Abstract
The Ms temperatures of high-carbon steels containing 1.07, 1.16 or 1.25%C quenched from the temperature range at which austenite and cementite coexist were measured by the quench-temper procedure of Greninger and Troiano (T.A.S.M. 28 (1940) 537).
The results obtained were as followg:
(1) With increasing of austenitizing temperature, Ms point is lowered markedly and gradually approaches to the constant temperature when austenitizing temperature rise beyond Acm line.
(2) The steels having globular pearlitic structure before the austenitizing, showed slightly higher Ms points than those of steels having lamellar pearlitic structure, but the difference was small and diminished with increasing of both austenitizing temperature and heating time.
(3) The Ms temperatures seems to depend on the carbon content of austenite, but not on the amount of coexisting cementite.
(4) The Ms temperatures for practical quenching of the high-carbon steels used in this study are about 240°C, and are much higher than those for quenched steels from the temperature range of austenite only.
