US3806378A - As-worked bainitic ferrous alloy and method - Google Patents

As-worked bainitic ferrous alloy and method Download PDF

Info

Publication number
US3806378A
US3806378A US00316962A US31696272A US3806378A US 3806378 A US3806378 A US 3806378A US 00316962 A US00316962 A US 00316962A US 31696272 A US31696272 A US 31696272A US 3806378 A US3806378 A US 3806378A
Authority
US
United States
Prior art keywords
transformation
alloy
bainitic
worked
ferrous alloy
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00316962A
Other languages
English (en)
Inventor
B Bramfitt
A Marder
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bethlehem Steel Corp
Original Assignee
Bethlehem Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bethlehem Steel Corp filed Critical Bethlehem Steel Corp
Priority to US00316962A priority Critical patent/US3806378A/en
Priority to CA186,146A priority patent/CA1014772A/en
Priority to GB5670073A priority patent/GB1453064A/en
Priority to IT54414/73A priority patent/IT1000369B/it
Priority to DE2362878A priority patent/DE2362878A1/de
Priority to FR7345588A priority patent/FR2211531B1/fr
Priority to JP48143402A priority patent/JPS4990621A/ja
Priority to US446550A priority patent/US3907614A/en
Application granted granted Critical
Publication of US3806378A publication Critical patent/US3806378A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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

