200907076 (1) 九、發明說明 【發明所屬之技術領域】 本發明係關於一種廉價的省鎳型沃斯田鐵系不鏽鋼， 其具有與SUS304不鏽鋼同等性能之冷間加工性以及耐腐 蝕性’而且在熱軋時不易產生耳部龜裂，具有與SUS 3 04 不鏽鋼同等程度之冷間輥軋特性，可使用於與SUS3 04不 鏽鋼類似的用途。 【先前技術】 作爲SUS 3 04不鏽鋼的主要代表的沃斯田鐵系不鏽鋼 係具有優異的冷間加工性、耐腐蝕性，已經有各種製品被 使用在各種用途、環境中。但是，作爲SUS3 04不鏽鋼的 代表之沃斯田鐵系不鏽鋼中，係使用大量昂貴的Ni作爲 原料。因此，會有因Ni資源的不足所導致的供需失衡問 題’還有一部分則是因爲鎳金屬被當成投機炒作對象所導 致的價格不穩定的問題。這些問題在沃斯田鐵系不鏽鋼的 生産中，是經常存在的大問題。 因此’爲了解決這種問題，以往就已經開始硏究以 Μη、N來取代沃斯田鐵系不鏽鋼中的Ni，已知的鋼材係 有以200系不鏽鋼爲首的由製造廠商所獨創的幾種鋼材。 但是’這些都是以Μη、N來取代Ni，所以雖然能夠某些 程度解決上述的價格面上的不穩定性，但是在其性質方面 仍然有許多點係不及於萬能的SUS 3 04不鏽鋼。 所存在的問題點，例如：這些替代鋼種在於製造性方 200907076 (2) 面’尤其是熱軋時發生耳部龜裂、冷軋時必 軋機的次數等等問題，在實際的製造過程中 降低、生産性的降低等等問題，因此在整體 是無法減少達到原料成本減少的程度。 、又，日本特開平3 -23 5 7號公報所揭示 .善了 ：含多量Μη的沃斯田鐵系不鏽鋼的熱 該例子中，係將Cu的過量添加視爲：會因 有損熱間加工性，因而限定了 Mn、Cu等的 是，其改善效果仍無法說是足夠，依然還是 時之耳部龜裂的問題。 【發明內容】 [發明所欲解決之課題] 本發明係有鑒於這種習知技術的問題點 。因此，本發明的主要課題係在於提供··一 田鐵系不鏽鋼，其具有與SUS304不鏽鋼同 性以及耐腐蝕性，而且價格更低廉。 [用以解決課題之手段] 本發明人等，針對沃斯田鐵系不鏽鋼的 製造性以及耐腐蝕性之關係加以硏究之結果 適量的Mn、Cu以及N來取代Ni，既可維 加工性’又可減少N i的比例之範圍，進而 須增加通過輥 ，發生良率的 成本價格上還 的例子，係改 間加工性。在 爲粒界脆化而 添加範圍，但 無法消除熱軋 而開發完成的 種省鎳型沃斯 等程度的製造 合金組成分、 ，找到了：以 持良好的熱間 完成了本發明 -5- 200907076 (3) 亦即，本發明的省鎳型沃斯田鐵系不鏽鋼，美 含有：以重量 ％ 計，0.〇4%SCS〇.12%、Si: 、3.00% SMnS 7.50%、PS 0.05%、SS 0.03% . SNiS 6.00%、16.00% SCrg 18.00%、Mo$〇 . 1.00% SCug 3.00%、0,05% $ NS 0.20% ’ 其餘200907076 (1) IX. INSTRUCTIONS OF THE INVENTION [Technical Fields of the Invention] The present invention relates to an inexpensive nickel-saving type of Worstian iron-based stainless steel having the same cold-working property and corrosion resistance as SUS304 stainless steel. It is not easy to produce ear cracks during hot rolling, and has the same cold rolling characteristics as SUS 3 04 stainless steel, and can be used for similar applications to SUS3 04 stainless steel. [Prior Art] As a main representative of SUS 3 04 stainless steel, the Worth Iron-based stainless steel has excellent cold-workability and corrosion resistance, and various products have been used in various applications and environments. However, in the Worstian iron-based stainless steel, which is representative of SUS3 04 stainless steel, a large amount of expensive Ni is used as a raw material. Therefore, there will be a problem of imbalance between supply and demand caused by the shortage of Ni resources, and part of it is because of the price instability caused by nickel metal being speculative. These problems are often a major problem in the production of Worthfield iron-based stainless steel. Therefore, in order to solve this problem, it has been studied in the past to replace Ni in Vostian iron-based stainless steel with Μη and N, and the known steels are those originally created by the manufacturer, including 200-series stainless steel. Kind of steel. However, these are all replaced by Μη and N, so although the above-mentioned instability on the price side can be solved to some extent, there are still many points in the nature that are not as good as the versatile SUS 3 04 stainless steel. The problems that exist, for example, are that the alternative steel grades are in the manufacturing process of 200907076 (2) surface 'especially the occurrence of ear cracks during hot rolling, the number of times the mill must be rolled during cold rolling, etc., which are reduced in the actual manufacturing process. The problem of reduced productivity, etc., so the overall reduction in the cost of raw materials cannot be reduced. Furthermore, it is disclosed in Japanese Unexamined Patent Publication No. Hei 3-23-5. It is good: the heat of the Worthian iron-based stainless steel containing a large amount of Μη. In