US3340046A - Age-hardenable austenitic stainless steel - Google Patents
Age-hardenable austenitic stainless steel Download PDFInfo
- Publication number
- US3340046A US3340046A US446469A US44646965A US3340046A US 3340046 A US3340046 A US 3340046A US 446469 A US446469 A US 446469A US 44646965 A US44646965 A US 44646965A US 3340046 A US3340046 A US 3340046A
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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
Definitions
- This invention pertains to age-hardenable stainless steel, and in particular, to such steel which exhibits improved strength and oxidation resistance in the age-hardened condition and excellent service life in contact with hot, sulfur-containing materials.
- Age-hardened austenitic stainless steel is known, having been disclosed in, for example, Payson US. Patent No. 2,706,696, Payson et al. US. Patent No. 2,686,116, and Canadian Patent No. 632,186.
- Such steel is of use wherever non-magnetic steel of good elevated-temperature creep strength is required.
- nickel-free I mean to include only those steels that do not have a purposeful addition of nickel made to them, either by the use of nickel-bearing scrap or by the addition of nickel as an alloying element. Such nickel-free steel would, of course, contain under 0.75%, and more usually under 0.30%, of nickel.
- Sulfur-resistant age-hardenable austenitic stainless steel will find use, for example, in diesel engine valves, in equipment for making carbon electrodes for use in the electric furnace (which equipment is during use exposed to a mixtureof graphite and sulfur-bearing tar or pitch), in apparatus used in that part of the petroleum-refining industry which is concerned with the refining of sulfurbearing crude oils, in the roasting of sulfide-type ores, and in numerous other places in the chemical process industries and elsewhere wherein metal is exposed to the action of a hot sulfur-containing material in the gaseous, liquid, or solid state.
- diesel engine valves made of steel of the instant invention exhibit a service life superior to that of the best steel hitherto used for such purpose.
- chromium-manganesecarbon-nitrogen steels which exhibit, upon rapid cooling from a sufliciently high solution temperature (e.g., about 2200 F.), a microstructure composed entirely of austenite, the steels being in such condition relatively soft (under 30 C Rockwell), and which, upon aging for about 16 hours at about 1350 F., exhibit a microstructure composed of austenite with a fine carbide phase dispersed throughout the steel, especially within the grains, rather than at the grain boundaries.
- the steel exhibits considerable hardness in such condition, e.g., over 38 C Rockwell.
- Such steel is free of both the ferrite phase andthe sigma phase.
- Ferrite tends to form whenever ferrite-promoting elements, e.g., chromium, molybdenum, vanadium, tungsten, columbium, or tantalum, are present in larger amounts in comparison with the amounts present of austenite-promoting elements, e.g., nickel, manganese, carbon, and nitrogen.
- Sigma tends to form whenever the steels total content of certain elements (chromium, nickel, silicon, etc.) becomes too high. It has hitherto been considered desirable to avoid the formation of both ferrite and sigma phase.
- Ferrite has a relatively low strength at moderately elevated temperature (1200 to 1600 F.), and the sigma phase similarly affects the properties detrimentally, especially when it is permitted to occur in the steel in the form of relatively massive intergranular particles, as it sometimes does in Type 310 steel (25% Cr, 20% Ni, 1.50% max. Si, 0.25% max. C, 2.00% max. Mn, balance essentially iron).
- composition of the steel not only fall within the ranges specified above but also be balanced in its respective contents of carbon and nitrogen, on the one hand, and chromium and silicon, on the other hand, so that the steel contains sufficient carbon and nitrogen to ensure that no ferrite or martensite is formed upon quenching or cooling from the sglption-treating temperature.
- composition of the steel substantially satisfy the equation C+N 0.078(Cr+1.4 Si12.5)
- a phosphorus addition detracts from the forgeability of the steel but lowers somewhat the solution temperature required in heat treatment and promotes at elast slightly the strength of the steel.
- a sulfur addition improves machinability.
- Strength may be improved by adding one or more of the carbide-forming elements vanadium, molybdenum, tungsten, columbium, and tantalum, the total amount of these elements preferably being under 7 weight percent. Whenever any of the above-mentioned carbideforming elements is added, allowance must be made for appropriate adjustment of the required amount of carbon plus nitrogen. That is to say, the contents in weight percent of the five carbide-forming elements mentioned must be multiplied by appropriate coefficients, indicated below, and added to the quantity within the parentheses on the right-hand side of the equation given above.
