured, and evaluation of adhesion inhibition and evaluation of crack sensitivity were performed. The results are shown in Table 4. The bottom line of Table 4 indicates that the items thereof are deviated from the scope of the present invention.

如表4所顯示，在試料No.31~No.43，因為在本 發明範圍內，所以能夠得到良好的黏附抑制性及裂紋敏感性。As shown in Table 4, in sample No. 31 to No. 43, because in this Within the scope of the invention, good adhesion inhibition and crack sensitivity can be obtained.

另一方面，在試料No.44，因為鋼種AM的C含量 太低，所以雪明碳鐵的量不足且無法得到充分的潤滑性，致使在成形中與模具產生黏附。在試料No.45，因為鋼種AN的Cu含量太高，所以在熱軋中產生瑕疵，致使產生以該瑕疵作為起點之黏附。在試料No.46，因為鋼種AO的Ca含量太高，所以形成粗大的Ca氧化物，致使在壓縮試驗中產生以粗大的Ca氧化物作為起點之裂紋。在試料No.47，因為鋼種AP的Mo含量太高，所以肥粒鐵的延展性低，致使在壓縮試驗中產生以肥粒鐵的粒內裂紋作為起點之裂紋。在試料No.48，因為鋼種AQ的B含量太低，所以肥粒鐵的微摩擦係數低，致使產生黏附及在壓縮試驗中產生裂紋。在試料No.49，因為鋼種AR的Nb含量太高，所以肥粒鐵的延展性低，致使在壓縮試驗中產生以肥粒鐵的粒內裂紋作為起點之裂紋。在試料No.50，因為鋼種AS的Mn含量太低，所以在退火的冷卻中產生波來鐵變態且雪明碳鐵的球狀化率低，致使在壓縮試驗中產生以針狀雪明碳鐵作為起點之裂紋。 在試料No.51，因為鋼種AT的Ce含量太高，所以形成粗大的Ce氧化物，致使在壓縮試驗中產生以粗大的Ce氧化物作為起點之裂紋。在試料No.52，因為鋼種AU的B含量太高，所以形成硼化物，致使在壓縮試驗中產生以此作為起點之裂紋。在試料No.53，因為鋼種AV的Ni含量太高，所以肥粒鐵的微摩擦係數高，致使產生黏附。在試料No.54，因為 鋼種AW的V含量太高，所以肥粒鐵的延展性低，致使在壓縮試驗中產生以肥粒鐵的粒內裂紋作為起點之裂紋。在試料No.55，因為鋼種AX的Zr含量太高，所以形成粗大的Zr氧化物，致使在壓縮試驗中產生以粗大的Zr氧化物作為起點之裂紋。在試料No.56，因為鋼種AY的Cr含量太高，所以退火中之雪明碳鐵的球狀化受到阻礙且雪明碳鐵的粗大化受到抑制，致使壓縮試驗中產生以微細的針狀雪明碳鐵作為起點之裂紋。在試料No.57，因為鋼種AZ的Mn含量太低，所以在退火的冷卻中產生波來鐵變態且雪明碳鐵的球狀化率低，致使在壓縮試驗中產生以針狀雪明碳鐵作為起點之裂紋。在試料No.58，因為鋼種BA的Y含量太高，所以形成粗大的Y氧化物，致使在壓縮試驗中產生以粗大的Y氧化物作為起點之裂紋。在試料No.59，因為鋼種BB的La含量太高，所以形成粗大的La氧化物，致使在壓縮試驗中產生以粗大的La氧化物作為起點之裂紋。在試料No.60，因為鋼種BC的S含量太高，所以形成非金屬夾雜物之粗大的硫化物，致使在壓縮試驗中產生以粗大的硫化物作為起點之裂紋。在試料No.61，因為鋼種BD的W含量太高，所以肥粒鐵的延展性低，致使在壓縮試驗中產生以肥粒鐵的粒內裂紋作為起點之裂紋。在試料No.62，因為鋼種BE的Ti含量太低，所以BN析出且B的固熔量不足，而且肥粒鐵的微摩擦係數低，致使產生黏附及在壓縮試驗中產生裂紋。在試料No.63，因為鋼種BF的Si含量太低，所以雪明碳鐵在退火中過剩地粗大，致使在壓縮試驗中產生以粗大的雪明碳鐵作 為起點之裂紋。在試料No.64，因為鋼種BG的P含量太高，所以B在肥粒鐵與雪明碳鐵之界面的偏析係受到阻礙，致使在壓縮試驗中產生裂紋。在試料No.65，因為鋼種BH的Ta含量太高，所以肥粒鐵的延展性低，致使在壓縮試驗中產生以肥粒鐵的粒內裂紋作為起點之裂紋。在試料No.66，因為鋼種BI的Mg含量太高，所以形成粗大的Mg氧化物，致使在壓縮試驗中產生以粗大的Mg氧化物作為起點之裂紋。在試料No.67，因為鋼種BJ的C含量太高，所以雪明碳鐵的量過剩，致使在壓縮試驗中產生以雪明碳鐵作為起點之裂紋。On the other hand, in sample No. 44, because of the C content of the steel type AM Too low, so the amount of Xueming carbon iron is insufficient and sufficient lubricity is not obtained, resulting in adhesion to the mold during forming. In sample No. 45, since the Cu content of the steel type AN was too high, enthalpy was generated during hot rolling, so that adhesion with the ruthenium as a starting point was generated. In sample No. 46, since the Ca content of the steel species AO was too high, coarse Ca oxide was formed, resulting in cracks starting from coarse Ca oxide in the compression test. In sample No. 47, since the Mo content of the steel type AP was too high, the ductility of the ferrite iron was low, and cracks originating from the intragranular crack of the ferrite iron were generated in the compression test. In sample No. 48, since the B content of the steel grade AQ was too low, the micro-coefficient of ferrite iron was low, causing adhesion and cracking in the compression test. In sample No. 49, since the Nb content of the steel type AR was too high, the ductility of the ferrite iron was low, and cracks originating from the intragranular crack of the ferrite iron were generated in the compression test. In sample No. 50, since the Mn content of the steel species AS is too low, a wave-forming iron is generated in the cooling of the annealing and the spheroidization rate of the stellite carbon is low, resulting in the formation of acicular snow-melting carbon in the compression test. Iron as a starting point for cracks. In sample No. 51, since the Ce content of the steel type AT was too high, a coarse