TW201512425A - Ferritic stainless steel having excellent weld corrosion resistance - Google Patents
Ferritic stainless steel having excellent weld corrosion resistance Download PDFInfo
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Abstract
Description
本發明係關於一種不易產生因在進行熔接時自熔接對象材料滲入至焊珠之碳及氮、或自大氣滲入之氮所導致之耐蝕性之降低的肥粒鐵系不鏽鋼。 The present invention relates to a ferrite-based stainless steel which is less likely to cause a decrease in corrosion resistance due to carbon and nitrogen infiltrated into a bead to a bead during welding, or nitrogen which is infiltrated from the atmosphere.
肥粒鐵系不鏽鋼可以少於沃斯田鐵系不鏽鋼之Ni量而確保耐蝕性。由於Ni係昂貴之元素,故而肥粒鐵系不鏽鋼可較沃斯田鐵系不鏽鋼以更低成本進行製造。又,肥粒鐵系不鏽鋼具有與沃斯田鐵系不鏽鋼相比熱導率較高、熱膨脹率較小、進而不易引起應力腐蝕破裂等優異之特性。因此,肥粒鐵系不鏽鋼可應用於汽車排氣系構件、屋頂或建具等之建材、廚房設備或蓄水箱、蓄熱水箱等用水場所用材料等廣泛之用途。 The ferrite-based iron-based stainless steel can be less than the amount of Ni in the Vostian iron-based stainless steel to ensure corrosion resistance. Since Ni is an expensive element, the ferrite-based iron-based stainless steel can be manufactured at a lower cost than the Worthfield iron-based stainless steel. Further, the ferrite-based iron-based stainless steel has excellent characteristics such as higher thermal conductivity, less thermal expansion coefficient, and less stress corrosion cracking than the Worthfield iron-based stainless steel. Therefore, the ferrite-grained stainless steel can be used for a wide range of applications such as building materials for automobiles, roofing materials, building materials, kitchen equipment, water storage tanks, and water storage tanks.
於製作該等構造物時,將沃斯田鐵系不鏽鋼、尤其是SUS304(18%Cr~8%Ni)(JIS G 4305)等與肥粒鐵系不鏽鋼組合而使用之情形居多。作為此種不鏽鋼之熔接方法,通常使用TIG(Tungsten Inert Gas,鎢極惰性氣體)熔接。於該情形下,亦對熔接部要求與母材部同樣地具有良好之耐蝕性。 In the production of such structures, the use of the Worthfield iron-based stainless steel, in particular, SUS304 (18%Cr-8%Ni) (JIS G 4305) and the like, and the ferrite-grained stainless steel are used in combination. As a welding method of such a stainless steel, TIG (Tungsten Inert Gas) welding is usually used. In this case as well, it is required that the welded portion has good corrosion resistance similarly to the base material portion.
針對此種課題,提出有藉由添加與Cr相比與C及N之親和力較大之Ti或Nb,而將C及N以Ti或Nb之碳氮化物之形式固定,抑制Cr碳氮化物之生成而抑制敏化(sensitization)之產生,從而確 保良好之耐蝕性之方法。例如,於專利文獻1中揭示有藉由複合添加Ti與Nb而提高肥粒鐵系不鏽鋼之耐晶界耐蝕性的鋼。又,於專利文獻2中揭示有藉由添加Nb而提高耐晶界腐蝕性的鋼。 In order to solve such a problem, it is proposed to fix C and N in the form of Ti or Nb carbonitride by adding Ti or Nb having a higher affinity to Cr and C than N, and suppressing Cr carbonitride. Generate and suppress the generation of sensitization, thus A method of maintaining good corrosion resistance. For example, Patent Document 1 discloses a steel in which the grain boundary corrosion resistance of the ferrite-grained stainless steel is improved by the combined addition of Ti and Nb. Further, Patent Document 2 discloses a steel in which intergranular corrosion resistance is improved by adding Nb.
然而,任何發明均必須添加0.3質量%以上之Mo。Mo係提高母材之耐蝕性之元素。然而,由於為較強之肥粒鐵生成元素,故而於添加有0.3質量%之Mo之情形下,促進熔接部中之肥粒鐵相之產生,而助長熔接部之敏化,故而無法獲得充分之熔接部之耐蝕性。又,均必須添加0.1質量%以上之Nb。然而,於將包含大量之Nb之鋼進行熔接之情形下,有固溶Nb於熔接部以粗大Nb析出物之形式生成,而產生熔接破裂等問題之情形。若考慮到製造性或實用性,則藉由僅添加Nb或Ti等碳氮化物生成元素而獲得熔接部之耐蝕性之方法稱不上是最佳方案。 However, any invention must add 0.3% by mass or more of Mo. Mo is an element that improves the corrosion resistance of the base material. However, since it is a strong ferrite iron-forming element, in the case where 0.3% by mass of Mo is added, the generation of the ferrite-grain iron phase in the welded portion is promoted, and the sensitization of the welded portion is promoted, so that sufficient is not obtained. Corrosion resistance of the welded portion. Further, it is necessary to add 0.1% by mass or more of Nb. However, in the case where a steel containing a large amount of Nb is welded, solid solution Nb is formed in the form of coarse Nb precipitates in the welded portion, and problems such as weld cracking occur. In consideration of manufacturability or practicality, the method of obtaining the corrosion resistance of the welded portion by merely adding a carbonitride generating element such as Nb or Ti is not preferable.
專利文獻1:日本專利特開2007-270290號公報 Patent Document 1: Japanese Patent Laid-Open Publication No. 2007-270290
專利文獻2:日本專利特開2010-202916號公報 Patent Document 2: Japanese Patent Laid-Open Publication No. 2010-202916
因此,本發明之目的在於提供一種無需過度添加Ti或Nb之熔接部之耐蝕性優異的肥粒鐵系不鏽鋼。 Accordingly, an object of the present invention is to provide a ferrite-based iron-based stainless steel which is excellent in corrosion resistance of a welded portion which does not require excessive addition of Ti or Nb.
本發明者等人為了解決上述課題,對於可較先前進一步抑制熔接部之耐蝕性降低之技術進行努力研究。首先,發明者等人對 於用以獲得充分之熔接部之耐蝕性所容許之敏化之程度,使用16~20質量%Cr鋼系統地進行調查研究。結果發現,於由Cr碳氮化物所致之肥粒鐵相之晶界被覆率(關於晶界被覆率,參照實施例之測定方法)超過40%之情形下,因敏化導致之熔接部之耐蝕性之降低變得明顯。 In order to solve the above problems, the inventors of the present invention have made an effort to study a technique capable of further suppressing a decrease in corrosion resistance of a welded portion. First, the inventor and others The degree of sensitization allowed by the corrosion resistance of the sufficient welded portion was investigated using a 16-20 mass% Cr steel system. As a result, it has been found that in the case where the grain boundary coverage ratio of the ferrite-grained iron phase by Cr carbonitride (the measurement method of the grain boundary is referred to in the example) is more than 40%, the fusion portion is caused by sensitization. The reduction in corrosion resistance becomes apparent.
