US3917492A - Method of making stainless steel - Google Patents

Method of making stainless steel Download PDF

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Publication number
US3917492A
US3917492A US477469A US47746974A US3917492A US 3917492 A US3917492 A US 3917492A US 477469 A US477469 A US 477469A US 47746974 A US47746974 A US 47746974A US 3917492 A US3917492 A US 3917492A
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Prior art keywords
steel
cold
excess
tempering
temperature
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Expired - Lifetime
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US477469A
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Anders Lars Erik Backman
Stig Gunnar Forsberg
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Santrade Ltd
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Sandvik AB
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Assigned to SANTRADE LTD., A CORP. OF SWITZERLAND reassignment SANTRADE LTD., A CORP. OF SWITZERLAND ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SANDVIK AKTIEBOLAG, A CORP. OF SWEDEN
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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
    • C22C38/40—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
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys

Definitions

  • the present invention relates toa stainless chromium-nickel steel with high strength, and which at the same time has good ductility.
  • This invention also relates to a new method of treating such stainless steel in the form of band or wire to achieve these new characteristics of .stainless steel, said steel then being adaptable for use as a spring material in the form of wire or strip.
  • High strength material which at the same time has a good ductility is increasingly called for.
  • One method of strengthening steel consists in subjecting the steel to an appreciable cold reduction. This method is especially adaptable for certain types of austenitic stainless steel in which an austenitic structure is partially transformed by colddeformation into a hard martensitic structure. The mechanism of this structural transformation is well known and is disclosed in, for instance, British Pat. Nos. 722,427 and 766,971. These unstable austenitic steels have been in wide use especially as spring materials, and are available in the form of round wire or bands.
  • the requirement for good ductility often implies that it must be possible to carry out a succession of deformations of such material without any ensuing fractural formations. If the material is in the form of wire there is a requirement that it must be possible to have such wire wound'around a bar the diameter of which is approximately the same as that of the wire itself.
  • the normal procedure of processing such steel is to carry out a cold reduction to a level of strength and ductility such that the material then is able to be subjected to a shaping procedure into a final product.
  • Such a product is often also subjected to a final heat treatment at a temperature of 200-550C. during a few hours for strengthening purposes.
  • the invention thus resides in a new stainless steel which exhibits the unique combination of high strength and ductility and which also temperatures.
  • . lt is an object of the invention to provide a stainless chromium-nickel steel that is hardenable by cold-work into an austenitic-martensitic microstructure, said steel in the coId-WorkedconditiQn having a tensile strength in excess of 250,000 p.s.i., but'not in excess of 400,000
  • the invention provides such an alloy having a composition consisting essentially of, by weight, about 0.01 to 0.20% carbon, up to about 5% silicon, up to about 10% manganese, from about 13 to about 20% chromium, about 3 to 10% nickel, up to about 2.5% molybdenum, up to about 2.5% aluminum, and the balance being essentially iron except for small amounts of other elements which do not adversely affect the desired properties of the alloy.
  • I start with an austenitic stainless steel in the form of wire or strip, this steel having been hot rolled in the usual] manner and which has a composition comprising chromium in amounts sufficient to give the steel a metastable austenitic microstructure.
  • the steel is (or, may be) subjected to a conventional surface treatment such as pickling, grinding, sandblasting or similar treatment.
  • a conventional surface treatment such as pickling, grinding, sandblasting or similar treatment.
  • Such a material is then transformed into a wholly austenitic condition by annealing at a temperature of 950l C. and then quenching in water.
  • the steel is subjected to a cold reduction in one or several steps without intermediate annealings at a very large reduction of area, thus partially transforming the austenitic structure into a 'martensitic structure, an increased hardness simultaneously being obtained.
  • FIG. 1 is a diagramatic showing of the effect of total reduction on the ratio between yield point and ultimate tensile strength
  • FIG. 2 shows the effect of total reduction on the contraction of area immediately before rupture
  • FIG. 3 diagfamatically represents the improvement in properties under elevated temperature conditions in the case of a steel of the 18-8 type.
  • FIG. 4 is a modified Schaeffler diagram showing microstructures, attainable through practice of the present invention, in the cases of selected chromiumnickel steels.
  • FIG. 1 illustrates the effect of total reduction on the ratio
