US3476555A - Corrosion-resistant metallic articles and composition therefor - Google Patents
Corrosion-resistant metallic articles and composition therefor Download PDFInfo
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- US3476555A US3476555A US532623A US3476555DA US3476555A US 3476555 A US3476555 A US 3476555A US 532623 A US532623 A US 532623A US 3476555D A US3476555D A US 3476555DA US 3476555 A US3476555 A US 3476555A
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- 238000005260 corrosion Methods 0.000 title description 34
- 239000000203 mixture Substances 0.000 title description 33
- 230000007797 corrosion Effects 0.000 title description 27
- 229910000831 Steel Inorganic materials 0.000 description 43
- 239000010959 steel Substances 0.000 description 43
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 36
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 28
- 229910052759 nickel Inorganic materials 0.000 description 18
- 229910045601 alloy Inorganic materials 0.000 description 17
- 239000000956 alloy Substances 0.000 description 17
- 229910000851 Alloy steel Inorganic materials 0.000 description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 16
- 239000011651 chromium Substances 0.000 description 16
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 15
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 15
- 229910052804 chromium Inorganic materials 0.000 description 15
- 229910052757 nitrogen Inorganic materials 0.000 description 15
- 239000013535 sea water Substances 0.000 description 15
- 229910052710 silicon Inorganic materials 0.000 description 15
- 239000010703 silicon Substances 0.000 description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 13
- 229910052799 carbon Inorganic materials 0.000 description 13
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 11
- 238000005336 cracking Methods 0.000 description 11
- 229910052750 molybdenum Inorganic materials 0.000 description 11
- 239000011733 molybdenum Substances 0.000 description 11
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 9
- 229910052742 iron Inorganic materials 0.000 description 8
- 230000010287 polarization Effects 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- 239000011572 manganese Substances 0.000 description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- 229910052736 halogen Inorganic materials 0.000 description 4
- 150000002367 halogens Chemical class 0.000 description 4
- 229910052748 manganese Inorganic materials 0.000 description 4
- 229910052758 niobium Inorganic materials 0.000 description 4
- 239000010955 niobium Substances 0.000 description 4
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 3
- 240000007124 Brassica oleracea Species 0.000 description 3
- 229910052796 boron Inorganic materials 0.000 description 3
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 229910052715 tantalum Inorganic materials 0.000 description 3
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 3
- 229910052721 tungsten Inorganic materials 0.000 description 3
- 239000010937 tungsten Substances 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 239000012267 brine Substances 0.000 description 2
- 230000001627 detrimental effect Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 241000238366 Cephalopoda Species 0.000 description 1
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- 241000290149 Scapteriscus didactylus Species 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 244000309464 bull Species 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000788 chromium alloy Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000013213 extrapolation Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- -1 halide salts Chemical class 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/16—Drill collars
-
- 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
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
Definitions
- the alloy consists of up to 0.06% carbon (preferably 0.02 to 0.03% 0.80 to 3.00% silicon (preferably 0.8 to 1.2%), 2.0 to 20.0% manganese (preferably 5.5 to 9.0% 22 to 26% chromium, to 20% nickel (preferably 12 to 15%), 1.2 to 3.0% molybdenum, 0.2 to 1.5% nitrogen (preferably 0.3 to 0.5%), the balance iron with a maximum of 6% tungsten, niobium, tantalum, vanadium, copper or boron.
- Our present invention relates to an improved metallic composition having nonmagnetic and good welding characteristics and resistant to corrosion and pitting by corrosive and other influences and, more particularly, to an "improved alloy-steel composition'fhaving a higher yield point and tensile strength than earlier compositions of this general character.
- Typical steel-alloy compositions of this type contained up to 0.08 weight-percent carbon, 1.5 to 4 weight-percent silicon and 0.1 to 0.3 weight-percent nitrogen in addition to the indicated ranges of nickel and chromium.
- Other nickel'chromium alloys have also been proposed, such alloys containing between 12 and 40% chromiurn, 6 to 40% nickel and at least 1% but no more than 4% by weight copper.
- the nickel component in steels of the latter type can be partly or completely replaced by less than 4% or more than 6% manganese, or by cobalt.
