US3847599A - Corrosion resistant austenitic steel - Google Patents

Corrosion resistant austenitic steel Download PDF

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Publication number
US3847599A
US3847599A US00403347A US40334773A US3847599A US 3847599 A US3847599 A US 3847599A US 00403347 A US00403347 A US 00403347A US 40334773 A US40334773 A US 40334773A US 3847599 A US3847599 A US 3847599A
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percent
alloy
chromium
nitrogen
alloys
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US00403347A
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English (en)
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A Hartline
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Allegheny Ludlum Corp
Pittsburgh National Bank
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Allegheny Ludlum Industries Inc
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Application filed by Allegheny Ludlum Industries Inc filed Critical Allegheny Ludlum Industries Inc
Priority to US00403347A priority Critical patent/US3847599A/en
Priority to SE7410975A priority patent/SE421430B/xx
Priority to AT779574A priority patent/AT338857B/de
Priority to AU73884/74A priority patent/AU486525B2/en
Priority to DE19742447318 priority patent/DE2447318A1/de
Priority to IT53343/74A priority patent/IT1019356B/it
Priority to BR8195/74A priority patent/BR7408195D0/pt
Priority to FR7433402A priority patent/FR2246645A1/fr
Priority to NL7413055A priority patent/NL7413055A/xx
Priority to BE2053908A priority patent/BE820687A/fr
Priority to AR255924A priority patent/AR202144A1/es
Priority to CA210,802A priority patent/CA1022366A/fr
Priority to JP11463374A priority patent/JPS5737664B2/ja
Application granted granted Critical
Publication of US3847599A publication Critical patent/US3847599A/en
Assigned to ALLEGHENY LUDLUM CORPORATION reassignment ALLEGHENY LUDLUM CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). 8-4-86 Assignors: ALLEGHENY LUDLUM STEEL CORPORATION
Assigned to PITTSBURGH NATIONAL BANK reassignment PITTSBURGH NATIONAL BANK SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ALLEGHENY LUDLUM CORPORATION
Assigned to PITTSBURGH NATIONAL BANK reassignment PITTSBURGH NATIONAL BANK ASSIGNMENT OF ASSIGNORS INTEREST. RECORDED ON REEL 4855 FRAME 0400 Assignors: PITTSBURGH NATIONAL BANK
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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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese

