TWI645051B - Ferrous iron-based stainless steel - Google Patents

Ferrous iron-based stainless steel Download PDF

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TWI645051B
TWI645051B TW106143968A TW106143968A TWI645051B TW I645051 B TWI645051 B TW I645051B TW 106143968 A TW106143968 A TW 106143968A TW 106143968 A TW106143968 A TW 106143968A TW I645051 B TWI645051 B TW I645051B
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thermal fatigue
stainless steel
steel
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TW201827624A (en
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中村徹之
石川伸
杉原玲子
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日商杰富意鋼鐵股份有限公司
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    • C—CHEMISTRY; METALLURGY
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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    • C21D6/00—Heat treatment of ferrous alloys
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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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    • C21D8/0226—Hot rolling
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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    • C21D8/0236—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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Abstract

本發明係提供一種皮層密接性與熱疲勞特性優異，且耐冷凝水腐蝕性亦優異之肥粒鐵系不鏽鋼板。 The present invention provides a ferrous iron-based stainless steel plate having excellent skin adhesion and thermal fatigue characteristics, and excellent corrosion resistance to condensation water.

本發明之肥粒鐵系不鏽鋼板具有如下組成，該組成以質量%計含有C：0.010%以下、Si：1.0%以下、Mn：1.0%以下、P：0.040%以下、S：0.030%以下、Cr：17.0%以上且18.5%以下、N：0.015%以下、Nb：0.40%以上且0.80%以下、Ti：0.10%以上且0.40%以下、Al：0.20%以下、Ni：0.05%以上且0.40%以下、Co：0.01%以上且0.30%以下、Mo：0.02%以上且0.30%以下、Cu：0.02%以上且0.40%以下，且滿足以下之式(1)，並且剩餘部分包含Fe及不可避免之雜質。 The ferrous iron-based stainless steel plate of the present invention has the following composition, which contains C: 0.010% or less, Si: 1.0% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, Cr: 17.0% or more and 18.5% or less, N: 0.015% or less, Nb: 0.40% or more and 0.80% or less, Ti: 0.10% or more and 0.40% or less, Al: 0.20% or less, Ni: 0.05% or more and 0.40% or less Below, Co: 0.01% or more and 0.30% or less, Mo: 0.02% or more and 0.30% or less, Cu: 0.02% or more and 0.40% or less, and satisfying the following formula (1), and the remainder contains Fe and unavoidable Impurities.

C%+N%：0.018%以下 (1) C% + N%: below 0.018% (1)

式(1)中，C%、N%分別表示C、N之含量(質量%)。 In Formula (1), C% and N% represent the content (mass%) of C and N, respectively.

Description

肥粒鐵系不鏽鋼    Ferrous iron-based stainless steel   

本發明係關於一種皮層(scale)密接性、熱疲勞特性及耐冷凝水腐蝕性優異之肥粒鐵系不鏽鋼者。 The present invention relates to a ferritic iron-based stainless steel having excellent scale adhesion, thermal fatigue characteristics, and corrosion resistance to condensation water.

於汽車之排氣系統構件中，與上游側、尤其是引擎直接連接之排氣岐管係於最高使用溫度亦達到800~900℃之嚴酷環境下使用。因此，對於其材料，要求優異之熱疲勞特性，而主要使用添加有Nb之肥粒鐵系不鏽鋼。 Among automotive exhaust system components, exhaust manifolds that are directly connected to the upstream side, especially the engine, are used in harsh environments where the maximum operating temperature also reaches 800 to 900 ° C. Therefore, the material is required to have excellent thermal fatigue characteristics, and a ferritic iron-based stainless steel to which Nb is added is mainly used.

添加至肥粒鐵系不鏽鋼中之Nb係藉由固溶於鋼中而提昇高溫強度以使熱疲勞特性提高。然而，Nb有容易與鋼中之C或N鍵結而成為碳氮化物，從而固溶Nb量減少而熱疲勞特性降低之情況。作為其對策，亦有進行複合添加較Nb更容易與C或N鍵結之Ti而使C或Ni以Ti碳氮化物之形式生成，藉此防止Nb碳氮化物之生成。該Nb-Ti複合添加鋼之具代表性者為Type 441肥粒鐵系不鏽鋼(18%Cr-0.5%Nb-0.2%Ti)(EN10088-2：EN1.4509)，該鋼係廣泛用於汽車之排氣岐管等。 The Nb added to the ferrous iron-based stainless steel is solid-dissolved in the steel to increase the high-temperature strength to improve the thermal fatigue characteristics. However, Nb may be easily bonded to C or N in the steel to become a carbonitride, so that the amount of solid solution Nb may be reduced and the thermal fatigue characteristics may be reduced. As a countermeasure, it is also possible to prevent the formation of Nb carbonitride by compoundly adding Ti which is more easily bonded to C or N than Nb, so that C or Ni is formed as a Ti carbonitride. The representative of this Nb-Ti composite additive steel is Type 441 ferrous iron-based stainless steel (18% Cr-0.5% Nb-0.2% Ti) (EN10088-2: EN1.4509), which is widely used in automobiles Exhaust manifold, etc.

排氣岐管由於在引擎之啟動、停止時反覆遭受加熱及急冷之嚴酷之反覆氧化的環境下使用，故而若皮層剝離，則亞鐵酸鹽會直接暴露在高溫之排氣中從而進行氧化而板厚減少，且視情形有開孔或變形之情況。因此，對於汽車之排氣岐管所使用之Nb-Ti 複合添加肥粒鐵系不鏽鋼，亦要求皮層不會剝離之優異之皮層密接性。 The exhaust manifold is used under the severe repeated oxidation environment of heating and rapid cooling when the engine is started and stopped. Therefore, if the skin layer is peeled off, the ferrite will be directly exposed to the high temperature exhaust gas and oxidized. The thickness of the board is reduced, and there may be holes or deformations depending on the situation. Therefore, for the Nb-Ti compound-added ferrous iron-based stainless steel used in the exhaust manifold of automobiles, excellent skin adhesion is also required for the skin layer to not peel off.

作為提高Nb-Ti複合添加肥粒鐵系不鏽鋼之高溫強度或熱疲勞特性之方法，於專利文獻1及2中揭示有Mo之添加。於專利文獻3~5中揭示有Mo、Cu、W之添加。作為改善皮層密接性之方法，於專利文獻3中揭示有REM、Ca、Y、Zr之添加。於專利文獻5中揭示有REM、Ca之添加。於專利文獻6中揭示有藉由添加Co及Ni而改善了皮層密接性及熱疲勞特性之Nb-Ti複合添加肥粒鐵系不鏽鋼。 Patent Documents 1 and 2 disclose the addition of Mo as a method for improving the high-temperature strength or thermal fatigue characteristics of Nb-Ti composite-added ferrous iron-based stainless steel. The addition of Mo, Cu, and W is disclosed in Patent Documents 3 to 5. As a method for improving the adhesion of the cortex, Patent Document 3 discloses the addition of REM, Ca, Y, and Zr. Patent Document 5 discloses addition of REM and Ca. Patent Document 6 discloses an Nb-Ti compound-added ferrous iron-based stainless steel having improved skin adhesion and thermal fatigue characteristics by adding Co and Ni.

另一方面，對於配置於汽車排氣管零件之下游側之消音器或管體等，由於例如包含撒在道路上之融雪鹽之水飛散，或暴露在排氣被冷卻而產生之包含腐蝕性離子的冷凝水中，故而大多要求耐蝕性(以下，記載為耐冷凝水腐蝕性)，從而使用添加有Ti或Mo之肥粒鐵系不鏽鋼。作為例，可列舉JIS G4305中所規定之SUS436L(18%Cr-0.2%Ti-1%Mo)或SUS430LX(18%Cr-0.2%Ti)。 On the other hand, for a muffler or a pipe body disposed on the downstream side of an automobile exhaust pipe part, for example, water containing snowmelt salt scattered on the road is scattered or exposed to the exhaust gas and cooled to contain corrosiveness. Ion condensed water often requires corrosion resistance (hereinafter referred to as corrosion resistance of condensed water). Therefore, a ferrous iron-based stainless steel to which Ti or Mo is added is used. As an example, SUS436L (18% Cr-0.2% Ti-1% Mo) or SUS430LX (18% Cr-0.2% Ti) specified in JIS G4305 can be mentioned.

如上所述，上游側之排氣岐管等與下游之消音器等由於所要求之特性不同，因此雖使用適於各個用途之肥粒鐵系不鏽鋼，但若能夠用共通之肥粒鐵系不鏽鋼製造其，則可減少鋼種數，而且將不同材質之零件焊接之部位減少，從而零件之製造性穩定而能夠有效率地製造汽車。 As described above, the exhaust manifolds on the upstream side and the silencers on the downstream have different required characteristics, so although ferrous iron-based stainless steel suitable for each application is used, if common ferrous iron-based stainless steel can be used Manufacturing it can reduce the number of steel types, and reduce the number of welded parts of parts of different materials, so that the manufacturability of the parts is stable and the car can be manufactured efficiently.

