Isothermal decomposition of an Fe- C- B austenite

Abstract

The isothermal transformation in the temperature range between 650 and 900 C after austenitizing at the temperatures above 1100 C produced the rows of boron- constituent along the austenite grain boundaries, and they were confirmed to be Fe//2//3(C. B)//6. In the specimens austenitized at 900 C, the undissolved carbides were observed in random distribution and their crystal structure was either borocementite or Fe//2//3 (C. B)//6 in conformity with the previous treatment. In the primary ferrite, the homogeneous precipitation of very fine partcles were observed and they are thought to be Fe//2B.