Definitions

  • ABSTRACT A substantially non-porous, austenitic stainless steel that is resistant to dilute sulfuric acid and t0 chloride pitting, and a method of making it, are disclosed.
  • the steel includes from 21-45 percent manganese, from -30 percent chromium, from l-5 percent molybdenum, from 0.85-3 percent nitrogen, up to 2 percent [52 U.S. c1. .[75/122, 75/126 B, 75/126 J, Silicon, up w 1 Percent Carbon and the balance iron 75/129 and residuals.
  • the steel includes from 21-45 percent manganese, from -30 percent chromium, from l-5 percent molybdenum, from 0.85-3 percent nitrogen, up to 2 percent [52 U.S. c1. .[75/122, 75/126 B, 75/126 J, Silicon, up w 1 Percent Carbon and the balance iron 75/129 and residuals.
  • Austenitic stainless steels which are those consisting substantially of a single austenite phase, possess the best properties of corrosion resistance and good mechanical properties, particularly at high temperature. Austenitic stainless steels in the past have been steels in which chromium and nickel are the principal alloying agents. However, nickel is not an abundant metal and the increased demand for it has increased its price and made its supply uncertain, particularly in critical times.
  • the present invention is a chromium-manganesemolybdenum-nitrogen steel that is substantially nonporous, austenitic and highly resistant to attack by sulfuric acid and chloride environments.
  • the alloy of this invention contains from 21-45 percent manganese, from -30 percent chromium, from 1-5 percent molybdenum, from 0.85-3 percent nitrogen, up to 2 percent silicon, up to 1 percent carbon and the balance iron and residuals. All compositions in this specification and the following claims are in percent by weight of the total composition unless otherwise specified.
  • composition of the alloys must be balanced in accordance with the following equations:
  • chromium In the alloys of the present invention, chromium must be present to produce the same effect that it does in prior art alloys.
  • the alloys of this invention must contain from 10-30 percent chromium. At least 10 percent 2 is required to give the steel its outstanding corrosion resistance.
  • Chromium also has a secondary effect upon the strength of the steel and is a primary element in increasing the steels solubility for nitrogen.
  • An upper limit of 30 percent chromium is imposed as chromium is a ferrite former and excessive amounts of ferrite might form with higher chromium levels and in turn degrade the properties of the steel.
  • a preferred chromium content is in the range of 15-27 percent in that steels containing this range of chromium are easy to process while still having good corrosion resistance and strength.
  • the manganese in the alloy of this invention is present in amounts of from 2145 percent. Since manganese is an austenitizer and increases the solubility of nitrogen in the steel, amounts in excess of 21 percent are required. An upper limit of 45 percent, and preferably an upper limit of 30 percent, manganese is imposed for economic considerations and because manganese tends to attack furnace refractories.
  • Nitrogen a strong austenitizer, should be present in the steel in amounts of from 0.85-3 percent. At least 0.85 percent is required for its austenitizing effect and because it is the primary strengthening element of the steel. Amounts of nitrogen in excess of 3 percent tend to yield-porous ingots which are not satisfactory.
  • the nitrogen content of the alloy of this invention preferably is from l.05-l.5 percent.
  • the molybdenum content of the alloy of this invention must be between l-5 percent.
  • molybdenum has been known as an alloy additive in the past, in the present invention the molybdenum may be employed to reduce the amount of chromium and manganese employed, may be employed to increase the solubility of nitrogen, and most importantly reduces the susceptibility of the resultant alloy to attack by dilute sulfuric acid and to pitting attack by chlorides.
  • the molybdenumcontaining alloy of this invention is as strong or stronger than the above referred to chromium-manganese-nitrogen alloys.
  • Carbon is a well-known austenitizer and strengthener for steels and is employed in the alloys of this invention in amounts up to 1 percent.
  • concentration of carbon must be maintained below that level in that larger amounts can remove chromium from solid solution by combining with it to form chromium carbides and because carbon can reduce the solubility of the steel for nitrogen by occupying interstitial sites normally filled with nitrogen. It is preferred that less than 0.15 percent carbon be present in the alloy of this invention. Higher carbon contents require higher annealing temperatures to put carbides into solution.
  • the alloys of the present invention may tolerate silicon concentrations as high as 2 percent but preferably the silicon is below 1 percent. Higher quantities of silicon tend to remove manganese from the alloy in the form of manganese silicates and tend to form inclusions in the steel.
  • the residuals in the iron need not be identified and do not significantly affect the properties of the alloy, the usual residuals may be identified as phosphorus, sulfur, tungsten, cobalt and nickel.
  • the stainless steel composition of this invention is desirably a substantially one-phase austenitic mate rial, thermal treatments that tend to precipitate other phases should be avoided.
  • the method of preparation employed should avoid long dwell periods in the l,000-l,600F temperature range. Long dwell periods would be characterized by furnace cooling. For ordinary thicknesses air cooling or quenching are sufficient to carry the alloy through the l,000-1,600F range quickly enough to avoid precipitation of detrimental phases such as sigma phase.
  • the accompanying drawing illustrates two plots of the 1.0 percent nitrogen section of'the iron-chromiummanganese-nitrogen quaternary phase diagram.
  • One plot illustrates that section wherein the alloy contains only residual amounts of molybdenum while the molybdenum.
  • plot illustrates that section containing 3 percent molybedenum.
  • molybdenum has a significant effect both on the austenitic structure of the alloy and on the ability of the alloy to maintain nitrogen in solution both in the liquid phase and in the resultant solid phase.