Ce oxide was formed, resulting in cracks starting from a coarse Ce oxide in the compression test. In sample No. 52, since the B content of the steel grade AU was too high, boride was formed, so that cracks as a starting point were generated in the compression test. In sample No. 53, since the Ni content of the steel species AV was too high, the micro-coefficient of ferrite iron was high, resulting in adhesion. In sample No. 54, because The V content of the steel grade AW is too high, so the ductility of the ferrite iron is low, so that cracks originating from the intragranular crack of the ferrite iron are generated in the compression test. In sample No. 55, since the Zr content of the steel species AX was too high, a coarse Zr oxide was formed, resulting in cracks starting from a coarse Zr oxide in the compression test. In sample No. 56, since the Cr content of the steel grade AY was too high, the spheroidization of the stellite in the annealing was hindered and the coarsening of the swarf carbon iron was suppressed, resulting in a fine needle shape in the compression test. Xueming carbon iron as a starting point crack. In sample No. 57, since the Mn content of the steel grade AZ is too low, a wave-induced iron metamorphosis is generated in the cooling of the annealing and the spheroidization rate of the snow-capped carbon iron is low, so that acicular snow-forming carbon is generated in the compression test. Iron as a starting point for cracks. In sample No. 58, since the Y content of the steel type BA was too high, a coarse Y oxide was formed, resulting in cracks starting from a coarse Y oxide in the compression test. In sample No. 59, since the La content of the steel type BB was too high, coarse La oxide was formed, and cracks with coarse La oxide as a starting point were generated in the compression test. In sample No. 60, since the S content of the steel type BC was too high, coarse sulfides of non-metallic inclusions were formed, resulting in cracks starting from coarse sulfides in the compression test. In sample No. 61, since the W content of the steel type BD was too high, the ductility of the ferrite iron was low, and cracks originating from the intragranular crack of the ferrite iron were generated in the compression test. In sample No. 62, since the Ti content of the steel type BE was too low, BN precipitated and the amount of solid solution of B was insufficient, and the micro-coefficient of ferrite iron was low, causing adhesion and cracking in the compression test. In sample No. 63, since the Si content of the steel grade BF is too low, the sulphur carbon iron is excessively coarse in the annealing, so that coarse ferritic carbon iron is produced in the compression test. Crack as the starting point. In sample No. 64, since the P content of the steel BG was too high, the segregation of B at the interface between the ferrite iron and the swarf carbon iron was hindered, resulting in cracks in the compression test. In sample No. 65, since the Ta content of the steel type BH was too high, the ductility of the ferrite iron was low, and cracks originating from the intragranular crack of the ferrite iron were generated in the compression test. In sample No. 66, since the Mg content of the steel type BI was too high, coarse Mg oxide was formed, resulting in cracks starting from coarse Mg oxide in the compression test. In sample No. 67, since the C content of the steel type BJ was too high, the amount of ferritic carbon iron was excessive, so that cracks starting from swarf carbon iron were generated in the compression test.