  • the starting material, treated as related hereinbefore, is upon quenching subjected to cold deformation I with high reduction of area next to entering the brittle state, said area reduction amounting to 40-90%, preferably 60-85% thus partially transforming the aUStenand in FIG. 2 there is illustrated the effect of total reltle Structure Into martenslte the amount of Whleh duction on the contraction of area immediately before being usually 45-85% Whlle the remainder rupture.
  • curves illustratis ,austenite with small amounts of ferrite.
  • the material is Subjected to tempering at a scope of the invention in comparison with those illustemperature of -,P bly 250450C-, trating the method of the invention.
  • Steel ll were prepared d r isuch as the tempering temperature and the dimensions mens were ad ther fr for carrying out tests the 0f the je m y be from Some mlmltes p to 1042 results of which are set forth in the Table following hours or e g
  • the tempering time sua ly is hereinafter.
  • the material made subject'of these tests tween 15 minutes and 10 hours, and preferably was stainless steel wire subjected tocold drawing upon tween 2 d 5 hours h s tempering s necessary so as quench-annealing from 1050 C., the analysis of which to relieve those stresses which appear to a locally high was as f ll degree in the microstructure as a result of the cold working.
  • the material is further C Si Mn Cr Ni MO Fe cold reduced to a moderate reduction of area amount- I 8 0 1 ing to 540%, preferably l0- 30%.
  • the Table is also illustrative of the improved ultimate strength reached with the alloy of the invention, which amounts to 240 kp/mm (343,000 p.s.i.) upon tempering at 425 C. for a time of 4 hours plus reduction of area. After another tempering at 425 C. for a period of 4 hours the strength reached a level of 255 kp/mm (364,000 p.s.i.) whilst the material retained a high ductility, 2.5% in terms of ultimate elongation.
  • the results of these tests thus established that it is possible to achieve a considerable increase of ductility yet retaining a high strength levelby carrying out a method of processing according to the invention.
  • FIG. 3 refers to the relaxation permanence, which expression means the percentual loss of applied load at a certain temperature and for a length of time.
  • the diagram of FIG. 3 shows such a curve of steel 1 of 18-8 type not cold-worked according to the invention in comparison with steel 2 which is within the scope of the invention.
  • the curves refer to the percentual loss of an applied load of 60 kp/mm for a period of 24 hours at differing temperatures.
  • the diagram clearly shows the very good relaxation permanence of steel 2, this being a very important property of steels adapted for use as spring material.
  • the effect thus achievable by the method of the invention applies to all those austenitic, or essentially austenitic, steels wherein austenite is partially transformed into martensite as a result of deformation and where a heat treatment gives rise to precipitations which give rise to an increased strength level.
  • the chemical analysis thus must comprise an amount of chromium, usually in excess of 13%, that is sufi'icient to provide a metastable austenitic microstructure under the conditions that apply while deforming the steel.
  • the method of the invention is applicable to steel alloys having a composition in weight percentages, consisting essentially of about 0.01 to 0.20% carbon, up to about 6 5% silicon, up to about 10% manganese, about 13 to 20% chromium, about 3 to 10% nickel, up to about 2.5% molybdenum, up to about 2.5% aluminum, and the balance being essentially iron except for small amounts of other elements which do not adversely affect the desired properties of the alloy.
  • FIG. 4 there is shown a modified Schaeffler diagram from which is derivable the microstructure that will be the result of a certain steel analysis.
  • the dotted rectangle indicates the area within which the alloys appear in the broader aspects of the invention, whereas the smaller square therein corresponds to the more narrow and preferred ranges of analysis according to the practices of my invention, this last squared area being limited by the lines set by chromium equivalents in amounts of 15-25% and nickel equivalents in amounts of 5-15%, said chromium equivalent being given by the relation (%Cr+ %Mo +1.5 X Si 2 X Nb 3 X Ti) and said nickel equivalent being given by the relation (%Ni 0.5 X %Mn 30 X %C 11.5 X %N).
  • a method of making austenitic stainless steels having high tensile strength in excess of 250,000 p.s.i. but not in excess of 400,000 p.s.i. and preferably not in excess of 390,000 p.s.i., with high ductility in excess of 45% in terms of contraction of area before rupture and good properties under elevated temperature conditions in terms of relaxation permanence comprising, selecting an austenitic stainless steel of the transformation hardening type and containing from 0.01 to 0,20% carbon, up to about 5% silicon, up to about 10% manganese, from 13 to 20% chromium, from 3 to 10% nickel, up to about 25% molybdenum, up to about 25% aluminum and the balance essentially iron; annealing the steel at a temperature of 9501 100 C.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
US477469A 1973-06-08 1974-06-07 Method of making stainless steel Expired - Lifetime US3917492A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE7308126A SE373387B (sv) 1973-06-08 1973-06-08 Forfarande for framstellning av band eller trad, exv. rundtrad for fjederendamal

