Effects of Crystal Orientation Relationship between Bainite-lath and Austenite on Deformation Behaviors in a Bainitic Steel

Abstract

Size of bainite lath is sub-micron, corresponding to that of ultra-fine grained steel. Bainite has Kurdjumov-Sachs (K-S)crystal orientation relationship with austenite, in spite of the ultra-fine grained steel having no crystal orientation relationship. Parallelism of slip systems between variants was examined using stereographic analysis. The stereographic analysis clarified that the fraction of parallelism of slip systems in variants of bainite is greater than that of grains in ultra-fine grained steel without crystal orientation relationship. It could be suggested that 24 variants of bainite laths formed at random (intragranular bainite) are preferable to develop mechanical properties, for example, elongation and/or toughness.