this example, the excessive addition of Cu is regarded as: The workability, thus limiting the Mn, Cu, etc., is still not enough to improve the effect, and it is still a problem of ear cracking. SUMMARY OF THE INVENTION [Problems to be Solved by the Invention] The present invention is directed to the problems of the prior art. Therefore, the main problem of the present invention is to provide a field iron-based stainless steel which has the same properties as corrosion resistance of SUS304 stainless steel and is inexpensive. [Means for Solving the Problem] The inventors of the present invention have studied the relationship between the manufacturability and the corrosion resistance of the Worthfield iron-based stainless steel, and the Mn, Cu, and N are substituted for Ni, and the workability is satisfactory. 'It is also possible to reduce the range of the ratio of N i , and further increase the cost of passing through the roller, and the yield is good. In the range of the alloy composition for the embrittlement of the grain boundary, the alloy composition of the nickel-type Worth, which has been developed by hot rolling, cannot be eliminated, and it has been found that the present invention has been completed with a good heat. 200907076 (3) That is, the nickel-saving type of Worstian iron-based stainless steel of the present invention contains: in terms of % by weight, 0. 〇 4% SCS 〇 12.%, Si: , 3.00% SMnS 7.50%, PS 0.05 %, SS 0.03% . SNiS 6.00%, 16.00% SCrg 18.00%, Mo$〇. 1.00% SCug 3.00%, 0,05% $ NS 0.20% '
Fe以及不可避免的雜質所組成。 根據上述這樣的降低了 Ni添加率之成分範園 決熱軋時發生耳部龜裂等的問題，降低熱乳龜裂握 而且可成爲具有與SUS304不鏽鋼同等程度的耐肩 沃斯田鐵系不鏽鋼。 [發明之效果] 根據本發明的沃斯田鐵系不鏽鋼，係可提供： S U S 3 0 4不鏽鋼同等程度的製造性以及耐腐蝕性， 在與SUS304不鏽鋼類似的用途之廉價的省鎳型衫 系不鏽鋼。 【實施方式】 [用以實施本發明之最佳形態] 以下，將說明將本發明中的化學組成分加以 由。 (1) 0.04%SCS0.12% : C (碳）係沃斯 成元素，但是過量添加時’受到焊接所產生的熱 特徵爲 1.00% 2.00% 40 %、 部分由 ，可解 受性， 蝕性之 具有與 可使用 斯田鐵 定的理 鐵鋼形 響部、 -6 - 200907076 (4) 熱軋捲取後的熱軋鋼帶捲的熱的作用’ Cr碳化物將會在 粒界晶析出來，因而提高了粒界腐触感受性’進而變成也 很容易引起粒界型的應力腐蝕龜裂。此外，C的添加將會 導致固熔強化’使得冷間加工性降低。因此’將C添加率 . 的上限訂爲0.12重量％。又，如果C添加率變得太小的 話，沃斯田鐵鋼的穩定性降會降低’所以將c添加率的下 限訂爲〇.〇4重量％。 (2) SiS 1.00% ·· Si (砂）雖然是具有··熔解時的脫 氧劑的功能，同時又有強化耐腐蝕性的效果’但S1也是 肥粒鐵生成元素，如果過量添加的話’㈣於想要獲得沃斯 田鐵鋼組織很不利。又’如果S1的添加超過1 · 0 0重量％ 的話，不僅會妨礙熱間加工性，而且會助長σ相的生成’ 所以並不適宜。因此，將Si添加率的上限訂爲丨·00重量 %。 (3) 3·00%$Μη^7·50% : Μη (錳）係沃斯田鐵鋼 形成元素，可以抑制因加工所導致的麻田散鐵（α ’）的 生成，可降低加工硬化，所以對於提昇冷乳性係有利。想 要獲得這種效果’至少需要3·00重量％的添加率’但是 .如果Μη過量添加的話，會降低合金的耐腐蝕性，所以將 Μη添加率的上限訂爲7.50重量％。 (4) PS0.05% : Ρ (磷）的添加將會降低合金的耐 腐蝕性、熱間加工性，所以將其添加率的上限訂爲0.05 重量％。 (5) SSO.03% : S (硫）的添加量超過0.03重量％ 200907076 (5) 的話，將會增加夾雜物，且不僅會降低耐腐蝕性，在進行 熱間加工時又會明顯地提高龜裂感受性，所以將其添加率 的上限訂爲0·03重量％。 (6) 2.00%$NiS6.00% : Ni (鎳）係沃斯田鐵鋼 - 形成元素，想要獲得沃斯田鐵鋼組織的穩定化、良好的熱 . 間加工性以及冷間加工性的話，必須至少添加2.00重量 %。另一方面，N i係高價格的金屬，因此將其添加率的 上限訂爲6.00重量％。 (7) 16.00%gCr$18.00% : Cr (鉻）係用來提高 不鏽鋼的耐腐鈾性最有效的元素之一，想要使其發揮達到 與SUS3 04不鏽鋼同程度的耐腐蝕性’必須添加到達 16_00重量％以上。另一方面，Cr的添加超過18.00重量 %的話，將會導致ό肥粒鐵的生成、降低熱間加工性，所 以並不適宜。因此，C r的添加率的上限訂爲1 8 0 0重量％ 〇 (8 ) Mo S 0.40% : Mo (鋁）係與Cr同樣都是用來 提高不鏽鋼的耐腐蝕性很有效的元素。但是’因爲Mo的 價格昂貴，所以將其上限訂爲〇·4〇重量％。 . (9) 1.00%$CuS3.00% : Cu (銅）係具有沃斯田 鐵鋼形成元素的作用，並且具有軟化材料的效果’因此就 沃斯田鐵系不鏽鋼的冷間加工性而言’具有重要的作用’ 係可取代Ni的元素。想要使其發揮這種效果，必須至少 添加1.00重量％以上。但是，Cu的過量添加將會引起赤 熱脆性而使得熱間加工性惡化。因此’將Cu的添加率的 -8 - 200907076 (6) 上限訂爲3.00重量％，將下限定爲i.oo重量％。 (10) 0_05%SNS0.20% : N (氮）係與 C 同樣都是 沃斯田鐵鋼形成元素，具有穩定沃斯田鐵鋼組織的作用， 而可抑制肥粒鐵的生成，但是，想要使其充分地發揮這種 -效果’必須至少爲0 · 0 5重量％以上的添加率。另一方面 .，N具有很大的固熔強化能力，所以超過0.20重量％的 過量添加將會導致明顯的材料硬化，因此並不適宜。所以 將N的添加率的上限訂爲0.2〇重量％，將下限定爲〇 〇5 重量％。 已知熱間加工性係與鋼胚的5肥粒鐵量相關連。這是 與高溫領域時的沃斯田鐵鋼與肥粒鐵之間的轉換能量差値 所導致的龜裂有關。因此’將以表1所示的成分範圍進行 熔解和鑄造後的鑄錠的5肥粒鐵量，利用FISCHER製的 FERITSCOPE來加以測定，將該鑄錠進行120(TCx60分鐘 的加熱後’針對於以4段輥軋機進行熱軋時的熱龜裂狀況 加以調査。