[先前技術文獻]     [Prior technical literature]     [專利文獻]     [Patent Literature]    

專利文獻1：日本專利特開平4-224657號公報 Patent Document 1: Japanese Patent Laid-Open No. 4-224657

專利文獻2：日本專利特開平5-70897號公報 Patent Document 2: Japanese Patent Laid-Open No. 5-70897

專利文獻3：日本專利特開2004-218013號公報 Patent Document 3: Japanese Patent Laid-Open No. 2004-218013

專利文獻4：日本專利特開2008-240143號公報 Patent Document 4: Japanese Patent Laid-Open No. 2008-240143

專利文獻5：日本專利特開2009-174040號公報 Patent Document 5: Japanese Patent Laid-Open No. 2009-174040

專利文獻6：日本專利第5505570號公報 Patent Document 6: Japanese Patent No. 5505570

然而，專利文獻1~5所揭示之方法具有如下缺點：Mo或W價格昂貴並且會使鋼板之韌性等加工性降低。又，Cu具有如下缺點：不僅使常溫下之加工性大幅降低，而且使耐氧化性降低。又，於專利文獻1~5中，並無排氣岐管所需之熱疲勞特性或耐氧化性(皮層密接性)與消音器等所需之耐冷凝水腐蝕性同時得到評價者。進而，於將SUS436L(18%Cr-0.2%Ti-1%Mo)或SUS430LX(18%Cr-0.2%Ti)用於排氣岐管之情形時，存在熱疲勞特性不足之問題。 However, the methods disclosed in Patent Documents 1 to 5 have disadvantages in that Mo or W is expensive and reduces workability such as toughness of a steel sheet. In addition, Cu has the disadvantage that not only the workability at room temperature is greatly reduced, but also the oxidation resistance is lowered. Moreover, in Patent Documents 1 to 5, the thermal fatigue characteristics or oxidation resistance (skin adhesion) required for the exhaust manifold and the condensation water corrosion resistance required for a muffler, etc., were not evaluated at the same time. Furthermore, when SUS436L (18% Cr-0.2% Ti-1% Mo) or SUS430LX (18% Cr-0.2% Ti) is used in an exhaust manifold, there is a problem that thermal fatigue characteristics are insufficient.

如上所述，先前之肥粒鐵系不鏽鋼尚不可謂皮層密接性、熱疲勞特性及耐冷凝水腐蝕性之全部特性良好。 As described above, the conventional ferrous iron-based stainless steels are not all good in terms of skin adhesion, thermal fatigue characteristics, and condensation water corrosion resistance.

本發明係為了解決上述問題而完成者，其目的在於提供一種皮層密接性與熱疲勞特性優異，並且耐冷凝水腐蝕性亦優異之肥粒鐵系不鏽鋼。 The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to provide a ferrous iron-based stainless steel which is excellent in skin adhesion and thermal fatigue characteristics, and is also excellent in corrosion resistance to condensation water.

再者，本發明之所謂「皮層密接性優異」，係指反覆氧化試驗(加熱速度：5℃/sec、冷卻速度：1.5℃/sec)後之試片表面上皮層剝離之面積未達5%，該反覆氧化試驗係針對經研磨之冷軋退火板，於大氣中將於1000℃下保持20min及於100℃下保持1min 進行400個循環。 Moreover, the so-called "excellent adhesion of the skin layer" in the present invention means that the area of the skin layer peeled off on the surface of the test piece after repeated oxidation tests (heating rate: 5 ° C / sec, cooling rate: 1.5 ° C / sec) has not reached 5%. The repeated oxidation test is performed for 400 cycles of the milled cold-rolled annealed sheet, which is maintained in the atmosphere at 1000 ° C for 20 min and at 100 ° C for 1 min.

又，所謂「熱疲勞特性優異」，係指依據JSMS-SD-7-03，於200~900℃間反覆進行加熱、冷卻，與此同時，於拘束率0.6下反覆賦予應變，用各循環之於200℃下所檢測到之負重除以試片均熱平行部之剖面面積所得之值(應力)相對於第5個循環之應力，降低至75%之循環數(熱疲勞壽命)為660個循環以上。 In addition, the term "excellent thermal fatigue characteristics" means that heating and cooling are repeatedly performed between 200 and 900 ° C in accordance with JSMS-SD-7-03, and strain is repeatedly applied at a restraint rate of 0.6. The value (stress) obtained by dividing the load detected at 200 ° C by the cross-sectional area of the test specimen's soaking parallel section is reduced to 75% of the cycle number (thermal fatigue life) of 660 Loop above.

又，所謂「耐冷凝水腐蝕性優異」，係指將經研磨之冷軋退火板保持於包含Cl-：500ppm、SO4 2-：1000ppm且pH值：4、溫度：80℃之恆溫槽內，將溶液浸漬2小時與乾燥6小時設為1組而進行30組，腐蝕失重為10g/m2以下。 In addition, so-called "excellent corrosion resistance to cold water" refers to the milled in the cold-rolled annealed sheet held comprising Cl -: 500ppm, SO 4 2- : 1000ppm and pH: 4, temperature: 80 ℃ of a thermostat The solution was immersed for 2 hours and dried for 6 hours as one group to perform 30 groups, and the weight loss of corrosion was 10 g / m 2 or less.

本發明者等人對C+N量對於Nb-Ti-Co-Ni複合添加肥粒鐵系不鏽鋼之熱疲勞特性所造成的影響進行研究，發現藉由於含有Ti之鋼中將C+N量、Ti量限定為適當量而獲得進一步優異之熱疲勞特性。進而，進行關於Nb-Ti-Co-Ni複合添加肥粒鐵系不鏽鋼之耐冷凝水腐蝕性之研究，發現藉由添加適量之Mo、Cu兩者而能夠改善耐冷凝水腐蝕性，從而用於消音器等下游側之零件。 The present inventors have studied the influence of the amount of C + N on the thermal fatigue characteristics of Nb-Ti-Co-Ni compound-added ferrous iron-based stainless steel, and found that the amount of C + N, The amount of Ti is limited to an appropriate amount to obtain further excellent thermal fatigue characteristics. Furthermore, research was conducted on the corrosion resistance of condensed water of Nb-Ti-Co-Ni compound-added fertilizer-type iron-based stainless steel, and it was found that the addition of appropriate amounts of Mo and Cu can improve the corrosion resistance of condensed water, and is used in Muffler and other downstream parts.

本發明係基於以上見解而完成者，其主旨係如下所示。 The present invention has been completed based on the above findings, and the gist thereof is as follows.

[1]一種肥粒鐵系不鏽鋼，其具有如下組成，該組成以質量%計含有C：0.010%以下、Si：1.0%以下、Mn：1.0%以下、P：0.040%以下、S：0.030%以下、Cr：17.0%以上且18.5%以下、N：0.015%以下、Nb：0.40%以上且0.80%以下、Ti：0.10%以上且0.40%以下、Al：0.20%以下、Ni：0.05%以上且0.40%以下、Co：0.01%以上且 0.30%以下、Mo：0.02%以上且0.30%以下、Cu：0.02%以上且0.40%以下，且滿足以下之式(1)，並且剩餘部分包含Fe及不可避免之雜質。 [1] A ferrous iron-based stainless steel having a composition containing C: 0.010% or less, Si: 1.0% or less, Mn: 1.0% or less, P: 0.040% or less, and S: 0.030% by mass%. Below, Cr: 17.0% or more and 18.5% or less, N: 0.015% or less, Nb: 0.40% or more and 0.80% or less, Ti: 0.10% or more and 0.40% or less, Al: 0.20% or less, Ni: 0.05% or more and 0.40% or less, Co: 0.01% or more and 0.30% or less, Mo: 0.02% or more and 0.30% or less, Cu: 0.02% or more and 0.40% or less, and satisfying the following formula (1), and the remainder contains Fe and may not Avoid impurities.

C%+N%：0.018%以下 (1) C% + N%: below 0.018% (1)

式(1)中，C%、N%分別表示C、N之含量(質量%)。 In Formula (1), C% and N% represent the content (mass%) of C and N, respectively.

[2]如上述[1]所記載之肥粒鐵系不鏽鋼，其以質量%計進而含有選自Ca：0.0005%以上且0.0030%以下、Mg：0.0002%以上且0.0020%以下、B：0.0002%以上且0.0020%以下中之1種或2種以上。 [2] The ferrous iron-based stainless steel according to the above [1], further comprising, in mass%, selected from Ca: 0.0005% or more and 0.0030% or less, Mg: 0.0002% or more and 0.0020% or less, and B: 0.0002% One or more of 0.0020% or more.

[3]如上述[1]或[2]所記載之肥粒鐵系不鏽鋼，其以質量%計進而含有選自V：0.01%以上且0.50%以下、W：0.02%以上且0.30%以下、Zr：0.005%以上且0.50%以下中之1種或2種以上。 [3] The ferrous iron-based stainless steel according to the above [1] or [2], further comprising, in mass%, selected from V: 0.01% or more and 0.50% or less, W: 0.02% or more and 0.30% or less, Zr: one or more of 0.005% to 0.50%.

