Abstract
Some examinations of the fracture test of quenched specimen for measuring the austenite grain size are described. It was found that the fracture test measuring austenite grain size don't show the correct grain size such as by means of double quenching method on the steel containing below 0.4% of carbon. Also the fracture test applied to the steels for carburizing is not allowed.
And it was shown that the austenite grain size by means of fracture test, as well as on the double quenching method appears smaller as that by means of McQuaid test.