- austenitic corrosion-resistant chromiummanganese-nitrogen steels have been proposed with a composition of up to 0.06% carbon, up to 2% silicon, 10
- Nitrogen-free steels have also been proposed heretofore for incorporation in bodies in which surface pitting (or stress-corrosion cracking) is particularly disadvantageous.
- Antipitting or pitting resistant steels of this character have compositions of 4 to 20% by weight nickel, 10 to 40% by weight chromium, 1.5 to 3.5% by weight silicon, 1 to 5% by Weight molybdenum and trace amounts to 0.3% by weight carbon.
- Steel alloys consisting of up to 0.06% carbon, 0.35% silicon, 7% manganese, 18% chromium, 9.5% nickel, 1.3% molybdenum, 0.15% niobium, and 0.25% nitrogen or with a composition of up to 0.03% carbon, 0.35% silicon, 19% manganese, 18% chromium, 10% nickel, 1.8% molybdenum and 0.2% nitrogen (the balance being iron with all percents given by weight), have good corrosion resistance in sea water and also are relatively nonmagnetizable so that they have applications for many purposes including the construction of ships bulls and other underwater applications.
- the principal object of the present invention to provide a relatively high-strength steel-alloy composition resistant to corrosion and pitting and characterized by poor or negligible magnetizability and good weldability.
- the improved composition of the present invention is an austenitic steel alloy containing up to 0.06% by weight carbon, between 0.8 and 3.00% by weight silicon, 2 to 20% by weight manganese, 22 to 26% by weight chromium, to by weight nickel, 1.20 to 3% by weight molybdenum and 0.20 to 1.50% by weight nitrogen, the balance being constituted by iron and at most 6% by weight of one or more of the following components: tungsten, niobium or tantalum, titanium, vanadium, copper and boron. Both the upper and lower limits of the components mentioned above are critical and it has been found that the system is particularly sensitive to the chromium, molybdenum and nitrogen upper and lower limits.
- the carbon content ranges between 0.02 and 0.03% by weight
- the silicon content ranges between 0.80 and 1.20% by weight
- the manganese content ranges between 5.50 and 9% by weight
- the nickel content ranges between 12 and 15% by weight
- the nitrogen content is within the raneg of 0.30 to 0.50% by weight, all percents being of the final alloy composition.
- These compositions which according to a principal feature of this invention can be employed as the surface sheet, plate or jacket of all bodies to be exposed to chemical and other environmental pitting elfects and to stress corrosion cracking in sea water, salt solutions (e.g. brines) and other halide-containing solutions, the alloy being equally suitable for use in bodies to be exposed to these effects in their entirety.
- Suitable objects adapted to be manufactured from this alloy composition include the hull plates of seagoing vessels of all types, caissons to be immersed in sea water, tanks, pipelines, structural-steel shapes for underwater construction, brine-containing vessels and components to be inserted in brine solutions, and the like.
- Metallic members composed of the improved composition are not only resistant to fissure formation and corrosion in general but are also free from or resistant to pitting from other environmental phenomena in solutions similar to sea water and/or containing halide salts and corrosive halogens in general; bodies of this alloy also have a minimum yield point (to a strain of 0.2%) of 45 kp./mm. with a corresponding tensile strength, are substantially nonmagnetizable, and have excellent weldability.
- the improved steel has an unusually stable austenitic character and has a permeability value which lies substantially below the generally accepted limited of 1.01 gauss/oersted for nonmagnetizable steel.
- the proportions of silicon, chromium, molybdenum and the relationships of these proportions to one another are highly important to obtain the significant qualities of the improved steel, namely, the durable nonmagnetic character, the high yield point and toughness, the excellent weldability and the resistance to corrosion in sea water and halogen-containing solutions and halogens at low temperatures.
- the proportions and their relationships of manganese and nitrogen have been found to be especially critical in terms of the weldability of the composition and the increased toughness and strength, both compressive and tensile, of the steel bodies.
- the corrosion resistance of the bodies is such that other environmental effects beside those characteristic of galvanic corrosion and pitting are also materially diminished or rendered negligible.
