US3854937A - Pitting corrosion resistant austenite stainless steel - Google Patents

Pitting corrosion resistant austenite stainless steel Download PDF

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Publication number
US3854937A
US3854937A US00207021A US20702171A US3854937A US 3854937 A US3854937 A US 3854937A US 00207021 A US00207021 A US 00207021A US 20702171 A US20702171 A US 20702171A US 3854937 A US3854937 A US 3854937A
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percent
pitting corrosion
weight
corrosion resistance
nickel
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US00207021A
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English (en)
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T Muta
H Abo
S Noguchi
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Nippon Steel Corp
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Nippon Steel Corp
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    • 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
    • C22C38/18—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
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

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  • the present inventors have conducted various extensive studies to develop a pitting corrosion resistant (sea-water) stainless steel having an austenite structure. As a result, the present inventors have found that pitting corrosion resistance is remarkably improved by the combined effects of chromium and nitrogen when chromium is contained in an amount more than 23 percent and nitrogen is contained in an amount more than 0.3 percent, and have completed the development of a pitting corrosion resistant (sea-water) stainless steel having an austenite structure in which nitrogen ismade use of as a strong austenizer.
  • the basic composition of the present inventive stainless steel is:
  • FIGS. 1 and 2 show respectively effects on pitting corrosion resistance-of chromium contents.
  • FIGS. 3 and 4 show effects on pitting corrosion resistance of chromium and nitrogen contents.
  • FIG. 5 shows effects on the amount of solid soluble nitrogen of chromium and manganese contents.
  • FIG. 6 shows effects on pitting corrosion resistance of nickel contents.
  • FIG. 7 shows influences on the structure of chemical compositions.
  • FIG. 8 shows influences on hot workability of chemical compositions.
  • FIGS. 9 and 10 show effects on pitting corrosion resistance and sulfuric acid resistance of molybdenum contents.
  • the following three methods are used: a whole immersion test with a solution of ferric chloride (0.5 FeCl 25C, for 48 hrs.); a whole immersion test with a solution of ferric chloride and hydrochloric acid (50 g/l FeCl 1/20 N HCl, 50C, for 48 hrs.) and measurement of potentials inducing pitting corrosions in a salt solution acidified with sulfuric acid (3% NaCl 5% H 35C).
  • Chromium is a basic alloying element for stainless steels and effective for improving pitting corrosion resistance. From FIGS. 1 and 2, which show the effects on pitting corrosion resistance of chromium additions, it is understood that remarkable improvement of the pitting corrosion resistance is attained with chromium understood that substantially no pitting corrosion is caused when chromium is added in an amount more than 23 percent, judging from the aspects of both the corrosion rate and the pitting corrosion potential. Therefore, in the present invention, the lower limit of the chromium content is set as 23 percent. Although an increased chromium content gives better pitting corrosion resistance, with a chromium content of 30 percent as shown by the triangle mark in FIGS.
  • a twophase structure of ferrite and austenite appears in some grades, which deteriorates the pitting corrosion resistance.
  • hot workability is deteriorated when the chromium content is more than 30 percent, and 475embrittlement and oembrittlement occur more often in spite of the austenite base structure, thus damaging the hot and cold workabilities.
  • the upper limit of the chromium content is set at 30 percent in the present invention.
  • Nitrogen is one of the most important elements in the present inventive steel, and effective together with chromium for remarkably improving the pitting corrosion resistance.
  • FIGS. 3 and 4 show the combined effects on pitting corrosion resistance by chromium and nitrogen. Although nitrogen shows some improvement of pitting corrosion resistance with 18 percent chromium content, the corrosion rate does not decrease below a certain value even when nitrogen is increased and no effective prevention against pitting corrosion can be assured. However, when the chromium content reaches 25 percent, the effects on the improvement of pitting corrosion resistance of nitrogen become very remarkable, and as shown in FIG. 4 substantially no pitting corrosion is observed even by a more severe testing method when the nitrogen content exceeds 0.30 percent. For this reason, the lower limit of nitrogen content is set as 0.30 percent in the present invention.
  • an increased amount of nitrogen is desired, but since nitrogen is a gaseous component, the amount is limited by its solubility in the solid in order to prevent blow holes, which determines an upper limit of the nitrogen content.
  • the amount of nitrogen in solid solution depends on the chromium content as shown in FIG. 5, and with a chromium content of 30 percent, the amount of solid soluble nitrogen is only 0.45 percent. Also the amount of solid soluble nitrogen can be increased by an increased content of manganese, but as understood from FIG. 5, 0.45 percent is the upper limit for nitrogen when the chromium content is 30 percent even when manganese is added in an amount of 5.0 percent. Chromium is limited up to 30 percent from the points of hot and cold workabilities and manganese is limited up to 5.0 percent from the aspects of pitting corrosion resistance and hot workability, so that the upper limit of the nitrogen content is 0.45 percent in the present invention.
  • Nickel is an essential element for assuring the austenite structure of the present inventive stainless steel, and is also effective for improving pitting corrosion resistance to some degree, and also is an essential element for attaining good hot workability in the present inventive stainless steel.