又，在圖1，係顯示從試料No.1~No.25及 No.31~No.67，除了試料No.11、No.51、No.53及No.62以外之肥粒鐵的微摩擦係數與B含量之關係。如圖1所顯示，相較於B含量小於0.0004%時，B含量為0.0004%以上時，肥粒鐵的微摩擦係數係顯著地較低。Moreover, in Fig. 1, the samples No. 1 to No. 25 and No. 31 to No. 67, except for the relationship between the micro-coefficient of ferrite and the B content of samples No. 11, No. 51, No. 53, and No. 62. As shown in Fig. 1, when the B content is less than 0.0004% and the B content is 0.0004% or more, the micro-coefficient of ferrite iron is remarkably low.

(第3實驗)(3rd experiment)

在第3實驗，係在第1實驗所使用的鋼種及在第2實驗所使用的鋼種之中，針對在本發明的範圍內者(鋼種A~I及鋼種Z~AL)，在各種條件下進行熱軋及退火而製造高碳鋼板。 將該等條件顯示在表5~表7。表5~表7中的底線係顯示其數值為從本發明的範圍脫離。In the third experiment, among the steel types used in the first experiment and the steel types used in the second experiment, those within the scope of the present invention (steel type A~I and steel type Z~AL) under various conditions Hot rolling and annealing are performed to produce a high carbon steel sheet. These conditions are shown in Tables 5 to 7. The bottom line in Tables 5 to 7 shows that the values are deviated from the scope of the present invention.

然後，與第1實驗同樣地進行且針對各高碳鋼板 測定肥粒鐵的微摩擦係數和雪明碳鐵的球狀化率及平均粒徑，而且進行黏附抑制性的評價及裂紋敏感性的評價。將該等的結果顯示在表8~表10。表8~表10的底線係顯示其項目為從本發明的範圍脫離。Then, it was carried out in the same manner as in the first experiment and for each high carbon steel sheet. The micro-coefficient of ferrite iron and the spheroidization rate and average particle diameter of swarf carbon iron were measured, and evaluation of adhesion inhibition and evaluation of crack sensitivity were performed. The results of these are shown in Tables 8 to 10. The bottom lines of Tables 8 to 10 show that the items are excluded from the scope of the present invention.

