US3914135A - Method of improving steel properties by using controlled cooling rates - Google Patents

Method of improving steel properties by using controlled cooling rates Download PDF

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Publication number
US3914135A
US3914135A US340942A US34094273A US3914135A US 3914135 A US3914135 A US 3914135A US 340942 A US340942 A US 340942A US 34094273 A US34094273 A US 34094273A US 3914135 A US3914135 A US 3914135A
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Prior art keywords
steel
cooling
rate
preparing
thickness
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US340942A
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English (en)
Inventor
Isao Kozasu
Teruhiko Shimizu
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JFE Engineering Corp
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Nippon Kokan Ltd
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    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • C21D1/63—Quenching devices for bath quenching

Definitions

  • ABSTRACT A steel material exhibiting high yield strength and excellent toughness in which fine ferrite-pearlite struc- .8 C1aims,'3 Drawing Figures U.S. Patent Oct.21, 1975 Sheet1of3 3,914,135
  • Cooling Rore (C Sec) AS R
  • C Sec Cooling Rore
  • said hard spot isproducedin a location of said steel where many drop prm'itcooling water to *strike atcarIy coolingstage of'cooling.:Needless to say such phenomena bring about n'on-uniformitybf the mechanical. properties and especially deterioration of "toughness. In “a different manner from the above process, sometimes an air-blast c'ooling-is also'employed on said steel. It is obvious however obvious that a cooling rate capable of influencing on said properties of steel is difficult to obtained and, when it is employed without adding an alloying element, there is naturally a limit in improvement of yield-strength and toughness.
  • This invention has been developed to overcome the present situation.
  • the features of this invention lie in 5 subjecting a steel consisting of less than 0.25% C, 0.6
  • FIG. 1 is an.explanatory view of an accelerate coolin step with two-phase flow gas (mist).
  • FIG. 2- is a graph showing a relation between cooling rate and fracture appearance transition temperature and yield strength
  • FIG. 3 shows variation of the state of hardness through plate thickness depending upon cooling rate.
  • Cooling rate varied (average rate at 850C 450C) Cooling method:
  • Nb is a very effective element to produce said fine fer-I rite-pearlite structure under the above-mentioned ac-L celerated cooling rate.
  • ac-L celerated cooling rate On the other hand, in a steel I containing no Nb, there is shown little grain refining effect with said accelerate cooling. In a steel containing only V, said accelerated cooling is of no utility, because.
  • Nb+V less than 0.2% if necessary.
  • Heating temperature is within ordinary normalizing temperature range, i.e. more than Ac point and is limited to less than 1,000C. If said temperature is beyond 1,000C. said austenite grain tends to coarsen, and Nbcarbide tends to dissolve into the matrix, consequently, undesirable bainitic structure tends to be formed during cooling.
  • Cooling rate from the above-mentioned heating temperature is closely limited within the range of 0.8 "to 2.0C/sec.
  • the lower limit, i.e. 0.8C/s ec corresponds to an air-cooling rate for steel plate of to 12mm thickness and, accordingly, a noticeable effect has not yet been exhibited.
  • undesirable bainite begins to form even if martensite does not appear. If once said structure is formed, the discontinuous yield phenomenon disappears and the lowering of the yield stress is brought about. At the same time, the 50% fracture appearance transition temperature is raised. Consequently, efforts to improve said properties of steel will be brought to naught.
  • Such accelerate cooling as mentioned above may be carried out with water-cooling by the common spray nozzle. It is, however, recommended in this invention that a two-phase gas jet in which liquid is atomized is employed.
  • the features of said cooling system with said two-phase gas jet lie in that said cooling is thereby very uniform and is controllable with accuracy.
  • An example of two-phase gas jet system e.g. mist cooling system is shown in the accompanying drawing, wherein numeral 1 is a cooled steel material, 2 a spray nozzle, 3, a gas reservoir 4, a roller table 5 a feed pipe of gas, and 6 a feeding pipe for cooling water.
  • FIG. l-(a) A typical single nozzle arrangement of the above basic configuration is shown in FIG. l-(a), a double nozzle arrangement in FIG.
  • FIG. l-(c) also is an example of a reversing mechanism for said cooled material as an arrow shows. These configurations are selected as occasion demands.
  • FIG. 3 An example of variation of hardness through section is shown FIG. 3.
  • the upppr is Steel (G) and the lower is Steel (H).
  • the lower is Steel (H).
  • FIG. 3 it is understood that not only said hardness of steel G (not containing Nb) is influenced sensitively by the increase of said cooling rate, but also said yield stress is little improved.
  • Steel (H) (containing Nb)
  • said hardness is little changed in comparison with that of air-cooled, i.e. normalized, steel. It should be noted that this fact shows that said stable ferrite-pearite structure is fully produced.
  • FIG. 3 it is understood that the variation of hardness through at section is within the range of :1 (Vicker Hardness). There is no precedent for such uniformity.
  • the cooling rate i.e. accelerate cooling at 08C to 2.0C/sec. should be closely retained. In this way the distortion of steel can be minimized.
  • said steel material includes slab, tube, pipe, bar, section steel or the like.
  • step (i) heating the steel of step (i) from A point to 100- 0C, and iii. cooling said heated steel at a rate of 030 to 20C per second, until its transformation is completed, at
  • the method of preparing an improved steel material which includes the steps of:
  • step (i) heating the steel of step (i) from AC3 point to l000C, and iii. cooling said heated steel at a rate of 0.3C to 2.0C per second, until its transformation is completed, at a selected rate which yields a product I substantially free from martensite having high yield strength, and excellent toughness.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
US340942A 1972-03-15 1973-03-14 Method of improving steel properties by using controlled cooling rates Expired - Lifetime US3914135A (en)