- a steel composition of this type has, as a consequence of the aforedescribed qualities, been found to be especially suitable for use in ship construction where nonmagnetizability, high strength, good weldability and, especially, corrosion resistance in sea water are of exceptional importance. It will be understood, however, that the steels are also suitable for use in machine construction where the aforedescribed characteristics are desirable and can be used with advantage in chemical apparatus and locations at which thesteel may come into contact with chloride-containing solutions similar to sea Water or other halogen-containing media.
- austenitic steels in cold sea water are characterized by an apparently hitherto unknown intercrystalline type of stress corrosion which takes elfect with conventional chromium/ nickel steels in a relatively short time.
- chromiummanganese-nitrogen steel of conventional compositions have been found to deteriorate rapidly in cold sea Water as a consequence of corrosion of this latter type whereas the improved steel composition of the present invention is almost completely resistant to this type of corrosion.
- FIGS. 1-3 are polarization graphs of current and current density plotted along the ordinate against potential with respect to a saturated calomel electrode in millivolts plotted as the abscissa for steels I, II and III, respectively, of conventional compositions;
- FIG. 4 is a corresponding plot of the polarization characteristics of a steel IV of the improved composition of this invention.
- FIGS. 1-4 show the variation of current and current density with potential plotted against a satu- TABLE II C Si Mn Cr Mo Ni Nb N Steel 1, max 0. 07 0. 70 1. 18. 00 2. 50 13. 00 Steel, II, max. 0. 06 0. 35 7. 00 18. 00 1. 30 9. 50 0. 15 0. 25 Steel III, main--. 0. 03 0. 35 19. 00 18. 00 1. 80 10. 00 0. 20 Steel IV 0. 03 1. 18 6. 86 23. 31 1. 48 14. 30 0. 421
- the samples were from their open-circuit potential anodically polarized until the current density rose to a value of about 2X10 A/cm. (curve segments a) .and then with the indicated polarization speed were brought to a potential of about l400 mv. (curve segments b).
- the samples had a surface area exposed to polarization of 0.5 cm. (sample-surface area).
- An austenitic, readily weldable, substantially nonmagnetizable, steel alloy having a yield point of at least 45 kp./mm. (0.2% elongation) resistant to stress-corrosion cracking in sea-water environments consisting essentially of:
- An austenitic, readily weldable, substantially nonmagnetizable steel alloy having a yield point of at least 45 kp./mm. (0.2% elongation) resistant to stress-corrosion cracking in sea-water environments consisting essentially of:
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Description
NOV. 4, 1969 '7 KOHL A 3,476,555
CORROSION-RESISTANT METALLIC ARTICLES AND COMPOSITION THEREFOR Filed March 8, 1966 4 Sheets-$heet l Fl g.1
STEEL I I E /0" 10' DAQ Q N -4 E P 10 \u 4 a) q l /0 y In 8 :2: /0 g g 8 D -.I U t I I g I000 I 500 0 500 I000 I500 Pofenfial in mV NVEYTORS; POLARIZATION VELOCITY. Heinz Kohl Changes of mV every 30 sec. Herberf Souresny reading I5 sec. affer pafenfia! changa R Surface ffe s hlg polished. flhf gi NQY. 4, 1969 KQHL ETAL 3,476,555
CORROSION-RESISTANT METALLIC ARTICLES AND COMPOSITION THEREFOR Filed March 8, 1966 1 4 Sheets-Sheet 2 H. KOHL ETAL CORROSION-RESISTANT METALLIC ARTICLES AND COMPOSITION THEREFOR Filed March 8, 1966 4 Sheets-Sheet 5 Fig.3 STEELJJI .0 .0 w mm m m m m m d 4 il Py il I I f z 7 s v m mlm mm m v v I .I 15 x250 Pofenfial in mV MW m m mzu .mO Ee Hf m a Attorney Nov. 4, 1969- H. KOHL ETAL CORROSION-RESISTANT mmpmc ARTICLES AND COMPOSITION THEREFOR Filed March 8, 1966 4 Sheets-Sheet 4 Fig. 4
STEEL 1y Eu\ E mtmcu 25 4 2 3 A, w J 4 4 4.- m m. m m m m m m m P NNNVID $9, Q I I. III vmwwmlmww m lno e m H Y B i ltt orney United States Patent ABSTRACT OF THE liISCLOSURE An austenitic, readily weldable nonmagnetic steel alloy resistant to stress corrosion cracking and pitting. The alloy consists of up to 0.06% carbon (preferably 0.02 to 0.03% 0.80 to 3.00% silicon (preferably 0.8 to 1.2%), 2.0 to 20.0% manganese (preferably 5.5 to 9.0% 22 to 26% chromium, to 20% nickel (preferably 12 to 15%), 1.2 to 3.0% molybdenum, 0.2 to 1.5% nitrogen (preferably 0.3 to 0.5%), the balance iron with a maximum of 6% tungsten, niobium, tantalum, vanadium, copper or boron.