繼而,發明者等人對於降低由Cr碳氮化物所致之肥粒鐵相之晶界被覆率之方法進行研究。結果發現,藉由添加作為沃斯田鐵生成元素之Mn及Cu而使沃斯田鐵相穩定化,對於提高熔接部之耐蝕性極為有效。 Then, the inventors and the like have studied a method of lowering the grain boundary coverage of the ferrite-grained iron phase by Cr carbonitride. As a result, it has been found that the addition of Mn and Cu, which are iron-forming elements of Worthite, stabilizes the iron phase of the Vostian, and is extremely effective for improving the corrosion resistance of the welded portion.
即,發現於藉由添加Mn及Cu而使沃斯田鐵相穩定化之情形下,可抑制熔接時之肥粒鐵相之產生,並且藉由使肥粒鐵相之固溶限以上所含之C及N以固溶於固溶限較肥粒鐵相壓倒性大之沃斯田鐵相中之狀態進行穩定化,可防止由生成Cr碳氮化物導致之敏化,進一步提高熔接部之耐蝕性。 In other words, it has been found that when the iron phase of the Worth is stabilized by the addition of Mn and Cu, the generation of the iron phase of the ferrite during welding can be suppressed, and the solid solution limit of the iron phase of the ferrite is contained. The C and N are stabilized in a state in which the solid solution is dissolved in the iron phase of the ferrite iron phase which is overwhelmingly large, and the sensitization caused by the formation of Cr carbonitride is prevented, and the welded portion is further improved. Corrosion resistance.
進而,亦明確可知由於使C及N固溶於沃斯田鐵相中,故而與先前僅藉由Ti或Nb等使C及N之固定化相比,即便為更多之C及N量亦可防止敏化。發明者等人對於可獲得上述效果之鋼成分系統地進行調查研究,發現上述效果可於使沃斯田鐵相穩定化之C、N、Ni、Mn及Cu之含量滿足下式(1)之情形時獲得。 Further, it is also clear that since C and N are dissolved in the iron phase of the Vostian, the amount of C and N is more than that of the prior fixation of C and N by only Ti or Nb. It can prevent sensitization. The inventors have systematically investigated the steel components that can obtain the above effects, and found that the above effects can satisfy the following formula (1) in the content of C, N, Ni, Mn, and Cu in which the iron phase of the Vostian is stabilized. Obtained when the situation arises.
0.50<25×C+18×N+Ni+0.11×Mn+0.46×Cu (1) 0.50<25×C+18×N+Ni+0.11×Mn+0.46×Cu (1)
再者,式中之元素符號意指各元素之含量(質量%)。 Further, the element symbol in the formula means the content (% by mass) of each element.
進而,本效果可與作為先前技術之藉由添加Ti或Nb使C及N之固定化併用,故而即便無需過度添加Ti或Nb,亦可獲得與先前之鋼相比更優異之熔接部之耐蝕性。 Further, the present effect can be combined with the immobilization of C and N by adding Ti or Nb as a prior art, so that even if it is not necessary to excessively add Ti or Nb, corrosion resistance of the welded portion which is superior to the prior steel can be obtained. Sex.
本發明係基於上述知識見解而完成者,其主旨係如下所 述。 The present invention has been completed based on the above knowledge findings, and its subject matter is as follows Said.
[1]一種熔接部之耐蝕性優異之肥粒鐵系不鏽鋼,其特徵在於:以質量%計含有C:0.001~0.025%、Si:0.05~0.30%、Mn:0.35~2.0%、P:0.05%以下、S:0.01%以下、Al:0.05~0.80%、N:0.001~0.025%、Cr:16.0~20.0%、Ti:0.12~0.50%、Nb:0.002~0.050%、Cu:0.30~0.80%、Ni:0.05%以上且未滿0.50%、V:0.01~0.50%,並且滿足下述式(1),且滿足剩餘部分包含Fe及不可避免之雜質; 0.50<25×C+18×N+Ni+0.11×Mn+0.46×Cu (1) [1] A ferrite-based iron-based stainless steel excellent in corrosion resistance of a welded portion, comprising: C: 0.001 to 0.025% by mass, Si: 0.05 to 0.30%, Mn: 0.35 to 2.0%, P: 0.05 % or less, S: 0.01% or less, Al: 0.05 to 0.80%, N: 0.001 to 0.025%, Cr: 16.0 to 20.0%, Ti: 0.12 to 0.50%, Nb: 0.002 to 0.050%, Cu: 0.30 to 0.80% Ni: 0.05% or more and less than 0.50%, V: 0.01 to 0.50%, and satisfying the following formula (1), and satisfying the remainder containing Fe and unavoidable impurities; 0.50<25×C+18×N+Ni+0.11×Mn+0.46×Cu (1)
再者,式中之元素符號係指各元素之含量(質量%)。 In addition, the element symbol in the formula means the content (% by mass) of each element.
[2]如[1]記載之熔接部之耐蝕性優異之肥粒鐵系不鏽鋼,其特徵在於:進而以質量%計含有選自Zr:0.01~0.50%、W:0.01~0.20%、REM:0.001~0.10%、Co:0.01~0.20%、B:0.0002~0.010%、Sb:0.05~0.30%中之1種以上。 [2] The ferrite-based iron-based stainless steel having excellent corrosion resistance of the welded portion according to [1], which is further characterized by further comprising, in mass%, selected from the group consisting of Zr: 0.01 to 0.50%, W: 0.01 to 0.20%, and REM: 0.001 to 0.10%, Co: 0.01 to 0.20%, B: 0.0002 to 0.010%, and Sb: 0.05 to 0.30%.
根據本發明,可獲得即便於如C及N自熔接對象材料滲入至母材之熔接條件下亦具有優異之耐蝕性的肥粒鐵系不鏽鋼。 According to the present invention, it is possible to obtain a ferrite-based iron-based stainless steel which has excellent corrosion resistance even under the welding condition in which the material of the welding target material penetrates into the base material, such as C and N.
以下,對於本發明之各構成要件之限定原因進行說明。 Hereinafter, the reasons for limiting the respective constituent elements of the present invention will be described.
首先,說明規定本發明之鋼之成分組成之原因。再者,成分%均指質量%。 First, the reason for specifying the composition of the steel of the present invention will be explained. Furthermore, the component% refers to the mass%.
C係不可避免含有之元素。C量越高強度越高,C量越少加工性越高。為了獲得充分之強度而必須含有0.001%以上。然而,若含有超過0.025%,則加工性之降低變得明顯,並且容易產生因由Cr碳化物之析出導致之局部性缺Cr所引起之耐蝕性之降低(敏化)。因此,C量係設為0.001~0.025%之範圍。但是,雖然就耐蝕性及加工性之觀點而言,C量越低越好,但極度降低C量於精煉時花費時間,於製造上欠佳。因此,較佳為0.003~0.018%之範圍。更佳為0.005~0.012%之範圍。 Elements that are inevitably contained in the C system. The higher the amount of C, the higher the strength, and the less the amount of C, the higher the processability. In order to obtain sufficient strength, it is necessary to contain 0.001% or more. However, when the content is more than 0.025%, the decrease in workability is conspicuous, and the decrease in corrosion resistance (sensitization) due to localized Cr deficiency due to precipitation of Cr carbide is likely to occur. Therefore, the amount of C is set to be in the range of 0.001 to 0.025%. However, in terms of corrosion resistance and workability, the C amount is preferably as low as possible, but the amount of C is extremely lowered, which takes time in refining, and is not preferable in terms of production. Therefore, it is preferably in the range of 0.003 to 0.018%. More preferably, it is in the range of 0.005 to 0.012%.
