Journal Published Online: 23 June 2009
Volume 6, Issue 7

A New Method to Study the Effect of Cooling Rate on the Decomposition of Austenite in Advanced High Strength Sheet Steels

CODEN: JAIOAD

Abstract

A new modified Jominy holder and specimen were developed to study the effect of chemical composition, intercritical annealing temperature, and cooling rates on the transformation behavior of a series of dual-phase sheet steels. Correlations between temperature, time, and the distance from the water quenched end were developed using a laboratory view data acquisition program. In addition, the hardness and microstructure along the length of the sheet steel sample were determined as a function of cooling rate from the intercritical annealing temperature. Special chemical regents were used to reveal new ferrite, bainite, and other microstructural components, which were also evaluated by optical, scanning, and transmission electron microscopy. Critical cooling rate equations, based on steel composition, volume fraction of austenite and intercritical annealing temperatures, were developed to avoid or minimize the formation of new ferrite and bainite. The results of this work show that the modified Jominy test is an effective and efficient way to evaluate the hardenability of sheet steels.

Author Information

Cho, K.
Basic Metals Processing Research Institute, Dept. of Mechanical Engineering and Materials Science, Univ. of Pittsburgh, Pittsburgh, PA
Garcia, C.
Basic Metals Processing Research Institute, Dept. of Mechanical Engineering and Materials Science, Univ. of Pittsburgh, Pittsburgh, PA
Hua, M.
Basic Metals Processing Research Institute, Dept. of Mechanical Engineering and Materials Science, Univ. of Pittsburgh, Pittsburgh, PA
Lee, J.
Quality Control Dept. Hot & Cold Rolled Steel QC Group, POSCO, Pohang, Korea
Ahn, Y.
Automotive Steel Products Research Group Technical Research Labs., POSCO, Gwangyang-si, Korea
DeArdo, A.
Basic Metals Processing Research Institute, Dept. of Mechanical Engineering and Materials Science, Univ. of Pittsburgh, Pittsburgh, PA, Finland
Pages: 12
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Stock #: JAI101822
ISSN: 1546-962X
DOI: 10.1520/JAI101822