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JP47025801A JPS4894618A (no) 1972-03-15 1972-03-15

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US (1) US3914135A (no)
JP (1) JPS4894618A (no)
CA (1) CA994220A (no)
DE (1) DE2313015B2 (no)
FR (1) FR2176130B1 (no)
GB (1) GB1417624A (no)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4198249A (en) * 1977-07-02 1980-04-15 Lukens Steel Company Steel substrate for glassing
US4236551A (en) * 1977-05-05 1980-12-02 Veb Schwermaschinenbau-Kombinat Ernst Thalmann Magdeburg Method of and apparatus for cooling rolled wire
US4318534A (en) * 1980-10-09 1982-03-09 Midland-Ross Corporation Plate quench
EP0053913A1 (en) * 1980-12-04 1982-06-16 Uss Engineers And Consultants, Inc. Method for producing high-strength deep-drawable dual-phase steel sheets
US4376661A (en) * 1978-06-16 1983-03-15 Nippon Steel Corporation Method of producing dual phase structure cold rolled steel sheet
US4407487A (en) * 1980-01-15 1983-10-04 Heurtey Metallurgie Device for cooling metal articles
US20070122601A1 (en) * 2005-11-28 2007-05-31 Martin Gary S Steel composition, articles prepared there from, and uses thereof

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5910415B2 (ja) * 1978-12-27 1984-03-08 新日本製鐵株式会社 耐応力腐食割れ性の優れた高張力線材及び棒鋼の製造法
AU537333B2 (en) * 1979-11-09 1984-06-21 La Salle Steel Co. Process for annealing steels
GB2125831B (en) * 1980-01-04 1984-10-24 Heurtey Metallurgie Cooling of metal
DE10256394A1 (de) * 2002-12-02 2004-06-17 Benteler Stahl/Rohr Gmbh Verfahren zur Herstellung eines Stahlrohrs sowie Verwendung eines Stahlwerkstoffs zur Herstellung längsnahtgeschweißter Rohre

