Abstract
In the present investigation, the authors developed the new method for revealing the austenite grain boundaries in the steels. The new method contained the special polishing and the proper etching of the specimens which were hardened and tempered to the brittle sorbitic structure.
The results obtained in this investigation are summarized as follows:
(1) When the specimens are rapidly cooled and tempered in 550°C, the austenite grain boundaries can be revealed with the etchant (Fe Cl3-HCl alcohol solution).
(2) The grain boundaries are revealed by the dark field illumination in details rather than by bright field illumination.
(3) The actual austenite grain sizes are more easily estimated by the new method, and the results coincide with the grain sizes obtained by the carburizing method under the same austenitizing conditions.