Si係對熔接部之耐蝕性之提高較為有效之元素。為了獲得該效果而必須含有0.05%以上,含量越多其效果越大。然而,若Si含量超過0.30%,則熔接部之成形性或韌性降低,故而欠佳。因此,Si量係設為0.05~0.30%之範圍。較佳為0.05~0.25%之範圍。進而較佳為0.08~0.20%之範圍。 The Si system is an effective element for improving the corrosion resistance of the welded portion. In order to obtain this effect, it is necessary to contain 0.05% or more, and the more the content, the greater the effect. However, when the Si content exceeds 0.30%, the formability and toughness of the welded portion are lowered, which is not preferable. Therefore, the amount of Si is set to be in the range of 0.05 to 0.30%. It is preferably in the range of 0.05 to 0.25%. Further, it is preferably in the range of 0.08 to 0.20%.
Mn於本發明中為尤其重要之元素。Mn係有效作為脫氧劑之元素,並且具有使沃斯田鐵相穩定化之效果。藉由含有既定量之Mn,可抑制熔接時之肥粒鐵相之產生,藉由使肥粒鐵相之固溶限以上所含之C及N,以固溶於固溶限較肥粒鐵相大之沃斯田鐵相中之狀態進行穩定化,而表現出防止由生成Cr碳氮化物導致之敏化之效果,提高熔接部之耐蝕性。為了獲得該等效果,必須含有0.35%以上之Mn。然而,若 Mn含量超過2.0%,則母材過度硬質化而延展性降低,並且於熔接部產生由熔接部之硬質化導致之韌性之降低,故而欠佳。因此,Mn量係設為0.35~2.0%之範圍。較佳為0.50~1.5%之範圍。進而較佳為0.75~1.25%之範圍。 Mn is an especially important element in the present invention. Mn is effective as an element of a deoxidizer and has an effect of stabilizing the iron phase of Vostian. By containing a certain amount of Mn, it is possible to suppress the generation of the iron phase of the ferrite during welding, and to dissolve the solid solution in the solid solution limit by the C and N contained in the solid solution limit of the iron phase of the ferrite. The state in the iron phase of the Volkswagen phase is stabilized, and the effect of preventing sensitization caused by the formation of Cr carbonitride is exhibited, and the corrosion resistance of the welded portion is improved. In order to obtain such effects, it is necessary to contain 0.35% or more of Mn. However, if When the Mn content is more than 2.0%, the base material is excessively hardened and the ductility is lowered, and the toughness due to the hardening of the welded portion is lowered in the welded portion, which is not preferable. Therefore, the amount of Mn is set to be in the range of 0.35 to 2.0%. It is preferably in the range of 0.50 to 1.5%. Further preferably, it is in the range of 0.75 to 1.25%.
P係不可避免含有於鋼中之元素,過量含有會降低熔接性,容易產生晶界腐蝕。該傾向於含有超過0.05%時變得明顯。因此,P量係設為0.05%以下。較佳為0.03%以下。 P is inevitably contained in steel, and excessive inclusion reduces weldability and is likely to cause grain boundary corrosion. This tends to become apparent when it contains more than 0.05%. Therefore, the P amount is set to 0.05% or less. It is preferably 0.03% or less.
S亦係與P同樣地不可避免含有於鋼中之元素,因含有超過0.01%而耐蝕性降低。因此,S量係設為0.01%以下。較佳為0.008%以下。 S is also an element which is inevitably contained in steel in the same manner as P, and the corrosion resistance is lowered because it contains more than 0.01%. Therefore, the S amount is set to 0.01% or less. It is preferably 0.008% or less.
Al亦係與Si同樣地提高熔接部之耐蝕性之元素。Al係與N之親和力較Cr更強,故而於N混入至熔接部之情形下,具有使N以Al氮化物之形式而非Cr氮化物之形式析出,而抑制敏化之效果。又,Al亦係有用於製鋼步驟中之脫氧之元素。該等效果可以含有0.05%以上而獲得。然而,若含有Al超過0.80%,則肥粒鐵晶粒粗大化,加工性或製造性降低。因此,Al量係設為0.05~0.80%之範圍。較佳為0.10~0.60%之範圍。進而較佳為0.15~0.50%之範圍。 Al is also an element which improves the corrosion resistance of the welded portion in the same manner as Si. Since the affinity between Al and N is stronger than that of Cr, when N is mixed into the welded portion, N is precipitated in the form of Al nitride instead of Cr nitride, and the effect of sensitization is suppressed. Further, Al is also an element for deoxidation in the steel making step. These effects can be obtained by containing 0.05% or more. However, when Al is contained in an amount of more than 0.80%, the ferrite grains are coarsened, and workability or manufacturability is lowered. Therefore, the amount of Al is set to be in the range of 0.05 to 0.80%. It is preferably in the range of 0.10 to 0.60%. Further preferably, it is in the range of 0.15 to 0.50%.
N係與C同樣地不可避免含有於鋼中之元素。若N含量較高,則強度提高,N含量越少加工性越高。為了獲得充分之強度,含有0.001%以上較為適當。然而,若含量超過0.025%,則延展性明顯降低,並且產生由助長Cr氮化物之析出所導致之耐蝕性之降低,故而欠佳。因此,N量係設為0.001~0.025%之範圍。就耐蝕性之觀點而言,N越低越好。然而,為了降低N量而必須增加精煉時間,而導致製造性降低。因此,較佳為設為0.003~0.025%之範圍。更佳為0.003~0.015%之範圍。進而較佳為0.003~0.010%之範圍。 The N system is inevitably contained in steel in the same manner as C. If the N content is high, the strength is increased, and the smaller the N content, the higher the workability. In order to obtain sufficient strength, it is appropriate to contain 0.001% or more. However, if the content exceeds 0.025%, the ductility is remarkably lowered, and the corrosion resistance due to the precipitation of the promoted Cr nitride is lowered, which is not preferable. Therefore, the amount of N is set to be in the range of 0.001 to 0.025%. From the viewpoint of corrosion resistance, the lower the N, the better. However, in order to reduce the amount of N, it is necessary to increase the refining time, resulting in a decrease in manufacturability. Therefore, it is preferably in the range of 0.003 to 0.025%. More preferably, it is in the range of 0.003 to 0.015%. Further, it is preferably in the range of 0.003 to 0.010%.