Our present invention relates to an improved metallic composition having nonmagnetic and good welding characteristics and resistant to corrosion and pitting by corrosive and other influences and, more particularly, to an "improved alloy-steel composition'fhaving a higher yield point and tensile strength than earlier compositions of this general character.
The problem of corrosion of metal bodies has long generated many efforts in metallurgic research and technology to provide relatively high-strength metallic compositions which are resistant to corrosion (e.g. electrolytic erosion) and stress-corrosion pitting or cracking in the presence of corrosive and other detrimental environments. Many efforts along these lines have been undertaken in connection with the metallurgy of steel and other iron alloys since such alloys afford high strength and relatively low cost. One of the major steps forward in this field was the discovery that nickel-chromium steel alloys containing between 16 and 20 weight-percent chromium and 8 to 14 weight-percent nickel were capable of resisting galvanic corrosion and, especially, the formation of fissures, cracks and other dislocations by electrochemical reaction. Typical steel-alloy compositions of this type contained up to 0.08 weight-percent carbon, 1.5 to 4 weight-percent silicon and 0.1 to 0.3 weight-percent nitrogen in addition to the indicated ranges of nickel and chromium. Other nickel'chromium alloys have also been proposed, such alloys containing between 12 and 40% chromiurn, 6 to 40% nickel and at least 1% but no more than 4% by weight copper. The nickel component in steels of the latter type can be partly or completely replaced by less than 4% or more than 6% manganese, or by cobalt.
More recently, austenitic corrosion-resistant chromiummanganese-nitrogen steels have been proposed with a composition of up to 0.06% carbon, up to 2% silicon, 10
,to 20% chromium, 8 to 22% manganese, from 0.05 to a maximum of 0.5% nitrogen and from trace amounts to 2.5% nickel, the balance being iron (all percentages by "ice weight). A composition of this latter type had somewhat improved resistance to stress-corrosion cracking.
Nitrogen-free steels have also been proposed heretofore for incorporation in bodies in which surface pitting (or stress-corrosion cracking) is particularly disadvantageous. Antipitting or pitting resistant steels of this character have compositions of 4 to 20% by weight nickel, 10 to 40% by weight chromium, 1.5 to 3.5% by weight silicon, 1 to 5% by Weight molybdenum and trace amounts to 0.3% by weight carbon. In addition, it has been suggested heretofore to provide steels resistant to pitting in halogencontaining (salt) solutions with a composition of up to 0.07% carbon, 2 to 2.5 silicon, up to 2% manganese, 16.5 to 18.5% chromium, 12 to 14% nickel, and 2 to 2.5% molybdenum, the balance being iron (all percents by weight). Steel alloys consisting of up to 0.06% carbon, 0.35% silicon, 7% manganese, 18% chromium, 9.5% nickel, 1.3% molybdenum, 0.15% niobium, and 0.25% nitrogen or with a composition of up to 0.03% carbon, 0.35% silicon, 19% manganese, 18% chromium, 10% nickel, 1.8% molybdenum and 0.2% nitrogen (the balance being iron with all percents given by weight), have good corrosion resistance in sea water and also are relatively nonmagnetizable so that they have applications for many purposes including the construction of ships bulls and other underwater applications.