- the coefficients to be used are as follows: 2.3 for vanadium, 1.4 for molybdenum, 0.63 for tungsten, 2.8 for columbium, and 1.4 for tantalum.
- the steel In applications that involve the use of the steel at high temperature in contact with oxygen-containing atmospheres, it is considered desirable that the steel not contain any molybdenum or vanadium, inasmuch as these elements are known to form volatile or molten oxides.
- the steel may con tain appropriate amounts of other machinability-promoting elements such as tellurium, bismuth, lead, or selenium.
- titanium it may prove advantageous to add to the steel a small amount of titanium or another element capable of influencing the morphology of the inclusions of sulfides or other machinability-improving inclusion in the steel.
- Use of amounts of titanium greater than about 0.5% are not recommended, however, as such larger amounts of titanium tend to react with the nitrogen in the steel.
- Carbon 0.40 to 0.60 Nitrogen 0.40 to 0.60 Chromium 18.0 to 21.0 Manganese 10.5 to 14.0 Nickel 0 to 0.35 Silicon 2.00 to 3.00 Iron 1 Balance Except for unavoidable impurities and other elements in niinoii amounts not detrimentally affecting the properties of t e s eel.
- nickel-free Cr-Mn-C-N austenitic steel having a silicon content related to the chromium content of the steel as indicated in the following tabulation:
- Such steel will exhibit particularly good resistance to oxidation in air or another oxygen-containing atmosphere at an elevated temperature such as 15002200 F., as evidenced by a weight loss, after six 16-hour cycles of exposure in air at 2150 F. (1177 C.) of 0.5 gram per square inch or less. This value compares quite favorably with the figure of about 6 or 7 grams per square inch under the same conditions observed when testing another steel (2lCr4Ni-9Mn0.25Si-0.4N-0.5C) now used for diesel engine valves.
- Steel of the present invention is, like the other agehardenable austenitic stainless steel of prior art, preferably heat-treated by first heating to a solution-treatment temperature of 2100 to 2300 F. (e.g., 2150 F.), then rapidly cooling by quenching in oil or water, and then finally aging to a desired hardness by heating of a substantial period such as about 10 to 100 hours at a temperature of about 1600 to 1200 F.
- the steels of the invention have imparted to them by such heat treatment good strength and hardness, such as a 100-hour creep-rupture strength at 1200 F. of 41,000 p.s.i., a room-temperature hardness, as heat-treated, of Rockwell C 40 or greater.
- Table I there are presented results of elevatedtemperature tensile properties that are typical of steels of the present invention.
- the following composition is set forth: 21% chromium, 0.2% nickel, 12% manganese, 0.50% carbon, 2.8% silicon, 0.40% nitrogen, and the remainder iron expect for unavoidable impurities in minor amounts not detrimentally affecting the properties.
- Table VI presents the chemi- Reduction of Area (percent) Stress Rupture (1,000 p.s.i.)
- FIGURES 1 and 2 An appreciation of the criticality of the inter-relation between chromium content and scilicon content can be obtained from an examination of FIGURES 1 and 2, in which the above data is plotted.
