Original scientific paper
End -quench Hardenability Test for Gas Quenched Steels
Darko LANDEK
; University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Zagreb, Croatia
Božidar LIŠČIĆ
; University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Zagreb, Croatia
Tomislav FILETIN
; University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Zagreb, Croatia
Thomas LÜBBEN
; Stiftung Institut für Werkstofftechnik, Bremen, Germany
Abstract
Hardenability is usually characterized by the Jominy end-quenched test.
For steel grades quenched in oil or water this test is enough selective, and
for them a good fixed correlation between cooling time from 800 to 500 °C
(t8/5) and the distance from the quenched end can be established. For steel
grades of high hardenability, the Jominy test is not enough selective and
sensitive. To establish hardenability for these steels a new hardenability
testing method with the modified Jominy test specimen has been proposed
after initial investigations at Stiftung Institut für Werkstofftechnik at
University of Bremen. The proposed method is based on the high pressure
gas end-quenching of cylindrical specimen with variations of kind of gas,
pressure and its velocity to achieve more gradual decrease of cooling rates
along the specimen and to make the hardenability test more selective with
a broader range of lower cooling rates. The conducted experiments and the
heat transfer simulation of cooling curves at different locations in the end-
quenched probe gives possibilities for determination of cooling time t8/5
at different distances from the quenched end, for set quenching conditions.
In addition, from the conducted end-quenched tests and simulation results,
the relation between hardness distribution and the cooling times t8/5 has
been established for tested quench conditions.
Keywords
Cooling time t8/5; Gas quenching; Hardenability; Jominy test; Modeling
Hrčak ID:
74522
URI
Publication date:
28.2.2011.
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