While it has been found to be possible heretofore to provide individual steel compositions which have an excellent resistance to corrosion and resist pitting or stresscorrosion cracking in sea water and other detrimental environments, other steel alloys which are nonmagnetizable, and still others Which are weldable, each of these steels has been found to be unsatisfactory in at least one of these respects or to have a relatively low yield point and/or poor weldability. Steel-alloy compositions of this character have, therefore, been cold-worked by conventional forging, rolling, or deformation processes after being formed into an article in order to overcome these disadvantages by increasing the yield point of the body and composition and thus the eifective strength of the metal. It has, however, been found that an increase of the yield point produced by cold-working of a steel-alloy composition is accompanied by a decrease in the magnetic-permeability value of the composition and thus in increasing magnetizability. Moreover, the higher strength obtained by cold-working in this manner is lost in the region of those metallic zones which are heated by welding operations.
It is, therefore, the principal object of the present invention to provide a relatively high-strength steel-alloy composition resistant to corrosion and pitting and characterized by poor or negligible magnetizability and good weldability.
We have now surprisingly discovered that this object and others which will become apparent hereinafter can be attained by the use of a chromium-nic-kel-manganesenitrogen steel alloy of austenitic crystal and grain structure which, while possibly overlapping some of the compositional ranges of known steel alloys, differs markedly therefrom in the relationship of the critical components, and is permanently nonmagnetic and has a strength and yield point far superior to the corrosion-resistance (i.e. resistance to cracking and pitting) of steel alloys provided heretofore. The improved composition of the present invention is an austenitic steel alloy containing up to 0.06% by weight carbon, between 0.8 and 3.00% by weight silicon, 2 to 20% by weight manganese, 22 to 26% by weight chromium, to by weight nickel, 1.20 to 3% by weight molybdenum and 0.20 to 1.50% by weight nitrogen, the balance being constituted by iron and at most 6% by weight of one or more of the following components: tungsten, niobium or tantalum, titanium, vanadium, copper and boron. Both the upper and lower limits of the components mentioned above are critical and it has been found that the system is particularly sensitive to the chromium, molybdenum and nitrogen upper and lower limits. Best results are obtained, however, when the carbon content ranges between 0.02 and 0.03% by weight, the silicon content ranges between 0.80 and 1.20% by weight, the manganese content ranges between 5.50 and 9% by weight, the nickel content ranges between 12 and 15% by weight and the nitrogen content is within the raneg of 0.30 to 0.50% by weight, all percents being of the final alloy composition. These compositions, which according to a principal feature of this invention can be employed as the surface sheet, plate or jacket of all bodies to be exposed to chemical and other environmental pitting elfects and to stress corrosion cracking in sea water, salt solutions (e.g. brines) and other halide-containing solutions, the alloy being equally suitable for use in bodies to be exposed to these effects in their entirety. Suitable objects adapted to be manufactured from this alloy composition include the hull plates of seagoing vessels of all types, caissons to be immersed in sea water, tanks, pipelines, structural-steel shapes for underwater construction, brine-containing vessels and components to be inserted in brine solutions, and the like.
Metallic members composed of the improved compositionare not only resistant to fissure formation and corrosion in general but are also free from or resistant to pitting from other environmental phenomena in solutions similar to sea water and/or containing halide salts and corrosive halogens in general; bodies of this alloy also have a minimum yield point (to a strain of 0.2%) of 45 kp./mm. with a corresponding tensile strength, are substantially nonmagnetizable, and have excellent weldability. The improved steel has an unusually stable austenitic character and has a permeability value which lies substantially below the generally accepted limited of 1.01 gauss/oersted for nonmagnetizable steel. This low permeability does not materially change under the severe cold-deformation stresses which are applied to bodies of, for example, steel plate for use in ship hulls. Moreover, the strength of such steels and their toughness are correspondingly very high. In a quenched state, the yield points (to 0.2% elongation) can increase to values greater than 50 kp./mm. without further treatment. Surprisingly, such steels, in spite of their proportionately high silicon content, evidence excellent weldability and also are not subject to the formation of discontinuities during thermal elongation or shrinkage under rapidly altering thermal conditions.