Cr係為確保不鏽鋼之耐蝕性最重要之元素。若Cr含量未滿16.0%,則因熔接所導致之氧化,無法在表層之Cr減少之焊珠或其周邊獲得充分之耐蝕性。又,進一步助長因在熔接時自熔接對象材料或大氣混入之N導致之敏化,故而欠佳。另一方面,若Cr含量超過20.0%,則韌性降低或退火後之除鏽性降低,故而欠佳。因此,Cr量係設為16.0%~20.0%之範圍。較佳為16.5%~19.0%之範圍。進而較佳為17.0~18.5%之範圍。 Cr is the most important element to ensure the corrosion resistance of stainless steel. If the Cr content is less than 16.0%, oxidation due to welding may not be sufficient to obtain sufficient corrosion resistance in the bead of the surface layer where Cr is reduced or the periphery thereof. Further, it is further advantageous because it is sensitized by the N of the material to be welded or the N mixed in at the time of welding. On the other hand, when the Cr content exceeds 20.0%, the toughness is lowered or the rust-removing property after annealing is lowered, which is not preferable. Therefore, the amount of Cr is set to be in the range of 16.0% to 20.0%. It is preferably in the range of 16.5% to 19.0%. Further preferably, it is in the range of 17.0 to 18.5%.
Ti係與C及N優先地結合而抑制因由Cr碳氮化物之析出導致之敏化所引起之耐蝕性降低的元素。該效果可藉由含有0.12%以上而獲得。然而,若含量超過0.50%,則生成粗大之Ti碳氮化物,引起表面缺陷,故而欠佳。因此,Ti量係設為0.12~0.50%之範圍。較佳為0.15~0.40%之範圍。進而較佳為0.20~0.35%之範圍。 The Ti system preferentially combines with C and N to suppress an element having a reduced corrosion resistance due to sensitization caused by precipitation of Cr carbonitride. This effect can be obtained by containing 0.12% or more. However, if the content exceeds 0.50%, coarse Ti carbonitride is formed, which causes surface defects and is therefore unsatisfactory. Therefore, the amount of Ti is set to be in the range of 0.12 to 0.50%. It is preferably in the range of 0.15 to 0.40%. Further preferably, it is in the range of 0.20 to 0.35%.
Nb係與C及N優先地結合而抑制因由Cr碳氮化物之析出導致之敏化所引起之耐蝕性降低的元素。又,Nb亦具有使熔接部之結晶粒徑微細化,而提高熔接部之韌性及彎曲性之效果。該等效果可以含有0.002%以上而獲得。另一方面,Nb亦係使再結晶溫度上升之元素,若含有超過0.050%,則使再結晶所需之退火溫度高溫化,故而於使用高速冷軋板退火線之退火步驟中退火變得不充分,產生因混合存在未再結晶晶粒與再結晶晶粒所導致之加工性之降低,故而欠佳。因此,Nb量係設為0.002~0.050%之範圍。較佳為0.010~0.045%之範圍。進而較佳為0.015~0.040%之範圍。 The Nb system preferentially combines with C and N to suppress an element having a reduced corrosion resistance due to sensitization caused by precipitation of Cr carbonitride. Further, Nb also has an effect of improving the toughness and flexibility of the welded portion by making the crystal grain size of the welded portion fine. These effects can be obtained by containing 0.002% or more. On the other hand, Nb is also an element which raises the recrystallization temperature, and if it contains more than 0.050%, the annealing temperature required for recrystallization is increased, so annealing does not occur in the annealing step using the high-speed cold-rolled sheet annealing line. Sufficient, it is less preferable because the workability due to the presence of unrecrystallized grains and recrystallized grains is reduced. Therefore, the amount of Nb is set to be in the range of 0.002 to 0.050%. It is preferably in the range of 0.010 to 0.045%. Further preferably, it is in the range of 0.015 to 0.040%.
Cu係提高耐蝕性之元素,且係對提高水溶液中或附有弱酸性水滴時之母材及熔接部之耐蝕性尤其有效之元素。又,Cu係與Ni同樣地為較強之沃斯田鐵生成元素,具有抑制熔接部中之肥粒鐵相之產生,抑制由Cr碳氮化物之析出導致之敏化之效果。該等效果可以含有0.30%以上而獲得。另一方面,若含有Cu超過0.80%,則熱加工性降低,故而欠佳。因此,Cu量係設為0.30~0.80%之範圍。較佳為0.30~0.60%之範圍。進而較佳為0.35~0.50%之範圍。 Cu is an element which improves the corrosion resistance, and is an element which is particularly effective for improving the corrosion resistance of the base material and the welded portion in the aqueous solution or when the weak acid water droplets are attached. In addition, the Cu system is a strong Worstian iron-forming element similarly to Ni, and has an effect of suppressing generation of a ferrite-grain iron phase in the welded portion and suppressing sensitization caused by precipitation of Cr carbonitride. These effects can be obtained by containing 0.30% or more. On the other hand, when Cu is contained in an amount of more than 0.80%, hot workability is lowered, which is not preferable. Therefore, the amount of Cu is set to be in the range of 0.30 to 0.80%. It is preferably in the range of 0.30 to 0.60%. Further preferably, it is in the range of 0.35 to 0.50%.
Ni係提高不鏽鋼之耐蝕性之元素,且係於無法形成鈍態皮膜而產生活性溶解之腐蝕環境中抑制腐蝕進行之元素。又,Ni係較強之沃斯 田鐵生成元素,具有抑制於熔接部生成肥粒鐵,抑制由Cr碳氮化物之析出導致之敏化之效果。該等效果可藉由含有0.05%以上而獲得。然而,若含有0.50%以上之Ni,則加工性降低,此外應力腐蝕破裂敏感性增強。進而,Ni係昂貴之元素,故而導致製造成本之增大,因而欠佳。因此,Ni量係設為0.05%以下且未滿0.50%之範圍。較佳為0.10~0.30%之範圍。進而較佳為0.15~0.25%之範圍。 Ni is an element which improves the corrosion resistance of stainless steel and is an element which suppresses corrosion in a corrosive environment in which active film is not formed by forming a passive film. Also, Ni is stronger than Voss The iron-forming element has an effect of suppressing the formation of ferrite iron in the welded portion and suppressing sensitization caused by precipitation of Cr carbonitride. These effects can be obtained by containing 0.05% or more. However, when Ni is contained in an amount of 0.50% or more, the workability is lowered, and the stress corrosion cracking sensitivity is enhanced. Further, since Ni is an expensive element, the manufacturing cost is increased, which is not preferable. Therefore, the amount of Ni is set to be 0.05% or less and less than 0.50%. It is preferably in the range of 0.10 to 0.30%. Further preferably, it is in the range of 0.15 to 0.25%.