根據本發明，可獲得皮層密接性、熱疲勞特性及耐冷凝水腐蝕性優異之肥粒鐵系不鏽鋼。本發明之肥粒鐵系不鏽鋼由於耐熱性(皮層密接性、熱疲勞特性)與耐冷凝水腐蝕性兩者優異，故而可較佳地用於汽車之排氣系統構件之上游側、下游側兩側。 According to the present invention, a ferrous iron-based stainless steel excellent in skin adhesion, thermal fatigue characteristics, and resistance to condensation water corrosion can be obtained. The ferrous iron-based stainless steel of the present invention is excellent in both heat resistance (skin adhesion, thermal fatigue characteristics) and corrosion resistance of condensed water, so it can be preferably used for both the upstream side and the downstream side of an automobile exhaust system component side.

圖1係對熱疲勞試片進行說明之圖。 FIG. 1 is a diagram explaining a thermal fatigue test piece.

圖2係對熱疲勞試驗中之溫度及拘束條件進行說明之圖。 FIG. 2 is a diagram illustrating temperature and restraint conditions in a thermal fatigue test.

以下，對本發明詳細地進行說明。本發明之肥粒鐵系不鏽鋼具有如下組成，該組成以質量%計含有C：0.010%以下、Si：1.0%以下、Mn：1.0%以下、P：0.040%以下、S：0.030%以下、Cr： 17.0%以上且18.5%以下、N：0.015%以下、Nb：0.40%以上且0.80%以下、Ti：0.10%以上且0.40%以下、Al：0.20%以下、Ni：0.05%以上且0.40%以下、Co：0.01%以上且0.30%以下、Mo：0.02%以上且0.30%以下、Cu：0.02%以上且0.40%以下，且滿足以下之式(1)，並且剩餘部分包含Fe及不可避免之雜質，而皮層密接性與熱疲勞特性優異，並且耐冷凝水腐蝕性亦優異。 Hereinafter, the present invention will be described in detail. The ferrous iron-based stainless steel of the present invention has the following composition, which contains C: 0.010% or less, Si: 1.0% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, and Cr in mass%. : 17.0% or more and 18.5% or less, N: 0.015% or less, Nb: 0.40% or more and 0.80% or less, Ti: 0.10% or more and 0.40% or less, Al: 0.20% or less, Ni: 0.05% or more and 0.40% or less , Co: 0.01% or more and 0.30% or less, Mo: 0.02% or more and 0.30% or less, Cu: 0.02% or more and 0.40% or less, and satisfying the following formula (1), and the remainder contains Fe and inevitable impurities In addition, the skin layer has excellent adhesion and thermal fatigue characteristics, and is also excellent in condensation water corrosion resistance.

C%+N%：0.018%以下 (1) C% + N%: below 0.018% (1)

式(1)中，C%、N%分別表示C、N之含量(質量%)。 In Formula (1), C% and N% represent the content (mass%) of C and N, respectively.

繼而，對規定本發明之肥粒鐵系不鏽鋼之成分組成之原因進行說明。再者，成分%只要無特別事先說明，則全部意指質量%。 Next, the reason for specifying the component composition of the ferrous iron-based stainless steel of the present invention will be described. In addition, as long as there is no special explanation in advance of a component%, all means the mass%.

C：0.010%以下     C: 0.010% or less    

C係對於提高鋼之強度有效之元素，該效果係於含有0.001%以上之C時獲得，因此C含量較佳為0.001%以上。另一方面，若含有超過0.010%之C，則導致皮層剝離，因此C含量係設為0.010%以下。再者，關於C含量，就確保韌性、加工性之觀點而言，又，就由於NbC粗大化或析出量變多，故而鋼中之固溶Nb量減少而熱疲勞特性降低之觀點而言，較理想為C含量較少，C含量較佳為設為0.008%以下。C含量更佳為0.005%以上。 C is an element effective for improving the strength of steel. The effect is obtained when C is contained in an amount of 0.001% or more. Therefore, the C content is preferably 0.001% or more. On the other hand, if C is contained in an amount exceeding 0.010%, the skin layer is peeled, so the C content is set to 0.010% or less. In addition, regarding the C content, from the viewpoint of ensuring toughness and workability, and from the viewpoint that NbC coarsens or the amount of precipitation increases, the amount of solid solution Nb in the steel decreases and the thermal fatigue characteristics decrease. The C content is preferably small, and the C content is preferably set to 0.008% or less. The C content is more preferably 0.005% or more.

Si：1.0%以下     Si: 1.0% or less    

Si係對於提高耐氧化性有效之元素，該效果係於含有0.01%以上之Si時獲得，因此Si含量較佳為0.01%以上。另一方面，若含 有超過1.0%之Si，則加工性降低，因此Si含量係設為1.0%以下。Si含量更佳為0.20%以上，進而更佳為0.30%以上。尤其是若將Ni含量設為0.20%以上且將Si含量設為0.30%以上，則皮層密接性尤其優異。又，Si含量較佳為1.00%以下，更佳為0.50%以下，進而較佳為0.40%以下。 Si is an element effective for improving the oxidation resistance. This effect is obtained when Si is contained in an amount of 0.01% or more. Therefore, the Si content is preferably 0.01% or more. On the other hand, if Si is contained in excess of 1.0%, the workability is lowered, so the Si content is set to 1.0% or less. The Si content is more preferably 0.20% or more, and still more preferably 0.30% or more. In particular, if the Ni content is 0.20% or more and the Si content is 0.30% or more, the skin layer adhesion is particularly excellent. The Si content is preferably 1.00% or less, more preferably 0.50% or less, and still more preferably 0.40% or less.

Mn：1.0%以下     Mn: 1.0% or less    

Mn係提高鋼之強度之元素，又，亦具有作為去氧劑之作用。該效果係於含有0.01%以上之Mn時獲得，因此Mn含量較佳為0.01%以上。另一方面，若含有超過1.0%之Mn，則使氧化增量明顯地增加而使耐氧化性降低，因此Mn含量係設為1.0%以下。Mn含量更佳為0.20%以上，進而更佳為0.30%以上。又，Mn含量較佳為1.00%以下，更佳為0.60%以下，進而較佳為0.50%以下。 Mn is an element that increases the strength of steel, and also has a role as a deoxidizer. This effect is obtained when Mn is contained in an amount of 0.01% or more, so the Mn content is preferably 0.01% or more. On the other hand, if Mn is contained in excess of 1.0%, the oxidation increase is significantly increased and the oxidation resistance is lowered. Therefore, the Mn content is set to 1.0% or less. The Mn content is more preferably 0.20% or more, and still more preferably 0.30% or more. The Mn content is preferably 1.00% or less, more preferably 0.60% or less, and still more preferably 0.50% or less.

P：0.040%以下     P: 0.040% or less    

P係使韌性降低之元素，較理想為減少P，P含量係設為0.040%以下。較佳為P含量為0.035%以下。更佳為P含量為0.030%以下。 P is an element that reduces toughness. It is more desirable to reduce P, and the P content is set to 0.040% or less. The P content is preferably 0.035% or less. More preferably, the P content is 0.030% or less.

S：0.030%以下     S: 0.030% or less    

S由於使成形性與耐蝕性降低，故而較理想為較少，S含量係設為0.030%以下。較佳為S含量為0.006%以下。更佳為S含量為0.003%以下。 S is preferably less because it reduces formability and corrosion resistance, and the S content is set to 0.030% or less. The S content is preferably 0.006% or less. More preferably, the S content is 0.003% or less.

Cr：17.0%以上且18.5%以下     Cr: 17.0% or more and 18.5% or less    

Cr係為了使耐蝕性及耐氧化性提高而需要之元素，為了獲得良好之耐蝕性及耐氧化性，而必須含有17.0%以上之Cr。若Cr含量未達17.0%，則有氧化皮層變得容易增大，不僅皮層密接性降低，而且熱疲勞特性亦降低之情形。進而，於冷凝水中之耐蝕性亦未充分地獲得。另一方面，若含有超過18.5%之Cr，則鋼硬質化而製造性或加工性降低，因此Cr含量係設為18.5%以下。較佳為Cr含量係17.5%以上且18.5%以下之範圍。 Cr is an element required to improve corrosion resistance and oxidation resistance. In order to obtain good corrosion resistance and oxidation resistance, it is necessary to contain 17.0% or more of Cr. If the Cr content is less than 17.0%, the oxide scale layer tends to increase, and not only the skin layer adhesion is reduced, but also the thermal fatigue characteristics may be reduced. Furthermore, the corrosion resistance in condensed water is not sufficiently obtained. On the other hand, if Cr is contained in an amount exceeding 18.5%, the steel is hardened and the manufacturability or processability is reduced. Therefore, the Cr content is set to 18.5% or less. The Cr content is preferably in a range of 17.5% to 18.5%.

N：0.015%以下     N: 0.015% or less    

N由於使鋼之韌性及加工性降低，故而較理想為較少，又，若N含量較多，則粗大之TiN析出，與TiN相伴，NbC大量地析出，從而鋼中固溶Nb量減少，由此熱疲勞特性降低。進而以粗大之TiN為起點，氧化皮層變得容易剝離，皮層密接性亦降低，因此N含量係設為0.015%以下。較佳為N含量為0.012%以下。更佳為N含量為0.010%以下。 N reduces the toughness and workability of the steel, so it is ideally less. Also, if the N content is large, coarse TiN precipitates, and along with TiN, NbC precipitates in large amounts, thereby reducing the amount of solid solution Nb in the steel. This reduces thermal fatigue characteristics. Furthermore, starting from the coarse TiN, the oxide scale layer is easily peeled and the skin layer adhesiveness is also reduced. Therefore, the N content is set to 0.015% or less. The N content is preferably 0.012% or less. More preferably, the N content is 0.010% or less.

