EBSD Characterization of Microstructure and Micro-texture in a Friction Stir-Welded DP600 Steel

摘要

The microstructure and micro-texture in different areas of a friction stir(FS)-welded DP600 steel were investigated by means of electron backscatter diffraction.The volume fraction of martensite and non-polygonal ferrite was evaluated based on the image quality(IQ)parameter.Analysis of grain boundaries revealed that the fraction of sub-grain boundaries as well as that of low-angle grain boundaries in the heat-affected zone(HAZ)and stir zone(SZ)was more than doubled compared to those in the DP600 steel base metal(BM).The micro-texture examination of the BM showed strong{112}and{111}components with an intensity 4.6 times of that random texture.The texture showed a memory effect in the HAZ,with a reduced overall intensity.Within the SZ,D_(1),D_(2) and E shear texture components together with a cube component were developed.Formation of these texture components of ferrite were attributed to the transformation of B and R texture components of prior austenite,which are evidences of continuous dynamic recrystallization mechanism in the SZ of the friction stir-welded DP600 steel.