Definitions

  • this invention is directed to the hot working cycle of a ferrous alloy characterized by an I-T diagram or S curve having a double nose or a pearlite transformation knee of the beginning curve above a broad bainitic bay region.
  • a ferrous alloy characterized by an I-T diagram or S curve having a double nose or a pearlite transformation knee of the beginning curve above a broad bainitic bay region.
  • Such an alloy is heated to an austenitizing temperature of about 1500 to 2200 F., and subjected to a plurality of working operations at successively lower temperatures, where the final working operation is conducted after the beginning of the austenite transformation to bainite and before the complete transformation thereof.
  • bainite has been metallurigical- 1y defined as one of the transformation products of austenite. Upon cooling the austenite, transformation to bainite occurs over the temperature range of about 1000 to 450 F.
  • the microstructure differs from pearlite, a high temperature austenite transformation product, in that it is acicular in nature.
  • the last generally recognized transformation product is martensite. Transformation to martensite must be directly from austenite, i.e. without prior transformation to ferrite, pearlite or bainite. Unlike the transformation to pearlite or bainite, it is not time dependent, but occurs almost instantly upon cooling.
  • the LT diagrams were developed by studying the transformation behavior of a steel at a series of temperatures below the A critical temperature, by quenching small samples to the desired temperature in a liquid bath, allowing them to transform isothermally and following the progress of the transformation metallographically. From this, the curves could be drawn. Very generally, this procedure included heating, quenching, holding, and cooling. It has since been determined that processing variations such as working or rolling affected the actual time and temperature of transformation, particularly the pearlite transformation. More specifically it was discovered that the inclusion of an austenite working step changed the transformation kinetics of the steel by United States Patent ice shifting the curve to a higher temperature. This phenomena has been confirmed by Y. E. Smith in an article in Metallurgical Transactions, v. 2, June 1971. Nevertheless, with the apparent limitations, the LT diagram remains as a significant factor in selecting the proper ferrous alloy and for predicting results when subjected to the process herein.
  • This invention is directed to an as-worked bainitic ferrous alloy and to a procedure involving the thermomechanical treatment of the said alloy. More particularly it relates to a process of heating said alloy to an austenitizing temperature between about 1500 to 2200 F. and subjecting the alloy to a plurality of working operations as it cools from said austenitizing temperature. While the final working should be conducted during the transformation of the austenite to bainite, the initial working should begin while the alloy is above 1500 F. By this procedure, an optimum combination of strength and toughness, in the as-worked condition, is produced.
  • the processed alloy is characterized by fine grains and cells, with very fine uniformly dispersed carbides.
  • a bainitic ferrous alloy characterized by an isothermal transformation diagram having the pearlite transformation knee of the beginning curve laterally displaced to the right of the lower temperature bainitic transformation knee, is heated to an austentitzing temperature between about 1500 to 2200 F., preferably at least about 1600 F., and subjected to at least two working steps, preferably at least five, to reduce the cross section thereof, with the final of said steps occurring within the bainite transformation region.
  • carbon while inherently present in steel, sho'uld be present in an amount sufficient to yield precipitatedcarbides upon final cooling.
  • all elemental additions aifect hardenability. This may be extended to say that all elemental additions, to a large or small degree, are effective in retarding isothermal transformation.
  • a number of elemental additions such as Mo, Cr, V, Si, Ti and Cb (identified for convenience as Group I elements), are effective in pushing the pearlite nose to the right.
  • molybdenum is one of the most effective of these additions.
  • the latter additions should be distinguished from some other elemental additions, such as Mn, Ni, B, N and Co, which act to shift the entire S curve to the right; these ma be identified as Group II elements.
  • the alloy contain at least .25 by weight, molybdenum. But, when a lesser amount is used, it is desirable to use at least .75%, preferably, 1.00%, by weight, chromium.
  • this invention begins by heating a bainitic ferrous alloy to an austenitizing temperature of about 1500 to 2200" F. where the first working, such as rolling, should start. Several reductions or passes, preferably at least four, on the order of about 10% minimum for each reduction, should occur between the starting temperature and the onset of the bainitic transformation or the B temperature which occurs in the range of 900 to 1100 F. This sequence causes grain refinement of the austenite by repeated deformation and recrystallization. Additions of carbide forming elements may aid in the refinement of austenite grain size by precipitation in the austenite.
  • the microstructure of the as-worked alloys of this invention consists of a fine, elongated grain structure, with a lath-like substructure and fine carbides, on the order of 0.01 to 0.03 am. in size, at the lath boundaries and dispersed within the laths.
  • This structure is also associated with a dominant crystallographic texture of (111) [110], this designation is based upon the well known Miller Crystallographic Index System. *On rolled plates this texture is measured on the transverse plane, or perpendicular to the rolling direction. The intensity thereof ranges from 2.5 to 3.5 times random as measured by the nine-plane, inverse pole figure technique. A value of 1.0 represents a completely random orientation, whereas 9.0 shows or the orientation of a single crystal.
  • the improved properties of the alloys of this invention can best be demonstrated with rolling data and specific properties of six bainitic alloys treated by the method herein, and by the conventional hot rolling process, each of which are schematically illustrated in the figure.
  • the chemistry, by weight percent, for the bainitic ferrous alloys are given in Table II, with the rolling data and property results in Table III.
  • K r g?elapse time for alloys finished above 1,590 F. was approximately 3 minutes; the elapse time for alloys finished between 1,190 700 F. ranged between and 26 minutes.
  • a method of producing a high strength ferrous alloy having a 01-15 notch toughness transition temperature less than about 25" F. in the as-rolled condition said alloy characterized by an isothermal transformation diagram having the pearlite transformation knee of the beginning curve laterally displaced to the right of the lower temperature bainitic transformation knee, and consisting essentially, by weight, of about .03 to .65% carbon, a minimum of about .25 molybdenum, an addition of at least one element selected from the group consisting of boron, manganese, nickel, and chromium, balance essentially iron, said method comprising the steps of heating said alloy to an austenitizing temperature between about 1500" to 2200 F., and subjecting the alloy to a plurality of working steps which are conducted at progressively lower temperatures, and the final working step being conducted after the initiation of the austenite transformation to bainite and before the complete transformation thereof.
  • each of said working steps reduces the cross section of the alloy by at least 10%.