Nb：0.40%以上且0.80%以下     Nb: 0.40% or more and 0.80% or less    

Nb係具有固溶於鋼中，使高溫強度明顯上升而使熱疲勞特性提高之效果之元素。該效果係於含有0.40%以上之Nb時獲得。另一方面，於含有超過0.80%之過量Nb時，不僅使鋼之韌性降低，而且於高溫下形成Laves相(Fe2Nb)而反倒使高溫強度降低，因此Nb含量係設為0.80%以下。Nb含量較佳為0.43%以上，更佳為0.45%以上。又，Nb含量較佳為0.60%以下，更佳為0.50%以下。 Nb is an element that has a solid solution in steel, which significantly increases the high temperature strength and improves the thermal fatigue characteristics. This effect is obtained when Nb is contained in an amount of 0.40% or more. On the other hand, when excessive Nb is contained in excess of 0.80%, not only the toughness of the steel is reduced, but also the Laves phase (Fe 2 Nb) is formed at a high temperature and the high-temperature strength is reduced. Therefore, the Nb content is set to 0.80% or less. The Nb content is preferably 0.43% or more, and more preferably 0.45% or more. The Nb content is preferably 0.60% or less, and more preferably 0.50% or less.

Ti：0.10%以上且0.40%以下     Ti: 0.10% or more and 0.40% or less    

Ti係優先與C、N連結而生成碳氮化物，藉此防止Nb碳氮化物之生成，並且使耐蝕性、成形性及焊接部之晶界腐蝕性提高。為了獲得該等效果，而必須含有0.10%以上之Ti。若Ti含量未達0.10%，則無法使C、N完全地以Ti碳氮化物之形式生成，而形成Nb碳氮化物，從而Nb固溶量減少而熱疲勞特性降低。另一方面，於含有超過0.40%之過量Ti時，Ti碳氮化物之析出量增加，與此相伴，Nb碳氮化物變得容易析出，由此Nb固溶量減少，因此熱疲勞特性降低。進而，由於Ti碳氮化物之析出量增加而皮層密接性亦降低，以粗大之Ti碳氮化物為起點而產生腐蝕，因此亦使耐冷凝水腐蝕性降低。因此，Ti含量係設為0.40%以下。Ti含量較佳為0.15%以上。又，Ti含量較佳為0.30%以下，更佳為0.25%以下。 Ti is preferentially linked to C and N to generate carbonitrides, thereby preventing the formation of Nb carbonitrides, and improving the corrosion resistance, formability, and grain boundary corrosion of the welded portion. In order to obtain these effects, Ti must be contained in an amount of 0.10% or more. If the Ti content is less than 0.10%, C and N cannot be completely formed as Ti carbonitrides, and Nb carbonitrides are formed. As a result, the amount of Nb solid solution decreases and thermal fatigue characteristics decrease. On the other hand, when excessive Ti is contained in excess of 0.40%, the precipitation amount of Ti carbonitrides increases, and as a result, Nb carbonitrides are easily precipitated, so that the solid solution amount of Nb is reduced, and thus the thermal fatigue characteristics are reduced. Furthermore, since the amount of Ti carbonitrides is increased, the skin adhesion is also reduced, and corrosion occurs due to the coarse Ti carbonitrides as a starting point. Therefore, the corrosion resistance to condensed water is also reduced. Therefore, the Ti content is set to 0.40% or less. The Ti content is preferably 0.15% or more. The Ti content is preferably 0.30% or less, and more preferably 0.25% or less.

Al：0.20%以下     Al: 0.20% or less    

Al係對於去氧有效之元素，該效果係於含有0.01%以上時獲得，因此Al含量較佳為0.01%以上。另一方面，由於使鋼硬質化而使加工性降低，故而Al含量係設為0.20%以下。Al含量更佳為0.02%以上。又，Al含量較佳為0.10%以下，更佳為0.06%以下。 Al is an element effective for deoxidation, and the effect is obtained when it contains 0.01% or more. Therefore, the Al content is preferably 0.01% or more. On the other hand, since the workability is reduced by hardening the steel, the Al content is set to 0.20% or less. The Al content is more preferably 0.02% or more. The Al content is preferably 0.10% or less, and more preferably 0.06% or less.

Ni：0.05%以上且0.40%以下     Ni: 0.05% or more and 0.40% or less    

Ni係於本發明中為了確保皮層密接性而重要之元素，為了獲得該效果而必須含有0.05%以上之Ni。若Ni未達0.05%，則有皮層密接性降低，皮層發生剝離之點成為起點而導致熱疲勞破壞之情形。又，如下所述，本發明之鋼係藉由含有適量之Co而降低熱膨 脹係數，因此與未添加Co之鋼或Co之含量不足之鋼相比，以更少量之Ni含量獲得上述效果。另一方面，Ni為價格昂貴之元素，除此以外，若含有超過0.40%之Ni，則於高溫下生成γ相而反倒使皮層密接性降低。因此，Ni含量係設為0.05%以上且0.40%以下之範圍。Ni含量較佳為0.10%以上，更佳為0.20%以上。又，Ni含量較佳為0.30%以下，更佳為0.25%以下。 Ni is an element important in the present invention to ensure skin adhesion, and in order to obtain this effect, it is necessary to contain 0.05% or more of Ni. If the Ni content is less than 0.05%, the adhesion of the skin layer is lowered, and the point where the skin layer peels off becomes the starting point, which may cause thermal fatigue failure. Further, as described below, the steel of the present invention reduces the thermal expansion coefficient by containing an appropriate amount of Co. Therefore, the above-mentioned effect is obtained with a smaller amount of Ni content than a steel without Co addition or a steel with insufficient Co content. On the other hand, Ni is an expensive element. In addition, if Ni is contained in an amount exceeding 0.40%, a γ phase is generated at a high temperature and the skin adhesion is reduced. Therefore, the Ni content is set to a range of 0.05% to 0.40%. The Ni content is preferably 0.10% or more, and more preferably 0.20% or more. The Ni content is preferably 0.30% or less, and more preferably 0.25% or less.

Co：0.01%以上且0.30%以下     Co: 0.01% or more and 0.30% or less    

Co於本發明中為重要之元素。Co係提高熱疲勞特性所需要之元素，因此，必須含有至少0.01%以上之Co。Co係降低鋼之熱膨脹係數而使升溫時之膨脹量變少，從而使於升溫及冷卻時所產生之應變量變小，藉此可提高熱疲勞特性。進而，藉由鋼之熱膨脹係數減少，而鋼與皮層之熱膨脹係數之差變小，從而於冷卻時皮層變得不易剝離。因此，藉由含有更少量之Ni而有可防止皮層之剝離之效果。另一方面，若含有超過0.30%之Co，則於氧化皮膜與亞鐵酸鹽之界面Co濃化，而皮層密接性降低。若含有超過0.30%之Co，則該界面濃化之副作用會抵消由上述熱膨脹係數減少造成之皮層剝離防止效果，而於冷卻時皮層剝離。因此，Co含量係設為0.01%以上且0.30%以下。Co含量較佳為0.02%以上，更佳為0.03%以上。又，Co含量較佳為0.10%以下。 Co is an important element in the present invention. Co is an element required for improving thermal fatigue characteristics, and therefore, it must contain at least 0.01% of Co. Co system reduces the thermal expansion coefficient of steel, reduces the expansion amount during heating, and reduces the amount of strain generated during heating and cooling, thereby improving thermal fatigue characteristics. Furthermore, as the thermal expansion coefficient of the steel decreases, the difference between the thermal expansion coefficient of the steel and the skin layer becomes smaller, so that the skin layer becomes difficult to peel off during cooling. Therefore, by containing a smaller amount of Ni, there is an effect of preventing peeling of the skin layer. On the other hand, if Co is contained in excess of 0.30%, Co is concentrated at the interface between the oxide film and the ferrite, and the adhesion of the skin layer is reduced. If Co is contained in excess of 0.30%, the side effect of thickening the interface will offset the skin layer peeling prevention effect caused by the decrease in the above-mentioned thermal expansion coefficient, and the skin layer peels during cooling. Therefore, the Co content is set to 0.01% to 0.30%. The Co content is preferably 0.02% or more, and more preferably 0.03% or more. The Co content is preferably 0.10% or less.