如表8所顯示，在試料No.72、No.74、 No.77~No.80、No.82、No.83、No.85及No.88~92，因為係在本發明範圍內，所能夠得到良好的黏附抑制性及裂紋敏感性。如表9所顯示，試料No.103、No.105、No.106、No.108~No.111、No.114~No.117及No.120~No.122，因為均在本發明範圍內，所以能夠得到良好的黏附抑制性及裂紋 敏感性。如表10所顯示，試料No.131、No.133、No.134、No.136、No.139、No.141~No.143、No.145、No.147、No.148、No.151及No.152，因為均在本發明範圍內，所以能夠得到良好的黏附抑制性及裂紋敏感性。As shown in Table 8, in sample No. 72, No. 74, No. 77 to No. 80, No. 82, No. 83, No. 85, and No. 88 to 92 are excellent in adhesion inhibition and crack sensitivity because they are within the scope of the present invention. As shown in Table 9, Sample No. 103, No. 105, No. 106, No. 108 to No. 111, No. 114 to No. 117, and No. 120 to No. 122 are all within the scope of the present invention. So that good adhesion inhibition and cracking can be obtained Sensitivity. As shown in Table 10, Sample No. 131, No. 133, No. 134, No. 136, No. 139, No. 141 to No. 143, No. 145, No. 147, No. 148, No. 151 Further, since No. 152 is within the scope of the present invention, good adhesion inhibition and crack sensitivity can be obtained.

另一方面，在試料No.71，因為退火保持溫度太 高，所以體積膨脹大，致使熱軋鋼捲鬆開而產生擦痕且亦產生捆縛帶引起的壓痕。又，B結晶的膜厚度的偏差大且肥粒鐵的微摩擦係數大。因而產生黏附。而且，雪明碳鐵係過剩地粗大化，致使在壓縮試驗中產生以粗大的雪明碳鐵作為起點之裂紋。在試料No.73，因為捲取溫度太高，所以在熱軋鋼板中生成具有粗大的板層(lamella)之波來鐵，致使退火中之雪明碳鐵的球狀化係受到阻礙且雪明碳鐵的球狀化率低。又，伴隨著鏽垢的除去而形成大的凹凸且肥粒鐵的微摩擦係數大。因此，產生黏附及壓縮試驗中的裂紋。 在試料No.75，因為退火保持時間為太短，所以肥粒鐵的微摩擦係數大且雪明碳鐵的平均粒徑小。因此，產生黏附及壓縮試驗中的裂紋。在試料No.76，因為鋼胚加熱溫度太低，所以B及Mn等的偏析係未消除，致使肥粒鐵的微摩擦係數大。因此，產生黏附及壓縮試驗中的裂紋。在試料No.81，因為捲取溫度太高，所以與試料No.73同樣地產生黏附及壓縮試驗中的裂紋。在試料No.84，因為冷卻速度為太高，所以在冷卻中產生波來鐵變態，致使在壓縮試驗中產生以針狀雪明碳鐵作為起點之裂紋。又，因為無法在高碳鋼板表面形成B結晶良好的膜，所以肥粒鐵的微摩擦係數高，致使 產生黏附。在試料No.86，因為退火保持溫度太高，所以與試料No.81同樣地產生黏附及壓縮試驗中的裂紋。在試料No.87，因為捲取溫度太低，將鏽垢除去之結果，鋼板表面粗糙化且產生黏附。On the other hand, in sample No. 71, because annealing keeps the temperature too High, so the volume expansion is large, causing the hot-rolled steel coil to loosen to cause scratches and also cause indentation caused by the strap. Further, the variation in the film thickness of the B crystal is large and the micro-coefficient of the ferrite iron is large. Thus adhesion occurs. Further, the smectite carbon steel was excessively coarsened, so that cracks with coarse swarf carbon iron as a starting point were generated in the compression test. In sample No. 73, since the coiling temperature was too high, a ferrite having a coarse lamella was formed in the hot-rolled steel sheet, causing the spheroidization of the stellite in the annealing to be hindered and snow. The spheroidization rate of carbon steel is low. Further, large irregularities are formed accompanying the removal of rust, and the micro-coefficient of ferrite is large. Therefore, cracks in the adhesion and compression tests are generated. In Sample No. 75, since the annealing holding time was too short, the micro-coefficient of ferrite iron was large and the average particle diameter of Xueming carbon iron was small. Therefore, cracks in the adhesion and compression tests are generated. In sample No. 76, since the steel embryo heating temperature was too low, the segregation of B and Mn was not eliminated, and the micro-coefficient of ferrite iron was large. Therefore, cracks in the adhesion and compression tests are generated. In Sample No. 81, since the coiling temperature was too high, cracks in the adhesion and compression tests occurred in the same manner as in Sample No. 73. In sample No. 84, since the cooling rate was too high, a wave of iron was deformed during cooling, and cracks having acicular stellite as a starting point were generated in the compression test. Moreover, since a film having a good B crystal cannot be formed on the surface of the high carbon steel sheet, the micro-coefficient of ferrite iron is high, resulting in high Produces adhesion. In Sample No. 86, since the annealing holding temperature was too high, cracks in the adhesion and compression tests occurred in the same manner as in Sample No. 81. In sample No. 87, since the coiling temperature was too low, the surface of the steel sheet was roughened and adhesion was caused as a result of removing the scale.