然後，解析該成分與5肥粒鐵量之間的關係， 而獲得了以式1所表示的<5肥粒鐵量（％ )的關係式。根 據式1可以得知：沃斯田鐵鋼形成元素係可降低<5肥粒鐵 量，肥粒鐵形成元素係可使得（5肥粒鐵量增加。又，特別 可加以說明的事情爲：Μη的添加量很少的話，將會變成 沃斯田鐵鋼形成元素，相反地，Μη的添加量很多的話， 將會變成肥粒鐵形成元素。這種事情係可藉由在式1中設 置Μη的項與設置Μη2的項來表示。 200907076 (7) [表l] C Si Μη Ni Cr Mo Cu N 0.018 0.30 2.0 1.2 15.6 0 0.50 0.06 0.160 1.10 1 1.3 5.6 18.9 0.55 3.2 0.23 5肥粒鐵量（％ ) = -3 2.1 - 1 3 5C + 4.7Si-0.043Mn + 0.0 135Mn2-3.3Ni + 4.3Cr + 3 _ 1 Mo-0.66Cu- 1 1 9N …式 1 從鑄錠實際測定的ό肥粒鐵量與式1的6肥粒鐵量之 關係以及熱軋時的熱龜裂發生狀況顯示到第1圖。根據第 1圖可以得知：從式1所算出的<5肥粒鐵量超過9 · 0 0 %的 話，熱龜裂的發生確率將會變高。 而且也確認出：熱間加工性與S含有率之關係將會受 到Ν含有率之影響。第2圖是顯示出熱龜裂發生之有無與 Ν以及S含有量之關係。可以得知· ν S 0 . 1 1 %的時候， 不會發生熱龜裂之S的上限値係隨著Ν的降低而變高。 亦即’得知··不會發生熱龜裂的S的範圍係隨著Ν的含 有量’而處於下列的式2的關係。此外，也得知：Ν的含 有量超過0.11%的話，S的範圍係處於式3的關係。 『/。$0.11的時候，8(??11〇$- 8 3 3.3"/。+ 116_7 …式 2 Ν%>0.11 的時候，S(ppm)S25 …式 3 N的含有量與S的含有量之間，會發生這種關係的機 制的原因，係被認爲是以下所述的理由。亦即，因N含 有量的降低，雖然<5肥粒鐵量會增加，但是同時沃斯田鐵 -10 - 200907076 (8) 鋼中的N固熔量也減少，沃斯田鐵鋼的高溫強度會降低 。另一方面，（5肥粒鐵中，n幾乎不會固熔，所以無論N 含有量是增或減，高溫強度的變化都很小。因此，在熱軋 溫度域中’沃斯田鐵鋼與5肥粒鐵之間的變形能量差値變 - 小’因N含有量的降低，熱龜裂感受性將會變低。 . 另一方面’一般而言，已知S含量的增加將會提高熱 龜裂感受性。這是因爲S會偏析在粒界，導致高溫時的粒 界變得脆弱的緣故。被認爲是：如果是較低的N的話’ 則因較低的N含量所導致的熱龜裂感受性的降低程度剛 好是與因S的增加所導致的熱龜裂感受性的增加程度兩者 互相抵消。因此，被認爲是：N的含量愈低的話，即使含 有較多的S，也不會造成熱龜裂。 此外，被作爲沃斯田鐵系不鏽鋼的耐腐蝕性的指標來 使用之「孔蝕電位」也會受到合金的成分組成之影響。因 此，將對於表2所示的基本成分，分別改變Mn、Ni、Cr 以及Cu的添加量後的材料予以熔解和鑄造之後的鑄錠， 進行冷軋以製作成冷軋鋼板，並且測定了這種冷軋鋼板的 孔蝕電位。然後，將合金的組成成分與所測定到的孔蝕電 位進行回歸分析，因而獲得：以式4來表示的用來取得與 孔蝕電位具有密接的相關關係的孔蝕電位指數（PRE )之 關係式。 -11 - 200907076 (9) [表2]Fe and inevitable impurities. According to the above-described method of reducing the Ni addition rate, the problem of occurrence of ear cracks during hot rolling is reduced, and the hot milk cracker is reduced, and the shoulder-resistant Worth iron-based stainless steel having the same degree as the SUS304 stainless steel can be obtained. . [Effects of the Invention] According to the invention, the Vostian iron-based stainless steel can provide the same degree of manufacturability and corrosion resistance as SUS 3 0 4 stainless steel, and an inexpensive nickel-saving shirt type for use similar to SUS304 stainless steel. stainless steel. [Embodiment] [Best Mode for Carrying Out the Invention] Hereinafter, the chemical composition in the present invention will be described. (1) 0.04%SCS0.12% : C (carbon) is a Voss element, but when it is excessively added, the heat characteristics caused by welding are 1.00% 2.00% 40%, partly due to, resolvability, corrosion It has the effect of heat of the hot-rolled steel coils that can be used with the iron-iron steel part of the steed, and -6 - 200907076 (4) hot rolled steel coils will be crystallized at the grain boundaries. Therefore, the grain boundary corrosion sensitivity is improved, and it becomes a stress-corrosion crack which is also liable to cause grain boundary type. In addition, the addition of C will cause the solid solution strengthening to lower the cold workability. Therefore, the upper limit of the C addition rate is set to 0.12% by weight. Further, if the C addition rate becomes too small, the stability reduction of the Worthite iron steel is lowered. Therefore, the lower limit of the c addition rate is set to 〇.〇4% by weight. (2) SiS 1.00% ·· Si (sand) has the function of deoxidizing agent at the time of melting, and has the effect of enhancing corrosion resistance. 