Mo：0.02%以上且0.30%以下     Mo: 0.02% or more and 0.30% or less    

Mo係藉由固溶強化使鋼之強度增加而使熱疲勞特性提高，並且使耐鹽害腐蝕性提高，藉此使耐冷凝水腐蝕性提高之元素，該效 果係於含有0.02%以上之Mo時獲得。然而，Mo係價格昂貴之元素，並且若大量地含有Mo，則不僅產生表面缺陷，而且室溫下之加工性亦降低。為了不產生表面缺陷而獲得良好之表面性狀，Mo含量必須設為0.30%以下。因此，Mo含量係設為0.02%以上且0.30%以下之範圍。Mo含量較佳為0.04%以上。又，Mo含量較佳為0.10%以下。 Mo is an element that increases the strength of steel through solid solution strengthening, improves thermal fatigue characteristics, and improves salt corrosion resistance, thereby improving the corrosion resistance of condensed water. The effect is that Mo contains 0.02% or more Get it. However, Mo is an expensive element, and if Mo is contained in a large amount, not only surface defects are generated, but processability at room temperature is also reduced. In order to obtain good surface properties without causing surface defects, the Mo content must be 0.30% or less. Therefore, the Mo content is set to a range of 0.02% to 0.30%. The Mo content is preferably 0.04% or more. The Mo content is preferably 0.10% or less.

Cu：0.02%以上且0.40%以下     Cu: 0.02% or more and 0.40% or less    

Cu具有如下效果：藉由以ε-Cu之形式微細地析出而強化鋼而使熱疲勞特性提高，並且使耐硫酸腐蝕性提高，藉此使耐冷凝水腐蝕性提高。為了獲得該等效果，而必須含有0.02%以上之Cu。另一方面，若含有超過0.40%之Cu，則氧化皮層密接性降低而耐反覆氧化性降低。進而，ε-Cu變得容易粗大地析出而耐冷凝水腐蝕性亦降低。因此，Cu含量係設為0.40%以下。因此，Cu含量係設為0.02%以上且0.40%以下之範圍。Cu含量較佳為0.04%以上。又，Cu含量較佳為0.10%以下。 Cu has the effect of strengthening the steel by fine precipitation in the form of ε-Cu to improve the thermal fatigue characteristics and the sulfuric acid corrosion resistance, thereby improving the corrosion resistance of condensed water. In order to obtain these effects, Cu must be contained in an amount of 0.02% or more. On the other hand, if Cu is contained in an amount exceeding 0.40%, the adhesion of the oxide layer is lowered and the reoxidation resistance is lowered. Furthermore, ε-Cu is liable to precipitate coarsely, and the corrosion resistance to condensation water is also reduced. Therefore, the Cu content is set to 0.40% or less. Therefore, the Cu content is set to a range of 0.02% or more and 0.40% or less. The Cu content is preferably 0.04% or more. The Cu content is preferably 0.10% or less.

於本發明中，Mo與Cu分別使耐鹽害腐蝕性、耐硫酸腐蝕性提高，藉此使耐冷凝水腐蝕性提高，因此若單獨地含有Mo或Cu，則未獲得充分之耐冷凝水腐蝕性。於本發明中，由於含有適量之Mo與Cu兩者，故而獲得優異之耐冷凝水腐蝕性。 In the present invention, Mo and Cu respectively improve salt corrosion resistance and sulfuric acid corrosion resistance, thereby improving condensation water corrosion resistance. Therefore, if Mo or Cu is contained alone, sufficient condensation water corrosion resistance is not obtained. Sex. In the present invention, since both Mo and Cu are contained in appropriate amounts, excellent condensed water corrosion resistance is obtained.

C%+N%：0.018%以下 (1)     C% + N%: below 0.018% (1)    

式(1)中，C%、N%分別表示C、N之含量(質量%)。如上所述，關於C與N，就韌性、加工性、耐皮層剝離性之觀點而言，將各自 之含量設為0.010%以下且0.015%以下。進而，於本發明中，就熱疲勞特性之觀點而言，將C%+N%如上述式(1)般限定為0.018%以下。於C%+N%超過0.018%之情形時，粗大之Ti氮化物(TiN)大量地生成，與此相伴，NbC於TiN之周圍析出，因此NbC之析出量變多。若NbC之析出量變多，則固溶於鋼中之Nb量減少，而鋼之高溫強度降低，因此不會充分地獲得熱疲勞特性提高效果。因此，於複合添加有Nb與Ti之本發明中，為了充分地獲得Nb之固溶強化量，而將C%+N%設為0.018%以下。較佳為C%+N%為0.015%以下。於C%+N%為0.015%以下之情形時，所析出之TiN或NbC成為微細者，進而TiN微細化，藉此於其周圍析出之NbC之析出量減少，而鋼中固溶Nb量增加。進而，NbC本身微細地析出，藉此亦獲得析出強化效果。藉由該等效果而熱疲勞特性提高。更佳為C%+N%設為0.013%以下。 In Formula (1), C% and N% represent the content (mass%) of C and N, respectively. As described above, from the viewpoints of toughness, processability, and peel resistance of C and N, the respective contents are set to 0.010% or less and 0.015% or less. Furthermore, in this invention, from a viewpoint of a thermal fatigue characteristic, C% + N% is limited to 0.018% or less like Formula (1) mentioned above. When C% + N% exceeds 0.018%, coarse Ti nitrides (TiN) are formed in large quantities, and along with this, NbC precipitates around TiN, so the amount of NbC precipitates increases. If the amount of NbC precipitates increases, the amount of Nb solid-dissolved in the steel decreases, and the high-temperature strength of the steel decreases, so the effect of improving the thermal fatigue characteristics will not be sufficiently obtained. Therefore, in the present invention in which Nb and Ti are added in combination, in order to sufficiently obtain the solid solution strengthening amount of Nb, C% + N% is set to 0.018% or less. The C% + N% is preferably 0.015% or less. When C% + N% is less than 0.015%, the precipitated TiN or NbC becomes finer, and then TiN is refined, so that the amount of NbC precipitated around it decreases, and the amount of solid solution Nb in steel increases . Furthermore, NbC itself is finely precipitated, thereby obtaining a precipitation strengthening effect. These effects improve the thermal fatigue characteristics. More preferably, C% + N% is set to 0.013% or less.

本發明係皮層密接性與熱疲勞特性優異，並且耐冷凝水腐蝕性亦優異之肥粒鐵系不鏽鋼，其特徵在於含有上述必須成分，且剩餘部分包含Fe及不可避免之雜質。進而，可視需要以下述範圍含有選自Ca、Mg及B中之1種或2種以上、及/或選自V、W及Zr中之1種或2種以上。 The ferritic iron-based stainless steel which is excellent in the skin layer's adhesiveness and thermal fatigue characteristics, and also has excellent corrosion resistance to condensed water, is characterized by containing the above-mentioned essential components, and the remainder contains Fe and inevitable impurities. Furthermore, if necessary, one or two or more kinds selected from Ca, Mg, and B, and / or one or two or more kinds selected from V, W, and Zr may be contained in the following range.

Ca：0.000.5%以上且0.0030%以下     Ca: 0.000.5% or more and 0.0030% or less    

Ca係對於防止連鑄時容易產生之由Ti系介在物析出引起之噴嘴之堵塞有效的成分。該效果係於含有0.0005%以上之Ca時獲得。另一方面，為了不使表面缺陷產生而獲得良好之表面性狀，Ca含量較佳為設為0.0030%以下。因此，於含有Ca之情形時，Ca含量 較佳為設為0.0005%以上且0.0030%以下之範圍。更佳為Ca含量為0.0005%以上且0.0020%以下之範圍。進而較佳為Ca含量為0.0005%以上且0.0015%以下之範圍。 The Ca-based component is effective for preventing clogging of the nozzle caused by the precipitation of Ti-based intermediary substances which are easily generated during continuous casting. This effect is obtained when Ca is contained in an amount of 0.0005% or more. On the other hand, in order to obtain good surface properties without causing surface defects, the Ca content is preferably set to 0.0030% or less. Therefore, when Ca is contained, the Ca content is preferably set to a range of 0.0005% to 0.0030%. The Ca content is more preferably in a range of 0.0005% to 0.0020%. The Ca content is more preferably in a range of 0.0005% to 0.0015%.

Mg：0.0002%以上且0.0020%以下     Mg: 0.0002% or more and 0.0020% or less    

Mg係對於提高加工性或韌性有效之元素。進而Mg係對於抑制Nb或Ti之碳氮化物之粗大化有效之元素。若Ti碳氮化物粗大化，則會成為脆性破裂之起點，因此韌性降低。又，若Nb碳氮化物粗大化，則Nb於鋼中之固溶量降低，因此會導致熱疲勞特性降低。上述提高加工性及韌性，或抑制Nb及Ti之碳氮化物之粗大化的效果係於含有0.0002%以上之Mg時獲得。另一方面，若Mg含量超過0.0020%，則有使鋼之表面性狀變差之情形。因此，於含有Mg之情形時，Mg含量較佳為設為0.0002%以上且0.0020%以下之範圍。Mg含量更佳為0.0004%以上。又，Mg含量更佳為0.0015%以下，進而更佳為0.0010%以下。 Mg is an element effective for improving workability or toughness. Furthermore, Mg is an element effective for suppressing the coarsening of carbonitrides of Nb or Ti. When the Ti carbonitride is coarsened, it becomes a starting point of brittle fracture, and thus the toughness is reduced. In addition, if the Nb carbonitride is coarsened, the solid solution amount of Nb in the steel is reduced, and thus the thermal fatigue characteristics are reduced. The aforementioned effects of improving workability and toughness, or suppressing coarsening of carbonitrides of Nb and Ti are obtained when Mg is contained in an amount of 0.0002% or more. On the other hand, if the Mg content exceeds 0.0020%, the surface properties of the steel may be deteriorated. Therefore, when Mg is contained, the Mg content is preferably set to a range of 0.0002% or more and 0.0020% or less. The Mg content is more preferably 0.0004% or more. The Mg content is more preferably 0.0015% or less, and even more preferably 0.0010% or less.

