(19)
(11) EP 1 031 631 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
08.10.2003 Bulletin 2003/41

(43) Date of publication A2:
30.08.2000 Bulletin 2000/35

(21) Application number: 00850027.4

(22) Date of filing: 14.02.2000
(51) International Patent Classification (IPC)7: C21D 1/32, C21D 1/78
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 22.02.1999 SE 9900598

(71) Applicant: Ovako Steel AB
813 82 Hofors (SE)

(72) Inventors:
  • Lund, Thore
    813 33 Hofors (SE)
  • Larsson, Staffan
    731 52 Köping (SE)
  • Ölund, Patrik
    813 31 Hofors (SE)

(74) Representative: Westman, Per Börje Ingemar 
SKF Group Headquarters Innovation & Patents
415 50 Göteborg
415 50 Göteborg (SE)

   


(54) A method of spheroidizing annealing of hypo-eutectoid low alloy steel


(57) Method of spheroidizing annealing of hypo-eutectoid low alloy steel, wherein a hot rolled steel typical comprising ferrite and a high carbon phase such as pearlite or martensitic/bainitic microstructural constituents
  • a) is heated to a temperature between A1 and A3 until austenitic domains with higher carbon content than the base composition has been created,
  • b) the temperature is lowered and held under A1 to enable the austenite to transform into ferrite and carbides,
  • c) the temperature is held under A1 until a desired degree of spheroidizing of the carbide is obtained.






Search report