  • the equivalent nickel is 17 percent and the deficit of more than 2 percent may be supplemented by nickel addition.
  • the lower limit of the nickel content has been explained from the points of pitting corrosion resistance and the structure, but in conclusion, 10 percent is the minimum amount of nickel for assuring the desired pitting corrosion resistance.
  • the upper limit of the nickel content is determined from the point of hot workability which is one of the important properties of the present stainless steel.
  • FIG. 8 shows the effects on the hot workability by various chemical compositions.
  • the hot workability is estimated by the maximum edge cracking rate calculated from the maximum value of edge cracking depth of steel billets after .hot rolling.
  • the hot workabilities of the grades containing 10- 12 percent nickel and the grades containing 13 18 percent nickel are considerably different even when the equivalent nickel is the same. As understood from the figure, the hot workability tends to improved as the equivalent nickel is increased. However, at the border line of i2 l3 pecent nickel content, the hot workability is deteriorated when the nickel content is increased beyond the border line. This deterioration of hot working is due to hot embrittlement peculiar to highly alloyed steels, and can be alleviated by limiting the amounts of substitution type solid solution elements (Ni, Mo, Nb, Cr).
  • Ni 30 (C N) g 20 percent is its upper limit within this desired range, but it is possible to improve the hot workability by increasing nitrogen addition and limiting the amount of Mo and Nb so far long as the nickel content is up to 18 percent.
  • the upper limit of the nickel content is set as 18 percent in the present invention.
  • Both Mo and Nb are effective not only for improving the pitting corrosion resistance as well as Cr, N and Ni, but also M0 is effective for improving the resistance against sulfuric acid and Nb is effective for improving the resistance against the intergranular attacks.
  • M0 is effective for improving the resistance against sulfuric acid
  • Nb is effective for improving the resistance against the intergranular attacks.
  • pitting corrosion resistance but also ordinary corrosion resistance may be required.
  • Mo and Nb are sometimes added selectively for such purposes.
  • Mo contents in an amount more than 0.1 percent are required from the points of pitting corrosion resistance and sulfuric acid resistance as shown in FIGS. 9 and 10, and the lower limit of the Mo content is set as 0.1 percent.
  • Nb at least 0.05 percent of Nb is required for pitting corrosion resistance and resistance against intergranular attacks, and the lower limit of Nb addition is set as 0.05 percent.
  • a larger content of M0 is desirous from the points of pitting corrosion resistance and sulfuric acid resistance, but in order to maintain good hot workability as well as the austenite structure, the content of M0 is limited.
  • the upper limit of the Nb content is set as 2 percent in the present invention for the following reason: when the Nb content exceeds 2 percent, carbides and nitrides of niobium are produced in a large amount, thus deteriorating the pitting corrosion resistance, and in addition, fixation of carbon and nitrogen lowers the effective equivalent nickel so that it becomes more difficult to maintain the austenite structure.
  • Copper is not particularly effective for pitting corrosion resistance, but effective for ordinary corrosion resistance, such as, sulfuric acid resistance and hydrochloric acid resistance, and, similarly as Mo and Nb, it is desired to add copper according to the kinds and types of applications in which the steel is used.
  • the reason for setting its lower limit at 0.2 percent is that at copper contents below this limit, no substantial improvement is obtained, while the reason for its upper limit of 5 percent is that copper contents of more than 5 percent remarkably deteriorate the hot workability because of an excess beyond the solid solution limit of copper.
  • Carbon not only deteriorates the pitting corrosion resistance, but also accelerates intergranular attacks remarkably and therefore it is limited to an upper limit of 0.08 percent.
  • Silicon is effective to improve the pitting corrosion resistance to some degree, but is less effective in this respect as compared with Cr, Mo and Nb. Since silicon is a strong ferrite former, its content is limited from the point of maintenance of the austenite structure and its upper limit is set as 4 percent.
  • Manganese is an element which lowers the pitting corrosion resistance, but it is useful in a limited amount for increasing the amount of solid soluble nitrogen and thus increasing the addition of nitrogen which is remarkably effective for improving the pitting corrosion resistance. With manganese contents beyond 6 percent the deterioration of the pitting corrosion resistance increases too much in spite of the above favourable effects, and thus its upper limit is set as 6 percent.
  • Both phosphorus and sulfur are elements which deteriorate pitting corrosion resistance and thus it is desirous to minimize their contents. But these elements are unavoidable impurities which are present during a steel making process.
  • the reason for the upper limit of 0.040 percent for phosphorus is that phosphorus contents beyond this limit cause remarkable damage to weldability which is one of the most important properties of the present inventive steel.
  • the reason for the upper limit of 0.030 percent for sulfur is that its contents beyond this limit deteriorates the hot workability as well as the weldability.
  • All of boron, cerium and titanium improve the hot workability of the present inventive steel, and it is desired to add these elements particularly when severe hot workings are conducted. Although these elements are effective in a very small addition, excessive addition of those elements on the contary damages the cleanness of the steel and deteriorates the hot workability.
  • the upper limits of B, Ce and Ti are set as 0.01, 0.05 and 0.5 percent respectively.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
US00207021A 1970-12-14 1971-12-13 Pitting corrosion resistant austenite stainless steel Expired - Lifetime US3854937A (en)

