Investigation of idiomorphic ferrite and allotriomorphic ferrite using electron backscatter diffraction technique

Abstract

A heat treatment for a vanadium-containing steel involving high-temperature austenitisation followed by two-stage isothermal holding was deliberately conducted to produce allotriomorphic ferrite (ALF), idiomorphic ferrite (IDF) and martensite. The resulting microstructures and crystallographic relationships with respect to the parent austenite grains were examined using the electron backscatter diffraction technique. Results indicated that IDF grains did not possess a specific orientation relationship (OR) with respect to the surrounding austenite matrix. The detailed substructures of IDF were also examined. In contrast, the ALF grains had an approximate Kurdjumov–Sachs OR with respect to one or both of the adjacent austenite grains; the latter case was termed a dual OR and was analysed in detail.

The role of grain boundary ferrite evolution and thermal aging on creep cavitation of type 316H austenitic stainless steel

“…There were however 15 ferrites which exhibited rational ORs with both neighbouring austenite grains. This is the so-called 'dual orientation ferrite' as reported in [22,23] which is expected to be favoured on low index CSL boundary (e.g. Σ from 3 to 21).…”

“…Ferrite phase has a body-centred-cubic (bcc) crystal structure and exhibits some specific low-energy ORs with face-centred-cubic (fcc) austenite [22][23][24]. These ORs normally lie within 11 ° of a Bain OR [25], e.g.…”