  • Molybdenum within the composition limits set forth herein appears to be a replacement for chromium in that the combined molybdenum-chromium composition of the alloys determines where a two-phase austenite-ferrite alloy structure begins as compared with a single phase austenite structure, as well as where nitrogen precipitates from solution causing ingot porosity.
  • the area above line 1-A and 1'A generally represents compositions where a two-phase alloy of austenite and ferrite exists. As mentioned above, this two-phase system is undesirable because it does not have the good mechanical or chemical properties of a single-phase austenitic alloy.
  • the area below the lines l-A and 1A are single-phase austenitic alloys.
  • Equation (2) defines the lines 2B and 2'B.
  • the area below these lines represents compositions where nitrogen comes out of solution during solidification and creates porous ingots.
  • the areas above the lines 2B and 2'B' is where nitrogen remains in solution during solidification and non-porous ingots are formed.
  • the areas A-C-Band AC'-B therefor represent the areas in which the alloys of this invention and of the prior art fall for this particular cross section of the quaternary phase diagrams illustrated.
  • the alloys of the present invention fall in the area ACB. It may be noted that a single-phase alloy having no porousity may be obtained with substantially less chromium and with substantially less manganese in accordance with the present invention.
  • the alloys of Table l are substantially the same alloys with the exception of the molybdenum content. In effect, the alloys are all nominally 30 percent manganese, 20 percent chromium, 1 percent nitrogen alloys containing respectively a residual amount, 1, 2 and 3 percent molybdenum.
  • the alloys described in Table I were all prepared in the same way. All alloys were prepared from melted materials in an air induction furnace and were composited of commercial grades of ferroalloys and pure elements. The heats were cast from approximately 2,650F into 35 pound cast iron ingot molds. After solidification, the ingots were examined for porosity which was not observed in any of the alloys.
  • the hot processing of the alloys consisted of grinding to remove casting imperfections, heating the ingots at 2,250F for an appropriate amount of time, and hot rolling to the desired width and thickness. While the hot strength ap peared to increase with the addition of molybdenum,
  • the ingots were rolled without incident.
  • the hot rolled materials were annealed at 1,950F on a schedule of 120 minutes per inch of material thickness, subsequently blasted and pickled in a mixture of 15 percent nitric acid and 3 percent hydrofluoric acid, cold rolled percent to further homogenize the structure, final annealed at 1,950F on the same schedule as mentioned above and again pickled.
  • samples were obtained to determine the mechanical properties of the metals. These properties are set forth in Table II.
  • the strength data were obtained after annealing for 7 minutes at 1,950F because this treatment produces a condition of minimum strength and maximum ductility in all alloys so that truly comparative data are obtained. It may be noted that the addition of molybdenum does not have a significant effect upon the mechanical properties of a nominal 20 percent chromium-30 percent manganese-1 percent nitrogen stainless steel.
  • the alloys of this invention are resistant to pitting attack in chloride evironments.
  • the resistance to pitting attack was measured in a crevice corrosion test wherein standardized specimens of the various alloys are immersed in 10% ferric chloride solution for 72 hours.
  • the pitting attack is measured by the mean weight loss of a number ofsamples of each alloy.
  • the potentiokinetic technique is another method for nitrogen, p to 1 P carbon, P to 2 P Sill measuring the pitting resistance of an alloy to chloride 10 Con and the balance and feslduals Whefem the solutions.
  • an alloy specimen is placed composltlon 13 Such that! in contact with an appropriate chloride solution and an electrical potential is imposed on the specimen at ing %Mo O'8(%Mn) U'8(%N g creasing voltages until a breakthrough point at which a surge of current passes through the solution.
  • the specimens of alloys 1 through 4 inclusive were also subjected to standard corrosion testing to measure their resistance to sulfuric acid. Resistance of an alloy to sulfuric acid is measured by exposing an alloy specimen to sulfuric acid and obtaining the anodic polarization data and the cathodic polarization data and determining their intersection point on a plot of voltage versus current. A correlation is known to exist between the 2.
  • the alloy in accordance with claim 1 comprising from about l-3 percent molybdenum.
  • An alloy in accordance with claim 1 comprising 15-27 percent chromium.
  • An alloy in accordance with claim 1 comprising 105-1 .5 percent nitrogen.
  • An alloy in accordance with claim 1 comprising 0-0.l5 percent carbon.
  • An alloy in accordance with claim 1 comprising 0-1 .0 percent silicon.
  • a method for producing a substantially nonporous austenitic stainless steel which comprises compositing an alloy containing about 21-45 percent manganese, about 10-30 percent chromium, about l-5 percent molybdenum, about 0.85-3 percent nitrogen, up to 1 percent carbon, up to 2 percent silicon, and the balance iron and residuals, wherein the composition is intersection points of these lines and the resistance of Such that: the specimen to sulfuric acid corrosion. Intersection of 1. %Cr %Mo 0.8(%Mn) l 1.8(%N 0.1) 2 these lines at lower current flows indicates better resis- 28.5 tance to sulfuric acid. Table IV contains data obtained 2. 30(%C %N) 0.5 (%Mn)/%Cr+ %Mo+ in the foregoing test on specimens of alloys 1 through l.5 (%Si) g 1.5
  • the resistance to sulfuric acid for all specimens was melting said materials to form a homogeneous liquid measured at 1.0 normal concentration and the resisphase and solidifying the resultant liquid phase without tance of alloy 4 containing nominally 3% molybdenum a dwell period in the temperature range from about was also measured at 5.0 normal sulfuric acid. l,000-l,600F.
  • equation 1 contains an improperly typed parenthesis in the term 11.8 (%N 0.1)
  • equation 2 is somewat misleading in that the structure of this fraction would appear to contain only a Mn to Cr ratio.
  • the equation should read:
  • equation 1 Contains an improperly typed parenthesis in the term 11. 8(%N 0. l).
  • equation 2 is somewhat misleading in that the structure of this fraction would appear to contain only a Mn to Cr ratio.
  • the equation should read:

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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)
US00403347A 1973-10-04 1973-10-04 Corrosion resistant austenitic steel Expired - Lifetime US3847599A (en)

Priority Applications (13)

Application Number Priority Date Filing Date Title
US00403347A US3847599A (en) 1973-10-04 1973-10-04 Corrosion resistant austenitic steel
SE7410975A SE421430B (sv) 1973-10-04 1974-08-29 Austenitiskt rostfritt stal och forfarande for framstellning av detta
AT779574A AT338857B (de) 1973-10-04 1974-09-27 Korrosionsbestandiger, rostfreier, austenitischer stahl und verfahren zu seiner herstellung
AU73884/74A AU486525B2 (en) 1974-10-02 Corrosion resistant austenitic steel
IT53343/74A IT1019356B (it) 1973-10-04 1974-10-03 Perfezionamento negli acciai auste nitici resistenti alla corrosione
BR8195/74A BR7408195D0 (pt) 1973-10-04 1974-10-03 Liga de aco inoxidavel e processo para a producao da mesm
FR7433402A FR2246645A1 (en) 1973-10-04 1974-10-03 Corrosion resistant austenitic stainless steel - contg. copper, molybdenum and nickel with reduced nickel content
NL7413055A NL7413055A (nl) 1973-10-04 1974-10-03 Werkwijze ter bereiding van een niet poreus vrij austeniet staal, alsmede geheel of ltelijk hieruit bestaande voorwerpen.
DE19742447318 DE2447318A1 (de) 1973-10-04 1974-10-03 Korrosionsbestaendiger austenitischer rostfreier stahl
AR255924A AR202144A1 (es) 1973-10-04 1974-10-04 Aleacion de acero inoxidable que tiene mejor resistencia a la corrosion y procedimiento para producirla
BE2053908A BE820687A (fr) 1973-10-04 1974-10-04 Acier austenitique resistant a la corrosion
CA210,802A CA1022366A (fr) 1973-10-04 1974-10-04 Acier austenitique a l'epreuve de la corrosion
JP11463374A JPS5737664B2 (fr) 1973-10-04 1974-10-04

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3938990A (en) * 1973-11-28 1976-02-17 Allegheny Ludlum Industries, Inc. Method of making corrosion resistant austenitic steel
EP0065631A1 (fr) * 1981-03-20 1982-12-01 Kabushiki Kaisha Toshiba Acier résistant à la corrosion et non magnétisable, et anneau de retenue en cette matière pour générateur
US4481033A (en) * 1981-04-03 1984-11-06 Kabushiki Kaisha Kobe Seiko Sho High Mn-Cr non-magnetic steel
US4604781A (en) * 1985-02-19 1986-08-12 Combustion Engineering, Inc. Highly abrasive resistant material and grinding roll surfaced therewith
EP1069202A1 (fr) * 1999-07-15 2001-01-17 Schoeller-Bleckmann Oilfield Technology GmbH & Co KG Acier austenitique, paramagnetique, résistant à la corrosion et possédant une élasticité, une résistance mécanique et une tènacité èlevées, ainsi que son procédé de fabrication
US6767435B1 (en) * 1999-09-17 2004-07-27 Topy Kogyo Kabushiki Kaisha Bright surface structure and a manufacturing method thereof
EP1538232A1 (fr) * 2003-12-03 2005-06-08 BÖHLER Edelstahl GmbH Acier austenitique résistant à la corrosion
US20080000554A1 (en) * 2006-06-23 2008-01-03 Jorgensen Forge Corporation Austenitic paramagnetic corrosion resistant material