'B1 is also a ferrite-iron-forming element, if it is added in excess' (4) It is very unfavorable to get the Worth Iron and Steel organization. Further, if the addition of S1 exceeds 1.0% by weight, it will not only hinder the inter-heat processability, but also contribute to the formation of the σ phase. Therefore, the upper limit of the Si addition rate is set to 丨·00% by weight. (3) 3·00%$Μη^7·50% : Μη (Manganese) is a forming element of Worthite iron steel, which can suppress the formation of granulated iron (α ') due to processing, and can reduce work hardening. It is beneficial to improve the cold milk system. In order to obtain such an effect, at least an addition ratio of 30,000% by weight is required. However, if Μη is excessively added, the corrosion resistance of the alloy is lowered. Therefore, the upper limit of the Μn addition ratio is set to 7.50% by weight. (4) PS 0.05% : The addition of bismuth (phosphorus) will lower the corrosion resistance and hot workability of the alloy, so the upper limit of the addition ratio is set to 0.05% by weight. (5) SSO.03% : S (sulfur) added more than 0.03 wt% 200907076 (5), will increase inclusions, and will not only reduce corrosion resistance, but also significantly improve the heat processing Since the cracking sensitivity is, the upper limit of the addition rate is set to 0.03% by weight. (6) 2.00%$NiS6.00% : Ni (nickel) is a Vostian iron steel - forming element. To achieve stabilization of Worthite iron and steel, good heat, inter-processability and cold workability, at least Add 2.00% by weight. On the other hand, N i is a high-priced metal, so the upper limit of the addition ratio is set to 6.00% by weight. (7) 16.00%gCr$18.00% : Cr (chromium) is one of the most effective elements for improving the corrosion resistance of stainless steel. It is desirable to achieve the same degree of corrosion resistance as SUS3 04 stainless steel. 16_00% by weight or more. On the other hand, when the addition of Cr exceeds 18.00% by weight, the formation of granulated iron and the reduction of heat interfacial properties are not preferable. Therefore, the upper limit of the addition rate of Cr is set to 18,000% by weight 〇 (8) Mo S 0.40%: Mo (aluminum) is an element which is effective for improving the corrosion resistance of stainless steel as well as Cr. However, because Mo is expensive, the upper limit is set to 〇·4〇% by weight. (9) 1.00%$CuS3.00% : Cu (copper) has the effect of forming elements of Worthite iron and has the effect of softening the material 'so in terms of cold workability of Worthite iron-based stainless steel' An important role' is to replace the element of Ni. In order to exert this effect, it is necessary to add at least 1.00% by weight or more. However, excessive addition of Cu causes red hot brittleness to deteriorate the inter-heat processability. Therefore, the upper limit of -8 - 200907076 (6) of the addition ratio of Cu is set to 3.00% by weight, and the lower limit is defined as i.oo% by weight. (10) 0_05%SNS0.20% : N (nitrogen) is the same as C in the formation of Worthite iron and steel. It has the effect of stabilizing the Worthite iron and steel structure and suppresses the formation of ferrite iron. To fully exert this effect, the addition rate must be at least 0. 5% by weight or more. On the other hand, N has a large solid solution strengthening ability, so an excessive addition of more than 0.20% by weight will result in significant material hardening, and thus is not suitable. Therefore, the upper limit of the addition ratio of N is set to 0.2% by weight, and the lower limit is defined as 〇 5% by weight. It is known that the inter-heat processability is related to the amount of iron in the grain of the steel. This is related to the crack caused by the difference in conversion energy