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US3917492A true US3917492A (en) 1975-11-04

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US (1) US3917492A (enExample)
BE (1) BE816034A (enExample)
DE (1) DE2427038A1 (enExample)
FR (1) FR2232608B1 (enExample)
GB (1) GB1459915A (enExample)
SE (1) SE373387B (enExample)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4092180A (en) * 1977-05-03 1978-05-30 Grumman Aerospace Corporation Manufacture of torsion bars
DE2824393A1 (de) * 1977-06-14 1979-01-04 Fagersta Ab Walzdraht oder -strangmaterial
US4159218A (en) * 1978-08-07 1979-06-26 National Steel Corporation Method for producing a dual-phase ferrite-martensite steel strip
DE2929179A1 (de) * 1978-07-20 1980-01-31 Illinois Tool Works Bohrschraube aus rostfreiem stahl und verfahren zu deren herstellung
US4259126A (en) * 1978-10-19 1981-03-31 Wilkinson Sword Limited Method of making razor blade strip from austenitic steel
US4265679A (en) * 1979-08-23 1981-05-05 Kawasaki Steel Corporation Process for producing stainless steels for spring having a high strength and an excellent fatigue resistance
US4378246A (en) * 1980-03-19 1983-03-29 Nisshin Steel Co., Ltd. Precipitation hardening type stainless steel for spring
US4939097A (en) * 1986-06-02 1990-07-03 Litmus Concepts, Inc. Fecal occult blood test methods
US6274200B1 (en) * 1998-09-11 2001-08-14 Boeing North American, Inc. Method for preparing pre-coated ferrous-alloy components and components prepared thereby
US6383316B1 (en) * 1997-12-17 2002-05-07 Haldex Garphyttan Aktiebolag Cold drawn wire and method for the manufacturing of such wire
US6418994B1 (en) 1993-10-15 2002-07-16 Michelin Recherche Et Technique S.A. Tire having a stainless steel carcass reinforcement
US10329649B2 (en) * 2012-01-20 2019-06-25 Solu Stainless Oy Austenitic stainless steel product and a method for manufacturing same
US10738372B2 (en) * 2016-06-17 2020-08-11 Zhejiang University Method of processing fully austenitic stainless steel with high strength and high toughness

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0031399A3 (en) * 1979-07-30 1981-11-25 Consultronic (Int.)Ltd. Material for the production of stainless alpine ski edges
DE3108588A1 (de) * 1981-03-06 1982-09-23 Georg Fischer AG, 8201 Schaffhausen "chromstahlgussstueck"
US4533391A (en) * 1983-11-07 1985-08-06 Allegheny Ludlum Steel Corporation Work-hardenable substantially austenitic stainless steel and method
GB2168077A (en) * 1984-12-07 1986-06-11 Fulmer Res Inst Ltd Improvements in or relating to stainless steels