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2949355A (en) * 1955-07-27 1960-08-16 Allegheny Ludlum Steel High temperature alloy
US3029171A (en) * 1959-03-23 1962-04-10 Atlas Steels Ltd Age hardening of stainless steels with niobium silicides
US3556777A (en) * 1968-04-04 1971-01-19 Rexarc Inc Ferrous alloy containing high manganese and chromium

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2949355A (en) * 1955-07-27 1960-08-16 Allegheny Ludlum Steel High temperature alloy
US3029171A (en) * 1959-03-23 1962-04-10 Atlas Steels Ltd Age hardening of stainless steels with niobium silicides
US3556777A (en) * 1968-04-04 1971-01-19 Rexarc Inc Ferrous alloy containing high manganese and chromium

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3938990A (en) * 1973-11-28 1976-02-17 Allegheny Ludlum Industries, Inc. Method of making corrosion resistant austenitic steel
EP0065631A1 (fr) * 1981-03-20 1982-12-01 Kabushiki Kaisha Toshiba Acier résistant à la corrosion et non magnétisable, et anneau de retenue en cette matière pour générateur
EP0249117A3 (en) * 1981-03-20 1989-04-26 Kabushiki Kaisha Toshiba A process for preparing a crevice corrosion-resistant noa process for preparing a crevice corrosion-resistant non-magnetic steel n-magnetic steel
US4481033A (en) * 1981-04-03 1984-11-06 Kabushiki Kaisha Kobe Seiko Sho High Mn-Cr non-magnetic steel
US4604781A (en) * 1985-02-19 1986-08-12 Combustion Engineering, Inc. Highly abrasive resistant material and grinding roll surfaced therewith
US6454879B1 (en) * 1999-07-15 2002-09-24 Schoeller-Bleckman Oilfield Technology Gmbh & Co. Kg Process for producing a paramagnetic, corrosion-resistant material and like materials with high yield strength, strength, and ductility
EP1069202A1 (fr) * 1999-07-15 2001-01-17 Schoeller-Bleckmann Oilfield Technology GmbH & Co KG Acier austenitique, paramagnetique, résistant à la corrosion et possédant une élasticité, une résistance mécanique et une tènacité èlevées, ainsi que son procédé de fabrication
US6767435B1 (en) * 1999-09-17 2004-07-27 Topy Kogyo Kabushiki Kaisha Bright surface structure and a manufacturing method thereof
EP1538232A1 (fr) * 2003-12-03 2005-06-08 BÖHLER Edelstahl GmbH Acier austenitique résistant à la corrosion
US20050145308A1 (en) * 2003-12-03 2005-07-07 Bohler Edelstahl Gmbh Corrosion-resistant austenitic steel alloy
US7708841B2 (en) 2003-12-03 2010-05-04 Boehler Edelstahl Gmbh & Co Kg Component for use in oil field technology made of a material which comprises a corrosion-resistant austenitic steel alloy
US20100170596A1 (en) * 2003-12-03 2010-07-08 Boehler Edelstahl Gmbh & Co Kg Corrosion-resistant austenitic steel alloy
US7947136B2 (en) 2003-12-03 2011-05-24 Boehler Edelstahl Gmbh & Co Kg Process for producing a corrosion-resistant austenitic alloy component
US8454765B2 (en) 2003-12-03 2013-06-04 Boehler Edelstahl Gmbh & Co. Kg Corrosion-resistant austenitic steel alloy
US20080000554A1 (en) * 2006-06-23 2008-01-03 Jorgensen Forge Corporation Austenitic paramagnetic corrosion resistant material

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CA1022366A (fr) 1977-12-13

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