B：0.0002%以上且0.0020%以下     B: 0.0002% or more and 0.0020% or less    

B係對於提高加工性、尤其是二次加工性有效之元素。該等效果係於含有0.0002%以上之B時獲得。另一方面，若含有超過0.0020%之B，則有鋼之加工性、韌性降低之情形，因此B含量係設為0.0020%以下。因此，於含有B之情形時，B含量較佳為設為0.0002%以上且0.0020%以下之範圍。B含量更佳為0.0003%以上。又，B含量更佳為0.0010%以下。 B is an element effective for improving workability, especially secondary workability. These effects are obtained when B is contained in an amount of 0.0002% or more. On the other hand, if B is contained in an amount exceeding 0.0020%, the workability and toughness of the steel may be reduced. Therefore, the B content is set to 0.0020% or less. Therefore, when B is contained, the B content is preferably set to a range of 0.0002% or more and 0.0020% or less. The B content is more preferably 0.0003% or more. The B content is more preferably 0.0010% or less.

V：0.01%以上且0.50%以下     V: 0.01% or more and 0.50% or less    

V係對於高溫強度之提高有效之元素。又，亦具有抑制Ti或Nb之碳氮化物粗大化之效果。該效果係於含有0.01%以上之V時獲得。另一方面，若含有超過0.50%之V，則有粗大之V(C、N)析出而韌性降低之情形。因此，於含有V之情形時，V含量較佳為設為0.01%以上且0.50%以下之範圍。V含量更佳為0.02%以上。又，V含量更佳為0.20%以下。 V is an element effective for improving high temperature strength. It also has the effect of suppressing coarsening of carbonitrides of Ti or Nb. This effect is obtained when V is contained at 0.01% or more. On the other hand, if V is contained in excess of 0.50%, coarse V (C, N) may precipitate and the toughness may decrease. Therefore, when V is contained, the V content is preferably set to a range of 0.01% to 0.50%. The V content is more preferably 0.02% or more. The V content is more preferably 0.20% or less.

W：0.02%以上且0.30%以下     W: 0.02% or more and 0.30% or less    

W係與Mo同樣地，藉由固溶強化而使鋼之強度增加之元素，該效果係於含有0.02%以上之W時獲得。然而，W係價格昂貴之元素，又，若大量地含有W，則不僅產生表面缺陷，而且韌性等加工性大幅降低。為了獲得良好之表面性狀，W含量較佳為設為0.30%以下。因此，於含有W之情形時，W含量較佳為設為0.02%以上且0.30%以下之範圍。 W is an element that increases the strength of steel by solid solution strengthening, similar to Mo. This effect is obtained when W is contained in an amount of 0.02% or more. However, W is an expensive element, and if W is contained in a large amount, not only surface defects occur, but also workability such as toughness is greatly reduced. In order to obtain good surface properties, the W content is preferably set to 0.30% or less. Therefore, when W is contained, the W content is preferably set to a range of 0.02% or more and 0.30% or less.

Zr：0.005%以上且0.50%以下     Zr: 0.005% or more and 0.50% or less    

Zr係提高耐氧化性之元素。為了獲得該效果，較佳為將Zr含量設為0.005%以上。另一方面，若Zr含量超過0.50%，則Zr金屬間化合物析出而鋼變得容易脆化。因此，於含有Zr之情形時，Zr含量較佳為設為0.005%以上且0.50%以下。 Zr is an element that improves oxidation resistance. To obtain this effect, the Zr content is preferably set to 0.005% or more. On the other hand, if the Zr content exceeds 0.50%, the Zr intermetallic compound precipitates and the steel becomes easily brittle. Therefore, when Zr is contained, the Zr content is preferably set to 0.005% or more and 0.50% or less.

繼而，對本發明之肥粒鐵系不鏽鋼之製造方法進行說明。 Next, a method for manufacturing the ferrous iron-based stainless steel according to the present invention will be described.

本發明之肥粒鐵系不鏽鋼可使用通常之不鏽鋼之製 造方法。將包含上述成分組成之鋼於轉爐、電爐等熔解爐中進行熔製，進而經由盛桶精煉、真空精煉等2次精煉，並利用連鑄法或鑄錠-開坯輥軋法製成鋼片(鋼坯)，實施熱軋、熱軋板退火、酸洗而製成熱軋退火酸洗板。進而推薦經由冷軋、精退火、酸洗等各步驟而製成冷軋退火板之方法。一例係如下所述。 The ferritic iron-based stainless steel of the present invention can be produced by a usual method of stainless steel. The steel containing the above-mentioned composition is melted in a melting furnace such as a converter, an electric furnace, and the like, and then refined through secondary refining such as ladle refining and vacuum refining, and a continuous casting method or an ingot-open billet rolling method is used to make steel sheets (Slab), hot-rolled, hot-rolled sheet annealing, and pickling are performed to form a hot-rolled annealed pickled sheet. Furthermore, a method for forming a cold-rolled annealed sheet through various steps such as cold rolling, finish annealing, and pickling is recommended. An example is as follows.

於轉爐或電爐等中進行熔製，藉由氬氧脫碳(AOD，Argon Oxygen Decarburization)法或真空吹氧脫碳(VOD，Vacuum Oxygen Decarburization)法進行二次精煉，而熔製上述成分組成之熔鋼，藉由連鑄法製成鋼坯。將該鋼坯加熱至1000~1250℃，藉由熱軋而製成所需板厚之熱軋板。將該熱軋板於900℃~1100℃之溫度下實施連續退火後，藉由噴丸與酸洗進行脫皮層而製成熱軋退火酸洗板。亦能夠將該熱軋退火酸洗板直接地用於排氣岐管或凸緣、管或消音器等本發明之對象之用途，但亦可進而進行冷軋及退火、酸洗而製成冷軋退火酸洗板。於該冷軋步驟中，亦可視需要進行包含中間退火之2次以上之冷軋。包含1次或2次以上之冷軋之冷軋步驟之總軋縮率係設為60%以上、較佳為70%以上。冷軋板退火溫度為900~1150℃，較佳為950~1100℃。又，根據用途，亦可於酸洗後施加輕度之輥軋(調質軋製等)而調整鋼板之形狀、品質。又，亦可設為光澤退火精加工(Bright Annealed Finish)，即於包含氫之還原氣氛下進行退火而省略酸洗。 Melting in a converter or electric furnace, etc., secondary refining is performed by the Argon Oxygen Decarburization (AOD) method or the Vacuum Oxygen Decarburization (VOD) method, and the above components are melted. Molten steel is made into billets by continuous casting. The slab is heated to 1000 to 1250 ° C, and a hot-rolled sheet having a desired thickness is produced by hot rolling. The hot-rolled sheet was subjected to continuous annealing at a temperature of 900 ° C to 1100 ° C, and then a peeling layer was performed by shot blasting and pickling to prepare a hot-rolled annealed pickled sheet. The hot-rolled, annealed and pickled sheet can also be used directly for the purposes of the present invention, such as exhaust manifolds, flanges, tubes, or mufflers, but it can also be cold-rolled, annealed, and pickled to produce cold Roll annealed pickled plate. In this cold rolling step, if necessary, two or more cold rollings including intermediate annealing may be performed. The total reduction ratio of the cold rolling step including one or two or more cold rolling steps is set to 60% or more, and preferably 70% or more. The annealing temperature of the cold rolled sheet is 900 ~ 1150 ° C, preferably 950 ~ 1100 ° C. Depending on the application, the shape and quality of the steel sheet may be adjusted by applying mild rolling (such as temper rolling) after pickling. In addition, it may be set as Bright Annealed Finish, that is, annealing is performed in a reducing atmosphere containing hydrogen, and pickling is omitted.

使用以上述方式製造所得之熱軋退火板製品或冷軋退火板製品，實施與各自用途相符之彎曲加工等，而成形為汽車或機車之排氣管、觸媒外筒材及火力發電設備之排氣通道或燃料電池相關構件。用以將該等構件焊接之焊接方法並無特別限定，可應用 鎢極鈍氣電弧焊(TIG，tungsten inert gas arc welding)、金屬極鈍氣電弧焊(MIG，metal inert gas arc welding)、混合氣遮護金屬電孤焊(MAG，metal active gas arc welding)等各種弧焊方法、或者點焊、縫焊等電阻焊方法、及電縫焊方法等高頻電阻焊、高頻感應焊。 Using the hot-rolled annealed plate products or cold-rolled annealed plate products manufactured in the above-mentioned manner, and performing bending processing according to their respective applications, etc., they are formed into exhaust pipes for automobiles or locomotives, outer cylinders for catalysts, and thermal power generation equipment Exhaust passage or fuel cell related components. The welding method for welding these components is not particularly limited, and tungsten inert gas arc welding (TIG), metal inert gas arc welding (MIG), or hybrid Various arc welding methods such as MAG (metal active gas arc welding), or resistance welding methods such as spot welding and seam welding, and high frequency resistance welding and high frequency induction welding such as electric seam welding.

