Grain-scale characterization of transformation textures

Abstract

Orientation relationships during the austenite-to-ferrite (-to-) phase transformation were investigated using electron back-scattered diffraction (EBSD) on a bainitic steel containing retained austenite. The steel was hot rolled within the austenite phase ®eld, but below the`no-recrystallization' temperature, to two different strains. The observed orientation relationships between the bainite and retained austenite are expressed in Rodrigues±Frank space. The exact Kurdjumov±Sachs relation was never found. The local spread of orientation in the parent austenite (owing to deformation) is seen to be inherited by the bainite. This is attributed to the displacive mode of transformation to bainite. The in¯uence of austenite prior deformation on the occurrence of variant selection was also studied. It is shown that a critical strain is necessary in order to observe a signi®cant amount of variant selection.

Representation of orientation relationships in Rodrigues–Frank space for any two classes of lattice

“…For example, the classical orientation relationships for cubic crystals, i.e. the Bain (Bain, 1924), Kurdjumov-Sachs (Kurdjumov & Sachs, 1930), Nishiyama-Wassermann (Nishiyama, 1934;Wassermann, 1935), Pitsch (Pitsch, 1962) and Greninger-Troiano (Greninger & Troiano, 1949) relationships, have recently been identified and represented in this space and compared with experimental data obtained by EBSD techniques (Godet et al, 2004;He et al, 2005He et al, , 2006.…”

In-Situ Observation of Texture Changes during Phase Transformations in Ultra-Low-Carbon Steel

“…[35,36] Humbert et al [37] suggest that macroscopic sample dimensions control the selection. Wittridge and Jonas [38] attribute it to the deformation microstructure, Bate and Hutchinson [39] think that elastic interaction is the cause, whereas Bru¨ckner and Gottstein [34] also consider the crystallographic compatibility at grain boundaries and triple junctions in addition to the Fig.…”

Beneficial influence of an intercritically rolled recovered ferritic matrix on the mechanical properties of TRIP-assisted multiphase steels

“…A prior 2 h annealing at 200°C allowed the martensite and austenite to be distinguished [24]. Some specimens were also characterised by EBSD [25]. They were first ground and subsequently polished with diamond paste down to 1 mm.…”