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2553707A (en) * 1947-01-31 1951-05-22 Armco Steel Corp Stainless steel spring
US2795519A (en) * 1954-03-27 1957-06-11 Sandvikens Jernverks Ab Method of making corrosion resistant spring steel and product thereof
US3152934A (en) * 1962-10-03 1964-10-13 Allegheny Ludlum Steel Process for treating austenite stainless steels
US3281287A (en) * 1962-02-27 1966-10-25 Sandvikens Jernverks Ab Corrosion resistant edge tool and method of making the same
US3698963A (en) * 1970-09-21 1972-10-17 Brunswick Corp Ultrahigh strength steels

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2553707A (en) * 1947-01-31 1951-05-22 Armco Steel Corp Stainless steel spring
US2795519A (en) * 1954-03-27 1957-06-11 Sandvikens Jernverks Ab Method of making corrosion resistant spring steel and product thereof
US3281287A (en) * 1962-02-27 1966-10-25 Sandvikens Jernverks Ab Corrosion resistant edge tool and method of making the same
US3152934A (en) * 1962-10-03 1964-10-13 Allegheny Ludlum Steel Process for treating austenite stainless steels
US3698963A (en) * 1970-09-21 1972-10-17 Brunswick Corp Ultrahigh strength steels

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4092180A (en) * 1977-05-03 1978-05-30 Grumman Aerospace Corporation Manufacture of torsion bars
DE2824393A1 (de) * 1977-06-14 1979-01-04 Fagersta Ab Walzdraht oder -strangmaterial
DE2929179A1 (de) * 1978-07-20 1980-01-31 Illinois Tool Works Bohrschraube aus rostfreiem stahl und verfahren zu deren herstellung
US4159218A (en) * 1978-08-07 1979-06-26 National Steel Corporation Method for producing a dual-phase ferrite-martensite steel strip
US4259126A (en) * 1978-10-19 1981-03-31 Wilkinson Sword Limited Method of making razor blade strip from austenitic steel
US4265679A (en) * 1979-08-23 1981-05-05 Kawasaki Steel Corporation Process for producing stainless steels for spring having a high strength and an excellent fatigue resistance
US4378246A (en) * 1980-03-19 1983-03-29 Nisshin Steel Co., Ltd. Precipitation hardening type stainless steel for spring
US4939097A (en) * 1986-06-02 1990-07-03 Litmus Concepts, Inc. Fecal occult blood test methods
US6418994B1 (en) 1993-10-15 2002-07-16 Michelin Recherche Et Technique S.A. Tire having a stainless steel carcass reinforcement
US6383316B1 (en) * 1997-12-17 2002-05-07 Haldex Garphyttan Aktiebolag Cold drawn wire and method for the manufacturing of such wire
US6274200B1 (en) * 1998-09-11 2001-08-14 Boeing North American, Inc. Method for preparing pre-coated ferrous-alloy components and components prepared thereby
US10329649B2 (en) * 2012-01-20 2019-06-25 Solu Stainless Oy Austenitic stainless steel product and a method for manufacturing same
US10738372B2 (en) * 2016-06-17 2020-08-11 Zhejiang University Method of processing fully austenitic stainless steel with high strength and high toughness

Also Published As

Publication number Publication date
SE7308126L (enExample) 1974-12-09
FR2232608A1 (enExample) 1975-01-03
GB1459915A (en) 1976-12-31
SE373387B (sv) 1975-02-03
DE2427038A1 (de) 1974-12-19
BE816034A (fr) 1974-09-30
FR2232608B1 (enExample) 1981-01-09

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AS Assignment

Owner name: SANTRADE LTD., ALPENQUAI 12, CH-6002, LUCERNE, SWI

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SANDVIK AKTIEBOLAG, A CORP. OF SWEDEN;REEL/FRAME:004085/0132

Effective date: 19820908