A NEW OXIDIZING METHOD FOR REVEALING AUSTENITIC GRAINS

Abstract

A new oxidizing method for revealing austenitic grains is examined by using borax. When the specimen is exposed to air at high temperatures for a few seconds, the austenitic grain boundary is usually more oxidized than the matrix, and when such oxidized specimen is dipped into molten borax, the thin film of oxide melts away into borax, and the grain boundary appears clearly as a thin groove.
According to the results with some carbon steels and special steels, the present method seems to be superior to others in practical use on account of its simple and reliable technique.