between the Worthfield iron and the ferrite iron in the high temperature field. Therefore, the amount of iron in the ingot of the ingot which was melted and cast in the range shown in Table 1 was measured by FERITSCOPE manufactured by FISCHER, and the ingot was subjected to 120 (after heating for TC x 60 minutes). The hot cracking condition at the time of hot rolling in a four-stage rolling mill was investigated. Then, the relationship between the composition and the amount of iron in the five ferrites was analyzed, and the amount of <5 ferrite iron expressed by the formula 1 was obtained ( According to the formula 1, it can be known that the formation element of the Worthite iron steel can reduce the amount of iron in the <5 ferrite, and the elemental system of the ferrite and iron can make the amount of iron in the fertiliser increase. The explanation is as follows: if the amount of Μη added is small, it will become a forming element of Worthite iron and steel. Conversely, if the amount of Μη added is large, it will become a ferrite-iron forming element. The term of Μη is set in 1 and the term of Μη2 is set. 200907076 (7) [Table l] C Si Μη Ni Cr Mo Cu N 0.018 0.30 2.0 1.2 15.6 0 0.50 0.06 0.160 1.10 1 1.3 5.6 18.9 0.55 3.2 0.23 5 Iron content (%) = -3 2.1 - 1 3 5C + 4.7Si-0 .043Mn + 0.0 135Mn2-3.3Ni + 4.3Cr + 3 _ 1 Mo-0.66Cu- 1 1 9N Formula 1 The relationship between the amount of iron in the ferrite and the amount of iron in the formula 6 and the heat The occurrence of thermal cracking during rolling is shown in Fig. 1. According to Fig. 1, it can be seen that if the amount of <5 fat iron calculated from the formula 1 exceeds 9.0%, the occurrence rate of thermal cracking will be It is also confirmed that the relationship between the hot workability and the S content rate is affected by the bismuth content rate. Fig. 2 shows the relationship between the occurrence of thermal cracking and the strontium content and the S content. When it is known that ν S 0 . 1 1 %, the upper limit of S which does not cause thermal cracking increases with the decrease of enthalpy. That is, it is known that S does not cause thermal cracking. The range is in the following formula 2 in accordance with the content of cerium. Further, it is also known that when the content of cerium exceeds 0.11%, the range of S is in the relationship of Formula 3. When 『/.$0.11, 8(??11〇$- 8 3 3.3"/.+ 116_7 ... Formula 2 Ν%>0.11, S(ppm)S25 ... Formula 3 N content and S content will occur between Mechanism of this relationship The reason is considered to be the reason described below. That is, due to the decrease in the N content, although the amount of iron in the <5 fertilizer will increase, at the same time the Vostian Iron-10 - 200907076 (8) steel The N solid solution is also reduced, and the high temperature strength of Worthfield iron and steel is reduced. On the other hand, (5) in the ferrite iron, n hardly solidifies, so whether the N content is increased or decreased, the change in high temperature strength is small. Therefore, in the hot rolling temperature domain, 'Worthian Iron and Steel and 5 The difference in deformation energy between the ferrite and iron is small - small 'the thermal cracking sensitivity will be lower due to the decrease in the N content. On the other hand, 'in general, it is known that an increase in the S content will increase the hot turtle. Fission sensitivity. This is because S segregates at the grain boundary, causing the grain boundary to become fragile at high temperatures. It is considered