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JP45110594A JPS508967B1 (pl) 1970-12-14 1970-12-14

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4032367A (en) * 1974-10-28 1977-06-28 Langley Alloys Limited Corrosion resistant steels
US4060389A (en) * 1975-01-10 1977-11-29 Toyo Soda Manufacturing Co., Ltd. Apparatus for use in the ammonia soda process or the ammonium chloride soda process
DE2752083A1 (de) * 1976-12-02 1978-06-08 Allegheny Ludlum Ind Inc Warmverformbarer, austenitischer, nichtrostender stahl
FR2372903A1 (fr) * 1976-12-02 1978-06-30 Allegheny Ludlum Ind Inc Acier inoxydable austenitique resistant a la corrosion
EP0067501A1 (en) * 1981-03-20 1982-12-22 Hitachi, Ltd. Alloy suitable for use in a radioactive radiation environment and a reactor core component formed therefrom
EP0220141A2 (en) * 1985-09-05 1987-04-29 Santrade Ltd. High nitrogen containing duplex stainless steel having high corrosion resistance and good structure stability
EP0333422A1 (en) * 1988-03-17 1989-09-20 Allegheny Ludlum Corporation Austenitic stainless steel
DE3837456C1 (en) * 1988-05-17 1990-03-29 Thyssen Edelstahlwerke Ag, 4000 Duesseldorf, De Use of a fully austenitic steel for components which are severely stressed corrosion-chemically and mechanically
US5393487A (en) * 1993-08-17 1995-02-28 J & L Specialty Products Corporation Steel alloy having improved creep strength
US5783143A (en) * 1994-02-18 1998-07-21 Handa; Takuo Alloy steel resistant to molten zinc
EP1361290A1 (en) * 2002-05-10 2003-11-12 Nippon Steel Corporation Steel for chemical tank, excellent in sulfuric acid corrosion resistance and pitting corrosion resistance
US20050194073A1 (en) * 2004-03-04 2005-09-08 Daido Steel Co., Ltd. Heat-resistant austenitic stainless steel and a production process thereof
US9803267B2 (en) 2011-05-26 2017-10-31 Upl, L.L.C. Austenitic stainless steel

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2839392A (en) * 1955-07-28 1958-06-17 Du Pont Corrosion resistant alloy
US2920954A (en) * 1958-04-15 1960-01-12 Cooper Alloy Corp Stainless steel alloy of high hardness
US3151979A (en) * 1962-03-21 1964-10-06 United States Steel Corp High strength steel and method of treatment thereof
US3152934A (en) * 1962-10-03 1964-10-13 Allegheny Ludlum Steel Process for treating austenite stainless steels
US3306736A (en) * 1963-08-30 1967-02-28 Crucible Steel Co America Austenitic stainless steel
US3567434A (en) * 1967-03-17 1971-03-02 Langley Alloys Ltd Stainless steels
US3615368A (en) * 1967-06-19 1971-10-26 Boehler & Co Ag Geb Nickel-chromium steel having increased resistance to corrosion
US3659882A (en) * 1968-12-02 1972-05-02 Schoeller Bleckman Stahlwerke Nonmagnetic corrosion-resistant drill string members
US3716353A (en) * 1970-03-10 1973-02-13 Nippon Kokan Kk Austenitic heat resisting steel