在試料No.101，因為退火保持溫度太低，所以B 在肥粒鐵與沃斯田鐵之界面的偏析係受到抑制且肥粒鐵的微摩擦係數大，致使產生黏附。又，B在肥粒鐵與雪明碳鐵之界面的偏析亦受到抑制，致使在壓縮試驗中產生裂紋。 在試料No.102，因為精加工輥軋溫度太高，所以伴隨著鏽垢的除去而形成大的凹凸且肥粒鐵的微摩擦係數大。因此產生黏附。在試料No.104，因為鋼胚加熱溫度太高，所以B原子在鋼胚加熱中產生氧化且肥粒鐵的微摩擦係數大。因此產生黏附。在試料No.107，因為冷卻速度為太高，所以在冷卻中產生波來鐵變態，致使在壓縮試驗中產生以針狀雪明碳鐵作為起點之裂紋。又，在高碳鋼板表面無法形成B結晶良好的膜且肥粒鐵的微摩擦係數高，致使產生黏附。 在試料No.112，因為鋼胚加熱溫度太高，所以與試料No.104同樣地產生黏附。在試料No.113，因為精加工輥軋溫度太低且組織的各向異性強，致使在壓縮試驗中產生以不均勻組織作為起點之裂紋。又，將鏽垢除去之結果、鋼板表面粗糙化且產生黏附。在試料No.118，因為退火保持溫度太低，所以與試料No.101同樣地產生黏附及在壓縮試驗中產生裂紋。In sample No. 101, since annealing keeps the temperature too low, B The segregation system at the interface between the ferrite iron and the Vostian iron is suppressed and the micro-coefficient of ferrite iron is large, resulting in adhesion. Moreover, the segregation of B at the interface between the ferrite iron and the ferritic carbon iron was also suppressed, resulting in cracks in the compression test. In sample No. 102, since the finishing rolling temperature was too high, large irregularities were formed accompanying the removal of rust, and the micro-coefficient of ferrite iron was large. Therefore, adhesion occurs. In sample No. 104, since the heating temperature of the steel embryo is too high, the B atom is oxidized in the heating of the steel embryo and the micro-coefficient of the ferrite iron is large. Therefore, adhesion occurs. In Sample No. 107, since the cooling rate was too high, a wave-forming iron was deformed during cooling, so that cracks with needle-like stellite as a starting point were generated in the compression test. Further, a film having a good B crystal cannot be formed on the surface of the high carbon steel sheet, and the micro-coefficient of the ferrite iron is high, resulting in adhesion. In sample No. 112, since the steel embryo heating temperature was too high, adhesion occurred similarly to sample No. 104. In sample No. 113, since the finishing rolling temperature was too low and the anisotropy of the structure was strong, cracks having uneven structure as a starting point were generated in the compression test. Further, as a result of removing the rust, the surface of the steel sheet was roughened and adhered. In Sample No. 118, since the annealing holding temperature was too low, adhesion occurred in the same manner as in Sample No. 101, and cracks occurred in the compression test.