to be: if it is a lower N, then the hot turtle caused by the lower N content The degree of reduction in fission sensitivity is exactly offset by the increase in the degree of thermal cracking caused by the increase in S. Therefore, it is considered that the lower the content of N, even if it contains more S, In addition, the "hole corrosion potential" used as an indicator of the corrosion resistance of the Worthite iron-based stainless steel is also affected by the composition of the alloy. Therefore, it will be basically shown in Table 2. Ingredients, changing the amount of Mn, Ni, Cr, and Cu added The material is melted and cast, and then cold-rolled to form a cold-rolled steel sheet, and the pitting potential of the cold-rolled steel sheet is measured. Then, the composition of the alloy and the measured pitting potential are performed. Regression analysis, thus obtaining the relationship of the pitting potential index (PRE) used to obtain the correlation with the pitting potential in Equation 4. -11 - 200907076 (9) [Table 2]
鋼種A 0.08C-0.3Si-10Mn-Ni-14Cr-2Cu-0.13N 鋼種B 0.05C-0.5Si-8Mn-4Ni-15Cr-1.5Cu-0.05N 鋼種C 0.05C-0.5Si-8Mn-4Ni-15Cr-1.5Cu-0.12N 鋼種D 0.06C-0.6Si-3.5Mn-4.5Ni-17Cr-2.5Cu-0.1N 鋼種E 0.05C-0.5Si-4Mn-6.5Ni-17Cr-2Cu-0.05N 孔蝕電位指數（％ ) =Cr+3 . 3 Mo + 3 ON-Mn …式 4 [實施例] 利用高周波熔解爐來製作出38mmx90mmxl50mm的 鑄錠，對於表面進行機械硏削之後，在電氣爐內進行 1 200 °C X6 0分鐘的加熱，再以4段輥軋機進行熱軋直到厚 度變成3mm爲止。然後，對於所製得的熱軋鋼板進行 1 100 °C x6分鐘的退火處理，藉由浸漬在氟硝酸中以除去 鏽皮之後，再以4段輥乳機進行冷軋直到厚度變成0.8mm 爲止。然後，將這個冷軋所製得的冷軋鋼板進行1 1 OOt X 2分鐘的退火處理，藉由浸漬在氟硝酸中以除去鏽皮。 表3係顯示出合金的組成成分、依據式1的5肥粒鐵 量、有無熱龜裂以及依據式4的孔蝕電位指數。開發鋼1 〜15係：5肥粒鐵量爲9.00%以下，熱軋時不會發生龜 裂’而且可獲得與SUS3 04不鏽鋼同等程度的孔蝕電位指 數。此外，比較鋼6則是與SUS 3 04不鏽鋼相當的鋼。 另一方面，比較鋼1的鋼材是因爲含有超過7.50重 量％的Μη，所以與比較鋼6 ( = SUS304 )比較時，孔蝕 電位指數大幅地變小，在耐腐蝕性方面也大幅地不及於 -12- 200907076 (10) SUS3 04不鏽鋼。而且，含有超過3.00重量％的Cu’並 且（5肥粒鐵量也多於9.0%，所以會發生熱龜裂。比較鋼 2的鋼材是因爲含有超過7.50重量％的Μη，所以孔蝕電 位指數變小，並且δ肥粒鐵量多於9.0 %，因此會發生熱 龜裂。比較鋼3以及4比較鋼的鋼材，因爲含有0.4重量 %以上的Μ〇，所以顯示出良好的孔鈾電位指數，但是， 因爲（5肥粒鐵量多於9.0%，所以會發生熱龜裂。比較鋼 5的鋼材，含有超過7_50重量％的]vin，而且含Cr未達 16.00重量％，因此與比較鋼6 ( = SUS304)互相比較時 ，孔蝕電位指數大幅地變小，是與比較鋼1同樣地，在耐 腐蝕性上遠不及SU S3 04不鏽鋼。 又，比較例7則是因爲含C u超過3. 〇 〇重量％，所以 會發生熱龜裂。 -13- 200907076(11) 孔蝕電位 指數(％) 17.2 17.4 17.2 17.8 16.5 16.7 18.3 18.2 17.3 18.8 17.3 17.2 ;17.5 17.9 18_4 13.3 卜 c> 18.0 19.4 \〇 00 19.4 17.2 熱龜裂 堞 裢 摧 塘 璀 摧 摧 璀 璀 摧 璀 璀 摧 璀 摧 璀 5-肥粒鐵 ΓΠ od Ο od so 00 ο 卜 寸· Ο σν ON 00 00 寸 〇\ 16..6 〇\ Q\ 11.7 〇\ 〇6 卜 〇6 CN 0.194 ; 0.109 0.108 1 0.156 ί 0.148 1 0.162 1 0.110 i 1 0.115 1 0.117 0.142 0.096 0.098 0.103 0.174 I 0.160 I \ 0.135 1 0.067 I 0.139 I 1 0.136 1 0.046 I 0.046 I 0.199 3 U 2.08 2.60 2.58 1 2.53 j 2.57 2.57 1 2.01 «ο in 2.51 2.63 2.60 1 2.66 ,2.74 2.57 I :2,65 3.12 2.59 2.60 1.64 0.30 1—^ cn 〇 1 0.10 0.27 I 0.23. 1 I 0.23 I 0.25 1 0.21 1 1 0.31 I 1 0.27 1 0.27 1 1 0.27 I 0.25 1 1 0.27 1 1 0.28 I 0.26 1—— 0.24 . I ! 0.27 I 0.08 I 0.95 I 1.41 ι 0.00 1 0.18 I 0.09 17.38 , 1 17.15 1 1 17.29 1 17.40 1 17.32 I 17.18 17.12 1 17.08 1 1 17.10 1 17.36 17.36 1 17.08 17.28 I___ _ I 17.55 J 17.76 16.67 117.0$ | 16.46 1 16.49 ,15.13 18.43 17.21 2 1 2.20 L—2.54 —1 L^-94 I L2-46 1 3.03 I L—..3.43 I L^78 I 4.75 1 L_4.75 1 4.70 4.64 ! 4.61 4.68 2.61 1 ! 3.60 2.19 ! 2.24 ! 2.20 2.20 4.07 8.08 2.18 on 1 0.0020 1 1 0.0020 1 1 0.0020 | 0.0020 I 0.0020 0.0020 0.0020 0.0020 O' s o o | 0.0006 | 0.0009 0.0003 0.0006 | 0.0024 | 0.0022 ! 0.0020 | 0.0020 | 0.0020 | 0.0020 ,0.0020 0.0020 0.0020 Oh 1 0.032 1 1 0.029 1 | 0.029 I 「0.028 | 「0.026 | 0.029 1 0.030 1 0.030 | 0.030 I 0.030 0.027 1 0.026 1 0.026 「0.027 | 「0.027 | Γ 0.034 | 0.032 Γ 0-032 | 0.031 ,0.028 ! 