V係提高耐蝕性或加工性之元素,具有於熔接部混入N之情形下藉由與N結合而抑制Cr氮化物之生成,降低熔接部之敏化之效果。該效果可藉由含有0.01%以上而獲得。然而,若含量超過0.50%,則加工性降低,故而欠佳。因此,V量係設為0.01~0.50%之範圍。較佳為0.05~0.30%之範圍。進而較佳為0.08~0.20%之範圍。 The V-based element which improves corrosion resistance and workability has the effect of suppressing the formation of Cr nitride by bonding with N when N is mixed in the welded portion, and the effect of sensitization of the welded portion is reduced. This effect can be obtained by containing 0.01% or more. However, if the content exceeds 0.50%, the workability is lowered, which is not preferable. Therefore, the V amount is set to be in the range of 0.01 to 0.50%. It is preferably in the range of 0.05 to 0.30%. Further, it is preferably in the range of 0.08 to 0.20%.
再者,式中之元素符號意指各元素之含量(質量%)。 Further, the element symbol in the formula means the content (% by mass) of each element.
為了使熔接部之C及N固溶於沃斯田鐵相中而固定化,必須於熔接後之冷卻組織中產生沃斯田鐵相。為了於熔接後之冷卻過程中產生沃斯田鐵相,必須滿足上述式(1)。於式(1)之右邊為0.50以下之情形下,沃斯田鐵相之穩定化變得不充分,無法於熔接部產生僅使本發明提供之固溶C及固溶N有效地固定化之沃斯田鐵相。因此,式(1)之右邊係設為超過0.5。較佳為0.60以上。更佳為0.70以上。 In order to fix the C and N of the welded portion in the Worthfield iron phase, it is necessary to produce the Worthfield iron phase in the cooled structure after welding. In order to generate the Worthfield iron phase during the cooling process after welding, the above formula (1) must be satisfied. When the right side of the formula (1) is 0.50 or less, the stabilization of the iron phase of the Vostian is insufficient, and it is impossible to effectively immobilize the solid solution C and the solid solution N provided by the present invention in the welded portion. Worthfield iron phase. Therefore, the right side of the formula (1) is set to exceed 0.5. It is preferably 0.60 or more. More preferably, it is 0.70 or more.
以上為本發明之基本化學成分,剩餘部分包含Fe及不可避免之雜質。再者,作為不可避免之雜質,可容許Ca:0.0020%以 下。 The above is the basic chemical composition of the present invention, and the remainder contains Fe and unavoidable impurities. Furthermore, as an unavoidable impurity, Ca: 0.0020% can be tolerated under.
進而,除上述基本成分以外,亦可以抑制焊珠之敏化及提高耐蝕性等之目的而含有以下之元素。 Further, in addition to the above-described basic components, the following elements may be contained for the purpose of suppressing sensitization of the bead and improving corrosion resistance and the like.
Zr具有與C及N結合而抑制敏化之效果。該效果可藉由含有0.01%以上而獲得。然而,若含有超過0.50%,則加工性降低。又,Zr為昂貴之元素,故而過度之添加會導致製造成本之增加,故而欠佳。因此,於含有Zr之情形下,較佳為設為0.01~0.50%之範圍。更佳為0.10~0.35%之範圍。 Zr has an effect of inhibiting sensitization by combining with C and N. This effect can be obtained by containing 0.01% or more. However, if it contains more than 0.50%, workability will fall. Further, since Zr is an expensive element, excessive addition causes an increase in manufacturing cost and is therefore unsatisfactory. Therefore, in the case of containing Zr, it is preferably in the range of 0.01 to 0.50%. More preferably, it is in the range of 0.10 to 0.35%.
W係與Mo同樣地具有提高耐蝕性之效果。該效果可藉由含有0.01%以上而獲得。然而,若含有超過0.20%,則強度上升,導致由軋壓負重之增大等所導致之製造性之降低,故而欠佳。因此,於含有W之情形下,較佳為設為0.01~0.20%之範圍。更佳為0.05~0.15%之範圍。 The W system has an effect of improving corrosion resistance similarly to Mo. This effect can be obtained by containing 0.01% or more. However, when the content is more than 0.20%, the strength is increased, and the manufacturability due to an increase in rolling load or the like is lowered, which is not preferable. Therefore, in the case where W is contained, it is preferably in the range of 0.01 to 0.20%. More preferably, it is in the range of 0.05 to 0.15%.
REM具有提高耐氧化性之效果,對抑制氧化皮之形成而抑制熔接回火色正下方之缺Cr區域之形成較為有效。為了獲得該效果,必須含有0.001%以上。然而,若含有超過0.10%,則會降低酸洗性等製造性。又,REM係與Zr同樣為昂貴之元素,故而過度之含有會導致製造成本之增加,因而欠佳。因此,於含有REM之情形下,較佳為設為0.001 ~0.10%之範圍。更佳為0.010~0.08%之範圍。 REM has an effect of improving oxidation resistance, and is effective for suppressing the formation of scale and suppressing the formation of a Cr-deficient region directly under the fusion tempering color. In order to obtain this effect, it is necessary to contain 0.001% or more. However, when it contains more than 0.10%, the manufacturability, such as pick-up property, will fall. Further, since REM is an expensive element as Zr, excessive addition causes an increase in manufacturing cost, which is not preferable. Therefore, in the case of containing REM, it is preferably set to 0.001. ~0.10% range. More preferably, it is in the range of 0.010 to 0.08%.
Co係提高韌性之元素。該效果可藉由含有0.01%以上而獲得。另一方面,若含有超過0.20%,則會降低製造性。因此,於含有Co之情形下,較佳為設為0.01~0.20%之範圍。更佳為0.05~0.15%之範圍。 Co is an element that enhances toughness. This effect can be obtained by containing 0.01% or more. On the other hand, if it contains more than 0.20%, the manufacturability will fall. Therefore, in the case of containing Co, it is preferably in the range of 0.01 to 0.20%. More preferably, it is in the range of 0.05 to 0.15%.
B係改善二次加工脆性之元素,其效果可藉由含有0.0002%以上而獲得。然而,若含有超過0.010%,則會誘發因過度之固溶強化所導致之延展性之降低。因此,於含有B之情形下,較佳為設為0.0002~0.010%之範圍。更佳為0.0010~0.0075%之範圍。 B is an element which improves the brittleness of secondary processing, and the effect can be obtained by containing 0.0002% or more. However, if it is more than 0.010%, the decrease in ductility due to excessive solid solution strengthening is induced. Therefore, in the case where B is contained, it is preferably in the range of 0.0002 to 0.010%. More preferably, it is in the range of 0.0010 to 0.0075%.
Sb係與Al相同,於TIG熔接之氣體遮蔽不充分之情形下,具有捕捉自大氣混入之N之效果,且於應用於具有難以進行充分之氣體遮蔽之複雜形狀之構造體之情形下,為尤其有效之元素。該效果可藉由含有0.05%以上而獲得。然而,若含有超過0.30%,則於製鋼步驟中生成非金屬中介物,使表面性狀變差。又,熱軋板之韌性變差。因此,於含有Sb之情形時,較佳為設為0.05~0.30%之範圍。更佳為0.05~0.15%之範圍。 Sb is the same as Al, and when the gas shielding of TIG welding is insufficient, it has the effect of capturing N mixed in the atmosphere, and is applied to a structure having a complicated shape in which sufficient gas shielding is difficult. Especially effective element. This effect can be obtained by containing 0.05% or more. However, if it contains more than 0.30%, a non-metal intermediaries are formed in the steel making process, and the surface property is deteriorated. Moreover, the toughness of the hot rolled sheet deteriorates. Therefore, in the case of containing Sb, it is preferably in the range of 0.05 to 0.30%. More preferably, it is in the range of 0.05 to 0.15%.