- Age-hardenable austenitic stainless steel consisting essentially of, in weight percent
- Age-hardenable austenitic stainless steel consisting essentiall of, in Weight percent,
- Age-hardenable austenitic stainless steel consisting essentially of, in weight percent,
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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)
Description
Claims (1)
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US446469A US3340046A (en) | 1965-03-29 | 1965-03-29 | Age-hardenable austenitic stainless steel |
GB239166A GB1108384A (en) | 1965-01-22 | 1966-01-18 | Age hardenable stainless steel alloy |
ES0321954A ES321954A1 (en) | 1965-01-22 | 1966-01-19 | Age hardenable stainless steel alloy |
DE19661533197 DE1533197B1 (en) | 1965-01-22 | 1966-01-19 | USE OF A HARDENABLE, AUSTENITIC, STAINLESS STEEL ALLOY AS A MATERIAL FOR DIESEL ENGINE VALVES |
BE675396D BE675396A (en) | 1965-01-22 | 1966-01-20 | |
SE818/66A SE319016B (en) | 1965-01-22 | 1966-01-21 | |
DK33166A DK120050B (en) | 1965-01-22 | 1966-01-21 | Maturable hardened austenitic stainless steel. |
JP353166A JPS5017410B1 (en) | 1965-01-22 | 1966-01-22 |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US446469A US3340046A (en) | 1965-03-29 | 1965-03-29 | Age-hardenable austenitic stainless steel |
Publications (1)
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US3340046A true US3340046A (en) | 1967-09-05 |
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Application Number | Title | Priority Date | Filing Date |
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US446469A Expired - Lifetime US3340046A (en) | 1965-01-22 | 1965-03-29 | Age-hardenable austenitic stainless steel |
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Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1896155A (en) * | 1930-04-29 | 1933-02-07 | Electro Metallurg Co | Corrosion resistant articles of manufacture |
US1943782A (en) * | 1930-04-29 | 1934-01-16 | Electro Metallurg Co | Corrosion resistant article |
US2706696A (en) * | 1951-04-24 | 1955-04-19 | Crucible Steel Company | Age hardening austenitic steel |
US2789049A (en) * | 1954-11-03 | 1957-04-16 | Mckay Co | High strength welding steel |
US2805942A (en) * | 1953-11-05 | 1957-09-10 | Crucible Steel Co America | Alloy steel and articles thereof |
US2862812A (en) * | 1958-05-16 | 1958-12-02 | Crucible Steel Co America | Substantially nickel-free austenitic and corrosion resisting cr-mn-n steels |
US2876096A (en) * | 1957-12-27 | 1959-03-03 | Crucible Steel Co America | Non-magnetic austenitic steel |
GB892667A (en) * | 1957-07-12 | 1962-03-28 | Crucible Steel Co America | Improvements relating to alloy steels |
US3029171A (en) * | 1959-03-23 | 1962-04-10 | Atlas Steels Ltd | Age hardening of stainless steels with niobium silicides |
US3151979A (en) * | 1962-03-21 | 1964-10-06 | United States Steel Corp | High strength steel and method of treatment thereof |
US3165401A (en) * | 1957-03-20 | 1965-01-12 | Int Harvester Co | Alloy steel for cast parts resistant to high temperatures and corrosion |
-
1965
- 1965-03-29 US US446469A patent/US3340046A/en not_active Expired - Lifetime
Patent Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1896155A (en) * | 1930-04-29 | 1933-02-07 | Electro Metallurg Co | Corrosion resistant articles of manufacture |
US1943782A (en) * | 1930-04-29 | 1934-01-16 | Electro Metallurg Co | Corrosion resistant article |
US2706696A (en) * | 1951-04-24 | 1955-04-19 | Crucible Steel Company | Age hardening austenitic steel |
US2805942A (en) * | 1953-11-05 | 1957-09-10 | Crucible Steel Co America | Alloy steel and articles thereof |
US2789049A (en) * | 1954-11-03 | 1957-04-16 | Mckay Co | High strength welding steel |
US3165401A (en) * | 1957-03-20 | 1965-01-12 | Int Harvester Co | Alloy steel for cast parts resistant to high temperatures and corrosion |
GB892667A (en) * | 1957-07-12 | 1962-03-28 | Crucible Steel Co America | Improvements relating to alloy steels |
US2876096A (en) * | 1957-12-27 | 1959-03-03 | Crucible Steel Co America | Non-magnetic austenitic steel |
US2862812A (en) * | 1958-05-16 | 1958-12-02 | Crucible Steel Co America | Substantially nickel-free austenitic and corrosion resisting cr-mn-n steels |
US3029171A (en) * | 1959-03-23 | 1962-04-10 | Atlas Steels Ltd | Age hardening of stainless steels with niobium silicides |
US3151979A (en) * | 1962-03-21 | 1964-10-06 | United States Steel Corp | High strength steel and method of treatment thereof |
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Owner name: COLT INDUSTRIES OPERATING CORP. Free format text: MERGER AND CHANGE OF NAME;ASSIGNOR:CRUCIBLE CENTER COMPANY (INTO) CRUCIBLE INC. (CHANGED TO);REEL/FRAME:004120/0308 Effective date: 19821214 |
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Owner name: CRUCIBLE MATERIALS CORPORATION, A DE CORP. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:COLT INDUSTRIES OPERATING CORP.;REEL/FRAME:004194/0621 Effective date: 19831025 Owner name: CRUCIBLE MATERIALS CORPORATION, PENNSYLVANIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:COLT INDUSTRIES OPERATING CORP.;REEL/FRAME:004194/0621 Effective date: 19831025 |