0.027 0.032 G S 1 6.38 1 [3.89 I 「4.04 1 5.06 I 6.08 | 6.01 1 3·18 [3.20 1 1 4-18 1 | 3.72 I 「3.75 1 [3.76 1 Γ 3-76^ 「5.69 1 493 1 J-31 Ί 9.59 1 5·78Ί 5.82 ,7.88 1.00 「6.30 0.32 , | 0.29 I [0.32 ] | 0.32 I 0.33 丨 0.32 ] [0.48 1 1 0.48 1 Γ〇.43 1 | 0.59 I 1 0.61 ] 0.59 0.61 ] [0.35 I 0.30 | | 0.34 °·31 1 ! 0.33 丨 0.44 0.52 0.32 u 1 0.0700 1 | 0.0940 | | 0.0910 1 | 0.0820 I | 0.0820 1 | 0.0820 I | 0.0580 1 0.0550 I 0.0580 Π | 0.0547 | 1 0.0653 1 ι 0.0629 1 0.0570 j | 0.0808 1 | 0.0808 | | 0.0560 I | 0.0800 | | 0.0580 | | 0.0600 | :0.0490 | 0.0670 | | 0.0730 開發鋼1 |開發鋼2 j開發鋼3 | |開發鋼4 j開發鋼5 |開發鋼6 1 I開發鋼7 i 1開發鋼8 ι j開發鋼9 j 開發鋼10 j開發鋼ιι 1 1開發鋼12 1 1開發鋼13 1 開發鋼14 |開發鋼15 I 比較鋼1 j比較鋼2 | 丨比較鋼3 | 丨比較鋼4 | |比較鋼5 | |比較鋼6 | |比較鋼7 | -14- 200907076 (12) 又，第3圖係顯示出開發鋼3〜6、9以及比較鋼6 ( =SUS 3 04 )進行冷軋時的硬度的變化。根據第3圖可知 :任何一種開發鋼都是與比較鋼6同等級或者加工硬化的 變化程度都很小。 .【圖式簡單説明】 第1圖係顯示出δ肥粒鐵量與熱龜裂的關係之圖表。 第2圖係顯示出相對於Ν量與S量之熱龜裂的發生 狀況之圖表。 第3圖係顯示出開發鋼3〜6、9以及比較鋼6之相對 於冷軋率之硬度變化之圖表。 -15-Steel type A 0.08C-0.3Si-10Mn-Ni-14Cr-2Cu-0.13N Steel type B 0.05C-0.5Si-8Mn-4Ni-15Cr-1.5Cu-0.05N Steel type C 0.05C-0.5Si-8Mn-4Ni-15Cr -1.5Cu-0.12N steel grade D 0.06C-0.6Si-3.5Mn-4.5Ni-17Cr-2.5Cu-0.1N steel grade E 0.05C-0.5Si-4Mn-6.5Ni-17Cr-2Cu-0.05N pitting potential index (%) = Cr + 3. 3 Mo + 3 ON-Mn Formula 4 [Example] A high-frequency melting furnace was used to produce an ingot of 38 mm x 90 mm x 150 mm, and after mechanical boring of the surface, 1 200 ° was performed in an electric furnace. C X6 was heated for 0 minutes and then hot rolled in a 4-stage rolling mill until the thickness became 3 mm. Then, the obtained hot-rolled steel sheet was annealed at 1 100 ° C for 6 minutes, and after being immersed in fluoronitric acid to remove scale, it was cold-rolled by a 4-stage roll mill until the thickness became 0.8 mm. . Then, the cold-rolled steel sheet obtained by this cold rolling was annealed at 1 10000 t for 2 minutes, and immersed in fluoronitric acid to remove scale. Table 3 shows the composition of the alloy, the amount of iron in accordance with Formula 1, the presence or absence of thermal cracking, and the pitting potential index according to Formula 4. In the development of steel 1 to 15 series, the amount of iron in 5 fertilizers is 9.00% or less, and cracking does not occur during hot rolling, and a pitting potential index equivalent to that of SUS3 04 stainless steel can be obtained. In addition, Comparative Steel 6 is a steel equivalent to SUS 3 04 stainless steel. On the other hand, since the steel material of the comparative steel 1 contains more than 7.50% by weight of Μη, when compared with the comparative steel 6 (= SUS304), the pitting potential index is greatly reduced, and the corrosion resistance is also largely inferior to the corrosion resistance. -12- 200907076 (10) SUS3 04 stainless steel. Further, it contains more than 3.00% by weight of Cu' and (5) the amount of ferrite is more than 9.0%, so thermal cracking occurs. The steel of Comparative Steel 2 is because it contains more than 7.50% by weight of Μη, so the pitting potential index It becomes smaller, and the amount of δ ferrite is more than 9.0%, so thermal cracking occurs. Comparing the steels of steels 3 and 4 compared steel, since it contains 0.4% by weight or more, it shows a good pore uranium potential index. However, because (5 ferrite iron content is more than 9.0%, hot cracking will occur. Compared with steel 5, steel containing more than 7-50% by weight] vin, and containing less than 16.00% by weight of Cr, therefore compared with steel When 6 (= SUS304) is compared with each other, the pitting potential index is greatly reduced, and in the same manner as the comparative steel 1, the corrosion resistance is far less than that of the SU S3 04 stainless steel. Further, the comparative example 7 is because the C u is exceeded. 