It has been found that the proportions of silicon, chromium, molybdenum and the relationships of these proportions to one another are highly important to obtain the significant qualities of the improved steel, namely, the durable nonmagnetic character, the high yield point and toughness, the excellent weldability and the resistance to corrosion in sea water and halogen-containing solutions and halogens at low temperatures. The proportions and their relationships of manganese and nitrogen have been found to be especially critical in terms of the weldability of the composition and the increased toughness and strength, both compressive and tensile, of the steel bodies. In fact, the corrosion resistance of the bodies is such that other environmental effects beside those characteristic of galvanic corrosion and pitting are also materially diminished or rendered negligible.
4 EXAMPLE A steel sample containing 0.03% by weight carbon, 1.18% by Weight silicon, 6.86% by weight manganese, 23.31% by weight chromium, 14.30% by weight nickel, 1.48% by weight molybdenum, and 0.421% by weight nitrogen, the balance being iron, has the following characteristic after quenching from the temperature of about 1050 C. in water:
TABLE I Yield point at 0.2% strain kp./mm. 50.3-54.1 Tensile strength kp./mm. 90.4-94.2 Elongation percent 44.0-43.6 Contraction do 71.0-65.0 Notched-bar impact-strength, DVM test mkp./cm. 27.5 Permeability ,u. gauss/oersted 1.003
A steel composition of this type has, as a consequence of the aforedescribed qualities, been found to be especially suitable for use in ship construction where nonmagnetizability, high strength, good weldability and, especially, corrosion resistance in sea water are of exceptional importance. It will be understood, however, that the steels are also suitable for use in machine construction where the aforedescribed characteristics are desirable and can be used with advantage in chemical apparatus and locations at which thesteel may come into contact with chloride-containing solutions similar to sea Water or other halogen-containing media.
In connection with stress-corrosion-fissure formation, it must be observed for the sake of completion that with austenitic steels different types of corrosion are experienced. The so-called classic fissure corrosion arises with all commercially available chromium-nickel steels in hot, highly concentrated chloride solutions and is characterized by the formation of transcrystalline fissures, crevices and other dislocations. .The improved steel of the present invention has been found to be only slightly more resistant to this type of corrosion than the presently available chromium-nickel steels of the character described earlier. However, experiments as to the temperature and concentration dependency of this form of corrosive action has shown that the corrosion process, upon extrapolation, can give rise to such transcrystalline fissure formation in cold sea water only upon the lapse of several hundreds of years.
Of more serious consequence is the discovery that austenitic steels in cold sea water are characterized by an apparently hitherto unknown intercrystalline type of stress corrosion which takes elfect with conventional chromium/ nickel steels in a relatively short time. In fact, chromiummanganese-nitrogen steel of conventional compositions have been found to deteriorate rapidly in cold sea Water as a consequence of corrosion of this latter type whereas the improved steel composition of the present invention is almost completely resistant to this type of corrosion.
The improved corrosion resistance of the improved steel of the present invention in sea water will be readily apparent from a comparison of the current-density/voltage curves of steels of the composition of that of the present invention and conventional corrosion-resistance steel alloys. The polarization characteristics of such steels will be evident from the following description, reference being made to the accompanying drawing in which:
FIGS. 1-3 are polarization graphs of current and current density plotted along the ordinate against potential with respect to a saturated calomel electrode in millivolts plotted as the abscissa for steels I, II and III, respectively, of conventional compositions; and
FIG. 4 is a corresponding plot of the polarization characteristics of a steel IV of the improved composition of this invention.
The graphs of FIGS. 1-4 show the variation of current and current density with potential plotted against a satu- TABLE II C Si Mn Cr Mo Ni Nb N Steel 1, max 0. 07 0. 70 1. 18. 00 2. 50 13. 00 Steel, II, max. 0. 06 0. 35 7. 00 18. 00 1. 30 9. 50 0. 15 0. 25 Steel III, main--. 0. 03 0. 35 19. 00 18. 00 1. 80 10. 00 0. 20 Steel IV 0. 03 1. 18 6. 86 23. 31 1. 48 14. 30 0. 421
The samples were from their open-circuit potential anodically polarized until the current density rose to a value of about 2X10 A/cm. (curve segments a) .and then with the indicated polarization speed were brought to a potential of about l400 mv. (curve segments b). The samples had a surface area exposed to polarization of 0.5 cm. (sample-surface area).
