Isothermal Transformation in Eutectoid Steel

A e ute c toid s te e l c onta ining nomina lly 1 w t. % N i a nd 1. 05 w t. % C r, 0. 12 w t. % M n ba la nc e Fe w a s s upplie d in the form of s hort c irc ula r rods . Spe c ime ns w ith 21 mm dia me te r, a nd 1. 5 mm thic k, e a c h s pe c ime n w oC for 25 min in a dry a rgon a tmos phe re . Sa mple s w e re the n is othe rma lly tra ns - forme d into Tin ba th for diffe re nt time s a t te mpe ra ture ra nge 280 -580oC be fore que nc hing in w a te r. The s ta rt a nd e nd time s for tra ns forma tion w e re de te rmine d by optic a l e xa mina tion of s pe c ime ns e tc he d w ith 2% N ita l. Ba inite mic ros truc ture w a s s tudie d us ing optic a l, s c a nning a G row th ra te w e re me a s ure d from ba inite pre c ipita te s a round the gra in bounda rie s by us ing the optic a l mic ros c ope . Als o, the a us te nite s ta bility ba y re gion w a s s tudie d by TEM a nd c la s s ifie d into thre e re gions to