3. 〇〇% by weight, so thermal cracking will occur. -13- 200907076(11) Pitting potential index (%) 17.2 17.4 17.2 17.8 16.5 16.7 18.3 18.2 17.3 18.8 17.3 17.2 ;17.5 17.9 18_4 13.3 卜 c> 18.0 19.4 \〇00 19.4 17.2 Hot cracked smashing pond璀 璀璀 璀璀 璀璀 璀璀 璀 璀 - - - 璀 od od od 00 00 00 00 00 00 00 00 00 00 00 00 σ 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. 16. Q Q Q Q Q Q Q Q Q Q Q 6 CN 0.194 ; 0.109 0.108 1 0.156 ί 0.148 1 0.162 1 0.110 i 1 0.115 1 0.117 0.142 0.096 0.098 0.103 0.174 I 0.160 I \ 0.135 1 0.067 I 0.139 I 1 0.136 1 0.046 I 0.046 I 0.199 3 U 2.08 2.60 2.58 1 2.53 j 2.57 2.57 1 2.01 «ο in 2.51 2.63 2.60 1 2.66 , 2.74 2.57 I :2,65 3.12 2.59 2.60 1.64 0.30 1—^ cn 0.11 0.10 0.27 I 0.23. 1 I 0.23 I 0.25 1 0.21 1 1 0.31 I 1 0.27 1 0.27 1 1 0.27 I 0.25 1 1 0.27 1 1 0.28 I 0.26 1 - 0.24 . I ! 0.27 I 0.08 I 0.95 I 1.41 ι 0.00 1 0.18 I 0.09 17.38 , 1 17.15 1 1 17.29 1 17.40 1 17.32 I 17.18 17.12 1 17.08 1 1 17.10 1 17.36 17.36 1 17.08 17.28 I___ _ I 17.55 J 17.76 16.67 117.0$ | 16.46 1 16.49 , 15.13 18.43 17.21 2 1 2.20 L—2.54 —1 L^-94 I L2-46 1 3.03 IL—..3.43 IL ^78 I 4.75 1 L_4.75 1 4.70 4.64 ! 4.61 4.68 2.61 1 ! 3.60 2.19 ! 2.24 ! 2.20 2.20 4.07 8.08 2.18 on 1 0.0020 1 1 0.0020 1 1 0.0020 | 0.0020 I 0.0020 0.0020 0.0020 0.0020 O' soo | 0.0006 | 0.0009 0.0003 0.0006 | 0.0024 | 0.0022 ! 0.0020 | 0.0020 | 0.0020 | 0.0020 ,0.0020 0.0020 0.0020 Oh 1 0.032 1 1 0.029 1 | 0.029 I ”0.028 | "0.026 | 0.029 1 0.030 1 0.030 | 0.030 I 0.030 0.027 1 0.026 1 0.026 "0.027 | "0.027 | Γ 0.034 | 0.032 Γ 0-032 | 0.031 , 0.028 ! 0.027 0.032 GS 1 6.38 1 [3.89 I "4.04 1 5.06 I 6.08 | 6.01 1 3·18 [3.20 1 1 4-18 1 | 3.72 I "3.75 1 [3.76 1 Γ 3-76^ "5.69 1 493 1 J-31 Ί 9.59 1 5·78Ί 5.82 , 7.88 1.00 "6.30 0.32 , | 0.29 I [0.32 ] | 0.32 I 0.33 丨0.32 ] [0.48 1 1 0.48 1 Γ〇.43 1 | 0.59 I 1 0.61 ] 0.59 0.61 ] [0.35 I 0.30 | | 0.34 °·31 1 ! 0.33 丨0.44 0.52 0.32 u 1 0.0700 1 | 0.0940 | | 0.0910 1 | 0.0820 I | 0.0820 1 | 0.0820 I | 0.0580 1 0.0550 I 0.0580 Π | 0.0547 | 1 0.0653 1 ι 0.0629 1 0.0570 j | 0.0808 1 | 0.0808 | | 0.0560 I | 0.0800 | 0.0580 | | 0.0600 | :0.0490 | 0.0670 | | 0.0730 Development Steel 1 | Development Steel 2 j Development Steel 3 | | Development Steel 4 j Development Steel 5 | Development Steel 6 1 I Development Steel 7 i 1 Development Steel 8 ι j Development Steel 9 j Development Steel 10 j Development Steel ιι 1 1 Development Steel 12 1 1 Development Steel 13 1 Development Steel 14 | Development Steel 15 I Comparison Steel 1 j comparison steel 2 | 丨 comparison steel 3 | 丨 comparison steel 4 | | comparative steel 5 | | comparative steel 6 | | comparative steel 7 | -14- 200907076 (12) Again, the third figure shows the development of steel 3 Changes in hardness during cold rolling of ~6, 9 and Comparative Steel 6 (=SUS 3 04). According to Fig. 3, it can be seen that any of the developed steels is of the same grade as the comparative steel 6 or the degree of work hardening is small. [Simplified Schematic] Figure 1 shows a graph showing the relationship between the amount of δ ferrite and thermal cracking. Fig. 2 is a graph showing the occurrence of thermal cracking with respect to the amount of enthalpy and the amount of S. Fig. 3 is a graph showing changes in hardness of the developed steels 3 to 6, 9 and the comparative steel 6 with respect to the cold rolling ratio. -15-