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1919983A (en) * 1932-03-01 1933-07-25 Gen Electric Method for producing low loss nonaging silicon steel sheets
US3098776A (en) * 1960-12-09 1963-07-23 Western Electric Co Methods of heat-treating low carbon steel
US3151005A (en) * 1959-07-09 1964-09-29 United States Steel Corp Method of producing grain-oriented electrical steel
US3335036A (en) * 1964-01-25 1967-08-08 Kawasaki Steel Co Deep drawing steel sheet and method for producing the same
US3522114A (en) * 1965-05-19 1970-07-28 Maximilianshuette Eisenwerk Production of steel for electrical sheet material
US3620856A (en) * 1968-12-17 1971-11-16 Sanyo Electric Works Process to improve magnetic characteristics of carbon steel
US3632456A (en) * 1968-04-27 1972-01-04 Nippon Steel Corp Method for producing an electromagnetic steel sheet of a thin sheet thickness having a high-magnetic induction
US3657022A (en) * 1965-08-10 1972-04-18 Nippon Kokan Kk Process for the manufacture of cold-rolled steel strip with superior mechanical workability, especially deep forming properties
US3661656A (en) * 1968-06-14 1972-05-09 Fagersta Bruks Ab Case-hardened steel product and process for its manufacture
US3671337A (en) * 1969-02-21 1972-06-20 Nippon Steel Corp Process for producing grain oriented electromagnetic steel sheets having excellent magnetic characteristics

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3544393A (en) * 1967-08-11 1970-12-01 Nat Steel Corp Method of manufacturing low carbon high tensile strength alloy steel
US3726723A (en) * 1970-05-11 1973-04-10 American Metal Climax Inc Hot-rolled low alloy steels

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1919983A (en) * 1932-03-01 1933-07-25 Gen Electric Method for producing low loss nonaging silicon steel sheets
US3151005A (en) * 1959-07-09 1964-09-29 United States Steel Corp Method of producing grain-oriented electrical steel
US3098776A (en) * 1960-12-09 1963-07-23 Western Electric Co Methods of heat-treating low carbon steel
US3335036A (en) * 1964-01-25 1967-08-08 Kawasaki Steel Co Deep drawing steel sheet and method for producing the same
US3522114A (en) * 1965-05-19 1970-07-28 Maximilianshuette Eisenwerk Production of steel for electrical sheet material
US3657022A (en) * 1965-08-10 1972-04-18 Nippon Kokan Kk Process for the manufacture of cold-rolled steel strip with superior mechanical workability, especially deep forming properties
US3632456A (en) * 1968-04-27 1972-01-04 Nippon Steel Corp Method for producing an electromagnetic steel sheet of a thin sheet thickness having a high-magnetic induction
US3661656A (en) * 1968-06-14 1972-05-09 Fagersta Bruks Ab Case-hardened steel product and process for its manufacture
US3620856A (en) * 1968-12-17 1971-11-16 Sanyo Electric Works Process to improve magnetic characteristics of carbon steel
US3671337A (en) * 1969-02-21 1972-06-20 Nippon Steel Corp Process for producing grain oriented electromagnetic steel sheets having excellent magnetic characteristics

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4236551A (en) * 1977-05-05 1980-12-02 Veb Schwermaschinenbau-Kombinat Ernst Thalmann Magdeburg Method of and apparatus for cooling rolled wire
US4198249A (en) * 1977-07-02 1980-04-15 Lukens Steel Company Steel substrate for glassing
US4376661A (en) * 1978-06-16 1983-03-15 Nippon Steel Corporation Method of producing dual phase structure cold rolled steel sheet
US4407487A (en) * 1980-01-15 1983-10-04 Heurtey Metallurgie Device for cooling metal articles
US4318534A (en) * 1980-10-09 1982-03-09 Midland-Ross Corporation Plate quench
EP0053913A1 (en) * 1980-12-04 1982-06-16 Uss Engineers And Consultants, Inc. Method for producing high-strength deep-drawable dual-phase steel sheets
US20070122601A1 (en) * 2005-11-28 2007-05-31 Martin Gary S Steel composition, articles prepared there from, and uses thereof
US7628869B2 (en) * 2005-11-28 2009-12-08 General Electric Company Steel composition, articles prepared there from, and uses thereof

Also Published As

Publication number Publication date
GB1417624A (en) 1975-12-10
FR2176130B1 (no) 1976-05-21
JPS4894618A (no) 1973-12-05
CA994220A (en) 1976-08-03
DE2313015A1 (de) 1973-09-27
FR2176130A1 (no) 1973-10-26
DE2313015B2 (de) 1978-11-09

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