Landscapes

  • 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 Treatment Of Strip Materials And Filament Materials (AREA)
US00316962A 1972-12-20 1972-12-20 As-worked bainitic ferrous alloy and method Expired - Lifetime US3806378A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US00316962A US3806378A (en) 1972-12-20 1972-12-20 As-worked bainitic ferrous alloy and method
CA186,146A CA1014772A (en) 1972-12-20 1973-11-19 As-worked bainitic ferrous alloy and method
GB5670073A GB1453064A (en) 1972-12-20 1973-12-06 Processing steel to a bainitic structure
DE2362878A DE2362878A1 (de) 1972-12-20 1973-12-18 Bearbeitete (as-worked) bainitische eisenlegierung und verfahren zu ihrer herstellung
IT54414/73A IT1000369B (it) 1972-12-20 1973-12-18 Metodo per produrre una lega fer rosa bainitica e lega cosi prodotta
FR7345588A FR2211531B1 (enrdf_load_stackoverflow) 1972-12-20 1973-12-19
JP48143402A JPS4990621A (enrdf_load_stackoverflow) 1972-12-20 1973-12-20
US446550A US3907614A (en) 1972-12-20 1974-02-27 Bainitic ferrous alloy and method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00316962A US3806378A (en) 1972-12-20 1972-12-20 As-worked bainitic ferrous alloy and method

Publications (1)

Publication Number Publication Date
US3806378A true US3806378A (en) 1974-04-23

Family

ID=23231481

Family Applications (1)

Application Number Title Priority Date Filing Date
US00316962A Expired - Lifetime US3806378A (en) 1972-12-20 1972-12-20 As-worked bainitic ferrous alloy and method

Country Status (7)

Country Link
US (1) US3806378A (enrdf_load_stackoverflow)
JP (1) JPS4990621A (enrdf_load_stackoverflow)
CA (1) CA1014772A (enrdf_load_stackoverflow)
DE (1) DE2362878A1 (enrdf_load_stackoverflow)
FR (1) FR2211531B1 (enrdf_load_stackoverflow)
GB (1) GB1453064A (enrdf_load_stackoverflow)
IT (1) IT1000369B (enrdf_load_stackoverflow)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3945858A (en) * 1973-03-19 1976-03-23 Nippon Kokan Kabushiki Kaisha Method of manufacturing steel for low temperature services
US3960612A (en) * 1973-08-15 1976-06-01 Nippon Steel Corporation Method for producing a low temperature high strength tough steel
US4008103A (en) * 1970-05-20 1977-02-15 Sumitomo Metal Industries, Ltd. Process for the manufacture of strong tough steel plates
US4060431A (en) * 1975-08-23 1977-11-29 Thyssen Edelstahlwerke Aktiengesellschaft Heat-treatable steel
US4088511A (en) * 1976-07-29 1978-05-09 Lasalle Steel Company Steels combining toughness and machinability
US4343661A (en) * 1978-11-15 1982-08-10 Caterpillar Tractor Co. Method of making a low temperature bainite steel alloy gear
DE3201204A1 (de) * 1982-01-16 1983-08-11 M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8900 Augsburg "verwendung eines kohlenstoff-mangan-stahles fuer bauteile mit hoher festigkeit und zaehigkeit bei einfacher waermebehandlung"
EP0020357B1 (en) * 1978-11-15 1984-07-18 Caterpillar Tractor Co. Lower bainite alloy steel article
FR2588570A1 (fr) * 1985-09-19 1987-04-17 Man Nutzfahrzeuge Gmbh Procede pour la fabrication d'elements de construction en acier a haute resistance avec en meme temps une haute tenacite, ces pieces presentant lesdites proprietes meme apres une deformation thermique
US5257522A (en) * 1991-07-09 1993-11-02 Nippon Steel Corporation Process of hot forging at ultrahigh temperature
US5542995A (en) * 1992-02-19 1996-08-06 Reilly; Robert Method of making steel strapping and strip and strapping and strip
WO2014082945A1 (de) * 2012-11-27 2014-06-05 Robert Bosch Gmbh Metallischer werkstoff

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8320622D0 (en) * 1983-07-30 1983-09-01 British Steel Corp Alloy steels
FR2679924B1 (fr) * 1991-07-30 1993-12-10 Ascometal Procede de fabrication d'un tube en acier a paroi mince, acier pour la realisation de ce tube et tube pour cadre de cycle obtenu.
CN103468906A (zh) * 2013-09-17 2013-12-25 北京科技大学 一种低温温轧制备2000MPa级纳米尺度贝氏体钢工艺

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1078411A (fr) * 1952-03-12 1954-11-18 Philips Nv Procédé d'affinage d'acier à tremper

