Extrinsic stacking faults and twinning in hadfield manganese steel single crystals

Abstract

University of Paderborn, Lehrstuhl fu¨r Werkstoffkunde, D-33095 Paderborn, Germany(Received June 26, 2000)(Accepted in revised form August 21, 2000)Keywords: Twinning; Austenite; Solid solution strengthening; Dislocation mobility; Extrinsicstacking faultsIntroductionExtrinsic stacking faults (SFs) have not been commonly observed in fcc materials. In some specialoccasions, pairs of extrinsic-intrinsic SFs are reported in the low stacking fault energy (SFE) copper andsilver alloys [1]. However, extrinsic SFs can form in elemental and compound semiconductors withprior multiple slip activation [2]. The basic driving factors for the extrinsic extension of partialdislocations in these materials are: a) the different mobility of partial dislocations because of theinherent crystal structure [3], b) lower extrinsic stacking fault energy [4], c) high applied stress levelsbecause of predeformation and low temperatures. The purpose of this work is to demonstrate extrinsicSFs in certain crystallographic orientations in a low SFE steel.Hadfield steel is an fcc material (g