A comparison of the graph of FIG. 4 (steel IV of the present invention) shows that the characteristic curve of this steel has an inflection point substantially higher than that of the other steels, indicating that the steel of the improved composition has a much wider passive range than the samples provided for comparison purposes. This will be readily evident from the graph b which intersects the current density line equivalent to 10' A/cm. at point P for each curve as indicated in the graphs. This intersection point P lies between -l00 and --200 mv. for the steels IIII whereas the intersection point P for the improved steel IV lies at +1000 mv. Since corrosion processes commonly involve a current density between the curves a and b, it is apparent that the steels I-III will undergo corrosive deterioration for example pitting when the potential lies above 100 mv. whereas corrosion of steel IV can occur only with a rise in potential above +1000 mv. Steels with polarization curves of the char acter illustrated in FIG. 4 have not hitherto been known.
Stress-corrosion cracking Sample rods of the improved steel with a test portion of 5 mm. in diameter and 20 mm. in length were placed under a tension of 63 kp./mrn. (about 70% of 0' in aerated boiling sea water prepared in accordance with the German Industrial Standard mentioned above. The test specimen was removed after 2000 hours and found to be completely free from stress corrosion cracking. By contrast, conventional steels after a corresponding period were found under a microscope to have a multiplicity of stress-corrosion formed fissures and crevices.
We claim:
1. An austenitic, readily weldable, substantially nonmagnetizable, steel alloy having a yield point of at least 45 kp./mm. (0.2% elongation) resistant to stress-corrosion cracking in sea-water environments consisting essentially of:
up to 0.06 weight-percent carbon,
0.80 to 3.00 weight-percent silicon,
2.00 to 20.00 weight-percent manganese,
22.00 to 26.00 weight-percent chromium,
10.00 to 20.00 weight-percent nickel,
1.20 to 3.00 weight-percent molybdenum,
0.20 to 0.50 weight-percent nitrogen, and the balance iron with a maximum of 6 percent by weight of tungsten, niobium, tantalum, titanium, vanadium, copper and boron.
2. The alloy defined in claim 1 wherein said carbon is present in a proportion of 0.02 to 0.03 percent by weight of the alloy.
3. The alloy defined in claim 1 wherein said silicon is present in a proportion of 0.80 to 1.20 percent by Weight of the alloy.
4. The alloy defined in claim 1 wherein said manganese is present in a proportion of 5.50 to 9.00 percent by weight of the alloy.
5. The alloy defined in claim 1 wherein said nickel is present in a proportion of 12.00 to 15.00 percent by weight of the alloy.
6. The alloy defined in claim 1 wherein said nitrogen is present in a proportion of 0. 30 to 0.50 percent by weight of the alloy.
7. An austenitic, readily weldable, substantially nonmagnetizable steel alloy having a yield point of at least 45 kp./mm. (0.2% elongation) resistant to stress-corrosion cracking in sea-water environments consisting essentially of:
0.03 weight-percent carbon,
1.18 weight-percent silicon,
6.86 weight-percent manganese,
23.31 weight-percent chromium,
14.30 Weight-percent nickel,
1.48 weight-percent molybdenum,
0.42 weight-percent nitrogen, and
the balance iron.
References Cited UNITED STATES PATENTS 3,152,934 10/1964 Lula 3,235,378 2/1966 Jennings. 3,306,736 2/ 1967 Rundell 75-1285 FOREIGN PATENTS 691,855 8/1964 Canada.