在試料No.132，因為冷卻速度太低且B結晶的 膜厚度的偏差大，而且肥粒鐵的微摩擦係數大。因此產生黏附。又，雪明碳鐵過剩地粗大化，致使在壓縮試驗中產生以粗大的雪明碳鐵作為起點之裂紋。在試料No.135，因為精加工輥軋溫度太低，所以組織的各向異性強，致使在壓縮試驗中產生以不均勻組織作為起點之裂紋。又，將鏽垢除去之結果，鋼板表面粗糙化且產生黏附。在試料No.137，因為捲取溫度太低，所以將鏽垢除去之結果，鋼板表面粗糙化且產生黏附。在試料No.138，因為退火保持時間太長，所以體積膨脹大，致使熱軋鋼捲鬆開而產生擦痕且亦產生捆縛帶引起的壓痕。又，B結晶的膜厚度的偏差大且肥粒鐵的微摩擦係數大，因此產生黏附。而且，雪明碳鐵係過剩地粗大化，致使在壓縮試驗中產生以粗大的雪明碳鐵作為起點之裂紋。在試料No.140，因為退火保持時間太短，所以肥粒鐵的微摩擦係數大且雪明碳鐵的平均粒徑小。因此產生黏附及壓縮試驗中的裂紋。在試料No.144，因為冷卻速度太低，所以與試料No.132同樣地產生黏附及壓縮試驗中的裂紋。在試料No.146，因為精加工輥軋溫度太高，所以伴隨著鏽垢的除去而形成大的凹凸且肥粒鐵的微摩擦係數大。因此產生黏附。在試料No.149，因為鋼胚加熱溫度太低，所以B及Mn等的偏析未消除且肥粒鐵的微摩擦係數大。因此產生黏附及壓縮試驗中的裂紋。在試料No.150，因為退火保持時間太長，所以與試料No.138同樣地產生黏附及壓縮試驗中的裂紋。In sample No. 132, because the cooling rate is too low and B crystallizes The deviation of the film thickness is large, and the micro-coefficient of ferrite iron is large. Therefore, adhesion occurs. Further, the sulphur carbon iron was excessively coarsened, so that cracks with coarse swarf carbon iron as a starting point were generated in the compression test. In Sample No. 135, since the finishing rolling temperature was too low, the anisotropy of the structure was strong, so that cracks with uneven structure as a starting point were generated in the compression test. Further, as a result of removing the rust, the surface of the steel sheet was roughened and adhesion occurred. In sample No. 137, since the coiling temperature was too low, the surface of the steel sheet was roughened and adhered as a result of removing the scale. In Sample No. 138, since the annealing holding time was too long, the volume expansion was large, causing the hot rolled steel coil to loosen to cause scratches and also to cause an indentation due to the binding tape. Further, the variation in the film thickness of the B crystal is large and the micro-coefficient of the ferrite iron is large, so that adhesion occurs. Further, the smectite carbon steel was excessively coarsened, so that cracks with coarse swarf carbon iron as a starting point were generated in the compression test. In Sample No. 140, since the annealing holding time was too short, the micro-coefficient of ferrite iron was large and the average particle diameter of Xueming carbon iron was small. Therefore, cracks in the adhesion and compression tests are generated. In sample No. 144, since the cooling rate was too low, cracks in the adhesion and compression tests occurred in the same manner as in sample No. 132. In sample No. 146, since the finishing rolling temperature was too high, large irregularities were formed accompanying the removal of rust, and the micro-coefficient of ferrite iron was large. Therefore, adhesion occurs. In sample No. 149, since the steel embryo heating temperature was too low, segregation of B and Mn or the like was not eliminated and the micro-coefficient of ferrite iron was large. Therefore, cracks in the adhesion and compression tests are generated. In sample No. 150, since the annealing holding time was too long, cracks in the adhesion and compression tests were generated in the same manner as in sample No. 138.

在圖7，係顯示從第1實驗或第3實驗的實施例所 摘錄之試料的肥粒鐵的微摩擦係數與B含量之關係。如圖7所顯示，相較於B含量小於0.0008%，B含量為0.0008%以上時，肥粒鐵的微摩擦係數係較低。In Fig. 7, the embodiment from the first experiment or the third experiment is shown. The relationship between the micro-coefficient of fermented iron and the B content of the extracted sample. As shown in Fig. 7, when the B content is less than 0.0008% and the B content is 0.0008% or more, the micro-coefficient of ferrite iron is low.

