New orientation relationship with low interfacial energy in MC/ferrite system observed in Nb-Ti bearing steel during isothermal quenching process

Here we report a new crystallographic orientation relationship (OR) between MC-type carbide (M = metal) and ferrite matrix, observed in the specimen held isothermally at 600 °C for 20 min, named NEU-OR. The 〈110〉 _carbide //〈110〉 _ferrite alignment is the main difference from the well-known Baker–Nutting (BN) OR. NEU-OR is related to BN OR by the relative rotation of 45° about the zone axis of 〈110〉 _carbide . The interfacial energy between carbide and ferrite with NEU-OR is lower than that with BN OR based on semi-coherent dislocation theory, which benefits increases in the number density of precipitates.