繼而,對於本發明鋼之較佳製造方法進行說明。將上述成分組成 之鋼液利用轉爐、電爐、真空熔解爐等公知之方法進行熔製,利用連續鑄造法或鑄錠-開坯法而製成鋼素材(鋼坯)。將該鋼坯於1100~1250℃下加熱1~24小時後進行熱軋,或不進行加熱而於鑄造之狀態下直接進行熱軋,製成熱軋板。 Next, a preferred method of producing the steel of the present invention will be described. Composition of the above ingredients The molten steel is melted by a known method such as a converter, an electric furnace, or a vacuum melting furnace, and a steel material (steel billet) is produced by a continuous casting method or an ingot-opening method. The slab is heated at 1100 to 1250 ° C for 1 to 24 hours, then hot rolled, or directly hot rolled in a state of being cast without heating, to obtain a hot rolled sheet.
通常,熱軋板係於800~1100℃下實施1~10分鐘之熱軋板退火。再者,亦可根據用途而省略熱軋板退火。繼而,熱軋板酸洗後,藉由冷軋而製成冷軋板後,實施再結晶退火、酸洗而製成製品。 Usually, the hot rolled sheet is annealed at 800 to 1100 ° C for 1 to 10 minutes. Further, the hot rolled sheet annealing may be omitted depending on the application. Then, after the hot-rolled sheet is pickled, the cold-rolled sheet is formed by cold rolling, and then recrystallization annealing and pickling are carried out to obtain a product.
就延伸性、彎曲性、加壓成形性及形狀之觀點而言,冷軋較理想為以50%以上之軋縮率進行。冷軋板之再結晶退火較佳為通常於JIS G 0203之表面整飾、No.2B完成品之情形下獲得良好之機械性質,及自酸洗性之方面而言於800~950℃下進行。又,對要求更有光澤之部位之構件有效的是最後進行BA退火(輝面退火)。再者,為了於冷軋後及加工後進而提高表面性狀,亦可實施研磨等。 From the viewpoints of elongation, flexibility, press formability, and shape, cold rolling is preferably carried out at a rolling reduction ratio of 50% or more. The recrystallization annealing of the cold-rolled sheet is preferably carried out in the case of the surface finishing of JIS G 0203, the finished product of No. 2B, and the mechanical properties at 800 to 950 ° C in terms of pickling. . Further, it is effective for the member requiring a more lustrous portion to perform BAR annealing (gloss annealing). Further, in order to further improve the surface properties after cold rolling and after the processing, polishing or the like may be performed.
以下,基於實施例更詳細地說明本發明。 Hereinafter, the present invention will be described in more detail based on examples.
將具有表1所示之化學組成之不鏽鋼於50kg小型真空熔解爐中進行熔製。將該等鋼塊於1150℃下加熱1小時後,實施熱軋而製成3.5mm厚之熱軋板。繼而,對該等熱軋板以950℃實施1分鐘之熱軋板退火後,對表面進行珠粒噴擊處理,其後於溫度80℃、20質量%硫酸溶液中浸漬120秒後,於包含15質量%硝酸及3質量%氫氟酸之溫度55℃之混合酸中浸漬60秒,藉此進行酸洗,進行除鏽。 The stainless steel having the chemical composition shown in Table 1 was melted in a 50 kg small vacuum melting furnace. The steel blocks were heated at 1,150 ° C for 1 hour, and then hot rolled to obtain a hot rolled sheet having a thickness of 3.5 mm. Then, the hot-rolled sheet was annealed at 950 ° C for 1 minute, and then subjected to bead blasting treatment on the surface, followed by immersion in a 20% by mass sulfuric acid solution at a temperature of 80 ° C for 120 seconds. The mixture was immersed in a mixed acid of 15% by mass of nitric acid and 3% by mass of hydrofluoric acid at a temperature of 55 ° C for 60 seconds to carry out pickling and derusting.
進而,進行冷軋直至板厚成為0.8mm,於弱還原性環境氣體(氫氣:5vol%、氮氣:95vol%、露點:-40℃)下以900℃進行1分鐘之再結晶退火,獲得冷軋退火板。將該冷軋退火板於溫度50℃、 包含15質量%硝酸及0.5質量%鹽酸之混合酸液中進行電解酸洗,藉此進行除鏽處理,獲得冷軋酸洗退火板。 Further, cold rolling was performed until the thickness of the sheet was 0.8 mm, and recrystallization annealing was performed at 900 ° C for 1 minute in a weakly reducing atmosphere (hydrogen: 5 vol%, nitrogen: 95 vol%, dew point: -40 ° C) to obtain cold rolling. Annealed plate. The cold rolled annealed sheet is at a temperature of 50 ° C, The mixed acid solution containing 15% by mass of nitric acid and 0.5% by mass of hydrochloric acid is subjected to electrolytic pickling to thereby perform a rust removing treatment to obtain a cold-rolled pickling annealed sheet.
再者,表1-1、表1-2係連續之一連串之表。 Furthermore, Table 1-1 and Table 1-2 are a series of consecutive tables.
使用所製作之冷軋板及市售之沃斯田鐵系不鏽鋼SUS304(C:0.07質量%、N:0.05質量%、Cr:18.2質量%、Ni:8.2質量%)之板厚0.8mm之冷軋板,進行對接TIG熔接(butt TIG welding)(本發明之冷軋板:母材,熔接對象材料:SUS304)。將熔接電流設為90A,熔接速度設為60cm/min,遮蔽氣體係以15L/min使用含有8vol%之氮氣、2vol%之氧氣之氬氣。所獲得之正面側之焊珠寬度約為3mm。 The cold-rolled sheet produced and the commercially available Vostian iron-based stainless steel SUS304 (C: 0.07 mass%, N: 0.05 mass%, Cr: 18.2 mass%, and Ni: 8.2 mass%) were cooled to a thickness of 0.8 mm. The rolled sheet was subjected to butt TIG welding (the cold rolled sheet of the present invention: base material, welding target material: SUS304). The welding current was set to 90 A, the welding speed was set to 60 cm/min, and the shielding gas system used argon gas containing 8 vol% of nitrogen and 2 vol% of oxygen at 15 L/min. The obtained bead width on the front side was about 3 mm.
採取所製作之包含焊珠之試驗片而進行以下之試驗。 The following test was carried out using the prepared test piece containing the bead.