產業上之可利用性Industrial availability

本發明係能夠利用在例如汽車的驅動系統零件、鋸及切削工具等各種鋼鐵製品所使用之高碳鋼板的製造產業及利用產業。In the present invention, it is possible to use a manufacturing industry and a utilization industry of high-carbon steel sheets used for various steel products such as automobile drive system parts, saws, and cutting tools.

Claims (4)

一種高碳鋼板，其特徵在於具有下述表示之化學組成：以質量%計，C：0.30%~0.70%、Si：0.07%~1.00%、Mn：0.20%~3.00%、Ti：0.010%~0.500%、Cr：0.01%~1.50%、B：0.0004%~0.0035%、P：0.025%以下、Al：0.100%以下、S：0.0100%以下、N：0.010%以下、Cu：0.500%以下、Nb：0.000%~0.500%、Mo：0.000%~0.500%、V：0.000%~0.500%、W：0.000%~0.500%、Ta：0.000%~0.500%、Ni：0.000%~0.500%、Mg：0.000%~0.500%、Ca：0.000%~0.500%、Y：0.000%~0.500%、 Zr：0.000%~0.500%、La：0.000%~0.500%、及Ce：0.000%~0.500%，且剩餘部分：Fe及不純物；並且具有下述表示之組織：雪明碳鐵的球狀化率：80%以上，且雪明碳鐵的平均粒徑：0.3μ m~2.2μ m；又在表面的肥粒鐵的微摩擦係數小於0.5。A high carbon steel sheet characterized by having the chemical composition shown below: C: 0.30% to 0.70%, Si: 0.07% to 1.00%, Mn: 0.20% to 3.00%, Ti: 0.010% by mass% 0.500%, Cr: 0.01% to 1.50%, B: 0.0004% to 0.0035%, P: 0.025% or less, Al: 0.100% or less, S: 0.0100% or less, N: 0.010% or less, Cu: 0.500% or less, Nb : 0.000% to 0.500%, Mo: 0.000% to 0.500%, V: 0.000% to 0.500%, W: 0.000% to 0.500%, Ta: 0.000% to 0.500%, Ni: 0.000% to 0.500%, Mg: 0.000 %~0.500%, Ca: 0.000%~0.500%, Y: 0.000%~0.500%, Zr: 0.000%~0.500%, La: 0.000%~0.500%, and Ce: 0.000%~0.500%, and the remaining part: Fe and impurities; and having the following structure: spheroidization rate of sedum carbon iron: 80% or more, and average particle diameter of ferritic carbon iron: 0.3 μ m to 2.2 μ m; The micro-coefficient of iron is less than 0.5. 如請求項1之高碳鋼板，其中前述化學組成中：Nb：0.001%~0.500%、Mo：0.001%~0.500%、V：0.001%~0.500%、W：0.001%~0.500%、Ta：0.001%~0.500%、Ni：0.001%~0.500%、Mg：0.001%~0.500%、Ca：0.001%~0.500%、Y：0.001%~0.500%、Zr：0.001%~0.500%、La：0.001%~0.500%、或Ce：0.001%~0.500%，或是該等的任意組合成立。The high carbon steel sheet of claim 1, wherein the chemical composition: Nb: 0.001% to 0.500%, Mo: 0.001% to 0.500%, V: 0.001% to 0.500%, W: 0.001% to 0.500%, Ta: 0.001 %~0.500%, Ni: 0.001%~0.500%, Mg: 0.001%~0.500%, Ca: 0.001%~0.500%, Y: 0.001%~0.500%, Zr: 0.001%~0.500%, La: 0.001%~ 0.500%, or Ce: 0.001% to 0.500%, or any combination of these is established. 