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4008103A (en) * 1970-05-20 1977-02-15 Sumitomo Metal Industries, Ltd. Process for the manufacture of strong tough steel plates
US3945858A (en) * 1973-03-19 1976-03-23 Nippon Kokan Kabushiki Kaisha Method of manufacturing steel for low temperature services
US3960612A (en) * 1973-08-15 1976-06-01 Nippon Steel Corporation Method for producing a low temperature high strength tough steel
US4060431A (en) * 1975-08-23 1977-11-29 Thyssen Edelstahlwerke Aktiengesellschaft Heat-treatable steel
US4088511A (en) * 1976-07-29 1978-05-09 Lasalle Steel Company Steels combining toughness and machinability
EP0020357B1 (en) * 1978-11-15 1984-07-18 Caterpillar Tractor Co. Lower bainite alloy steel article
US4343661A (en) * 1978-11-15 1982-08-10 Caterpillar Tractor Co. Method of making a low temperature bainite steel alloy gear
DE3201204A1 (de) * 1982-01-16 1983-08-11 M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8900 Augsburg "verwendung eines kohlenstoff-mangan-stahles fuer bauteile mit hoher festigkeit und zaehigkeit bei einfacher waermebehandlung"
FR2588570A1 (fr) * 1985-09-19 1987-04-17 Man Nutzfahrzeuge Gmbh Procede pour la fabrication d'elements de construction en acier a haute resistance avec en meme temps une haute tenacite, ces pieces presentant lesdites proprietes meme apres une deformation thermique
US4737202A (en) * 1985-09-19 1988-04-12 M A N Nutzfahrzeuge Gmbh Method of producing steel components that simultaneously have high strength and high ductility and which retain these properties even after a hot forming operation
US5257522A (en) * 1991-07-09 1993-11-02 Nippon Steel Corporation Process of hot forging at ultrahigh temperature
US5542995A (en) * 1992-02-19 1996-08-06 Reilly; Robert Method of making steel strapping and strip and strapping and strip
WO2014082945A1 (de) * 2012-11-27 2014-06-05 Robert Bosch Gmbh Metallischer werkstoff

Also Published As

Publication number Publication date
GB1453064A (en) 1976-10-20
FR2211531A1 (enrdf_load_stackoverflow) 1974-07-19
IT1000369B (it) 1976-03-30
FR2211531B1 (enrdf_load_stackoverflow) 1979-03-30
CA1014772A (en) 1977-08-02
DE2362878A1 (de) 1974-07-04
JPS4990621A (enrdf_load_stackoverflow) 1974-08-29

Similar Documents

Publication Publication Date Title
US3806378A (en) As-worked bainitic ferrous alloy and method
US3907614A (en) Bainitic ferrous alloy and method
DeArdo Accelerated cooling: a physical metallurgy perspective
EP0320003B1 (en) Method of producing steel having a low yield ratio
US4343661A (en) Method of making a low temperature bainite steel alloy gear
US4533405A (en) Tubular high strength low alloy steel for oil and gas wells
US4609410A (en) Method for producing high-strength deep-drawable dual-phase steel sheets
CA1133287A (en) Lower bainite alloy steel article and method of making same
JPH0156124B2 (enrdf_load_stackoverflow)
US3895972A (en) Thermal treatment of steel
JPS62267420A (ja) 耐遅れ破壊性の優れた高張力、高靭性線材の製造法
US6939418B2 (en) Process for the thermomechanical treatment of steel
US3288657A (en) Special heat treating method of steels
US3502514A (en) Method of processing steel
US3826694A (en) Thermal treatment of steel
EP0020357B1 (en) Lower bainite alloy steel article
CN109689238B (zh) 钢管的在线制造方法
US4453986A (en) Tubular high strength low alloy steel for oil and gas wells
Penha et al. Tempering of steels
US3567527A (en) Metallurgical process and product
USRE27505E (en) Method for producing ultrafine grained steel
CA1182387A (en) Method for producing high-strength deep drawable dual phase steel sheets
JP3214731B2 (ja) 低温靱性に優れた非調質棒鋼の製造方法
US3470037A (en) Method of treating alloy steel
JPH059576A (ja) 低温靱性に優れた非調質棒鋼の製造方法