[實施例]     [Example]    

將具有表1所示之成分組成之No.1~40之鋼於真空熔解爐中進行熔製、鑄造而製成30kg鋼塊。繼而，加熱至1170℃後，進行熱軋而製成厚度35mm×寬度150mm之板片。將該板片一分為二。將其中一個藉由鍛造而製成剖面為30mm×30mm之角棒，於950~1050℃之範圍內進行退火後，進行機械加工，而製作圖1所示之熱疲勞試片。使用該試片而進行下述之熱疲勞試驗。關於退火溫度，係於950~1050℃之溫度範圍內確認組織並且逐個成分地設定。關於以下之退火，亦相同。 The steel having No. 1 to 40 having the component composition shown in Table 1 was melted and cast in a vacuum melting furnace to make a 30 kg steel block. Then, after heating to 1170 ° C., hot rolling was performed to produce a sheet having a thickness of 35 mm × width of 150 mm. Divide the plate into two. One of them was made into an angle rod having a cross section of 30 mm × 30 mm by forging, and was annealed in a range of 950 to 1050 ° C, and then machined to produce a thermal fatigue test piece shown in FIG. 1. Using this test piece, the following thermal fatigue test was performed. Regarding the annealing temperature, the structure is confirmed within a temperature range of 950 to 1050 ° C and is set on a component-by-component basis. The same applies to the following annealing.

使用上述一分為二後之另一個板片，加熱至1050℃後，進行熱軋而製成板厚5mm之熱軋板。其後，於900~1050℃之溫度範圍內進行熱軋板退火，進行酸洗而製作熱軋退火酸洗板。於該階段用肉眼觀察鋼板之表面性狀。藉由冷軋將其之板厚設為2mm，於900~1050℃之溫度範圍內進行精退火而製成冷軋退火板。將其供於下述之反覆氧化試驗及冷凝水浸漬試驗。 The other sheet after being divided into two was heated to 1050 ° C and then hot rolled to produce a hot rolled sheet having a thickness of 5 mm. Thereafter, the hot-rolled sheet is annealed in a temperature range of 900 to 1050 ° C, and pickled to produce a hot-rolled annealed pickled sheet. At this stage, the surface properties of the steel plate were observed with the naked eye. The sheet thickness was set to 2 mm by cold rolling, and finish annealing was performed in a temperature range of 900 to 1050 ° C to produce a cold rolled annealed sheet. These were subjected to the following repeated oxidation test and condensed water immersion test.

<反覆氧化試驗>     <Repeat oxidation test>    

自上述冷軋退火板切出20mm寬×30mm長之尺寸，利用#320研磨紙(emery paper)對全部6個面進行研磨後供於試驗。氧化試驗條件係於大氣中，將於1000℃下保持20min及於100℃下保持1min 反覆400個循環。關於加熱速度及冷卻速度，係分別以5℃/sec、1.5℃/sec進行。於試驗後目視觀察皮層有無剝離，而評價皮層密接性。將所獲得之結果全部示於表1中。 A size of 20 mm wide by 30 mm long was cut out from the cold-rolled annealed sheet, and all 6 sides were polished with # 320 polishing paper (emery paper) for testing. The oxidation test conditions are in the atmosphere, and will be maintained at 1000 ° C for 20min and 100 ° C for 1min. Repeat 400 cycles. The heating rate and cooling rate were performed at 5 ° C / sec and 1.5 ° C / sec. After the test, the skin layer was visually observed for peeling, and the skin layer adhesion was evaluated. The obtained results are all shown in Table 1.

<熱疲勞試驗>     <Thermal fatigue test>    

針對上述熱疲勞試驗用試片，於200~900℃間反覆進行加熱、冷卻，與此同時，於如圖2所示之拘束率0.6下反覆賦予應變，從而測定熱疲勞壽命。測定方法係依據日本材料學會標準 高溫低循環試驗法(JSMS-SD-7-03)。首先，用各循環之於200℃下所檢測到之負重除以圖1所示之試片均熱平行部之剖面面積(50.3mm2)，而設為該循環之應力。將該循環中之應力相對於行為穩定之第5個循環之應力降低至75%的循環數設為熱疲勞壽命。用該壽命循環數來評價熱疲勞特性。將所獲得之結果全部示於表1中。 The test piece for the thermal fatigue test was repeatedly heated and cooled at 200 to 900 ° C, and strain was repeatedly applied at a restraint rate of 0.6 as shown in FIG. 2 to measure the thermal fatigue life. The measurement method is based on the Japanese Society of Materials Standard High Temperature and Low Cycle Test Method (JSMS-SD-7-03). First, the load detected at 200 ° C. for each cycle is divided by the cross-sectional area (50.3 mm 2 ) of the soaking parallel portion of the test piece shown in FIG. 1, and the stress is set as the stress of the cycle. The number of cycles in which the stress in this cycle was reduced to 75% of the stress in the fifth cycle with stable behavior was defined as the thermal fatigue life. The number of life cycles was used to evaluate the thermal fatigue characteristics. The obtained results are all shown in Table 1.

再者，關於上述拘束率，如圖2所示，拘束率η=a/(a+b)，a係(自由熱膨脹應變量-控制應變量)/2，b係控制應變量/2。又，所謂自由熱膨脹應變量，係於完全不賦予機械應力而升溫之情形時之應變量，所謂控制應變量，係表示相對於在室溫下完全不負載應力之狀態的應變量。因拘束而於材料產生之實質拘束應變量係(自由熱膨脹應變量-控制應變量)，即，相對於自由熱膨脹應變量之應變量。 In addition, as shown in FIG. 2, the restraint rate described above is a restraint rate η = a / (a + b), a is (free thermal expansion strain-control strain) / 2, and b is control strain / 2. In addition, the so-called free thermal expansion strain is a strain when the temperature is raised without giving mechanical stress at all, and the so-called control strain is a strain that represents a state with no stress at room temperature at all. The material restraint strain generated by the restraint on the material (free thermal expansion strain-control strain) is the strain relative to the free thermal expansion strain.

<冷凝水浸漬試驗>     <Condensation water immersion test>    

自上述中所製作之冷軋退火板切出60mm寬×80mm長之尺寸，利用#320研磨紙對全部6個面進行研磨後供於試驗。於試驗時 端部經保護帶被覆。試驗溶液係模擬冷凝水，並調整為包含Cl-：500ppm、SO4 2-：1000ppm且pH值：4。以使溫度成為80℃之方式保持於恆溫槽內。試驗係將溶液浸漬2小時及乾燥6小時設為1組而進行30組。試驗後，將腐蝕生成物去除，測定試驗前後之重量，藉此算出腐蝕失重。 A 60 mm width × 80 mm length was cut out from the cold-rolled annealed sheet produced above, and all 6 sides were polished with # 320 abrasive paper for testing. The end is covered with a protective tape during the test. The test solution was simulated to condense water and adjusted to include Cl − : 500 ppm, SO 4 2 − : 1000 ppm, and pH: 4. The temperature was maintained in a thermostatic bath so that the temperature became 80 ° C. The test was performed by immersing the solution for 2 hours and drying for 6 hours. After the test, the corrosion product was removed, and the weight before and after the test was measured to calculate the weight loss of the corrosion.

再者，於表1中，各試驗之判定基準係如下所述。 In addition, in Table 1, the determination criteria of each test are as follows.

(1)皮層密接性：將反覆氧化試驗後之試片表面皮層剝離之面積為0%(利用目視觀察未發現皮層剝離)者判定為◎(合格)，將超過0%且未達5%者判定為○(合格)，將為5%以上者判定為×(不合格)。 (1) Cortex adhesion: The skin peeling area on the surface of the test piece after the repeated oxidation test is 0% (the skin peeling is not found by visual observation) is judged as ◎ (pass), and it is more than 0% and less than 5% It was judged as ○ (passed), and those with 5% or more were judged as x (unacceptable).

(2)熱疲勞特性：將熱疲勞壽命為750個循環以上者判定為◎(合格)，將為660個循環以上且未達750個循環者判定為○(合格)，將未達660個循環判定為×(不合格)。 (2) Thermal fatigue characteristics: Those who have a thermal fatigue life of 750 cycles or more are judged as ◎ (passed), those who have 660 cycles or more and less than 750 cycles are judged as ○ (passed), and have not reached 660 cycles It was judged as x (unsatisfactory).

(3)耐冷凝水腐蝕性：將腐蝕失重為5g/m2以下者設為◎(合格)，將超過5g/m2且為10g/m2以下者設為○(合格)，將超過10g/m2者設為×(不合格)。 (3) Corrosion resistance to condensed water: Set the weight loss of corrosion to 5 g / m 2 or less as ◎ (pass), set the weight loss of more than 5 g / m 2 to 10 g / m 2 as ○ (pass), or exceed 10 g / m 2 is set to × (Failure).