一種高碳鋼板之製造方法，其特徵在於具有以下步驟：進行鋼胚的熱軋而製得熱軋鋼板之步驟；及 進行前述熱軋鋼板的酸洗，且在前述酸洗之後，進行前述熱軋鋼板的退火之步驟；其中前述鋼胚具有下述表示之化學組成：以質量%計，C：0.30%~0.70%、Si：0.07%~1.00%、Mn：0.20%~3.00%、Ti：0.010%~0.500%、Cr：0.01%~1.50%、B：0.0004%~0.0035%、P：0.025%以下、Al：0.100%以下、S：0.0100%以下、N：0.010%以下、Cu：0.500%以下、Nb：0.000%~0.500%、Mo：0.000%~0.500%、V：0.000%~0.500%、W：0.000%~0.500%、Ta：0.000%~0.500%、Ni：0.000%~0.500%、Mg：0.000%~0.500%、Ca：0.000%~0.500%、 Y：0.000%~0.500%、Zr：0.000%~0.500%、La：0.000%~0.500%、及Ce：0.000%~0.500%，且剩餘部分：Fe及不純物；又前述進行熱軋之步驟中，係將鋼胚加熱溫度設為1000℃以上且小於1150℃，將精加工輥軋溫度設為830℃以上且950℃以下，且將捲取溫度設為450℃以上且700℃以下；又前述進行退火之步驟具有以下步驟：將前述熱軋鋼板保持在730℃以上且770℃以下的溫度3小時以上且60小時以下之步驟；其次，將前述熱軋鋼板以1℃/hr以上且60℃/hr以下的冷卻速度冷卻至650℃為止之步驟。A method for producing a high carbon steel sheet, comprising the steps of: performing hot rolling of a steel blank to obtain a hot rolled steel sheet; Performing the pickling of the hot-rolled steel sheet, and performing the annealing step of the hot-rolled steel sheet after the pickling; wherein the steel embryo has the chemical composition shown below: C: 0.30% to 0.70% by mass% , Si: 0.07% to 1.00%, Mn: 0.20% to 3.00%, Ti: 0.010% to 0.500%, Cr: 0.01% to 1.50%, B: 0.0004% to 0.0035%, P: 0.025% or less, Al: 0.100 % or less, S: 0.0100% or less, N: 0.010% or less, Cu: 0.500% or less, Nb: 0.000% to 0.500%, Mo: 0.000% to 0.500%, V: 0.000% to 0.500%, W: 0.000%~ 0.500%, Ta: 0.000% to 0.500%, Ni: 0.000% to 0.500%, Mg: 0.000% to 0.500%, Ca: 0.000% to 0.500%, Y: 0.000% to 0.500%, Zr: 0.000% to 0.500%, La: 0.000% to 0.500%, and Ce: 0.000% to 0.500%, and the remainder: Fe and impurities; and in the aforementioned step of performing hot rolling, The steel slab heating temperature is set to 1000 ° C or more and less than 1150 ° C, and the finishing rolling temperature is set to 830 ° C or more and 950 ° C or less, and the coiling temperature is set to 450 ° C or more and 700 ° C or less; The step of annealing has the following steps: maintaining the hot-rolled steel sheet at a temperature of 730 ° C or higher and 770 ° C or lower for 3 hours or longer and 60 hours or shorter; secondly, the hot-rolled steel sheet is 1 ° C / hr or more and 60 ° C / The cooling rate below hr is cooled to 650 ° C. 如請求項3之高碳鋼板之製造方法，其中前述化學組成中：Nb：0.001%~0.500%、Mo：0.001%~0.500%、V：0.001%~0.500%、W：0.001%~0.500%、Ta：0.001%~0.500%、Ni：0.001%~0.500%、Mg：0.001%~0.500%、 Ca：0.001%~0.500%、Y：0.001%~0.500%、Zr：0.001%~0.500%、La：0.001%~0.500%、或Ce：0.001%~0.500%，或是該等的任意組合成立。The method for producing a high carbon steel sheet according to claim 3, wherein the chemical composition: Nb: 0.001% to 0.500%, Mo: 0.001% to 0.500%, V: 0.001% to 0.500%, W: 0.001% to 0.500%, Ta: 0.001% to 0.500%, Ni: 0.001% to 0.500%, Mg: 0.001% to 0.500%, Ca: 0.001% to 0.500%, Y: 0.001% to 0.500%, Zr: 0.001% to 0.500%, La: 0.001% to 0.500%, or Ce: 0.001% to 0.500%, or any combination of these is established.