自冷軋退火後之試驗片、及熔接後之試驗片中採取20mm見方之試驗片,製作殘留10mm見方之測定面且經片材被覆之試驗片。針對於熔接後之試驗片,以包含焊珠之方式採取試驗片,並直接殘留由熔接產生之回火色(氧化皮膜)。於30℃之3.5質量%NaCl溶液中對該等試驗片測定母材及熔接部之點蝕電位。於測定時,不進行試驗片之研磨或鈍態化處理,除此以外之測定方法係依據JIS G 0577(2005)。 A test piece of 20 mm square was taken from the test piece after the cold rolling annealing and the test piece after the welding, and a test piece having a measurement surface of 10 mm square and covered with a sheet was produced. For the test piece after welding, a test piece was taken in such a manner as to include a bead, and the tempering color (oxidation film) generated by welding was directly left. The pitting potentials of the base material and the welded portion were measured for the test pieces in a 3.5 mass% NaCl solution at 30 °C. At the time of measurement, the test piece was not subjected to grinding or passivation treatment, and the other measurement methods were based on JIS G 0577 (2005).
將母材之點蝕電位:150mV以上、熔接部之點蝕電位:0mV以上設為合格。 The pitting potential of the base material: 150 mV or more, and the pitting potential of the welded portion: 0 mV or more was set as pass.
自熔接後之試驗片中採取包含焊珠之100mm見方之試驗片,利用#600砂紙對表面進行精研磨後將端面部密封,製作上述試驗片,並供於JIS H 8502中規定之中性鹽水噴霧循環試驗。中性鹽水噴霧循環試 驗係5質量%之NaCl溶液噴霧(35℃,2h)→乾燥(60℃,4h,相對濕度20~30%)→濕潤(moistness)(40℃,2h,相對濕度95%以上)為1循環。將對該試驗片實施15循環後未自母材或熔接部產生腐蝕之情形設為合格。 A test piece containing a bead of 100 mm square was used in the self-welding test piece, and the surface was subjected to finish grinding using #600 sandpaper, and the end surface portion was sealed to prepare the above test piece, and the neutral salt water specified in JIS H 8502 was prepared. Spray cycle test. Neutral salt spray cycle test Laboratory 5% by mass NaCl solution spray (35 ° C, 2 h) → dry (60 ° C, 4 h, relative humidity 20 ~ 30%) → moist (40 ° C, 2 h, relative humidity 95% or more) for 1 cycle . The case where the test piece was not subjected to corrosion from the base material or the welded portion after 15 cycles was set as a pass.
於經熔接之試驗片之焊珠之直角方向採取金屬組織觀察用試驗片,進行鏡面研磨後,藉由利用苦味酸鹽酸水溶液之蝕刻,而使金屬組織及析出物露出,並使用掃描型電子顯微鏡及能量分散型X射線光譜法,對組織進行觀察及進行析出物之相鑑定,測定焊珠部之肥粒鐵相之由Cr碳氮化物所致之晶界被覆率。 A test piece for metal structure observation was taken in the direction perpendicular to the bead of the welded test piece, and after mirror polishing, the metal structure and the precipitate were exposed by etching with a picric acid aqueous solution, and scanning electrons were used. Microscope and energy dispersive X-ray spectroscopy were used to observe the structure and identify the phases of the precipitates, and to measure the grain boundary coverage of the ferrite phase of the bead portion by Cr carbonitride.
晶界被覆率係利用影像分析裝置測定所拍攝之組織照片中之晶粒之晶界長度,並且同樣地利用影像分析裝置,測定與晶界上所析出之Cr碳氮化物之晶界平行方向之直徑,根據晶界被覆率(%)=(與晶界上之Cr碳氮化物之晶界平行方向之直徑之總計)÷(晶粒之晶界長度之總計)×100之式而算出。 The grain boundary coverage ratio is measured by the image analyzer to measure the grain boundary length of the crystal grains in the photographed tissue, and the image analysis device is used to measure the grain boundary parallel to the Cr carbonitride precipitated on the grain boundary. The diameter is calculated according to the grain boundary coverage ratio (%) = (the total of the diameters in the direction parallel to the grain boundary of the Cr carbonitride on the grain boundary) ÷ (the total of the grain boundary lengths of the crystal grains) × 100.
將由Cr碳氮化物所致之肥粒鐵相之晶界被覆率為40%以下之情形設為合格。 The case where the grain boundary coverage ratio of the ferrite grain iron phase by Cr carbonitride was 40% or less was regarded as acceptable.
自所製作之冷軋退火板中與軋壓方向平行地採取JIS 13B號拉伸試驗片,依據JIS Z2241進行拉伸試驗,測定斷裂伸長率。 A tensile test piece of JIS No. 13B was taken from the cold-rolled annealed sheet produced in parallel with the rolling direction, and a tensile test was carried out in accordance with JIS Z2241, and the elongation at break was measured.
將斷裂伸長率為25%以上設為合格。 The elongation at break was 25% or more.
冷軋退火後,用肉眼觀察經除鏽之鋼板表面,確認是否無除鏽不良及線狀瑕疵等表面缺陷。 After the cold rolling annealing, the surface of the rust-removed steel sheet was observed with the naked eye to confirm whether there were no surface defects such as poor rust removal and linear flaws.
將無鏽皮殘留或表面缺陷而獲得良好之表面外觀設為合格基準。 A good surface appearance is obtained by leaving no scale residue or surface defects.
將試驗結果示於表2。 The test results are shown in Table 2.
滿足本發明要件之鋼No.1~20均為母材之點蝕電位為150mV以上、焊珠之點蝕電位為0mV以上,並且即便藉由中性鹽水噴霧循環試驗而亦未產生腐蝕,即便於實施與沃斯田鐵系不鏽鋼熔接之情形下亦可獲得充分之耐蝕性。又,鋼No.1~20均為熔接後之由Cr碳氮化物所致之肥粒鐵相之晶界被覆率為40%以下,獲得既定之抗敏化效果。進而,獲得了基於拉伸試驗之斷裂伸長率均為25%以上之良好之加工特性,並且亦未確認到表面缺陷。 Steels No. 1 to 20 satisfying the requirements of the present invention have a pitting potential of 150 mV or more, and a pitting potential of the bead of 0 mV or more, and no corrosion occurs even by a neutral salt spray cycle test, even if In the case of welding with the Worthfield iron-based stainless steel, sufficient corrosion resistance can be obtained. Further, in the steel Nos. 1 to 20, the grain boundary coverage ratio of the ferrite-grained iron phase by Cr carbonitride after welding was 40% or less, and a predetermined anti-sensitization effect was obtained. Further, good processing characteristics in which the elongation at break based on the tensile test was 25% or more were obtained, and surface defects were not confirmed.
另一方面,於Cr量超過本發明範圍之鋼No.21中,熱軋後之鋼板之韌性明顯降低,無法實施以後之製造步驟,而未能評價特性。 On the other hand, in Steel No. 21 in which the amount of Cr exceeded the range of the present invention, the toughness of the steel sheet after hot rolling was remarkably lowered, and the subsequent production steps could not be performed, and the characteristics could not be evaluated.
於Cr量低於本發明範圍之鋼No.22中,無法獲得充分之點蝕電位,又,於中性鹽水噴霧循環試驗中,自母材及熔接部產生腐蝕,未能獲得既定之耐蝕性。 In steel No. 22 in which the amount of Cr is lower than the range of the present invention, sufficient pitting potential cannot be obtained, and in the neutral salt spray cycle test, corrosion occurs from the base material and the welded portion, and the predetermined corrosion resistance is not obtained. .