根據表1，作為本發明例之No.1~20及36~40係全部皮層密接性及熱疲勞特性、耐冷凝水腐蝕性均優異。Si與Ni之含量為較佳範圍(Si≧0.30%及Ni≧0.20%)之本發明例No.2~4、6、9、10、12、14~16、19、20、36~40係皮層密接性尤其優異。C+N與Ti、Co、Mo、Cu之含量為較佳範圍(C+N≦0.015%、Ti≧0.15%、Co≧0.02%、Mo≧0.04%、Cu≧0.04%)之本發明例No.1、2、6~11、16、38係熱疲勞特性尤其優異。Mo與Cu之含量為較佳範圍(Mo≧0.04%及Cu≧0.04%)之本發明例No.1、2、6~11、16、18、36~40係耐冷凝水腐蝕性尤其優異。又，本發明例之全部熱軋退火酸洗板之表面性狀係無表面缺陷而良好。 According to Table 1, all the skin layers No. 1 to 20 and 36 to 40, which are examples of the present invention, are excellent in adhesiveness, thermal fatigue characteristics, and corrosion resistance to condensation water. Examples No. 2 ~ 4,6,9,10,12,14 ~ 16,19,20,36 ~ 40 of the present invention whose content of Si and Ni are in a better range (Si ≧ 0.30% and Ni ≧ 0.20%) Cortical adhesion is particularly excellent. Contents of C + N and Ti, Co, Mo, Cu in a preferred range (C + N ≦ 0.015%, Ti ≧ 0.15%, Co ≧ 0.02%, Mo ≧ 0.04%, Cu ≧ 0.04%) .1,2,6 ~ 11,16,38 series are particularly excellent in thermal fatigue characteristics. Examples No. 1, 2, 6-11, 16, 18, 36-40 of the present invention in which the content of Mo and Cu are in a preferred range (Mo ≧ 0.04% and Cu ≧ 0.04%) are particularly excellent in corrosion resistance to condensed water. In addition, the surface properties of all the hot-rolled annealed pickled plates of the examples of the present invention are good without surface defects.

另一方面，Mo與Cu均未達本發明範圍之下限值之比較例No.21、24；Cu未達本發明範圍之下限值之比較例No.22；Mo未達本發明範圍之下限值之比較例No.23均耐冷凝水腐蝕性變得不合格。 On the other hand, Comparative Examples No. 21 and 24 where neither Mo nor Cu falls below the lower limit of the scope of the invention; Comparative Example No. 22 where Cu falls below the lower limit of the scope of the invention; Mo does not reach the lower limit of the invention In Comparative Example No. 23 of the lower limit, the corrosion resistance to condensation water was unacceptable.

C+N超過本發明範圍之上限值之比較例No.25係熱疲勞特性變得不合格。Co未達本發明範圍之下限值之比較例No.26係熱疲勞特性變得不合格。Ni未達本發明範圍之下限值之比較例No.27係皮層密接性與熱疲勞特性變得不合格。 The thermal fatigue characteristics of Comparative Example No. 25 whose C + N exceeded the upper limit of the range of the present invention became unacceptable. The thermal fatigue characteristics of Comparative Example No. 26, in which Co was below the lower limit of the scope of the present invention, became unacceptable. In Comparative Example No. 27, in which Ni did not reach the lower limit of the scope of the present invention, the adhesion and thermal fatigue characteristics of the cortical layer were unacceptable.

Ni與Co均未達本發明範圍之下限值之比較例No.28係皮層密接性與熱疲勞特性變得不合格。Cu超過本發明範圍之上限值之比較例No.29係皮層密接性、耐冷凝水腐蝕性變得不合格。 In Comparative Example No. 28, where both Ni and Co did not reach the lower limit of the scope of the present invention, the adhesion and thermal fatigue characteristics of the cortical layer were unacceptable. Comparative Example No. 29 based on Cu exceeding the upper limit of the range of the present invention was unsatisfactory in terms of adhesion to the skin layer and corrosion resistance to condensation water.

Ti超過本發明範圍之上限值之比較例No.30係皮層密接性、熱疲勞特性、耐冷凝水腐蝕性均變得不合格。C超過本發明範圍之上限值之比較例No.31係皮層密接性與熱疲勞特性，N超過本發明範圍之上限值之比較例No.32係皮層密接性與熱疲勞特性變得不合格。 Comparative Example No. 30 based on Ti exceeding the upper limit of the scope of the present invention was unsatisfactory in terms of skin adhesion, thermal fatigue characteristics, and corrosion resistance to condensation water. The comparative example No. 31 based on C exceeding the upper limit of the range of the present invention and the thermal fatigue characteristics, and the comparative example No. 32 based on the upper limit of the range of the present invention and the thermal fatigue characteristics qualified.

Cr未達本發明範圍之下限值之比較例No.33係皮層密接性、熱疲勞特性、冷凝水腐蝕性均變得不合格。Nb未達本發明範圍之下限值之比較例No.34及Ti未達本發明範圍之下限值之比較例No.35均熱疲勞特性變得不合格。 Comparative Example No. 33, in which Cr did not reach the lower limit of the scope of the present invention, had poor adhesion, thermal fatigue characteristics, and corrosiveness to condensation water. Comparative Example No. 34 in which Nb did not reach the lower limit of the range of the present invention and Comparative Example No. 35 in which Ti did not reach the lower limit of the range of the present invention became unacceptable.

根據以上情況明確，本發明範圍之鋼係皮層密接性、熱疲勞特性、耐冷凝水腐蝕性均優異。 From the above, it is clear that the steel-based skin layer within the scope of the present invention is excellent in adhesion, thermal fatigue characteristics, and resistance to condensation water corrosion.

(產業上之可利用性)     (Industrial availability)    

本發明之肥粒鐵系不鏽鋼板由於皮層密接性、熱疲勞特性、耐冷凝水腐蝕性均優異，故而不僅對於排氣歧管、各種排氣管、凸緣、轉換器外殼(converter case)或消音器等汽車等之排氣系統零件全部較佳，亦能夠以1種鋼種構成全部排氣管零件，而能夠於鋼材之獲取穩定性或焊接性之方面上變得有效率。進而，作為火 力發電系統之排氣系統構件或燃料電池用構件亦較佳。 The ferrous iron-based stainless steel plate of the present invention is excellent in skin adhesion, thermal fatigue characteristics, and corrosion resistance of condensed water, so it is not only applicable to exhaust manifolds, various exhaust pipes, flanges, converter cases, or converter cases. All exhaust system parts such as mufflers and other cars are preferred, and all exhaust pipe parts can also be composed of one type of steel, which can be effective in obtaining stability or weldability of steel materials. Furthermore, it is also preferable as a component of an exhaust system of a thermal power generation system or a component for a fuel cell.

Claims (3)

一種肥粒鐵系不鏽鋼，其具有如下組成，該組成以質量%計含有：C：0.010%以下、Si：1.0%以下、Mn：1.0%以下、P：0.040%以下、S：0.030%以下、Cr：17.0%以上且18.5%以下、N：0.015%以下、Nb：0.40%以上且0.80%以下、Ti：0.10%以上且0.40%以下、Al：0.18%以下、Ni：0.05%以上且0.40%以下、Co：0.01%以上且0.30%以下、Mo：0.02%以上且0.30%以下、Cu：0.02%以上且0.40%以下，且滿足以下之式(1)，並且剩餘部分包含Fe及不可避免之雜質，C%+N%：0.018%以下 (1)式(1)中，C%、N%分別表示C、N之含量(質量%)。A ferrous iron-based stainless steel having the following composition, which is contained in mass%: C: 0.010% or less, Si: 1.0% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, Cr: 17.0% or more and 18.5% or less, N: 0.015% or less, Nb: 0.40% or more and 0.80% or less, Ti: 0.10% or more and 0.40% or less, Al: 0.18% or less, Ni: 0.05% or more and 0.40% or less Below, Co: 0.01% or more and 0.30% or less, Mo: 0.02% or more and 0.30% or less, Cu: 0.02% or more and 0.40% or less, and satisfying the following formula (1), and the remainder contains Fe and unavoidable Impurities, C% + N%: 0.018% or less (1) In formula (1), C% and N% represent the content (mass%) of C and N, respectively. 如請求項1之肥粒鐵系不鏽鋼，其以質量%計進而含有選自Ca：0.0005%以上且0.0030%以下、Mg：0.0002%以上且0.0020%以下、B：0.0002%以上且0.0020%以下中之1種或2種以上。For example, the ferrous iron-based stainless steel according to claim 1 further includes, in mass%, selected from Ca: 0.0005% or more and 0.0030% or less, Mg: 0.0002% or more and 0.0020% or less, and B: 0.0002% or more and 0.0020% or less. One or more of them. 如請求項1或2之肥粒鐵系不鏽鋼，其以質量%計進而含有選自V：0.01%以上且0.50%以下、W：0.02%以上且0.30%以下、Zr：0.005%以上且0.50%以下中之1種或2種以上。For example, the ferrous iron-based stainless steel according to claim 1 or 2 further includes, in mass%, selected from V: 0.01% or more and 0.50% or less, W: 0.02% or more and 0.30% or less, and Zr: 0.005% or more and 0.50% or more. One or more of the following.
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