HY LAND BIZOT, Primary Examiner
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT207265A AT268345B (en) | 1965-03-09 | 1965-03-09 | Austenitic, corrosion-resistant chromium-nickel-manganese-nitrogen steel for the production of objects that are resistant to pitting and stress corrosion cracking in seawater and have non-magnetizability and good weldability |
Publications (1)
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US3476555A true US3476555A (en) | 1969-11-04 |
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US532623A Expired - Lifetime US3476555A (en) | 1965-03-09 | 1966-03-08 | Corrosion-resistant metallic articles and composition therefor |
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US (1) | US3476555A (en) |
AT (1) | AT268345B (en) |
GB (1) | GB1097004A (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3663215A (en) * | 1969-08-13 | 1972-05-16 | Armco Steel Corp | Wear-resistant stainless steel |
JPS508967B1 (en) * | 1970-12-14 | 1975-04-09 | ||
EP0231492A1 (en) * | 1985-12-20 | 1987-08-12 | Fried. Krupp Gesellschaft mit beschränkter Haftung | Austenitic, nitrogen-containing chromium-nickel-molybdenum-manganese steel; process for manufacturing this steel and uses thereof |
US5082625A (en) * | 1987-01-14 | 1992-01-21 | Toyota Jidosha Kabushiki Kaisha | Corrosion-resistant alloy for build-up welding |
US20080000554A1 (en) * | 2006-06-23 | 2008-01-03 | Jorgensen Forge Corporation | Austenitic paramagnetic corrosion resistant material |
US20110248071A1 (en) * | 2008-12-18 | 2011-10-13 | Japan Atomic Energy Agency | Austenitic welding material, and preventive maintenance method for stress corrosion cracking and preventive maintenance method for intergranular corrosion, using same |
US9803267B2 (en) | 2011-05-26 | 2017-10-31 | Upl, L.L.C. | Austenitic stainless steel |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS549125B1 (en) * | 1971-03-19 | 1979-04-21 | ||
US5340534A (en) * | 1992-08-24 | 1994-08-23 | Crs Holdings, Inc. | Corrosion resistant austenitic stainless steel with improved galling resistance |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA691855A (en) * | 1964-08-04 | C. Hull Frederick | Crack resistant austenitic stainless steel alloys | |
US3152934A (en) * | 1962-10-03 | 1964-10-13 | Allegheny Ludlum Steel | Process for treating austenite stainless steels |
US3235378A (en) * | 1963-11-14 | 1966-02-15 | Armco Steel Corp | Alloy steel and articles |
US3306736A (en) * | 1963-08-30 | 1967-02-28 | Crucible Steel Co America | Austenitic stainless steel |
-
1965
- 1965-03-09 AT AT207265A patent/AT268345B/en active
-
1966
- 1966-03-08 US US532623A patent/US3476555A/en not_active Expired - Lifetime
- 1966-03-09 GB GB10418/66A patent/GB1097004A/en not_active Expired
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA691855A (en) * | 1964-08-04 | C. Hull Frederick | Crack resistant austenitic stainless steel alloys | |
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 |
US3235378A (en) * | 1963-11-14 | 1966-02-15 | Armco Steel Corp | Alloy steel and articles |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3663215A (en) * | 1969-08-13 | 1972-05-16 | Armco Steel Corp | Wear-resistant stainless steel |
JPS508967B1 (en) * | 1970-12-14 | 1975-04-09 | ||
EP0231492A1 (en) * | 1985-12-20 | 1987-08-12 | Fried. Krupp Gesellschaft mit beschränkter Haftung | Austenitic, nitrogen-containing chromium-nickel-molybdenum-manganese steel; process for manufacturing this steel and uses thereof |
US5082625A (en) * | 1987-01-14 | 1992-01-21 | Toyota Jidosha Kabushiki Kaisha | Corrosion-resistant alloy for build-up welding |
US20080000554A1 (en) * | 2006-06-23 | 2008-01-03 | Jorgensen Forge Corporation | Austenitic paramagnetic corrosion resistant material |
US20110248071A1 (en) * | 2008-12-18 | 2011-10-13 | Japan Atomic Energy Agency | Austenitic welding material, and preventive maintenance method for stress corrosion cracking and preventive maintenance method for intergranular corrosion, using same |
US8322592B2 (en) * | 2008-12-18 | 2012-12-04 | Japan Atomic Energy Agency | Austenitic welding material, and preventive maintenance method for stress corrosion cracking and preventive maintenance method for intergranular corrosion, using same |
US9803267B2 (en) | 2011-05-26 | 2017-10-31 | Upl, L.L.C. | Austenitic stainless steel |
Also Published As
Publication number | Publication date |
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AT268345B (en) | 1969-02-10 |
GB1097004A (en) | 1967-12-29 |
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