| (19) |
 |
|
(11) |
EP 0 221 874 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
01.03.1989 Bulletin 1989/09 |
| (43) |
Date of publication A2: |
|
13.05.1987 Bulletin 1987/20 |
| (22) |
Date of filing: 05.11.1986 |
|
| (51) |
International Patent Classification (IPC)4: C21D 1/19 |
|
| (84) |
Designated Contracting States: |
|
AT DE ES FR GB SE |
| (30) |
Priority: |
05.11.1985 NO 854396
|
| (71) |
Applicant: Kverneland A/S |
|
N-4344 Kvernaland (NO) |
|
| (72) |
Inventors: |
|
- Furre, Arnold
N-4301 Sandnes (NO)
- Ronning, Trond A.
N-4344 Kvernaland (NO)
|
| (74) |
Representative: Roth, Ernst Adolf Michael et al |
|
GÖTEBORGS PATENTBYRA AB
Box 5005
402 21 Göteborg
402 21 Göteborg (SE) |
|
| |
|
| (54) |
A method of hardening steel |
(57) A method for hardening steel in which the steel is from an austenitic state cooled
through, or held at, that temperature range in which the transformation of the steel
to ferrite, pearlite or bainite occurs the most rapidly, and in which after the transformation
has taken place to a sufficient degree, rapid heating to hardening temperature is
performed with a brief holding time at that temperature before the steel is hardened
in the conventional manner in a suitable hardening medium.