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT268345B (de) * 1965-03-09 1969-02-10 Schoeller Bleckmann Stahlwerke Austenitischer, korrosionsbeständiger Chrom-Nickel-Mangan-Stickstoff-Stahl für die Herstellung von Gegenständen, die beständig gegen Lochfraß und Spannungsrißkorrosion in Meerwasser sind und Nichtmagnetisierbarkeit und gute Schweißbarkeit aufweisen
GB1079582A (en) * 1965-07-28 1967-08-16 Schoeller Bleckmann Stahlwerke Corrosion -resistant steel alloy

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2839392A (en) * 1955-07-28 1958-06-17 Du Pont Corrosion resistant alloy
US2920954A (en) * 1958-04-15 1960-01-12 Cooper Alloy Corp Stainless steel alloy of high hardness
US3151979A (en) * 1962-03-21 1964-10-06 United States Steel Corp High strength steel and method of treatment thereof
US3152934A (en) * 1962-10-03 1964-10-13 Allegheny Ludlum Steel Process for treating austenite stainless steels
US3306736A (en) * 1963-08-30 1967-02-28 Crucible Steel Co America Austenitic stainless steel
US3567434A (en) * 1967-03-17 1971-03-02 Langley Alloys Ltd Stainless steels
US3615368A (en) * 1967-06-19 1971-10-26 Boehler & Co Ag Geb Nickel-chromium steel having increased resistance to corrosion
US3659882A (en) * 1968-12-02 1972-05-02 Schoeller Bleckman Stahlwerke Nonmagnetic corrosion-resistant drill string members
US3716353A (en) * 1970-03-10 1973-02-13 Nippon Kokan Kk Austenitic heat resisting steel

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4032367A (en) * 1974-10-28 1977-06-28 Langley Alloys Limited Corrosion resistant steels
US4060389A (en) * 1975-01-10 1977-11-29 Toyo Soda Manufacturing Co., Ltd. Apparatus for use in the ammonia soda process or the ammonium chloride soda process
DE2752083A1 (de) * 1976-12-02 1978-06-08 Allegheny Ludlum Ind Inc Warmverformbarer, austenitischer, nichtrostender stahl
FR2372902A1 (fr) * 1976-12-02 1978-06-30 Allegheny Ludlum Ind Inc Acier inoxydable austenitique ductile a chaud
FR2372903A1 (fr) * 1976-12-02 1978-06-30 Allegheny Ludlum Ind Inc Acier inoxydable austenitique resistant a la corrosion
US4099966A (en) * 1976-12-02 1978-07-11 Allegheny Ludlum Industries, Inc. Austenitic stainless steel
EP0067501A1 (en) * 1981-03-20 1982-12-22 Hitachi, Ltd. Alloy suitable for use in a radioactive radiation environment and a reactor core component formed therefrom
EP0220141A2 (en) * 1985-09-05 1987-04-29 Santrade Ltd. High nitrogen containing duplex stainless steel having high corrosion resistance and good structure stability
EP0220141A3 (en) * 1985-09-05 1988-09-28 Santrade Ltd. High nitrogen containing duplex stainless steel having high corrosion resistance and good structure stability
EP0333422A1 (en) * 1988-03-17 1989-09-20 Allegheny Ludlum Corporation Austenitic stainless steel
US4911886A (en) * 1988-03-17 1990-03-27 Allegheny Ludlum Corporation Austentitic stainless steel
DE3837456C1 (en) * 1988-05-17 1990-03-29 Thyssen Edelstahlwerke Ag, 4000 Duesseldorf, De Use of a fully austenitic steel for components which are severely stressed corrosion-chemically and mechanically
US5393487A (en) * 1993-08-17 1995-02-28 J & L Specialty Products Corporation Steel alloy having improved creep strength
US5783143A (en) * 1994-02-18 1998-07-21 Handa; Takuo Alloy steel resistant to molten zinc
EP1361290A1 (en) * 2002-05-10 2003-11-12 Nippon Steel Corporation Steel for chemical tank, excellent in sulfuric acid corrosion resistance and pitting corrosion resistance
US20050194073A1 (en) * 2004-03-04 2005-09-08 Daido Steel Co., Ltd. Heat-resistant austenitic stainless steel and a production process thereof
EP1577414A2 (en) * 2004-03-04 2005-09-21 Daido Steel Co., Ltd. Heat-resistant austenitic stainless steel and a production process thereof
EP1577414A3 (en) * 2004-03-04 2005-11-23 Daido Steel Co., Ltd. Heat-resistant austenitic stainless steel and a production process thereof
US9803267B2 (en) 2011-05-26 2017-10-31 Upl, L.L.C. Austenitic stainless steel

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