於Mn量低於本發明範圍之鋼No.23中,母材雖已獲得充分之耐蝕性,但熔接部未獲得充分之耐蝕性。 In Steel No. 23 in which the amount of Mn is less than the range of the present invention, although the base material has obtained sufficient corrosion resistance, the welded portion has not obtained sufficient corrosion resistance.
另一方面,於Mn量或Al量超過本發明範圍之鋼No.24及25中,雖然已獲得既定之母材及熔接部耐蝕性,但因鋼板硬質化而延展性降低,未能獲得既定之機械特牲。 On the other hand, in Steel Nos. 24 and 25 in which the amount of Mn or the amount of Al exceeds the range of the present invention, although the corrosion resistance of the predetermined base material and the welded portion is obtained, the ductility is lowered due to the hardening of the steel sheet, and the predetermined property is not obtained. Mechanical specials.
於Ti量超過本發明範圍之鋼No.26中,雖然已獲得既定之耐蝕性及機械特性,但產生因生成大量之粗大Ti系中介物所導致之表面缺陷,未能獲得既定之表面性狀。 In Steel No. 26 in which the amount of Ti exceeds the range of the present invention, although the predetermined corrosion resistance and mechanical properties have been obtained, surface defects caused by the formation of a large amount of coarse Ti-based interpolymer have not been obtained, and a predetermined surface property has not been obtained.
雖然各元素之含量滿足本發明之範圍,但於沃斯田鐵穩定化元素之含量低於式(1)之範圍之鋼No.27~30中,已獲得既定之母材耐蝕性及機械特性。然而,無法獲得既定之焊珠部之點蝕電位及熔 接部之耐蝕性。對No.27~30之熔接部之剖面組織進行調查研究,結果可確認均於肥粒鐵相晶界析出有以晶界被覆率計50%以上之極多之Cr碳氮化物。認為於鋼No.27~30中,由於沃斯田鐵穩定化元素不足,故而於熔接後之冷卻中產生肥粒鐵相,未能抑制Cr碳氮化物於晶界上之生成,結果產生明顯之敏化,而未能獲得既定之熔接部之耐蝕性。 Although the content of each element satisfies the scope of the present invention, in the steel No. 27 to 30 in which the content of the stabilizing element of the Vostian iron is lower than the range of the formula (1), the corrosion resistance and mechanical properties of the predetermined base material have been obtained. . However, it is impossible to obtain the pitting potential and melting of the predetermined bead portion. Corrosion resistance of the joint. When the cross-sectional structure of the welded portion of No. 27 to 30 was investigated, it was confirmed that a large number of Cr carbonitrides having a grain boundary coverage ratio of 50% or more were precipitated at the grain boundary of the ferrite grain. It is considered that in the steel No. 27 to 30, since the stabilizing element of the Worthite iron is insufficient, the iron phase of the ferrite is generated during the cooling after the welding, and the formation of the Cr carbonitride on the grain boundary cannot be suppressed, and the result is conspicuous. Sensitized, but failed to obtain the corrosion resistance of the established weld.
根據以上之結果明確可知,根據本發明,無需過量添加Ti或Nb,而可獲得具有優異之耐蝕性、機械特性及表面性狀之肥粒鐵系不鏽鋼。 As is apparent from the above results, according to the present invention, it is possible to obtain a ferrite-based iron-based stainless steel having excellent corrosion resistance, mechanical properties, and surface properties without excessive addition of Ti or Nb.
本發明中獲得之肥粒鐵系不鏽鋼較佳為應用於藉由熔接而製作構造體之用途,例如消音器等汽車排氣系材料、建具或通氣口、管道等建築用材料等。 The ferrite-based iron-based stainless steel obtained in the present invention is preferably used for a structure in which a structure is produced by welding, such as an automobile exhaust material such as a muffler, a building material, a vent, a building material such as a pipe, and the like.
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JP4974542B2 (en) * | 2005-09-02 | 2012-07-11 | 日新製鋼株式会社 | Automotive exhaust gas flow path member |
JP4761993B2 (en) * | 2006-02-14 | 2011-08-31 | 日新製鋼株式会社 | Manufacturing method of ferritic stainless steel welded pipe for spinning |
JP5119605B2 (en) | 2006-03-31 | 2013-01-16 | Jfeスチール株式会社 | Ferritic stainless steel with excellent corrosion resistance of welds |
KR20080110662A (en) * | 2006-05-09 | 2008-12-18 | 닛폰 스틸 앤드 스미킨 스테인레스 스틸 코포레이션 | Stainless steel excellent in corrosion resistance, ferritic stainless steel excellent in crevice corrosion resistance and formability, and ferritic stainless steel excellent in crevice corrosion resistance |
JP5000281B2 (en) * | 2006-12-05 | 2012-08-15 | 新日鐵住金ステンレス株式会社 | High-strength stainless steel sheet with excellent workability and method for producing the same |
JP5387057B2 (en) * | 2008-03-07 | 2014-01-15 | Jfeスチール株式会社 | Ferritic stainless steel with excellent heat resistance and toughness |
JP2010202916A (en) | 2009-03-02 | 2010-09-16 | Nisshin Steel Co Ltd | Ferritic stainless steel excellent in corrosion resistance of welded part with austenite stainless steel |
JP5737952B2 (en) | 2011-01-05 | 2015-06-17 | 日新製鋼株式会社 | Nb-containing ferritic stainless steel hot rolled coil and manufacturing method |
EP2787096B1 (en) * | 2011-11-30 | 2016-10-12 | JFE Steel Corporation | Ferritic stainless steel |
ES2632781T3 (en) * | 2012-03-13 | 2017-09-15 | Jfe Steel Corporation | Ferritic stainless steel |
-
2014
- 2014-07-16 CN CN201480041182.5A patent/CN105408511B/en active Active
- 2014-07-16 WO PCT/JP2014/003767 patent/WO2015015735A1/en active Application Filing
- 2014-07-16 JP JP2014553008A patent/JP5700182B1/en active Active
- 2014-07-16 KR KR1020157036796A patent/KR101809812B1/en active IP Right Grant
- 2014-07-16 MY MYPI2016700273A patent/MY160981A/en unknown
- 2014-07-16 US US14/908,176 patent/US20160168673A1/en not_active Abandoned
- 2014-07-28 TW TW103125665A patent/TWI526547B/en not_active IP Right Cessation
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TWI526547B (en) | 2016-03-21 |
JPWO2015015735A1 (en) | 2017-03-02 |
CN105408511A (en) | 2016-03-16 |
WO2015015735A1 (en) | 2015-02-05 |
MY160981A (en) | 2017-03-31 |
CN105408511B (en) | 2018-09-07 |
KR101809812B1 (en) | 2017-12-15 |
US20160168673A1 (en) | 2016-06-16 |
KR20160014685A (en) | 2016-02-11 |
JP5700182B1 (en) | 2015-04-15 |
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